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Presentation type:
BG – Biogeosciences

EGU24-1832 | Orals | MAL12-BG | BG Division Outstanding Early Career Scientist Award Lecture

Volatile Organic Compounds: mediators of forest-atmosphere interactions and indicators of forest vulnerability 

Eliane Gomes Alves

Volatile organic compounds (VOCs) are important mediators of forest-atmosphere interactions, regulating plant performance and atmospheric processes. Amazonian forests comprise the dominant source of VOCs to the global atmosphere. Yet, there is a poor understanding of how VOC emissions vary in response to ecophysiological and environmental controls in Amazonian ecosystems and even less understanding of how ecosystem emissions respond to climate extremes and land use change. I will summarize my work on VOC emissions from different ecosystems and scales in the Amazon and point out that VOCs can be indicators of forest stress and, therefore, a possible metric of forest vulnerability. First, I will present the state-of-the-art of VOC emissions and their interactions with the climate system in the Amazon. Next, I will demonstrate how these interactions can differ when considering different forest types and environmental stresses, including extremes of heat and drought. Finally, I will highlight the recent progress of VOC emissions investigated in the so-called "Amazon arc of deforestation" and indicate the potential of VOCs as a metric of forest vulnerability in climate modeling.

How to cite: Gomes Alves, E.: Volatile Organic Compounds: mediators of forest-atmosphere interactions and indicators of forest vulnerability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1832, https://doi.org/10.5194/egusphere-egu24-1832, 2024.

EGU24-12020 | Orals | MAL12-BG | Vladimir Ivanovich Vernadsky Medal Lecture

Reflections regarding our biogeochemical studies in lakes and marine environments 

Daniel Conley

My fascination with the biogeosciences started with the investigation of nitrogen (N) and phosphorus (P) enrichment of lakes stimulating the growth of diatoms leading to increased sedimentation and eventual depletion of dissolved silicate from the water column. At that time most research on the global Si cycle was focused on weathering and had not explored the complexity of the terrestrial biogeochemical cycle. Our research demonstrated that diatoms and phytoliths, e.g. biogenic silica that accumulates in the living tissues of growing plants, are transported from lakes and rivers on the continents into the oceans. The emerging understanding is that the flux and isotopic composition of dissolved silicate delivered to the ocean has likely varied over time mediated by a fluctuating continental pool.

 

An important question we addressed was if reductions of P and N could reduce eutrophication and degradation of freshwater and marine ecosystems. Our analysis explored the rationale for only P or only N reductions and concluded that dual–nutrient reduction strategies were needed for aquatic ecosystems. A focus on only P or only N reduction should not be considered unless there is clear evidence or strong reasoning that reducing the inputs of only one nutrient is justified in that ecosystem and will not harm downstream ecosystems.

 

The depletion of dissolved oxygen in bottom waters is one of the common responses of aquatic ecosystems to eutrophication. A classic example is the semi-enclosed brackish Baltic Sea. Our research has shown that the Baltic Sea is the largest anthropogenically induced hypoxic area in the world, which has increased 10-fold during the last century due to increased nutrient inputs. Concurrently, the coastal zone has experienced increasing hypoxia during the same period with the Baltic Sea coastal zone containing over 20% of all known sites suffering from hypoxia worldwide. Our research has highlighted the continuously growing problems of hypoxia and anoxia with eutrophication.

 

Altered global biogeochemical cycles is not only a feature of the Anthropocene but ongoing geological processes. Our recent research has focused on the use of silicon isotope signatures of unaltered sponges and radiolarians to estimate dissolved silicate drawdown as a proxy for the changes in the productivity of diatom communities in the Mesozoic oceans and how the ocean chemistry changed with the evolution of diatoms. Our major results to date suggest that dissolved silicate has been low in the oceans for at least the last 100 million years because of the extreme efficiency of dissolved silicate uptake by diatoms reducing ocean concentrations.

 

My continued enchantment with biogeochemical processes and collaboration with other creative scientists has lead to uncovering new biogeochemical pathways which stimulates the drive to learn more about how ecosystems operate.

How to cite: Conley, D.: Reflections regarding our biogeochemical studies in lakes and marine environments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12020, https://doi.org/10.5194/egusphere-egu24-12020, 2024.

BG1 – General Biogeosciences

EGU24-763 | ECS | Posters on site | BG1.1

The influence of pyrolysis time, moisture, and plant species on carbon bridgehead fraction of charcoal 

Vinothan Sivapalan and William Hockaday

Paleofire reconstructions are a challenging endeavor primarily due to the numerous factors involved in wildfire frequency, behavior, and regimes. These factors include, but are not limited to fuel composition, moisture, soil types, climate/weather conditions, and topographical features. Therefore, development of robust wildfire proxies requires vigorous experimental testing for multiple variables. Here, we explore the influence of pyrolysis time, moisture, and plant species on a novel proxy for fire intensity—carbon bridgehead fraction of charcoal. Experimentally, we have produced charcoals from three native Texas plants: live oak (Quercus sp.), Ashe juniper (Juniperus ashei), and broomsedge bluestem (Andropogon virginicus) under a range of temperature (300-700°C), moisture (0-100% moisture capacity), and time (0-1 hr) conditions in a tube furnace. Samples were analyzed using solid-state C-13 nuclear magnetic resonance (NMR) spectroscopy with two experiments to calculate carbon bridgehead fraction: cross polarization – magic angle spinning (CP-MAS) to quantify total aromatic carbon and dipolar dephasing (DD) to quantify aromatic bridgehead carbon. Results reveal significant differences between vegetation types, with moisture delaying or slowing the rate of carbon bridgehead formation. Relationship between carbon bridgehead fraction and time are less clear and may be influenced by the formation of pyrolysis byproducts (such as pyroligneous acids and free radicals) and/or signal losses in the cross-polarization spectra. To assess the influence of these factors on carbon bridgehead fraction we plan to conduct additional analyses on our experimental charcoals, including electron paramagnetic resonance (EPR) spectroscopy to quantify the free radicals in samples and C elemental analysis to assess carbon observability by NMR. Future work involves ground truthing the proxy to modern wildfires and subsequently applying it to paleorecords.

How to cite: Sivapalan, V. and Hockaday, W.: The influence of pyrolysis time, moisture, and plant species on carbon bridgehead fraction of charcoal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-763, https://doi.org/10.5194/egusphere-egu24-763, 2024.

EGU24-1123 | ECS | Orals | BG1.1

Assessment of ecohydrological response of Himalayan Forest ecosystems to  forest fires 

Nagashree Ge and Ashutosh Sharma

Himalayan forests boast an incredible biodiversity, harboring a wide range of flora and fauna and playing a significant role in regulating water resources. Forest fires are one of the disturbances which constitute a major force influencing, even determining, the structure and functions of ecological components-populations, communities, and ecosystems. The ability to withstand disturbance is defined as resistance whereas resilience is the capacity to recover from disturbance. These two terms define the ecohydrological response to forest fire. This study insights on how remote sensing technique can be utilized for the measurement of ecohydrological response of a large extent of region subjected to forest fire based on resistance-resilience framework and how further implementation of these measures would help to know the changes in the interaction been vegetation and water cycle. Normalized burn ratio (NBR) is used to quantify the response.  The outcome of the study reveals that deciduous needled leaf forests are subjected frequently to forest fires compared to other classes of forests during 2002-2022. The regions considered for study showed moderate to high range of resistance but low resilience, signifying the region has gained and lost vegetations in the post-fire. There was a variation in rainfall and run-off occurred during the post-fire year for different burn severities. The present approach has the potential to quantify the response of ecosystems to the forest fire and related effects on hydrology of the region.

How to cite: Ge, N. and Sharma, A.: Assessment of ecohydrological response of Himalayan Forest ecosystems to  forest fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1123, https://doi.org/10.5194/egusphere-egu24-1123, 2024.

From March to April, widespread forest fires and agro-residue burning frequently occur in Southeast Asia, which release large amounts of gas species and aerosols and impact air quality over the wide source and downwind regions. In this study, we investigated the impact of biomass burning (BB) over Southeast Asia on particulate matter concentrations and aerosol properties in downwind areas of the low-latitude plateau from 1 March to 30 April 2019, with a focus on a typical pollution event in Kunming (KM), the capital of Yunnan Province, by using a wide variety of observations from the Chenggong ground monitoring station in Yunnan University, an air quality network in China, satellite retrievals and ERA-5 reanalysis data and numerical simulation. A regional pollution event contributed by BB pollutants from Southeast Asia and the India-Myanmar trough occurred in Yunnan Province on 31 March to 1 April 2019, which was the only typical pollution event that pollution transmission ran through central Yunnan Province from south to north since 2013, when the Airborne Pollution Action Plan was unveiled by China government. The daily mean PM2.5, PM1, and black carbon concentrations increased by 73.3 μg m−3 (78%), 70.5 μg m−3 (80%), and 7.7 μg m−3 (83%), respectively, and the scattering and absorbing coefficients increased by 471.6 Mm−1 and 63.5 Mm−1 , respectively, at the Chenggong station. The southwest winds exceeding 2 km vertically thick appeared in front of the India-Myanmar trough over the fire regions, pushing BB plumes northward into Yunnan Province. The model results show that 59.5% of PM2.5 mass produced by BB in Yunnan Province was sourced from the Myanmar-Thailand border, and 29.3% was from western Myanmar at a lower altitude (<4.9 km), which indicated that BB in the Myanmar-Thailand border was the dominant contributor.

How to cite: Fan, W., Li, J., Han, Z., and Wu, J.: Impacts of biomass burning in Southeast Asia on aerosols over the low-latitude plateau in China: an analysis of a typical pollution event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1471, https://doi.org/10.5194/egusphere-egu24-1471, 2024.

EGU24-1756 | ECS | Orals | BG1.1

Direct Estimation of Carbon Emissions from High Latitude Fires: The Adapted FREM Approach 

Will Maslanka and Martin Wooster

Landscape fires are a widespread natural phenomenon that directly influences carbon cycling through the combustion of organic material. Space-based remote sensing, including Active Fire (AF), remains the only way to estimate wildfire activity accurately on the regional-to-global scale. Fire emission inventories generally fall into two categories. “Bottom-up” methodologies rely on observations of AF counts, Fire Radiative Power (FRP), or burned area to estimate the amount of biomass burned, or “Top-down” methodologies, which directly relate observations of FRP to landscape fire emission estimates. Bottom-up methods tend to have a reliance on uncertain parameters, such as pre-fire fuel load and combustion completeness, or a conversion factor between FRP and fuel consumption rate. The Fire Radiative Energy Emission (or FREM) approach is one such top-down methodology that has removed such a reliance, by directly relating FRP to observed rates of emissions, such as CO or aerosols, but has so far been used with geostationary FRP data only. Whilst very effective at lower latitudes, due to the poor spatial resolution and extreme viewing geometry of geostationary data at higher latitudes, the approach is not applicable for fires in this region in its current format. However, by using polar orbiting FRP data and making use of the high latitude orbital convergence, this study looks to adapt the FREM approach to deliver direct estimation of carbon emissions for high latitude (>60°N) landscape fires. We use direct observations of FRP, from Suomi-NPP, NOAA-20 and MODIS, along with observations of Total Column Carbon Monoxide from TROPOMI onboard Sentinel-5P. A series of cloud-free plumes and associated FRP data were identified in Deciduous and Evergreen Needleleaf biomes in North America and Russia in the summers of 2019 – 2023. The resulting emission coefficients and emission totals were compared to pre-existing top-down and bottom-up emission coefficients and totals from the FEER, GFAS, and GFED inventories for high latitude fires between 2018-2023. This adapted FREM approach is shown to provide direct emission estimates without recourse to significant assumptions and can do so in real time – opening up a new avenue for real-time fire emission estimation at high latitudes.

How to cite: Maslanka, W. and Wooster, M.: Direct Estimation of Carbon Emissions from High Latitude Fires: The Adapted FREM Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1756, https://doi.org/10.5194/egusphere-egu24-1756, 2024.

EGU24-2099 | ECS | Orals | BG1.1

Exploring the effect of vegetation photosynthesis phenology on wildfire dynamics 

Gengke Lai, Jialing Li, Jun Wang, Chaoyang Wu, Yongguang Zhang, Constantin M. Zohner, and Josep Peñuelas

2023 has witnessed a record-breaking extreme wildfire season in Canada from coast to coast, following closely to the unprecedented wildfire outbreaks in 2019/20 Australia and 2021 Siberia, causing far-reaching threats on terrestrial carbon stock, air quality, and human society. The heightened wildfire activity in specific regions prompts us to rethink the underlying factors driving the global wildfire dynamics. Climate change has been recognized as an important factor in amplifying wildfire risk, mainly through increasing temperature and reducing relative humidity. However, the role of vegetation productivity and phenology on wildfire dynamics remains elusive, even though which can exacerbate or mitigate the climate-induced fire risk. Importantly, changes in vegetation phenology can cause biophysical feedback to the climate system and land surface by modulating the exchanges of water and energy between land and the atmosphere. Considering the climate feedback of vegetation phenology, we hypothesize that peak photosynthesis timing (PPT) can contribute to wildfire activity. To explore it, we provide comprehensive analyses using multiple satellite-based photosynthesis observations from solar-induced chlorophyll fluorescence (SIF), and wildfire activity from national fire perimeters and MODIS global burned area records from 2001 to 2018, as well as diverse methodologies and models. In response to changes in various biological and climatic factors, we find PPT has advanced 1.10 ± 0.57 days per decade at a global scale. This earlier PPT acts to expand the extent of wildfires, with an increase in the global average burned fraction by 0.021% (~2.20 Mha) for every additional day of PPT advancement. Satellite observations and the Earth system modeling consistently reveal that this expansion is attributed to the intensified drought conditions during the potential fire season, induced by the earlier PPT that can modulate the global patterns of temperature, precipitation, and surface soil moisture. Furthermore, current fire-vegetation models participating in the FireMIP project underestimate the sensitivity of burned area to PPT, despite reproducing their negative correlation. Our findings highlight the importance of climate-vegetation-fire feedback loops in future prediction of wildfire dynamics and the strategy of climate change adaptation and mitigation.

How to cite: Lai, G., Li, J., Wang, J., Wu, C., Zhang, Y., Zohner, C. M., and Peñuelas, J.: Exploring the effect of vegetation photosynthesis phenology on wildfire dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2099, https://doi.org/10.5194/egusphere-egu24-2099, 2024.

EGU24-4071 | ECS | Posters on site | BG1.1 | Highlight

The Influence of Climate Teleconnections on Global Burned Area 

Yuquan Qu, Harry Vereecken, Sander Veraverbeke, and Carsten Montzka

Wildfires are known to be controlled by fuels and weather. Climate teleconnections may influence wildfires by altering fuel availability and fire weather. In this study, we used the random forest approach to systematically detect relationships between teleconnection climate indices (CIs) and burned area while accounting for different lag times. Results indicate that burned area is especially modulated by climate teleconnections in Africa and Australia. The Tropical Northern Atlantic (TNA) pattern was the most influential CI for the global burned area, followed by the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the Pacific–North American (PNA) pattern. To study pathways of how teleconnections affect the burned area, we distinguished two classes of fire drivers: bottom-up fuel availability and top-down weather conditions. Bottom-up fuel drivers showed higher correlation with CIs than top-down weather drivers and served as mediators between teleconnections and wildfires. The mediating effect of top-down weather drivers was only apparent in specific seasons. Our study highlights that in teleconnection-wildfire hotspot regions, knowledge of the relation between CIs and drivers of wildfires could improve long-term wildfire predictability. We recommend that bottom-up fuel drivers should also be integrated into wildfire predictive frameworks as they play an important mediating role in linking teleconnections and wildfires.

How to cite: Qu, Y., Vereecken, H., Veraverbeke, S., and Montzka, C.: The Influence of Climate Teleconnections on Global Burned Area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4071, https://doi.org/10.5194/egusphere-egu24-4071, 2024.

EGU24-5191 | ECS | Orals | BG1.1 | Highlight

Impacts of land use change and interannual climate variability on biomass burning emissions, air quality and public health in Amazon 

Tsin Hung Leo Ng, Amos P. K. Tai, Stephen Sitch, Luiz Aragao, and Shixian Zhai

Biomass burning in Amazon Basin has a significant impact on regional climate and deteriorates regional air quality, which poses a threat to human and ecosystem health. The fire-induced pollution worsens during dry season (Jul to Nov) and shows a strong seasonal variation. Past research has demonstrated that the occurrence of wildfires in Amazon is not only influenced by deforestation, but also interannual climate variability, particularly droughts. Here we estimate the impacts of deforestation and droughts on fire emissions and regional air quality between 2010 to 2015 by using Global Fire Emission Database Version 4 (GFED v4) to drive a global 3-D atmospheric chemical transport model GEOS-Chem High Performance (GCHP) and further examine the effect of PM2.5 and O3 on premature mortality across the region. By comparing the “fire-on” and “fire-off” scenarios, we find that biomass burning alone in normal years (2011 and 2013) contributes 5.7 μg m-3 (47.6% of the total concentration) PM2.5, 0.08 ppm (46.3%) CO, 0.03 ppb (85.0%) NOx, and 9.5 ppb (41.2%) O3; and these numbers during drought years (2010, 2012, 2014 and 2015) increase to 19.6 μg m-3 (74.7%) for PM2.5, 0.20 ppm (67.0%) for CO, 0.19 ppb (97.4%) for NOx, and 15.6 ppb (52.0%) for O3. We find that these pollutants from wildfires mainly concentrate in the south-eastern Amazon and then transport southward, thus strongly impacting public health in the downwind regions. We estimate that premature mortality due to long-term exposure to particulate matter and ozone by applying the simulated concentration to the concentration-response functions from the European Environment Agency. We find that ~8,500 and ~10,400 deaths per year are attributable to PM2.5 and O3 exposure for 2010-2015 respectively. During drought years, we discover there are 2.8% and 3.4% more deaths than normal years for PM2.5 and O3 exposure. Our study shows the significance of biomass burning emissions in shaping the air quality in the Amazon region, and highlights the impact of drought events on enhancing biomass emissions, worsening regional air quality and causing public health issues. Therefore, it is important to address the underlying causes of biomass burning in the Amazon, such as deforestation and land use change, and droughts, to protect the region's ecosystems and mitigate the impacts of climate change.

How to cite: Ng, T. H. L., Tai, A. P. K., Sitch, S., Aragao, L., and Zhai, S.: Impacts of land use change and interannual climate variability on biomass burning emissions, air quality and public health in Amazon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5191, https://doi.org/10.5194/egusphere-egu24-5191, 2024.

EGU24-5236 | ECS | Posters on site | BG1.1 | Highlight

Are there lightning Fires in the Amazon Rainforest? 

Cunhui Zhang, Thomas Janssen, Matt Jones, and Sander Veraverbeke

Tropical rainforests have exceptionally high biodiversity and store large amounts of carbon in biomass. However, large and frequent fires across tropical rainforests in the last decades threaten the ecosystem integrity of these ecosystems. The general belief is that fires in the Amazon rainforest are all human-ignited and that lightning fires do not occur in rainforests due to the predominant wet conditions. However, recent research indicates the possibility of lightning fires in tropical rainforests. Here, we aim to investigate the occurrence of lightning-ignited fires in the Amazon rainforest, a topic that has been largely overlooked in the current understanding of fire dynamics in this biome. We collected and analyzed data on lightning strikes, fire occurrences, and weather patterns derived from satellite imagery and climate datasets. The objective is to detect, quantify, and characterize lightning fires in the Brazilian Amazon rainforests, thereby providing new insights into the natural fire regime of this crucial ecosystem.

How to cite: Zhang, C., Janssen, T., Jones, M., and Veraverbeke, S.: Are there lightning Fires in the Amazon Rainforest?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5236, https://doi.org/10.5194/egusphere-egu24-5236, 2024.

EGU24-5348 | Posters on site | BG1.1

Wetlands in monoculture forests – how fire activity and different forest management strategies impact Sphagnum-dominated peatlands 

Katarzyna Marcisz, Mariusz Bąk, Mariusz Lamentowicz, Piotr Kołaczek, Thomas Theurer, Paweł Matulewski, and Dmitri Mauquoy

Monoculture forests are now a dominant forest type in Europe. Created for easier management and increased timber production, they are now witnessing many disturbances due to climate change, such as more frequent windthrows, droughts, fires or insect outbreaks. The functioning of forests impacts other elements of the landscape, including peatlands, which also have been affected by various natural and anthropogenic disturbances (e.g., drainage) that make them more vulnerable to drying and burning. We aim to recognize how peatland functioning has changed along with changing forest management strategies. For this we studied a Sphagnum-dominated peatland located in the Tuchola Pinewoods – one of the largest Scots pine (Pinus sylvestris) monoculture forest in Poland. We used high-resolution multi-proxy palaeoecology including pollen, plant macrofossils and testate amoebae, additionally focusing on a wide range of charcoal analyses: charcoal counts, charcoal morphological types, and Raman spectroscopy. Our results show that the studied peatland experienced several critical transitions in vegetation composition and hydrology over the last 600 years when new forest management techniques were introduced. A reduction in fire activity led to a dominance of Sphagnum and increased peat accumulation rates. Establishment of a monoculture forest further impacted the site and stabilized Sphagnum growth and acidity levels. We believe that these results can be helpful for the improvement of conservation planning for peatlands located in forested areas, especially in monoculture forests.

The study is funded by the National Science Centre, Poland (2020/39/D/ST10/00641).

How to cite: Marcisz, K., Bąk, M., Lamentowicz, M., Kołaczek, P., Theurer, T., Matulewski, P., and Mauquoy, D.: Wetlands in monoculture forests – how fire activity and different forest management strategies impact Sphagnum-dominated peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5348, https://doi.org/10.5194/egusphere-egu24-5348, 2024.

EGU24-5494 | ECS | Orals | BG1.1 | Highlight

Half of global burned area is due to managed anthropogenic fire: findings from a coupled socio-ecological modelling approach  

Oliver Perkins, Matthew Kasoar, Apostolos Voulgarakis, Tamsin Edwards, and James Millington

Globally, vegetation fires are a key component of many ecosystems and have substantial impacts on carbon emissions. Yet humans also use and manage fires for a huge range of purposes around the world, dependent on numerous social and biophysical factors. Existing representations of anthropogenic fire in dynamic global vegetation models (DGVMs) have been highly simplified, with readily available global variables (e.g. population density) used to estimate numbers of anthropogenic ignitions. Here, we present results from a novel coupled socio-ecological modelling approach to improve understanding of how human and biophysical factors combine to drive the spatio-temporal distribution of global fire regimes. Specifically, we present the integration of two process-based models. The first is the Wildfire Human Agency Model (WHAM!1), which draws on agent-based approaches to represent anthropogenic fire use and management. The second model is JULES-INFERNO2, a fire-enabled DGVM, which takes a physically-grounded approach to the representation of vegetation-fire dynamics.

The new WHAM-INFERNO model ensemble suggests that as much as half of all global burned area is generated by managed anthropogenic fires - typically small fires that are lit and spread according to specific land use objectives (such as crop residue burning). Furthermore, we demonstrate that including representation of managed anthropogenic fires in a coupled socio-ecological simulation can improve understanding of the biophysical drivers of unmanaged wildfires, by allowing clearer recognition of the role of anthropogenic land management in global fire regimes. Hence, WHAM-INFERNO is applied to understand how landscape fragmentation, wider land use change, and changes in human fire management have together led to observed recent declines in global burned area despite the warming climate. Overall, findings presented here have substantial implications for understanding of present and future fire regimes, indicating that changes to socio-economic systems are at least as important a consideration as climate change.  

1. Perkins, O., Kasoar, M., Voulgarakis, A., Smith, C., Mistry, J., and Millington, J. (2023). A global behavioural model of human fire use and management: WHAM! v1.0. EGUsphere, 1–42. 10.5194/egusphere-2023-2162.

2. Mangeon, S., Voulgarakis, A., Gilham, R., Harper, A., Sitch, S., and Folberth, G. (2016). INFERNO: a fire and emissions scheme for the UK Met Office’s Unified Model. Geosci. Model Dev. 9, 2685–2700. 10.5194/gmd-9-2685-2016.

How to cite: Perkins, O., Kasoar, M., Voulgarakis, A., Edwards, T., and Millington, J.: Half of global burned area is due to managed anthropogenic fire: findings from a coupled socio-ecological modelling approach , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5494, https://doi.org/10.5194/egusphere-egu24-5494, 2024.

EGU24-6077 | ECS | Orals | BG1.1

Updated Exposure Estimate for Indonesian Peatland Fire Smoke using Network of Low-cost Purple Air PM2.5 sensors 

Ailish M Graham, James B McQuaid, Thomas E L Smith, Hanun Nurrahmawati, Devina Ayona, Hasyim Mulawarman, Chaidir Adam, Dominick V Spracklen, Richard Rigby, and Shofwan A B Choiruzzad

Air pollutant emissions from wildfires on Indonesian peatlands lead to poor regional air quality across south-east Asia. Fine particulate matter (PM2.5) emissions are particularly high for peat fires leading to substantial population exposure to PM2.5. Despite this, air quality monitoring is limited in regions close to peat fires meaning the impacts of peatland fires on air quality is poorly understood and it is difficult to evaluate predictions from atmospheric chemistry models. To address this, we deployed a network of low-cost (Purple Air) PM2.5 sensors at 8 locations across Central Kalimantan, where peat fires are frequent. The sensors measured indoor and outdoor PM2.5 concentrations during August to December 2023. During the haze season (September 1st to October 31st), daily mean outdoor concentrations were 120 mg m-3 but peaked at >400 mg m-3. Indoor PM2.5 concentrations were only ~10% lower (mean 110 mg m-3), indicating that is difficult for the population to reduce their exposure to PM2.5 from fires. The reduction in mean PM2.5 concentrations between outdoor and indoor environments was larger in urban locations (-11%) compared with rural locations (-3%), suggesting urban housing may provide better protection from outdoor air pollution. To generate an updated assessment for the population’s exposure to peatland fire PM2.5 we combine the information from monitoring both indoor and outdoor PM2.5 concentrations with modelled ambient (outdoor) PM2.5 concentrations from the WRF-Chem atmospheric chemistry transport model. Our updated exposure assessment accounts for the population’s personal exposure to peatland fire PM2.5 for the first time.

How to cite: Graham, A. M., McQuaid, J. B., Smith, T. E. L., Nurrahmawati, H., Ayona, D., Mulawarman, H., Adam, C., Spracklen, D. V., Rigby, R., and Choiruzzad, S. A. B.: Updated Exposure Estimate for Indonesian Peatland Fire Smoke using Network of Low-cost Purple Air PM2.5 sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6077, https://doi.org/10.5194/egusphere-egu24-6077, 2024.

EGU24-6624 | ECS | Orals | BG1.1

Excessive fire occurrence in Romania from 2001 to 2022: Trends and drivers across ecoregions and land cover classes 

Till Mattes, Irene Marzolff, and Angelica Feurdean

Wildfire is an integral part of temperate ecosystems, but human activities have significantly altered fire regimes, including frequency, size, intensity and seasonality. Romania, located in central-eastern Europe, recently exhibited the highest biomass burning in Europe. However, little is known of the trends and determinants of fire recurrence, apart from the common use of fire to clear crop residues on arable land. This study utilizes satellite-based fire data (FIRMS) from 2001 to 2022 and land cover maps (CORINE) to investigate temporal trends in fire occurrence across ecoregions and land cover types in Romania and identify those most susceptible to fire.

Over 2001-2022, Romania witnessed a total of 0.44 fires/ km² averaging 0.02 fires/km²/yr. Our analysis revealed a declining trend in fire occurrence along an elevation gradient, from plains to hills, plateaus and mountains, aligning with the prevalence of the dominant land cover classes and climatic gradients. Agricultural land cover types demonstrated the highest fire incidence, with arable land exhibiting the highest rate (0.04 fires/km²/yr) and forests the lowest (below 0.01 fires/km²/yr). Following the accession of Romania to the EU in 2007 and the prohibition of agricultural fires, a reduction in burning on arable land (crop residues) can be observed, while the use of fire in other agricultural classes persisted or even increased, indicating a more complex effect of socio-economic developments on fire pattern. Specifically, areas more marginal for agriculture, such as complex agricultural fields interspaced with housing and natural vegetation continued to employ fire as a management tool.

Natural land cover classes, such as wetlands principally occupying the Danube Delta (0.06 fires/km²/yr) and natural grasslands (0.01 fires/km²/yr), also experienced substantial fire occurrences and an intensification in more recent periods. Given the rarity of naturally ignited fires (lightning) in Romania, the intentional use of fire to clear dry reed biomass for land regeneration appears to be prevalent also in moist areas. Remarkably, broadleaved and mixed forests burned more frequently than coniferous forests despite the latter having traits to convey high flammability and burn with high frequency. This feature suggests that fires in broadleaved forests, predominant at low and mid elevations, likely expanded from neighbouring agricultural lands.

Crucially, our analysis highlights that years with elevated fire occurrence coincide with extreme droughts and heatwaves (e.g., 2012, 2015), emphasizing the influence of extreme climate conditions in accelerating fire episodes and the spread of fires initiated in agricultural areas into natural and semi-natural habitats. Given the substantial occurrence of fires in agricultural land but also in natural habitats, such as wetlands and grasslands in Romania, research investigating the risks and vulnerability of these habitats to fire should be prioritized.

How to cite: Mattes, T., Marzolff, I., and Feurdean, A.: Excessive fire occurrence in Romania from 2001 to 2022: Trends and drivers across ecoregions and land cover classes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6624, https://doi.org/10.5194/egusphere-egu24-6624, 2024.

Wildfires have become more prevalent in recent years because of climate change. Meanwhile wildfires, as a major type of biomass burning, could emit a large amount of black carbon (BC) and brown carbon (BrC) to the atmosphere. Since BC and BrC play important roles in climate change, air pollution and human health issues, it is necessary to research their physicochemical properties to evaluate their impacts on urban areas. Here we present BC mass concentration and absorption coefficients measured by aethalometer (AE43), combing with the chemical constitutions acquired by GC-MS, during the record-breaking 2023 wildfire season in Canada. The back-trajectory analysis indicated that the smoke mainly came from north Quebec where the wildfires took place. We demonstrated how BC and BrC emitted by wildfires could affect urban regions after long-range transport.

How to cite: Li, H. and Ariya, P.: Measurement of Physicochemical Properties of Black Carbon and Brown Carbon and the Impacts of Canada Record-Breaking Wildfires in Summer 2023 , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6761, https://doi.org/10.5194/egusphere-egu24-6761, 2024.

EGU24-7467 | ECS | Posters on site | BG1.1

The Impact of Wildfires on Atmospheric Nitrogen Deposition in the United States: A Multiple Linear Regression-based Analysis 

Jiangshan Mu, Yingnan Zhang, Chenliang Tao, Zhou Liu, Yu Zhao, Lei Zhang, Yuqiang Zhang, and Likun Xue

Nitrogen deposition can exert a significant impact on global ecosystems. The increased occurrence of natural factors such as wildfires are becoming more important in atmospheric deposition especially with the continued decreases of the anthropogenic emissions in developed countries. In this study, we investigate the mechanisms by which the increasingly frequent wildfires affect nitrogen deposition in the United States using comprehensive datasets and multiple linear regression (MLR) methods. We found a downward trend in nitrogen deposition in the U.S. (-0.09 kgN ha yr-1), mainly due to the decreases in oxidative nitrogen deposition (-0.1 kgN ha yr-1). In contrast, reduced nitrogen deposition showed a slight increase (0.02 kgN ha yr-1). Our preliminary results show that wildfires contributed ~10% to the U.S. domestic deposition overall, but the magnitudes and signs of impact vary geographically, depending on the frequency and intensity of wildfires and the dominant deposition types. On average across the U.S., wildfires predominantly negatively contribute to wet deposition, while their contributions to dry deposition is smaller or slightly positive. Specifically, wildfires enhance dry deposition in the western U.S. while inhibiting wet deposition in the southeastern U.S. Wildfires exert a suppressive effect on both oxidized and reduced forms of nitrogen deposition in the southeastern U.S. Our study highlights the significant influence of wildfires on nitrogen deposition, underscoring the need to consider wildfire events in environmental management and policy-making.

How to cite: Mu, J., Zhang, Y., Tao, C., Liu, Z., Zhao, Y., Zhang, L., Zhang, Y., and Xue, L.: The Impact of Wildfires on Atmospheric Nitrogen Deposition in the United States: A Multiple Linear Regression-based Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7467, https://doi.org/10.5194/egusphere-egu24-7467, 2024.

EGU24-7895 | ECS | Posters on site | BG1.1

Vegetation types influence fine-scale drought impact on land surface cooling and burn patterns in the Siberian coastal tundra 

Nils Rietze, Jakob Assmann, and Gabriela Schapeman-Strub

In 2020, the Northeastern Siberian lowland tundra faced an extreme drought and unprecedented wildfires. The burning of carbon-rich soils in this region can release large amounts of carbon, worsening climate change and Arctic warming.  However, we know little about of how droughts impact vegetation and how this vegetation might become fuel for large fires in the typically wet landscapes of the Northeastern Siberian lowland tundra. We studied the impact of the extreme summer drought in 2020 on the tundra vegetation and the resulting burn patterns in the Indigirka lowlands using a combination of in-situ, thermal, and multispectral remote sensing data from drone and high-resolution satellite imagery. The fine-scale vegetation types revealed increased landscape-wide drought susceptibility indicated by an overall loss of land surface cooling. This suggests a shift towards an energy budget dominated by sensible heat flux, which may feed back and intensify the heatwave.  Further, we found that mostly dry vegetation types were affected by fire in the NE Siberian coastal tundra, while wetter vegetation types did not burn, leading to a fine-scale heterogeneous burn pattern. Our results indicate that the enhanced drought susceptibility of vegetation types may have led to higher fire fuel connectivity of the tundra landscape. Consequently, this may have resulted in the large burn extents observed in 2019 and 2020. Our analysis is an effort toward the prediction of fire fuel connectivity and fire management in remote Arctic areas.

How to cite: Rietze, N., Assmann, J., and Schapeman-Strub, G.: Vegetation types influence fine-scale drought impact on land surface cooling and burn patterns in the Siberian coastal tundra, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7895, https://doi.org/10.5194/egusphere-egu24-7895, 2024.

EGU24-8017 | ECS | Posters on site | BG1.1

Combining stand-level and remote sensing data to model post-fire recovery of Mediterranean tree-forest communities – A case study in Spain. 

Raul Hoffren, Juan de la Riva, Darío Domingo, María Teresa Lamelas, Paloma Ibarra, Alberto García-Martín, and Marcos Rodrigues

Mediterranean forests are recurrently affected by wildfires. Fire activity is expected to accelerate in the future due to landscape homogenization, fuel accumulation, and climate warming. A key aspect to prevent and mitigate the negative impacts of wildfires on ecosystems is to understand the factors that govern the recovery of forest communities. This study analyzes the post-fire recovery potential of four representative Mediterranean tree-communities (Pinus halepensis, Pinus nigra, Pinus pinaster, and Quercus ilex) affected by large wildfires (> 500 ha) during the summer of 1994 in Spain. For this purpose, information collected in the field 25 years after the fires in 203 forest plots (131 burned and 72 unburned control plots) was coupled with remote sensing, geospatial, and forest inventory data, to build an empirical model capable of assessing recovery. Remote sensing data provided a proxy for burn severity, through the Composite Burn Index, and allowed modelling the local topography (slope and aspect) of the terrain. The geospatial data included climatic information on temperature and precipitation trends. These data were entered into the model, calibrated using Random Forest, to provide information on the degree of recovery, inferred from the similarity (in terms of vegetation height, aboveground biomass, species diversity) between the burned and unburned control plots. Results showed that only the 25% of the burned plots can be considered as recovered. The burn severity had a significant effect on the recovery albeit strongly modulated by local topography. Overall, the key features of the recovered plots were a low-to-moderate burn severity and a favorable topographical setting, especially the shading effect of steep northwestern slopes. Furthermore, a warmer and more humid climate improved the capacity of recovery. These results constitute a valuable tool for improving forest management and preserving ecosystem services.

How to cite: Hoffren, R., de la Riva, J., Domingo, D., Lamelas, M. T., Ibarra, P., García-Martín, A., and Rodrigues, M.: Combining stand-level and remote sensing data to model post-fire recovery of Mediterranean tree-forest communities – A case study in Spain., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8017, https://doi.org/10.5194/egusphere-egu24-8017, 2024.

Wildfires pose an increasing threat to boreal forest and tundra ecosystems in boreal North America (Alaska and northwestern Canada), as their frequencies rise under global warming. These fires exhibit strong interannual variability that is influenced by regional atmospheric circulation. However, potential impacts of remote boundary forcings on regional fires and the underlying mechanisms remain unclear. This study provides a comprehensive analysis on the impacts of spring sea surface temperature (SST) and sea ice on interannual variability of burned area in this region during fire season (summer) from 1997 to 2020 using GFED5 burned area, SST and sea ice concentration data from the Met Office Hadley Centre, and ERA5 reanalysis data. Results show that in spring a warmer SST in the East Pacific and reduction of sea ice in the northern Chukchi Sea lead independently to an increase in burned area in boreal North America. The correlation coefficients between the SST and sea ice factors with the burned area in boreal North America are 0.43 and –0.44 respectively. The SST-fire relationships can be explained as follows: A warm SST anomaly in the East Pacific triggers a northeastward-propagated Rossby wave, inducing a high-pressure anomaly over boreal North America in spring. Consequently, this circulation anomaly causes a higher surface temperature and thus vegetation growth or drying. As temperatures rise and lightning activity intensifies in summer, burned area increases. On the other hand, the process of sea ice affecting burned area is different. A reduction in sea ice coverage in the northern Chukchi Sea leads to a decrease in surface albedo, resulting in an increase in heat flux. The heat release persists from spring to summer and causes a high-pressure circulation anomaly in boreal North America in summer, which suppresses regional water vapor convergence and precipitation, reducing soil moisture and surface air humidity and increasing vapor pressure deficit (VPD) thereby promoting fuel flammability.

How to cite: Zhao, Z., Lin, Z., and Li, F.: Impacts of Spring East Pacific SST and Arctic Sea Ice on Interannual Variability of Summer Burned Area in boreal North America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8303, https://doi.org/10.5194/egusphere-egu24-8303, 2024.

EGU24-8506 | Orals | BG1.1

Anticipating future extreme wildfire events by coupling ignition and success of initial attack models 

Pere Joan Gelabert Vadillo, Adrian Jiménez Ruano, Fellice Catelo, and Marcos Rodrigues Mimbrero

In recent years, the EU Commission has enacted various firefighting policies to combat and diminish the adverse effects of wildfires. The Mediterranean area has experienced an observable extension of its wildfire season, coupled with rapid shifts in fire-weather dynamics, resulting in exceptionally severe wildfire occurrences. As of 2022, the EU has recorded an approximate total burned area of 792,902 hectares, with forests accounting for 66% of this figure (Rodrigues et al., 2023).

The main objective of this study is to anticipate extreme wildfire conditions by providing a synthetic product depicting the chances of a fire event starting and escaping containment. To do so, we combined empirical models of ignition likelihood and effectiveness of the initial attack stage. We employed machine learning techniques to calibrate binary regression models using historical wildfire ignition data and geospatial layer depicting the main drivers of ignition and containment, namely: accessibility, human pressure on wildlands, fuel moisture and availability. We illustrate our approach along the Mediterranean coastal region of Spain. Our approach enables us to predict wildfire contention capacity under diverse population growth and climate warming scenarios. This strategy aims to improve disaster risk reduction by pointing wildfire management zones and prioritizing intervention in high-risk areas.

Results indicate a high predictive ability to model human-caused wildfire ignition (AUC>0.80) but a modest capability to capture the containment capability (AUC≈0.70). Accessibility by road largely controls the spatial pattern of ignition and containment, with dead fuel moisture content modulating the temporal pattern of probability. We further illustrate the approach by providing insights into future SSP (Shared Socieconomic Pathways) scenarios by synthesizing both products into comprehensive management zones (Rodrigues et al., 2022).

 

References

Rodrigues, M., Camprubí, À.C., Balaguer-Romano, R., Megía, C.J.C., Castañares, F., Ruffault, J., Fernandes, P.M., Dios, V.R. de, 2023. Drivers and implications of the extreme 2022 wildfire season in Southwest Europe. Science of The Total Environment 859, 160320. https://doi.org/10.1016/j.scitotenv.2022.160320

Rodrigues, M., Zúñiga-Antón, M., Alcasena, F., Gelabert, P., Vega-Garcia, C., 2022. Integrating geospatial wildfire models to delineate landscape management zones and inform decision-making in Mediterranean areas. Safety Science 147, 105616. https://doi.org/10.1016/j.ssci.2021.105616

How to cite: Gelabert Vadillo, P. J., Jiménez Ruano, A., Catelo, F., and Rodrigues Mimbrero, M.: Anticipating future extreme wildfire events by coupling ignition and success of initial attack models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8506, https://doi.org/10.5194/egusphere-egu24-8506, 2024.

EGU24-8507 | ECS | Posters on site | BG1.1

Unravelling Variability: Discrepancies in Amazonian Biomass Burning Emissions Under Different Emission Factor Scenarios  

Guilherme Mataveli, Matthew W. Jones, Gabriel Pereira, Saulo R. Freitas, Valter Oliveira, Esther Brambleby, and Luiz E.O. C. Aragão

Biomass burning (BB) plays a key role in the biosphere–atmosphere interaction. It is a major source of trace gases and aerosols that alters the atmosphere and the water cycle. Additionally, these emissions are often related to other detrimental impacts including biodiversity loss in fire-sensitive biomes, increase of respiratory diseases, and massive economic losses. BB emissions are used as inputs in models that estimate air quality and the effect of fires on Earth’s climate. Hence, an accurate estimation of BB emissions is paramount. While BB emissions spread over most of the global vegetated areas, the integration of orbital remote sensing and modelling is the most effective approach to estimate them from regional to global scales. BB emission estimation follows the relationship between burned biomass and the emission factor (EF - mass emitted of a given species, for example carbon dioxide, per mass of dry matter burned). The burned biomass can be estimated using two approaches: (i) based on the relationship among burned area, above-ground biomass, and combustion completeness; or (ii) based on fire radiative power (FRP), a quantitative measurement that is directly related to the rate of burned biomass and is estimated to each active fire detected by several orbital sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. EF values, which are Land Use and Land Cover (LULC) based, are required to estimate BB emissions independently on the approach adopted to estimate the burned biomass. Although novel approaches to improve the accuracy of BB emissions have been developed, the impact of EF values on the final estimated emissions remains uncertain. We have evaluated the impact of the EFs on the final estimate of fine particulate matter (PM2.5) emitted from BB in the Brazilian Amazon during a nineteen years’ time series (2002-2020) by running the PREP-CHEM-SRC emissions preprocessor tool under four EF scenarios: the tool original EF values based on the work of Andreae and Merlet (2001), the average EF values recently updated by Andreae (2019), and the minimum and maximum EF values also proposed by this author. The minimum (maximum) EF values were defined as the average EF value for each LULC class minus (plus) one standard deviation. The PM2.5 emissions were estimated at the spatial resolution of 0.1º using the FRP approach implemented on PREP-CHEM-SRC (3BEM_FRP model) having MODIS active fires as input, since this approach requires fewer inputs and the impact of the EFs over the emissions would be more evident. Our results showed that the annual average PM2.5 emission in the Amazon varied by 163% between the four EF scenarios (from1,426 Gg and 3,747 Gg), while the scenario based on the average values was the closest to the one based on PREP-CHEM-SRC original EF values (2,582 Gg and 2,213 Gg, respectively – an increase of 17%). These results contribute to the better understanding of how this single parameter impacts on the estimation of BB emissions.

How to cite: Mataveli, G., W. Jones, M., Pereira, G., R. Freitas, S., Oliveira, V., Brambleby, E., and E.O. C. Aragão, L.: Unravelling Variability: Discrepancies in Amazonian Biomass Burning Emissions Under Different Emission Factor Scenarios , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8507, https://doi.org/10.5194/egusphere-egu24-8507, 2024.

EGU24-8668 | ECS | Posters on site | BG1.1

Effect of long-range transported fire emissions on aerosol and cloud properties at high latitudes: In situ measurements and satellite observations 

Snehitha M. Kommula, Angela Buchholz, Yvette Gramlich, Tero Mielonen, Liqing Hao, Iida Pullinen, Lejish Vettikkat, Jorma Joutsensaari, Siegfried schobesberger, Petri Tiitta, Ari Leskinen, Dominic Heslin Rees, Sophie Haslett, Karolina Siegel, Chris Lunder, Paul Zieger, Radovan Krejci, Sami Romakkaniemi, Claudia Mohr, and Annele Virtanen

Global warming and climate change-induced rise in Earth’s temperature have increased the frequency of forest/wildfires over the past decade. Therefore, understanding the effect of fire emissions on aerosol-cloud interactions is crucial for improving Earth system models.

         We present observations from in-situ measurements of aerosol properties at the Puijo SMEAR IV station in eastern Finland and the Zeppelin Observatory in Ny-Ålesund, High Arctic. Both stations are frequently inside low-level clouds due to their topographic prominence. During the autumn of 2020, fire emissions from the same active fire region in south-eastern (SE) Europe reached both stations after ~2 - 8 days of atmospheric aging. This enabled us to investigate the changes in aerosol and cloud properties for clouds formed under the influence of aged fire emissions (referred to as the ‘fire’ period) and under cleaner conditions with no fire emission influence at these stations (‘non-fire’ period). The aerosol hygroscopicity parameter (κchem) was derived from the chemical composition data obtained from online aerosol mass spectrometers and was used to derive the number concentration of cloud condensation nuclei (NCCN) from the measured particle size distributions.

         At both stations, the aerosol number concentration in the accumulation mode and the cloud condensation nuclei concentration (NCCN) were higher during the fire period than during non-fire times. However, the aerosol hygroscopicity increased at Puijo but decreased a Zeppelin from the non-fire to fire period. At Puijo, in-situ measured cloud droplet number concentration (CDNC) was by a factor of ~7 higher when comparing fire to non-fire periods. This was in good agreement with the satellite observations (MODIS, Terra). At Puijo, the higher CCN concentrations during the fire period cause a depletion of the water vapor available for cloud droplet activation leading to larger observed activation diameters during cloud events despite the higher hygroscopicity of the aerosol particles.

         These observations show the importance of SE European fires for enhancing the CCN activity in Finland and the high Arctic. Results from this study emphasize the complex interplay between particle size and chemical composition, and how fires even from sources far away can have strong impacts in these remote regions.

How to cite: Kommula, S. M., Buchholz, A., Gramlich, Y., Mielonen, T., Hao, L., Pullinen, I., Vettikkat, L., Joutsensaari, J., schobesberger, S., Tiitta, P., Leskinen, A., Rees, D. H., Haslett, S., Siegel, K., Lunder, C., Zieger, P., Krejci, R., Romakkaniemi, S., Mohr, C., and Virtanen, A.: Effect of long-range transported fire emissions on aerosol and cloud properties at high latitudes: In situ measurements and satellite observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8668, https://doi.org/10.5194/egusphere-egu24-8668, 2024.

EGU24-9225 | ECS | Orals | BG1.1 | Highlight

Warming and cooling influences of North American boreal fires 

Max van Gerrevink, Sander Veraverbeke, Sol Cooperdock, Stefano Potter, Qirui Zhong, Michael Moubarak, Scott J. Goetz, Michelle C. Mack, James T. Randerson, Merritt R. Turetsky, Guido van der Werf, and Brendan M. Rogers

The Arctic-boreal region is warming rapidly, with consequences for northern ecosystems and global climate. Fires across the Arctic-boreal region are a major natural disturbance mechanism that initiate climate warming (positive) and cooling (negative) feedbacks. Understanding the net forcing effect from boreal fire on climate is crucial in managing and mitigating climate change impacts of boreal fires. Here we report radiative forcing estimates from boreal forest fires across Alaska and Western Canada (Arctic Boreal Vulnerability Experiment-domain). Our results integrate the effect of greenhouse gas emissions (warming) and aerosols emission (net cooling) have through direct combustion, post-fire vegetation recovery sequestering carbon (cooling), fire-induced permafrost degradation emitting CO2 and CH4 (warming), and changes in surface albedo (cooling). Alaskan fires are on average climate warming (1.34±2.95 W/m2 per burned area) – uncertainty given as spatial standard deviation, while Canadian fires show on average a climate cooling (‑2.26±2.48 W/m2 per burned area) effect. The emissions from the combustion of organic soils and post-fire permafrost thaw dominate the positive feedback for Alaskan fires, whereas the cooling effect of post-fire changes in surface albedo because of prolonged spring snow cover dominate for the western Canadian fires. Our work demonstrates large-scale spatial variability in the climate feedbacks from North American boreal forest fires. Such fine-scale spatial information on the warming and cooling influences of forest fires could be useful in designing forest management and fire suppression activities informed by climate impacts.

How to cite: van Gerrevink, M., Veraverbeke, S., Cooperdock, S., Potter, S., Zhong, Q., Moubarak, M., Goetz, S. J., Mack, M. C., Randerson, J. T., Turetsky, M. R., van der Werf, G., and Rogers, B. M.: Warming and cooling influences of North American boreal fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9225, https://doi.org/10.5194/egusphere-egu24-9225, 2024.

EGU24-9270 | ECS | Orals | BG1.1

What limits the growth of lightning fires in the remote northeast Siberian taiga? 

Thomas Janssen and Sander Veraverbeke

In recent years, boreal forests have experienced unprecedented fire activity. These fires have contributed substantially to carbon emissions and posed hazards to human health. In the remote northeast Siberian taiga, the vast majority of fires are ignited by lightning strikes and not by human activity. Furthermore, active fire suppression is largely absent in these remote areas, resulting in uncontrolled fire growth. Here, we present a detailed look at the places and times where these lightning fires do finally stop spreading and aim to identify the causes. We employ various remote sensing and geo-spatial datasets including fire weather as well as landscape variables such as the presence of surface water, road networks, woody fuel load, fire history, elevation and landcover, to pinpoint the limitations to fire growth along fire perimeters recorded between 2012 and 2022 at a 300-meter spatial resolution. We were able to attribute 87% of all fire perimeter locations to a statistically significant (p < 0.01) change in one or more of these fire limitations over either time (fire weather) or space (landscape). The analysis reveals that fire growth is mainly limited by a change in the vegetation (fuel type and fuel load) as well as a change to less favourable weather for fire spread, although there are clear regional differences in the importance of specific limitations. Overall, fire weather seems to be the most important limitation to fire growth in the north of the Siberian taiga where continuous permafrost is present. With a rising frequency of lightning strikes, droughts, and heatwaves in boreal regions, uncontrolled lightning fires have the potential to expand even further in the future, leading to significant implications for vulnerable permafrost landscapes and, consequently, the global carbon cycle.

How to cite: Janssen, T. and Veraverbeke, S.: What limits the growth of lightning fires in the remote northeast Siberian taiga?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9270, https://doi.org/10.5194/egusphere-egu24-9270, 2024.

EGU24-10145 | ECS | Posters on site | BG1.1

Burned area and climate extremes in different land covers in southeastern Australia 

Patrícia Páscoa, Ana Russo, Andreia Ribeiro, and Célia Gouveia

Large burned areas (BA) in southeastern Australia were regularly registered during hot and dry years, such as the Black Saturday (2009) and the Black Summer (2019-2020) extreme bushfires. These types of extreme climate conditions are expected to become more frequent, leading to an increased risk of large BA in this region.

In this work, the influence of drought conditions and hot events on the BA in southeastern Australia was assessed, using correlation and copula functions. Bivariate copula functions were fitted, and conditional probabilities of large BA given climate extremes were computed. Three classes of drought intensity were studied, namely moderate, severe, and extreme, as well as three thresholds for temperature extremes, namely the 80th, 90th, and 95th percentiles. Monthly BA were computed as the sum of the burned pixels in the fire season (from October to March), using data from the MODIS Burned Area product. The analysis was performed on forests, grasslands, and savannas separately. Drought conditions were assessed with SPEI at several time scales, computed with data from the CRU TS4.07 dataset. Maximum and minimum daily temperature were retrieved from the ERA5 dataset.

Results showed that the correlation between BA and SPEI was high in the current and previous 1 month for all land covers, being highest in savannas and lowest in grasslands. Short time scales of SPEI had the highest correlation on grasslands, and the opposite was observed in forests and savannas. The correlation with maximum temperature increased until 10-15 days before the fire event and surpassed 0.6 over forests. Minimum temperature presented much lower correlations and there was not a pronounced increase in the previous days, as observed with the maximum temperature.

The conditional probability of large BA increased with the intensity of the drought on all land covers, and it reached almost 100% probability of exceeding the 50th percentile of BA under extreme droughts on forests and savannas. For the case of the 80th percentile of BA, the probability was lower, but the difference given drought and non-drought conditions was larger than for the 50th percentile. On savannas and forests, the conditional probability was still high when considering SPEI in the previous 2 and 3 months.

Maximum temperature yielded a higher probability of BA for the two highest percentiles. Savannas presented the lowest probability of BA given hot events, and forests the highest. The probability increased up to 10 days before the fire. Overall, the probabilities obtained given drought conditions are higher than given hot events, particularly for larger fires. Moreover, high probabilities obtained with large time scales and longer lead times are indicative of the importance of drought conditions before the fire season and may help predict the occurrence of large BA.

 

Acknowledgments: This study was partially supported by FCT (Fundação para a Ciência e Tecnologia, Portugal) through national funds (PIDDAC) – UIDB/50019/2020, by project Floresta Limpa (PCIF/MOG/0161/2019), and by project 2021 FirEUrisk, funded by European Union’s Horizon 2020 research and innovation programme under the Grant Agreement no. 101003890). A.R. was supported by FCT through https://doi.org/10.54499/2022.01167.CEECIND/CP1722/CT0006. 

How to cite: Páscoa, P., Russo, A., Ribeiro, A., and Gouveia, C.: Burned area and climate extremes in different land covers in southeastern Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10145, https://doi.org/10.5194/egusphere-egu24-10145, 2024.

EGU24-10377 | ECS | Posters on site | BG1.1

Human land occupation regulates the effect of the climate on the burned area of the Cerrado biome 

Carlota Segura-Garcia, David Bauman, Vera L. S. Arruda, Ane Alencar, and Imma Oliveras Menor

The Brazilian Cerrado is a heterogeneous biome formed by a mosaic of savannas, grasslands, and smaller patches of denser woody forms. In this biome, fire is a natural disturbance agent that contributes to maintaining its open ecosystems and rich biodiversity. However, modern human activities and climate change are altering its fire regimes. In tropical savannas, land-use expansion is usually associated to a decrease in burned area primarily through land fragmentation, but also through active fire suppression. Meanwhile, climate change is fostering fire weather conditions, exacerbating fire activity. Hence, the two main drivers of fire could be pushing burned area in opposite directions, both with important ecological consequences for the Cerrado. However, it remains unclear how these two drivers interact, which is essential to devise effective fire management policies and conservation plans.

In this study, we use a causal inference framework to quantify the interaction between anthropic area percentage – as a proxy of human presence and fragmentation – and various climatic variables on their effects on Cerrado’s burned area. As well, we explore the spatial structure of temporal trends in burned area, anthropic expansion and climate change, and quantify the causal effect of the last two on the former.

We use geospatial data from different sources on a 0.2o grid over the Cerrado for the period 1985 to 2020. We use burned area and land use data from the MapBiomas project, and climate re-analysis data from ERA5 Land, CHIRPS and TerraClimate. We design our models using Directed Acyclic Graphs, a graphic representation of the causal relations between the predictors and burned area that informs variable selection for causal inference. Hence, based on these DAGs, we build multilevel Bayesian regression models to quantify the effects of the predictors and their interactions.

We find that a larger presence of land-use activities keeps burned area low and, importantly, hinders the effects of the climate. That is, while in landscapes composed mostly of native vegetation hotter and drier conditions increase burned area as expected; in anthropic landscapes, humans completely limit burned area responsiveness to climate. We also find spatially heterogeneous increasing and decreasing trends in burned area over the period, but concentrated in those areas of the Cerrado that were mostly natural in 1985. In these areas, a large anthropic expansion brought about a decrease in burned area, while we observe an increase in burned area in relation to climate change only in the areas that remained intact throughout the study period.

In conclusion, burned area in the Cerrado is shaped primarily by the extent of human presence in the landscape, even limiting the effects of the climate, while climatic effects become relevant in areas with larger tracts of native vegetation, suggesting that these areas may be more vulnerable to climate change.

How to cite: Segura-Garcia, C., Bauman, D., S. Arruda, V. L., Alencar, A., and Oliveras Menor, I.: Human land occupation regulates the effect of the climate on the burned area of the Cerrado biome, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10377, https://doi.org/10.5194/egusphere-egu24-10377, 2024.

EGU24-10606 | ECS | Orals | BG1.1

Characterizing lightning-ignited wildfire occurrences at sub-grid scales in orography-aware NOAA/GFDL land model LM4.2 

Rui Wang, Enrico Zorzetto, Sergey Malyshev, and Elena Shevliakova

Lightning ignitions are the dominant causes of wildfires in many regions, responsible for 80% of burned areas at high latitudes and about 70% of fires in the Amazon rainforest. With global wildfire activities and extreme fire events (e.g., intensity, duration, and size) increasing under the changing climate conditions, understanding the interactions between lighting, landscape characteristics, and wildfires is crucial for predicting and mitigating the impacts of climate change. Cloud-to-ground lightning activities are driven by a combination of large- and local-scale factors, e.g., local atmospheric circulations and convection and topography. Furthermore, the number of lightning strikes is predicted to increase by 10 – 30 % per degree warming. Decadal satellite observations have revealed Earth’s lightning hotspots at very high resolution, however, there is a paucity of fine-scale lightning strikes and lightning-ignited wildfires (LIW) in the Earth system and climate models. Currently, many climate and ESM  models do not include fires at all or simulate them with meteorological inputs and grid-average lightning at the scale of atmospheric models (25 to 100 km), introducing large uncertainties of LIW due to the lack of information at the scales relevant to fire dynamics.  Lack of information about lightning trends and variability hinders the prediction and projection of fires and their contribution to carbon and other atmospheric tracers and global warming. For example, in the US National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL) ESM4.1 model, the fire model uses a climatology of lightning strikes from preindustrial to 2100.

In this presentation, we will demonstrate the implications of capturing subgrid lightning distributions in the GFDL land model LM4.2 for the global simulations of wildfire dynamics over the available records (1998-2013) and provide insights into future projections. LM4.2 captures sub-grid heterogeneity of land cover and use, soil geomorphology, and topography, facilitating the understanding of LIW distribution across global to regional and sub-grid scales. In this study, we leverage 0.1° × 0.1° lightning observations from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) in the GFDL LM4-HB to characterize fine-scale lightning strike distribution and associated LIW.

How to cite: Wang, R., Zorzetto, E., Malyshev, S., and Shevliakova, E.: Characterizing lightning-ignited wildfire occurrences at sub-grid scales in orography-aware NOAA/GFDL land model LM4.2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10606, https://doi.org/10.5194/egusphere-egu24-10606, 2024.

EGU24-10793 | ECS | Posters on site | BG1.1

A Decision Support System for Forest Fire Danger Notices in Ireland  

Padraig Flattery, Klara Finkele, Paul Downes, Alan Hally, and Ciaran Nugent

Since 2006 the Canadian Forest Fire Weather Index System (FWI) has been employed operationally at Met Éireann to predict the risk of forest fires in Ireland. Around 11% or 770,000 ha of the total land area of Ireland is afforested, but there are also large areas of open mountain and peatlands covered in grasses, dwarf-shrub and larger woody shrub type vegetation which can provide fuel for spring wildfires under suitable conditions. After winter, vegetation can be dead or have a very low live moisture content, and the flammability of this vegetation can be readily influenced by prevailing weather, especially following prolonged dry periods.

Different decision support tools are available to different sectors, namely:

  • The General Public: who have access to fire weather index meteograms on Met Éireann’s public website.
  • Local Authorities, who have access to the ANYWHERE multi-hazard warning system, which provides multiple sources of information about fire danger and propagation.
  • The Department of Agriculture, Food and Marine (DAFM), who are provided with information and additional support from National and European partners and networks.

DAFM is the Forest Protection authority in Ireland responsible for issuing Forest Fire Danger Notices which improve preparedness for fire responses and are based on a range of factors including information provided by Met Éireann who calculate the FWI and FWI components using observation data at synoptic stations, and the predicted FWI for the next five days ahead based on numerical weather prediction data. This allows fire responders to build resilience and prepare for impending fires.

The FWI is determined based on the types of forest fuel and how quickly they dry out/get rewetted, and components of fire behaviour. The FWI represents the fire intensity as the rate of energy per unit length of fire front (kW/m). The components which provide the most accurate indication of risk under Irish conditions are the Fine Fuel Moisture Code and Initial Spread Index, based on the fuels involved and ignition patterns observed to date. Since 2022 Met Eireann provide the FWI as well as the individual components Fine Fuel Moisture Content and Initial Spread Index via the public website for synoptic stations. These indices are based on observations and a seven-day forecast into the future using ECMWF predictions. This allows all county councils responsible for wildfire preparedness to access this information swiftly and directly.

Met Éireann also use the ANYWHERE multi-hazard warning tool which allows for visualisation of multiple fire-related risk factors and warning indices to be viewed simultaneously. The ANYWHERE system, in combination with our station-based forecast and antecedent conditions, provide fire managers and response teams with excellent information with which to make decisions.

How to cite: Flattery, P., Finkele, K., Downes, P., Hally, A., and Nugent, C.: A Decision Support System for Forest Fire Danger Notices in Ireland , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10793, https://doi.org/10.5194/egusphere-egu24-10793, 2024.

EGU24-10920 | ECS | Posters on site | BG1.1

Reconstructing 20th century burned area by combining global fire model input, satellite observations and machine learning 

Seppe Lampe, Lukas Gudmundsson, Vincent Humphrey, Inne Vanderkelen, Bertrand Le Saux, and Wim Thiery

The temporal coverage (∼2000 to present) of global burned area satellite observations limits many aspects of fire research e.g., long-term trend analysis, disentangling the effect of various drivers on fire behaviour and detection and attribution of changes to climate change. As a result, global fire models are more frequently being called upon to answer questions about past and future fire behaviour. Unfortunately, the limited temporal coverage of the observations also hinders the development and evaluation of these fire models. The current generation of global fire models from ISIMIP are able to simulate well some characteristics of regional fire behaviour such as mean state and seasonality. However, the performance of these models differs greatly from region to region, and aspects such as extreme fire behaviour are not well represented yet. Here, we explore the possibility of using machine learning algorithms to model burned area from the same input parameters that are passed to global climate models. Once trained, this data-driven model can be evaluated against regional proxies for past fire behaviour e.g., tree rings and charcoal records. Hopefully, this data-driven reconstruction can provide valuable insights on the 20th century burned area, and can help improve and evaluate fire models.

How to cite: Lampe, S., Gudmundsson, L., Humphrey, V., Vanderkelen, I., Le Saux, B., and Thiery, W.: Reconstructing 20th century burned area by combining global fire model input, satellite observations and machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10920, https://doi.org/10.5194/egusphere-egu24-10920, 2024.

EGU24-10947 | Orals | BG1.1 | Highlight

Burned area and fire emissions according to the fifth version of the Global Fire Emissions Database (GFED) 

Guido van der Werf, James Randerson, Dave van Wees, Yang Chen, Roland Vernooij, Louis Giglio, Joanne Hall, Douglas Morton, Kelley Barsanti, and Bob Yokelson

Quantifying burned area and associated fire emissions is paramount to understand how changing fire patterns affect radiative forcing and air quality. It is now well established that many fires are too small to be detected by coarse resolution satellite burned area products on which the Global Fire Emissions Database (GFED) relied. In the fifth version of GFED (GFED5) we therefore combine burned area derived from mapped coarse-resolution burned area from the MODIS sensor -which excels in detecting larger fires- with small-fire burned area. The latter is derived from MODIS active fire detections scaled to burned area using ratios constrained by higher-resolution burned area datasets from Landsat and Sentinel-2 for selected regions. Burned area in cropland regions was based on the Global Cropland Area Burned (GloCAB) dataset. Total global burned area is 61% higher than in GFED4s. We converted burned area to emissions using a simplified version of the CASA model used in previous GFED versions, but which now runs at a 500 m spatial resolution. This allows for better constrained modeled fuel loads based on field measurements. Although GFED5 emissions are aggregated to a 0.25 degree grid due to the statistical nature of deriving our burned area, we can now account for heterogeneity in fire processes within these large pixels. Emissions (3 Pg carbon per year) are roughly 50% higher than in GFED4 and we show how diverging trends in grassland versus forest ecosystems impact trends in total emissions. Finally, we show how converting fire carbon losses to trace gas and aerosol emissions is now better constrained due to the addition of several new emission factor measurement campaigns. In the savanna biome we now account for spatial and temporal variability in emission factors.

How to cite: van der Werf, G., Randerson, J., van Wees, D., Chen, Y., Vernooij, R., Giglio, L., Hall, J., Morton, D., Barsanti, K., and Yokelson, B.: Burned area and fire emissions according to the fifth version of the Global Fire Emissions Database (GFED), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10947, https://doi.org/10.5194/egusphere-egu24-10947, 2024.

EGU24-11206 | ECS | Posters on site | BG1.1 | Highlight

Global cloud-to-ground lightning data to inform wildfire ignition patterns 

Esther Brambleby, Sander Veraverbeke, Guilherme Mataveli, Manoj Joshi, and Matthew Jones

Lightning is recognised as a crucial wildfire ignition source worldwide, especially in remote regions including boreal and temperate forests where large carbon stocks are held. The societal consequences of these wildfires, as well as their contribution to climate change, can be immense. The occurrence of lightning is projected to increase in these areas under climate change, however robust assessments of lightning contribution to wildfire risk have been restricted to selected regions due to the narrow spatial extent of cloud-to-ground lightning records. Consequently, evaluations of lightning-fire relationships using existing global lightning observational datasets have been limited to considering the total amount of lightning. Only cloud-to-ground lightning can ignite a wildfire, therefore when considering impacts on wildfire risk it is essential to distinguish between lightning types.

Using Vaisala’s unique Global Lightning Dataset (GLD360), which discriminates between cloud lightning and cloud-to-ground lightning strikes, we present our preliminary analyses of the spatial patterns and seasonality of cloud-to-ground lightning. Here, we show the regional variation in the lightning frequency and the cloud-to-ground fraction, as well as the strength (current) and polarity of cloud-to-ground lightning strikes.

By considering cloud-to-ground lightning strikes only, we characterise the spatial and seasonal variation in lightning events with the potential to ignite wildfires. Combining global observations of lightning strikes with observations of individual fires and coincident meteorology will advance our mechanistic understanding of wildfire ignition potential in a range of weather conditions, improve the process representation of the ignition process in global models, and refine projections of changing wildfire risks under climate change.

How to cite: Brambleby, E., Veraverbeke, S., Mataveli, G., Joshi, M., and Jones, M.: Global cloud-to-ground lightning data to inform wildfire ignition patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11206, https://doi.org/10.5194/egusphere-egu24-11206, 2024.

This research delves into the dynamics of forest fires across various Indian regions, particularly during the unique COVID-19 lockdown period. The study's core focus is on the interaction between forest fires, climatic factors, and vegetation indices in a scenario of reduced human activity. It employs a multidimensional methodology, integrating satellite imagery and climatic data from periods before, during, and post-lockdown. The lockdown provides a critical opportunity to assess the impact of decreased human interference on forest fire patterns. Advanced statistical techniques are used to analyze the relationship between vegetation indices, fire occurrences, and meteorological conditions. This approach aims to uncover the underlying mechanisms driving these relationships, moving beyond simple trend identification. The research offers a nuanced perspective by differentiating natural factors from human influences. This distinction is vital in understanding the environmental dynamics during the lockdown. The findings have significant implications, offering insights for policymakers and environmentalists in enhancing forest fire management strategies. Emphasizing the need for a comprehensive understanding of environmental interactions, this study contributes to forming more informed and sustainable approaches to natural disaster management in the face of global challenges like climate change and pandemics.

How to cite: Kate, R. and Bhattacharya, J.: Forest Fires during COVID-19: Assessing Environmental Interactions and Fire Dynamics Amidst Reduced Human Intervention in India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11291, https://doi.org/10.5194/egusphere-egu24-11291, 2024.

EGU24-11432 | ECS | Posters on site | BG1.1 | Highlight

Northern high latitude peat fires: from lab to modelling  

Dimitra Tarasi, Eirini Boleti, Katie Blackford, Matthew Kasoar, Emmanouil Grillakis, Guillermo Rein, Hafizha Mulyasih, and Apostolos Voulgarakis

Climate warming is occurring most rapidly at high latitudes, heightening the vulnerability of carbon-rich peatlands to fire. Northern peatlands comprise the largest terrestrial carbon store, and exert a net cooling effect on the climate. Warmer and drier conditions due to the anticipated climate change are expected to contribute substantially to increased fire severity and frequency in the northern high latitudes, potentially shifting peatlands from being carbon sinks to being greenhouse gas emission sources. Therefore, peat fires, which are considered the largest and most persistent fires on Earth, can significantly impact the global carbon cycle, atmospheric composition, climate, air quality, and human health. Representing peatland fire feedbacks to climate in Earth system models is essential for accurately predicting the future of the climate system. Here, we present the first steps of an effort to distill lab results on peat burning and emissions into global fire modelling. Since peat moisture content and the depth of burn have been experimentally proved to be critical for the representation of peat fires, we aim to incorporate those mechanisms into a global model functionality. More specifically, we aim to represent the mechanistic understanding of the ignition and spread of peat fires in INFERNO-peat, the peat module of the JULES-INFERNO global fire model. To assess the added value of our updated model, we compare the simulated burnt area and carbon emissions with observation-based products. As boreal regions remain a big mystery for the future of our planet, our improved model representation of peat fires in northern high latitudes contributes to a better understanding of future atmospheric composition, radiative forcing and climate. 

How to cite: Tarasi, D., Boleti, E., Blackford, K., Kasoar, M., Grillakis, E., Rein, G., Mulyasih, H., and Voulgarakis, A.: Northern high latitude peat fires: from lab to modelling , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11432, https://doi.org/10.5194/egusphere-egu24-11432, 2024.

EGU24-11599 | ECS | Orals | BG1.1

Comparison and validation of state-of-the-art fire emissions models for the Amazon 

Dave van Wees, Vincent Huijnen, Matthias Forkel, Jos de Laat, Niels Andela, and Christine Wessollek

Amazon forest conservation is critical for reaching net-zero carbon emissions and protecting regional biodiversity but these efforts are at risk from deforestation, fire and drought. In particular, accurate quantification of carbon losses from forest and deforestation fires are required to understand long-term impacts of fire on the carbon cycle and inform management strategies. Recent developments in the detection of burned area, near-real time tracking of fire patch metrics, and higher-resolution fire emissions models allow for improved estimates of carbon losses from fire. Nevertheless, independent validation of these novel approaches often remains elusive, leading to large disagreement between different emissions inventories.

Here, we compare carbon emissions estimates from several state-of-the-art fire emissions models, including a 500-m resolution GFED version, GFAS, and the Sense4Fire project, in a case-study for the Amazon region. Where necessary, we have updated the models to extend to 2022 and to include the most recent version of model input data from MODIS (Collection 6.1). We analysed the added years of data to elucidate recent trends in fire-related carbon emissions across the Amazon and adjacent biomes. For validation, we ingested the CO emissions from the considered fire emissions models into an atmospheric transfer simulation (IFS-COMPO) and compared those to column CO observations from Sentinel-5P TROPOMI. Finally, we propose an optimization methodology for matching modelled CO concentrations to observations with the objective of constraining regional carbon losses from fire. Results provide novel insights into carbon losses from fire across different fire types and land use practices, and can be extended to global scale for improved estimates of global fire emissions.

How to cite: van Wees, D., Huijnen, V., Forkel, M., de Laat, J., Andela, N., and Wessollek, C.: Comparison and validation of state-of-the-art fire emissions models for the Amazon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11599, https://doi.org/10.5194/egusphere-egu24-11599, 2024.

EGU24-11809 | ECS | Posters on site | BG1.1

Analysing the effects of postfire oak afforestation on the provision of ecosystem services 

Luis Filipe Lopes, Erika S. Santos, Leónia Nunes, Paulo M. Fernandes, and Vanda Acácio

Forests play a substantial role in generating externalities and supporting services essential for maintaining key ecosystem functions and processes. Fire has long been a natural element of forest dynamics, contributing to model the structure, composition, and diversity of vegetation. However, changes in fire regimes in recent decades in Europe (e.g., more frequent and severe fires) have led to negative ecological, social, and economic impacts, particularly marked by a decline in the provision of ecosystem services. Mediterranean Europe, being a region highly prone to wildfires and currently experiencing a change in fire regimes, exemplifies this situation.

In this study, we aim to understand the effects of postfire oak afforestation on the provision of ecosystem services (ES). We analysed 15 afforestation projects with the deciduous Pyrenean oak (Quercus pyrenaica) carried out in 1994-2006 in similar soil type (Cambisols) in the North and Center of Portugal, including seven pure and eight mixed oak stands. For each project area, we identified an adjacent control area affected by the same fire event but without oak afforestation or evident management. In 2021-2022, for each project and control areas, we collected field data on: site conditions, stand characteristics, forest biometry, understory vegetation (height and cover), floristic richness and diversity, oak natural regeneration and litter. At the moment of data collection, the majority of projects (10) were 12 to 17 years old, with the remaining projects (5) having been implemented 21 to 25 years ago. Collected data was used to quantify provisioning ecosystem services (wood volume) and regulation and maintenance services (forest and litter carbon, fire protection, maintenance of nursery populations, habitats, and seed dispersal).

Afforested areas supplied more provisioning services (higher wood volume), as a consequence of a higher tree density when compared to non-afforested areas. Total carbon content and litter carbon were not significantly different between afforested and control areas. Nevertheless, afforested and control areas exhibited distinct patterns concerning carbon in the different forest layers: carbon in the tree layer was significantly higher in afforested areas, while carbon in the understory layer was significantly higher in control areas. Afforested areas also showed a significantly higher fire protection service, as a consequence of lower fuel load from regular understory shrub management. Lastly, we found no significant differences in services related to maintenance of nursery populations and habitats (estimated with floristic species and diversity), and seed dispersal (estimated with oak natural regeneration), although afforested areas presented a higher number of oak seedlings.

Our study shows that postfire afforestation in oak forests may have a positive, null or negative impact on ES, depending on the service under analysis, highlighting the existence of trade-offs among multiple ES. We emphasize the importance of a comprehensive understanding of the impacts of postfire afforestation on ES to guide postfire management, aiming to enhance forest resilience in the face of predicted climate change.

How to cite: Lopes, L. F., Santos, E. S., Nunes, L., Fernandes, P. M., and Acácio, V.: Analysing the effects of postfire oak afforestation on the provision of ecosystem services, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11809, https://doi.org/10.5194/egusphere-egu24-11809, 2024.

EGU24-11962 | Orals | BG1.1

The Great Fuel Moisture Survey: developing fundamental wildfire science and sustainable community owned agency in traditionally non-fire prone societies 

Nicholas Kettridge, Katy Ivison, Alistair Crawford, Gareth Clay, Claire Belcher, Laura Graham, and Kerryn Little

New fire vulnerable communities are emerging in traditionally non-fire prone regions of the world. But these communities are often largely unaware of the developing threat and do not hold the core wildfire knowledge to galvanise collective community-based action to mitigate the risk. Furthermore, we urgently require knowledge of fuel moisture dynamics and flammability of fuels in such regions to provide accurate assessments of fire danger at the national scale. Here we characterise the moisture content and flammability of heather through engaged environmental science, demonstrating the potential of the approach to develop a public consciousness and knowledge of wildfire within communities. Fuel sampling kits were sent to 150 samplers who collected ~1000 vegetation samples across the UK (from Land’s End to John O’Groats) over a period of two days during a single period of high fire danger. The validity of the volunteer approach for collecting high quality fuel moisture data was also assessed from the analysis of a separate ~1500 samples collected by 17 samplers in a single test plot. The approach provides a simple nationally available entry point for residents traditionally unaware of both the wildfire risk and the management of their community for wildfire mitigation. Empowering samplers offers potential future opportunity to create meaningful local datasets, to build communities, and in doing so give a strong voice to residents in regional and national policy discussions.

How to cite: Kettridge, N., Ivison, K., Crawford, A., Clay, G., Belcher, C., Graham, L., and Little, K.: The Great Fuel Moisture Survey: developing fundamental wildfire science and sustainable community owned agency in traditionally non-fire prone societies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11962, https://doi.org/10.5194/egusphere-egu24-11962, 2024.

EGU24-11965 | ECS | Posters on site | BG1.1

Effects of 2018 wildfire on soil properties in a peatland within the Peak District National Park (central England) 

Luigi Marfella, Mark A. Ashby, Georgia Hennessy, Rossana Marzaioli, Flora A. Rutigliano, and Helen C. Glanville

Peatland soil is a valuable component of natural capital by constituting the largest terrestrial carbon sink (~30% of the global soil carbon) and an essential freshwater source. Despite covering only ~3% of the Earth’s surface, peatlands provide crucial ecosystem services i.e. water-quality improvement and climate regulation by storing carbon in peat. However, peat degradation due to anthropogenic activities (e.g. drainage) as well as global climate change exposes this ecosystem to fire risk.
This study assessed the medium-term (~5 years) impacts of the 10 August 2018 wildfire within The Roaches Nature Reserve. This area spans the southeastern sector of the Peak District National Park and Special Area of Conservation (SAC-UK0030280). According to the Staffordshire Wildlife Trust (responsible authority for Reserve management), the human-caused fire broke out in a wooded area and aided by wind, spread to the peatland. Here, we integrated soil analyses and vegetation surveys of a burnt and unburnt area i) to assess possible correlations between soil biogeochemical properties and vegetation cover with ii) remote sensing to collect data on fire severity exploring temporal and spatial wildfire impacts.
Processing of satellite imagery highlighted a high-severity fire impact within the perimeter of the burned area, which predicts alteration of soil characteristics. Preliminary outcomes on the soil indicated deacidification and reduced water content in the burned peat remains 5 years post-fire.
Given that global peatland conservation is an important tool for addressing climate-change, this research appears necessary to develop effective management strategies, including rewetting of peatlands postfire.

How to cite: Marfella, L., Ashby, M. A., Hennessy, G., Marzaioli, R., Rutigliano, F. A., and Glanville, H. C.: Effects of 2018 wildfire on soil properties in a peatland within the Peak District National Park (central England), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11965, https://doi.org/10.5194/egusphere-egu24-11965, 2024.

The ignition, spread, and severity of wildfires are driven largely by weather conditions (Jain et al. 2020: https://doi.org/10.1139/er-2020-0019; Liu et al. 2013: https://doi.org/10.1371/journal.pone.0055618).  The main tool for weather prediction across the globe is a set of physical, coupled atmosphere/ocean models, called numerical weather prediction (NWP).  Despite rapid improvements in the last few decades, NWP alone is not sufficient for wildfire prediction, because it does not resolve every process related to wildfire.  One solution is to post-process NWP with statistical models, which correct the NWP model towards better resolving processes related to the phenomenon of interest (here, wildfire).  This post-processing is called model-output statistics (MOS) and typically involves linear regression.  However, recent work has advanced MOS by incorporating more powerful statistical models from deep learning (DL).  We use DL to predict extreme fire weather and behaviour at multi-day lead times throughout the United States.

 

For fire weather, we have trained U-nets -- a type of deep neural network -- to predict at lead times of 3-240 hours over the United States.  The output (target) variables are seven indices from the Canadian Fire Weather Index System (CFWIS), computed from the ECMWF Reanalysis version 5 (ERA5).  These seven indices include the fine-fuel moisture code (FFMC), initial-spread index (ISI), overall fire-weather index (FWI), etc.  Meanwhile, the input (predictor) variables come from five sources.  The first is a forecast time series of atmospheric state variables (height, temperature, humidity, and wind) from the Global Forecast System (GFS) NWP model.  The second is a forecast time series of surface and subsurface moisture (soil moisture, accumulated precipitation, and snow depth) from the GFS.  The third is a set of constant fields (terrain height/slope/aspect, land-sea mask, etc.) describing the underlying terrain.  The fourth is a lagged time series of CFWIS over the past several days, i.e., past target values.  The fifth is a forecast time series of CFWIS indices, computed by applying the CFWIS functions directly to GFS-forecast weather variables.  These are the uncorrected (GFS-only) CFWIS forecasts, to be corrected by the U-net.

 

For fire behaviour, we have trained random forests -- ensembles of decision trees -- to predict fire radiative power (FRP) at lead times of 1-48 hours over the United States.  The labels (correct answers) for FRP are obtained from the Regional ABI and VIIRS Emissions (RAVE) merged satellite product.  Predictors for the random forest include the first three sources listed for the U-net above, plus a lagged time series of FRP over the past 24 hours, i.e., past target values.

 

Both models -- the U-net for fire weather and the random forest for fire behaviour -- are trained with built-in uncertainty quantification.  Thus, at every lead time and grid point, both models provide an expected value and an estimate of their own uncertainty.  We will present objective evaluation results (for both the mean forecast and uncertainty) and explainable artificial intelligence (XAI) to understand what the models have learned, e.g., which spatiotemporal weather patterns in a given area are most conducive to extreme fire weather/behaviour.

How to cite: Lagerquist, R. and Kumler, C.: Using deep learning to improve multi-day forecasts of extreme fire weather and behaviour throughout the United States, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12223, https://doi.org/10.5194/egusphere-egu24-12223, 2024.

EGU24-12320 | ECS | Orals | BG1.1

Integrating Human Domain Knowledge into Artificial Intelligence for Hybrid Forest Fire Prediction: Case Studies from South Korea and Italy 

Hyun-Woo Jo, Shelby Corning, Pavel Kiparisov, Johanna San Pedro, Andrey Krasovskiy, Florian Kraxner, and Woo-Kyun Lee

Forest fires pose a growing global threat, exacerbated by climate change-induced heat waves. The intricate interplay between changing climate, biophysical, and anthropogenic factors emphasizes the urgent need for sophisticated predictive models. Existing models, whether process-based for interpretability or machine learning-based for automatic feature identification, have distinct strengths and weaknesses. This study addresses these gaps by integrating human domain knowledge, crucial for interpreting forest fire dynamics, into a machine learning framework. We introduce FLAM-Net, a neural network derived from IIASA's wildfire Climate impacts and Adaptation Model (FLAM), melding process-based insights of FLAM with machine learning capabilities. In optimizing FLAM-Net for South Korea, new algorithms interpret national-specific forest fire patterns, and multi-scale applications, facilitated by U-Net-based deep neural networks (DN-FLAM), yield downscaled predictions. Successfully tailored to South Korea's context, FLAM-Net and DN-FLAM reveal spatial concentration near metropolitan areas and the east coastal region, with temporal concentration in spring. Performance evaluation yields Pearson's r values of 0.943, 0.840, and 0.641 for temporal, spatial, and spatio-temporal dimensions. Projections based on Shared Socioeconomic Pathways (SSP) indicate an increasing trend in forest fires until 2050, followed by a decrease due to increased precipitation. During the optimization process of FLAM-Net for Italy, optimal parameters for sub-areas are identified. This involves considering biophysical and anthropogenic factors at each grid, contributing to improved localized projection optimization by utilizing various sets of optimal parameters. There by, this process illuminates the intricate connections between environmental factors and their interpretation in the dynamics of forest fires. This study demonstrates the advantages of hybrid models like FLAM-Net and DN-FLAM, seamlessly combining process-based insights and artificial intelligence for interpretability, accuracy, and efficient optimization. The findings contribute scientific evidence for developing context-specific climate resilience strategies, with global applicability to enhance climate resilience.

How to cite: Jo, H.-W., Corning, S., Kiparisov, P., San Pedro, J., Krasovskiy, A., Kraxner, F., and Lee, W.-K.: Integrating Human Domain Knowledge into Artificial Intelligence for Hybrid Forest Fire Prediction: Case Studies from South Korea and Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12320, https://doi.org/10.5194/egusphere-egu24-12320, 2024.

EGU24-12529 | ECS | Orals | BG1.1 | Highlight

GlobalRx: A global assemblage of regional prescribed fire records for use in assessments of climate change impacts 

Alice Hsu, Jane Thurgood, Adam Smith, Liana Anderson, Hamish Clarke, Stefan Doerr, Paulo Fernandes, Crystal Kolden, Cristina Santín, Tercia Strydom, and Matthew Jones and the GlobalRx Consortium

Prescribed (Rx) and controlled fires are an important land management tool used globally for a variety of reasons, including the reduction of hazardous fuel loads, ecological conservation, agriculture, and natural resource management. Its use has important implications for wildfire risk, biodiversity, and carbon storage. However, the use of Rx and controlled fires is highly dependent upon weather conditions, requiring a weather window during which a careful balance of temperature, moisture, and wind ensure that the burns achieve their objectives while minimizing ecological damage or risk to human lives or assets. The planning and execution of Rx burns must also consider how these weather conditions interact with the local vegetation and ecology. As fire weather is projected to grow more extreme under the impacts of climate change, there is a growing need to monitor this effect on the ability to carry out Rx burning.

Here, we introduce a new dataset, GlobalRx, which includes around 140,000 records of Rx and other controlled fires from 16 countries, encompassing 207 ecoregions and 13 biomes around the world. For each record, we have geolocated values of various metrics of fire weather and fire danger (e.g. fire weather indices, vapour pressure deficit) from the ERA5 meteorological reanalysis, as well as the biome, ecoregion, fuelbed type, and protected area status from global thematic layers. We demonstrate the usefulness of this dataset for analyzing viable meteorological windows under which Rx fires may be conducted across diverse environmental settings in the present climate, as well as how these Rx burning windows may shift under the threats of climate change. This dataset has potential to shed light on how Rx burning windows may shift under future climate change, as well as opportunities to understand other drivers and effects of Rx burning.

This project has been supported by valuable contributions from non-public data from a consortium of data providers: Parks Canada, South Africa National Parks, Brazilian Institute of the Environment and Renewable Natural Resources, East-Pyrenees Prescribed Burning Team, Institute for Nature Conservation and Forests (Portugal), Regional Forest Fire Service (Italy), Russian Federal Forestry Agency, H2020 LifeTaiga Project, Government of the Principality of Asturias, Council of Andalucía, Council of Galicia, Forestry England, National Forestry Commission of Mexico, ZEBRIS Geo-IT GmbH, Hokkaido University, Pau Costa Foundation, Asian Forest Cooperation Organization.

How to cite: Hsu, A., Thurgood, J., Smith, A., Anderson, L., Clarke, H., Doerr, S., Fernandes, P., Kolden, C., Santín, C., Strydom, T., and Jones, M. and the GlobalRx Consortium: GlobalRx: A global assemblage of regional prescribed fire records for use in assessments of climate change impacts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12529, https://doi.org/10.5194/egusphere-egu24-12529, 2024.

EGU24-13237 | Posters on site | BG1.1

The role of fire radiative power to estimate fire-related smoke pollution. 

Rita Durao, Catarina Alonso, Ana Russo, and Célia Gouveia

The intensity of a wildfire can be assessed based on its released energy, obtained through remote measurements of the fire's radiative power. Since the Fire Radiative Power (FRP) is proportional to the amount of burned biomass and therefore to smoke production. Higher FRP values are associated with more severe fires, suggesting higher levels of smoke production and, consequently, higher emissions of particulate matter and other pollutants. The specific composition of smoke emissions can vary depending on factors such as the type of vegetation burned, the temperature of the fire, and the combustion conditions. In general, fire smoke is composed of a variety of air pollutants, including gases (NOx, CO, VOCs, O3, PAHs, etc) and particulate matter (PM). The objective of this work is to evaluate the ability of FRP, to be used as an indicator of fire smoke pollution. Particulate matter (PMx) and carbon monoxide (CO) concentrations emitted during recent wildfires in Portugal are analyzed to assess the link between pollution concentration levels and fire intensity over the affected areas, taking into account the spatial and temporal characteristics of each event. For this purpose, two particularly severe fires with significant impacts on air quality in central and southern Portugal were analyzed namely the ones taking place in October 2017 and August 2018. Concentrations of PMx and CO were evaluated through CAMS data, and the radiative power through the FRP product of the SEVIRI/MSG disseminated by LSA-SAFThe results show that the emitted pollutant concentrations significantly exceeded the established daily target limit values (air quality and public health guidelines). The fire intensity, based on the emitted Radiative Energy (FRE) derived from FRP, aligns with the known severity of these events, consistent with the observed concentrations of air pollutants, being demonstrated that the FRP can be associated with smoke production, especially PMx emissions during a fire. Thus, the proposed methodology using FRP can be a valuable tool for assessing the impact of wildfires on air quality and understanding the potential for smoke dispersion over fire-affected regions. The role of FRP as an indicator of air pollution highlights the potential use of FRP in assisting in management activities, operational planning, and emergency intervention during ongoing fires. 

Acknowledgments: This study is partially supported by the European Union’s Horizon 2020 research project FirEUrisk (Grant Agreement no. 101003890); and by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES on behalf of DHEFEUS -2022.09185.PTDC and the project FAIR- 2022.01660.PTDC).

How to cite: Durao, R., Alonso, C., Russo, A., and Gouveia, C.: The role of fire radiative power to estimate fire-related smoke pollution., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13237, https://doi.org/10.5194/egusphere-egu24-13237, 2024.

EGU24-13416 | ECS | Posters on site | BG1.1

Two decades of fire-induced albedo change and associated radiative effect over sub-Saharan Africa 

Michaela Flegrova and Helen Brindley

Fire is an important, widespread Earth-system process, influencing local ecosystems and climate around the globe. Over half of global burned area occurs in Africa, with over 10% of the continent affected by fire every year. Fire temporarily alters the surface properties, including surface albedo, causing long-lasting changes to the surface radiation budget.

We present the analysis of 20 years of fire and albedo data in Africa, using the MODIS product suite. We show that fire causes an average immediate albedo decrease, recovering exponentially with a time constant of several weeks. While the magnitude of albedo changes shows large spatial and temporal variations and a strong land cover type (LCT) dependency, exponential recovery is observed in the majority of LCTs. We show that fires cause long-term brightening, observing on average a small positive albedo change 10 months after a fire, but we find this is driven almost exclusively by slow vegetation recovery in the Kalahari region.

Using downward surface shortwave flux estimates we calculate the fire-induced surface radiative forcing (RF), peaking at 5±2 Wm−2 in the burn areas, albeit with a significantly smaller effect when averaged temporally and spatially. We find that the average long-term RF is negative because of the brightening observed.

Our temporal analysis does not indicate a decrease in overall fire-induced RF, despite a well-documented reduction in burning in Africa in the recent decades, suggesting that the RF of individual fires is increasing because of higher levels of downward surface shortwave flux. We hypothesise this may be due to lower levels of smoke aerosols in the atmosphere.

How to cite: Flegrova, M. and Brindley, H.: Two decades of fire-induced albedo change and associated radiative effect over sub-Saharan Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13416, https://doi.org/10.5194/egusphere-egu24-13416, 2024.

EGU24-14202 | Posters on site | BG1.1 | Highlight

Evaluation of global fire simulations in CMIP6 Earth system models 

Fang Li, Xiang Song, Sandy Harrison, and Zhongda Lin

       Fire is the primary form of terrestrial ecosystem disturbance globally and a critical Earth system process. So far, most Earth system models (ESMs) have incorporated fire modeling, with 19 out of them submitted fire simulations to the CMIP6. Transitioning from CMIP5 to CMIP6, much more models submitted fire simulations and the dominant fire scheme has evolved from GlobFIRM to the Li scheme. However, it remains unknown how well CMIP6 ESMs perform in fire simulations. This study provides the first comprehensive evaluation of CMIP6 fire simulations, through comparisons with multiple satellite-based datasets and the Reading Paleofire Database of global charcoal records (RPD).

        Our results show that most CMIP6 models simulate the global amounts of present-day burned area and fire carbon emissions within the range of satellite-based products, and reproduce observed major features of spatial pattern and seasonal cycle as well as the relationships of fires with precipitation and population density, except for models employing the GlobFIRM fire scheme. Additionally, most CMIP6 models can reproduce the response of interannual variability of tropical fires to ENSO, except for some models incorporating the SPITFIRE fire scheme. From 1850 to 2015, CMIP6 models generally agree with RPD, with some discrepancies in southern South America before 1920 and in temperate and eastern boreal North America, Europe, and boreal Asia after 1990. Compared with CMIP5, CMIP6 has solved the serious issues of CMIP5 which simulates the global burned area less than half of observations, fails to capture the high burned area fraction in Africa, and underestimates seasonal variability. CMIP6 fire carbon emissions simulations are also closer to RPD. However, CMIP6 models still fail to capture the present-day significant decline in observed global burned area and fire carbon emissions partly due to underestimation in anthropogenic fire suppression, and fail to reproduce the spring peak in NH mid-latitudes mainly due to an underestimation of crop fires. Based on our findings, we identify potential biases in fire and carbon projection based on CMIP6 models. We also provide suggestions for the fire scheme development, and bias correction methods when generating multi-source merged fire products.

How to cite: Li, F., Song, X., Harrison, S., and Lin, Z.: Evaluation of global fire simulations in CMIP6 Earth system models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14202, https://doi.org/10.5194/egusphere-egu24-14202, 2024.

EGU24-14446 | ECS | Posters on site | BG1.1

Wildland Fire Smoke and Emissions Tradeoff Decision Support 

Laurel Sindewald, Shawn Urbanski, Karin Riley, Christopher Eckerson, Alex Dye, and Rachel Houtmann

In 2023, 6,551 wildfires across Canada burned 184,961 km2 of the landscape—about 5% of Canadian forests—emitting nearly 480 megatonnes of carbon, with emissions leading to air quality warnings as far away as Washington DC, USA. In early June, the air quality index in New York City was over 400, and by mid-June, smoke plumes passed above Europe. As wildland fires of increasing severity occur with increasing frequency, driven by global climate change and decades of fire suppression, societies near and far from high-risk ecosystems face increased exposure to wildfire emissions that may have both acute and long-term health impacts. Prescribed fire interventions show promise for reducing the risk of large wildfires in fire-prone ecosystems, but implementing prescribed fire can be difficult, in part due to concerns about the potential health impacts of prescribed fire smoke on nearby communities. To provide decision support for land managers aiming to reduce wildfire risk with prescribed fire treatments, we will produce a geospatial database of daily pollutant emissions and fire intensity from simulations of prescribed and wildland fires over a 20-year period for: 1) a baseline scenario of no management actions, 2) one or more scenarios of prescribed fire locations and timing based on interaction with tribes and Okanogan-Wenatchee National Forest (OWNF) managers, and 3) scenarios of prescribed fire locations and timing based on fire paths, locations of highly valued resources, areas available and suitable for treatment, determined by the research team. We can accomplish this by iterating between FSim, the Large Fire Simulator, which stochastically simulates large wildfire ignition and spread across a LANDFIRE fuels landscape, and FFE-FVS, the Forest Vegetation Simulator with the Fire and Fuels Extension, which simulates post-fire regeneration, forest growth, management actions including prescribed fire, fuel dynamics, and fuel consumption and pollutant emissions from prescribed fires and wildfires. Because FSim takes a Monte Carlo approach, simulating fires over 10,000 or more hypothetical fire seasons comprised of daily weather sequences, we will be able to estimate the probability of each landscape pixel burning in a wildfire and the conditional probability of that pixel burning at different flame lengths, allowing us to provide emissions estimates within a risk-assessment framework for managers. The framework will allow land managers to quantify the likelihood that smoke impacts from near-term prescribed fire treatments will be offset by reductions in severe smoke events from future wildfires. Additionally, the smoke event geospatial datasets may provide input into atmospheric transport models which could be used to simulate regional to national scale smoke impacts. We will pilot the project in Okanogan-Wenatchee National Forest, Washington, USA, working with the forest’s managers to design fuel treatment scenarios that will yield realistic fire occurrence trajectories and emission estimates to inform near-term prescribed fire operations. As a U.S. Federal Bipartisan Infrastructure Law Research & Development “proof of concept” project, the Wildland Fire Smoke and Emissions Tradeoff Decision Support project will inform U.S. Forest Service management policy and strategy around the use of prescribed fire in other National Forests in the U.S.

How to cite: Sindewald, L., Urbanski, S., Riley, K., Eckerson, C., Dye, A., and Houtmann, R.: Wildland Fire Smoke and Emissions Tradeoff Decision Support, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14446, https://doi.org/10.5194/egusphere-egu24-14446, 2024.

EGU24-14748 | ECS | Posters virtual | BG1.1

Reconstructing human-fire-vegetation inter-relationships in a protected dry tropical forest, Mudumalai National Park, southern India 

Prabhakaran Ramya Bala, Nithin Kumar, Diptimayee Behera, Anoop Ambili, and Raman Sukumar

Tropical dry forests are recognized globally as the first frontier of human land-use change, due to multiple factors that make them amenable to human occupation, especially with the use of fire. However, in southern India, biodiversity ‘hotspots’ with human habitation are not uncommon with a long-term co-existence of humans in pristine environments. This points to the need for more accurate evidence-based (using charcoal, pollen, phytoliths) understanding of if, when and how land use and land cover changes impact regional vegetation-fire relationships. We reconstruct the environmental history for Mudumalai National Park, a fire-prone dry forest with >30% of the park subject to annual fires and a west-to-east rainfall-vegetation gradient. We examined a 150 cm sediment profile from an excavation in a seasonal wetland in the wettest part. The record spans 1200 years in time (bracketing radiocarbon dates) with very low macrocharcoal counts (mean - 4), with highest numbers in the surface and near-surface layers. Molecular fire proxies Polycyclic Aromatic Hydrocarbons (PAHs) were also found present - Phenanthrene (Phe), Anthracene (Ant), Fluoranthene (Fl), Pyrene (Py), Benzo[ghi]fluoranthene (Bghi), Benz[a]anthracene (BaA), Chrysene (Chr), Benzo(b)fluoranthene (BbF), Benzo(k)fluoranthene (BkF), Benzo[e]pyrene (BeP), Benzo[a]pyrene (BaP), and Perylene (Pry). Notably, Fl, Py, Bghi, BbF, BaA,and BeP constituted 90% of the total concentrations. Diagnostic ratios of PAHs for source determination pointed at a pyrogenic source consistently across all samples. Paleovegetation proxies n-alkanes (C14-C33) were analyzed and the average chain length (ACL) showed a transition towards higher chain lengths towards the surface indicating a change towards grass sources (C31, C33) in addition to woody biomass-derived compounds (C27, C29). Further analysis to characterize the human-fire-vegetation relationships is underway and to our knowledge, as the first report from a protected forest in India, our study offers critical insights for forest fire management in forested landscapes.

How to cite: Ramya Bala, P., Kumar, N., Behera, D., Ambili, A., and Sukumar, R.: Reconstructing human-fire-vegetation inter-relationships in a protected dry tropical forest, Mudumalai National Park, southern India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14748, https://doi.org/10.5194/egusphere-egu24-14748, 2024.

EGU24-14762 | Orals | BG1.1

Climate change has increased fire PM2.5 and its associated health burden 

Chaeyeon Park, Kiyoshi Takahashi, Shinichiro Fujimori, Thanapat Jansakoo, Chantelle Burton, Huilin Huang, Sian Kou-Giesbrecht, Christopher Reyer, Matthias Mengel, and Eleanor Burke

Climate change has influenced fire activities, altering the fire risk associated with air pollution and human health. However, the specific contribution of climate change to fire risks on air pollution and health burden has not yet been discovered. In this study, three fire-vegetation models were employed to simulate fire aerosol emissions under two simulations over the past six decades: an observation climate scenario and a counterfactual scenario where the long-term climate change trend is removed. Combining fire aerosol emissions with a chemical transport model and an avoidable mortality risk model, we calculated global fire PM2.5 and its associated mortality. By comparing the results under the two simulations, we demonstrated the climate change has increased the fire PM2.5 and its mortality. The findings indicated an increase in fire mortality over the six decades: 46,401 in the 1960s and 98,748 in the 2010s, with 3-8% attributed to climate change. Clear relationships were observed between the contribution of climate change to fire mortality and relative humidity or air temperature in some regions. This suggests that fire risks in these regions are sensitive to climate change and necessitate the development of adaptation strategies to mitigate risks in the future.  

How to cite: Park, C., Takahashi, K., Fujimori, S., Jansakoo, T., Burton, C., Huang, H., Kou-Giesbrecht, S., Reyer, C., Mengel, M., and Burke, E.: Climate change has increased fire PM2.5 and its associated health burden, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14762, https://doi.org/10.5194/egusphere-egu24-14762, 2024.

EGU24-14891 | Orals | BG1.1

Fire hazard trajectories under climate change and management scenarios 

Marcos Rodrigues, Pere Gelabert, Teresa Lamelas, Raúl Hoffrén, Juan de la Riva, Darío Domingo, Cristina Vega-García, Paloma Ibarra, Aitor Ameztegui, and Lluís Coll

In this work we showcase the in-progress results from the FirePATHS project (PID2020-116556RA-I00). The project aims to assess the evolution of fire danger under different emission and forest management scenarios through the explicit interaction of the climate-vegetation-fire system. For this purpose, a methodological framework combining different simulation models of the elements of this system is proposed. The core of the process lies in the modeling of vegetation dynamics at stand scale according to different trajectories of climatic evolution to characterize the state and typology of fuels and the subsequent simulation of potential fire behavior during the 21st century.

We analyzed a set of 114 Pinus halepensis plots, surveyed in the field during 2017;  68 plots burned during the summer of 1994 and 46 unburned control stands. We used the medfate model to simulate forest functioning and dynamics, which provides the necessary fuel model parameters to be entered into fire behavior models (Fuel Characteristics Classification System, implemented in medfate as well). The combination of these two approaches provides time-varying estimates of fire behavior metrics (e.g., flame length or rate of spread). The simulation was conducted under SSP climate scenarios (SSP 126, 245, 370 and 585) depicting different levels of climate warming, vegetation dynamics and, hence, fire danger. Likewise, we devised a set of forest management prescriptions aimed at reducing climate vulnerability of tree communities and reducing extreme wildfire potentials. A baseline scenario with no management was also assessed.

We observed very contrasting trajectories between burned and control stands, with the first leading to increasing fuel loads, except in SSP 585. Fire potentials depicted a significant increase in surface fire behavior, with adaptive and mitigation management being able to mitigate it to some extent.

How to cite: Rodrigues, M., Gelabert, P., Lamelas, T., Hoffrén, R., de la Riva, J., Domingo, D., Vega-García, C., Ibarra, P., Ameztegui, A., and Coll, L.: Fire hazard trajectories under climate change and management scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14891, https://doi.org/10.5194/egusphere-egu24-14891, 2024.

EGU24-15398 | Posters on site | BG1.1

Effects of recent increase in anomalous fires and smokes at high latitude regions on regional atmosphere 

Kwon-Ho Lee, Kwanchul Kim, and Dasom Lee

Spatiotemporal patterns and trends of atmospheric aerosols in high latitude region have been analyzed. Aerosol observation data from 2000-2022 acquired from the earth observing satellites including the Moderate Resolution Imaging Spectroradiometer (MODIS), the Ozone Monitoring Instrument (OMI), or geostationary satellites such as the Geostationary Korea Multi-Purpose Satellite-2A (GK-2A) . Results showed that Aerosol Optical Thickness (AOT) over the high latitude region has gradually decreased before 2016. However, AOT has increased significantly over the past 8 years. This increase was clearly shown in North America and North Asia, and was associated with an increase with fire activities. Smoke plumes originated from fire active fires transported eastward with meteorology, but occasionally moved toward the Arctic region. The occurrence of fires and the production and transport of aerosols will be a consequence or factor of the recent rapid climate change.

Acknowledgement: This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2019R1I1A3A01062804).

 

How to cite: Lee, K.-H., Kim, K., and Lee, D.: Effects of recent increase in anomalous fires and smokes at high latitude regions on regional atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15398, https://doi.org/10.5194/egusphere-egu24-15398, 2024.

EGU24-15436 | ECS | Posters on site | BG1.1

Investigation of spatiotemporal variability in South American wildfire emissions and its impacts on CO concentrations 

Maria Paula Velasquez Garcia, Richard Pope, Steven Turnock, and Martyn Chipperfield

Wildfires in South America are a significant concern, causing high emissions and deforestation rates. They affect air quality, radiation balance, and sensitive ecosystems like the Amazon rainforest. Wildfires are expected to intensify with future land use and climate changes, making it crucial to enhance decision-making tools. Models of atmospheric composition, combined with wildfire emissions inventories, support decision-making by simulating events and their impacts on air quality. There are currently a range of wildfire/biomass burning emission inventories, which all use different approaches. This can lead to substantial differences in estimated emissions and thus impacts on atmospheric composition estimation.  This study aims to assess four inventories (2004-2022) in South America: Global Fire Emissions Database (GFED), Fire INventory from NCAR (FINN), Global Fire Assimilation System (GFAS) and Brazilian Biomass Burning Emission Model (3BEM-FRP), focussing on carbon monoxide (CO) given its relatively large emission and complementary satellite missions retrieving atmospheric CO. Our results analyse the temporal consistency in the emission seasonal cycles from the inventories and quantify the spatial agreement/differences between them. We also exploit the Measurements Of Pollution In The Troposphere (MOPITT) retrieved CO to assess the links between emission inventory tendencies with that of the atmospheric temporal evolution. Finally, we use an offline version of the INteractive Fire and Emission algoRithm for Natural envirOnments (INFERNO) model, within the Joint UK Land Environment Simulator (JULES) framework to investigate simulated skill of emissions of CO against the observational constraints above as INFERNO is the fire model of choice in the UK Earth System Model (UKESM).

How to cite: Velasquez Garcia, M. P., Pope, R., Turnock, S., and Chipperfield, M.: Investigation of spatiotemporal variability in South American wildfire emissions and its impacts on CO concentrations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15436, https://doi.org/10.5194/egusphere-egu24-15436, 2024.

EGU24-15518 | Posters on site | BG1.1

Integrating stakeholders’ opinion in land management to build climate resilience in the context of fire risk 

Valentina Bacciu, José Costa Saura, Grazia Pellizzaro, Bachisio Arca, Pierpaolo Duce, Donatella Spano, and Costantino Sirca

The Mediterranean region, already a climate change hotspot, is experiencing milder winters, hotter and drier summers, and increased extreme weather events, leading to longer fire seasons and increasing fire impacts. The socio-economic consequences of wildfires are significant, including the loss of human lives, infrastructure, and economic activity. Additionally, wildfires contribute significantly to climate change, accounting for up to 20% of global greenhouse gas emissions annually. Climate change is expected to worsen these conditions in the near future.

Given these circumstances, it is necessary to accelerate the transition towards the implementation of integrated and holistic fire management approaches aligned with future hazards. In the framework of The HUT project (The Human-Tech Nexus - Building a Safe Haven to cope with Climate Extremes), financed by the Horizon Europe program, the "Ogliastra-DEM8" case study (located in Sardinia, Italy) is aimed at responding to this necessity.

In particular, the main objective of The HUT is to mitigate the effects of climate-related events, by integrating and leveraging best practices and successful multi-disciplinary experiences and focusing on the prevention and preparedness phases of the disaster risk management cycle. In this context, the specific aim of the "Ogliastra-DEM8" case study is to provide the scientific/knowledge base needed to help policymakers and decision-makers defining adaptation and mitigation strategies that are effective in reducing fire impacts and associated costs in the short to medium-term under a changing climate. Towards this end, innovative tools (e.g., fire simulators, catastrophe insurance products, nature-based solutions) and stakeholder engagement, including participatory methods, will be developed.

This work presents the first phase of the work aimed at evaluating enablers and barriers to multi-hazard/systemic risk reduction by (i) reviewing the literature from other projects based in Sardinia, (ii) mapping and engaging stakeholders during an initial round of workshops, and (iii) debating fire-smart land management and adaptation options. Preliminary results indicate key barriers such as stakeholder conflicts, administrative silos, lack of political will, and funding complexities. All these elements contributed to varying degrees to the lack of a comprehensive approach towards integrated and sustainable management of the entire territory. On the other hand, enablers include stakeholder engagement, evidence of performance and co-benefits, and community awareness.

Further work will integrate stakeholder opinions into fire exposure and risk mapping under climate change conditions, with the goal of selecting and co-designing with them which fire-smart land management and adaptation options can be applied and where to protect the most important and vulnerable communities and ecosystems.

How to cite: Bacciu, V., Costa Saura, J., Pellizzaro, G., Arca, B., Duce, P., Spano, D., and Sirca, C.: Integrating stakeholders’ opinion in land management to build climate resilience in the context of fire risk, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15518, https://doi.org/10.5194/egusphere-egu24-15518, 2024.

EGU24-16087 | Posters on site | BG1.1

Assessing post-fire soil erosion and water contamination risk in European fire-affected catchmentswith WEPPcloud-EU WATAR watershed model 

Jonay Neris, Carmen Sánchez-García, Marta Basso, Roger Lew, Anurag Srivastava, Mariana Dobre, Pete Robichaud, Erin Brooks, Cristina Santin, and Stefan Doerr

Soil and ash are key sources of sediment, carbon, nitrogen, and associated pollutant movement following a wildfire. Their transport into freshwater systems can pose severe environmental and socio-economic implications including impacts to water quality and aquatic ecosystems, disruptions to drinking water supply and high remediation costs, as well as the depletion of carbon and nutrients from areas affected by erosion. We assessed the risk of soil erosion, ash and contaminant transport, and water contamination in three burned European catchments in Central Europe (Germany and the Czech Republic), Portugal and Spain using the European Water Erosion Prediction Project cloud interface with the Wildfire Ash Transport and Risk (WEPPcloud-EU WATAR) watershed model. The watersheds varied in size from 100 to 22,000 ha and represent distinct climatic conditions. To our knowledge, this is the first application of this model in European post-fire scenarios. We calibrated and validated the model using catchment runoff data (where available) and nearby streamflow data from both pre- and post-fire periods when runoff data was unavailable. Additionally, we used sediment transport data (where available) along with ash contaminant content data to calibrate and validate erosion and ash transport rates. Model performance was assessed using statistics like Nash-Sutcliffe Efficiency (NSE), coefficient of determination (R2) and percent bias (PBias (%)). Once the model was calibrated and validated, we estimated the post-fire risk of soil erosion, ash transport, and ash pollutant concentrations in the affected areas. The simulations provided the probabilities of occurrence and return periods for severe erosion events, as well as for ash and contaminant transport events. Based on these simulations, we identified hillslopes that were the main sources of runoff, erosion, ash and contaminant transport. This information is important to managers who can prioritize the application of mitigation treatments and prevention plans. Given the projected increase in fire weather in many regions in Europe, our findings suggest that the WEPPcloud-EU WATAR model is an increasingly useful tool in predicting and mitigating soil erosion and water contamination impacts of European burnt catchments.

How to cite: Neris, J., Sánchez-García, C., Basso, M., Lew, R., Srivastava, A., Dobre, M., Robichaud, P., Brooks, E., Santin, C., and Doerr, S.: Assessing post-fire soil erosion and water contamination risk in European fire-affected catchmentswith WEPPcloud-EU WATAR watershed model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16087, https://doi.org/10.5194/egusphere-egu24-16087, 2024.

EGU24-16263 | ECS | Orals | BG1.1

Fire, permafrost, and people: Late Holocene fire regimes and their impacts on lake systems in Yakutia, Siberia 

Ramesh Glückler, Elisabeth Dietze, Stefan Kruse, Andrei Andreev, Boris K. Biskaborn, Evgenii S. Zakharov, Izabella Baisheva, Amelie Stieg, Shiro Tsuyuzaki, Kathleen Stoof-Leichsenring, Luidmila A. Pestryakova, and Ulrike Herzschuh

The Republic of Sakha (Yakutia), the coldest permanently inhabited region on Earth, is characterized by unique ecological relationships between larch forest, permafrost, and wildfires. Together, they can stabilize each other, preserving the larch-dominated biome. Abundant lakes have important cultural and subsistence-related functions and are dynamically connected to warming permafrost processes. Recently intensified wildfire seasons, however, raised questions regarding the causes and impacts of long-term (centennial to millennial) fire regime changes. Despite recent progress, eastern Siberia is still sparsely covered by reconstructions of long-term fire history. This also limits any evaluation of fire regime impacts on permafrost lake development and catchment erosion. Past studies have shown the benefit of combining paleoecological fire reconstructions with geochemical data to shed light on fire regime changes and their impacts on lake catchments, as well as traces of potential human land use.

We present nine new records of Late Holocene wildfire activity, based on macroscopic charcoal in lake sediments (including information on charcoal particle sizes, morphologies, and length to width ratios), accompanied by sediment geochemistry data from high-resolution XRF core scanning. The studied lakes are located in the Lena-Amga interfluve of the Central Yakutian Lowlands, the Verkhoyansk Mountains, and the Oymyakon Highlands. The new data cover both thermokarst and glacial lakes, and a range from remote to rural settings and low to high elevations. Charcoal concentration in the lowland lakes is on average three times as high as in the highland lakes. Contrary to our hypothesis, charcoal concentration in most lakes is negatively correlated to many XRF-derived lithogenic elements indicating detrital input from catchment erosion (e.g., Ti, K). Reminiscent of earlier findings [1], multiple lowland sites share a signal of sharply decreasing biomass burning around 1300 CE. This coincides with the initial settlement of the Sakha people and increased catchment erosion. The new fire reconstructions allow for the evaluation of potential human impacts on past fire regime changes in Yakutia, while improving the region’s representation in global synthesis studies.

[1]  Glückler R. et al. (2021): Wildfire history of the boreal forest of south-western Yakutia (Siberia) over the last two millennia documented by a lake-sediment charcoal record. Biogeosciences 18 (13): 4185–4209. https://doi.org/10.5194/bg-18-4185-2021.

How to cite: Glückler, R., Dietze, E., Kruse, S., Andreev, A., Biskaborn, B. K., Zakharov, E. S., Baisheva, I., Stieg, A., Tsuyuzaki, S., Stoof-Leichsenring, K., Pestryakova, L. A., and Herzschuh, U.: Fire, permafrost, and people: Late Holocene fire regimes and their impacts on lake systems in Yakutia, Siberia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16263, https://doi.org/10.5194/egusphere-egu24-16263, 2024.

EGU24-16293 | ECS | Posters on site | BG1.1 | Highlight

Global atmospheric impacts of aerosols emitted from the 2023 Canadian wildfires 

Iulian-Alin Rosu, Matt Kasoar, Eirini Boletti, Mark Parrington, and Apostolos Voulgarakis

Wildfires are a central but relatively unexplored component of the Earth system. Severe wildfire events can lead to intense destruction of both nature and property, as was the case during the anomalously intense 2023 Canadian wildfire event. Last year, approximately 5% of the total forest area of Canada burned [1] [2], which is the highest wildfire damage Canada has ever sustained [1].

Conditions pertaining to climate change and modifications in atmospheric conditions are considered to be responsible for this record series of wildfires [3]. Increasing mean temperatures and decreasing humidity in the region has exacerbated wildfire risk. Carbon emissions from the 2023 Canadian wildfires have been the highest on record [4], including large amounts of carbonaceous aerosol which can exert substantial atmospheric radiative forcing. Also, Canadian fire emissions contributed around 20% of global emissions from vegetation fires. Thus, beyond the well-known health risks of wildfire emission compounds, it is important to also study the consequences of these emissions on large-scale atmospheric composition and meteorological behavior.

In this work, the global and regional atmospheric impact of the previously mentioned series of wildfires is investigated using the EC-Earth3 and UKESM1 earth system models. Simulated atmospheric conditions with and without the wildfire emissions, as provided by the Copernicus Atmosphere Monitoring Service (CAMS) Global Fire Assimilation System (GFAS), are compared through atmospheric modelling in the context of the Canadian 2023 fire season. The investigation reveals the connections between the emissions produced by this series of wildfires and atmospheric phenomena of importance, such as large-scale circulation, temperature patterns, and precipitation.

[1] "Fire Statistics". Canadian Interagency Forest Fire Centre. Retrieved January 4, 2024.

[2] The State of Canada’s Forests: Annual Report 2022. Canadian Minister of Natural Resources.

[3] Barnes, Clair, et al. "Climate change more than doubled the likelihood of extreme fire weather conditions in eastern Canada." (2023).

[4] “Copernicus: Emissions from Canadian wildfires the highest on record – smoke plume reaches Europe”. Atmosphere Monitoring Service, Copernicus. Retrieved January 4, 2024.

How to cite: Rosu, I.-A., Kasoar, M., Boletti, E., Parrington, M., and Voulgarakis, A.: Global atmospheric impacts of aerosols emitted from the 2023 Canadian wildfires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16293, https://doi.org/10.5194/egusphere-egu24-16293, 2024.

EGU24-16592 | ECS | Posters on site | BG1.1 | Highlight

Exploring the role of post-fire erosion as a carbon sink mechanism 

Antonio Girona-García, Diana Vieira, Stefan Doerr, and Cristina Santín

Wildfires release approximately 2.1 Pg C to the atmosphere each year. The impact of wildfires on the carbon cycle, however, extends well beyond direct emissions, involving complex interactions among various source and sink processes. One such process, the enhanced post-fire soil organic carbon (SOC) erosion, remains unquantified as a potential C sink mechanism. Post-fire SOC erosion functions as a C sink when the subsequent burial and stabilization of eroded C offsite, coupled with the recovery of net primary production and SOC content onsite, outweigh the C losses to the atmosphere during post-fire transport of SOC. In this work, we synthesize published data on post-fire SOC erosion and evaluate its overall potential to act as C sink. In addition, we estimate its magnitude at continental scale following the 2017 wildfire season in Europe, showing that SOC erosion can indeed play a quantitatively significant role in the overall C balance of wildfires. 

How to cite: Girona-García, A., Vieira, D., Doerr, S., and Santín, C.: Exploring the role of post-fire erosion as a carbon sink mechanism, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16592, https://doi.org/10.5194/egusphere-egu24-16592, 2024.

EGU24-16676 | ECS | Orals | BG1.1

Study of greenhouse gases emitted by biomass burnings with a decade of infrared observation of CO2 and CH4 by IASI 

Victor Bon, Cyril Crevoisier, and Virginie Capelle

Biomass burnings are one of the major sources of greenhouse gases in the atmosphere, impacting air quality, public health, climate, ecosystem dynamics, and land-atmosphere exchanges. In the tropics, South America represents about 10 % of the tropical emissions and present a large diversity of biomes and fire conditions. Over the last two decades, satellite observations have provided crucial information, notably via active fires detection, Fire Radiative Power (FRP) estimates and burned area (BA) measurements from imagers such as Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS). Global inventories (e.g., GFED, GFAS, FEER, QFED, etc.) heavily rely on these satellite-derived indicators to estimate emissions from biomass burnings. However, emissions derived from these various models can significantly differ among them and large uncertainties persist regarding fire emissions, their variability, and their links with several drivers (e.g., type of combustion, vegetation, transport, etc.).

In this context, we propose a novel approach to estimate emissions from biomass burnings by directly using greenhouse gas concentrations in the atmosphere derived from spaceborne observations. Leveraging a decade of observations from the Infrared Atmospheric Sounding Radiometer (IASI) on-board the three Metop satellites, we have access to an unprecedented spatial coverage of global mid-tropospheric CO2 and CH4 concentrations twice a day (9:30 AM/PM LT). From this dataset, we developed the Daily Tropospheric Excess (DTE) method, which is based on the use of the diurnal cycle of biomass burnings and the vertical transport of their emissions to link the observed diurnal variations of the mid-tropospheric CO2 and CH4 concentrations to burnings activities.

We will demonstrate the relevance of the DTE for analyzing CO2 and CH4 emissions from various type of burnings, biomes, and human activities across South America. This will be achieved by comparing DTE with existing indices of fire characteristics such as FRP and BA from MODIS/SUOMI satellite observations, alongside global emissions databases like GFED and GFAS. Globally, we will show that their spatial distribution, seasonal intensity, and interannual variability are consistent with each other, even if some differences have been found and will be discussed. Additionally, geostationary data from GOES-R, MSG, and Himawari-8 satellites will be used to analyze the impact of observation times on the differences observed between the various datasets and the DTE.

How to cite: Bon, V., Crevoisier, C., and Capelle, V.: Study of greenhouse gases emitted by biomass burnings with a decade of infrared observation of CO2 and CH4 by IASI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16676, https://doi.org/10.5194/egusphere-egu24-16676, 2024.

EGU24-17593 | Orals | BG1.1

Effect of combustion conditions on aerosol particle emissions from savanna and grassland fires 

Ville Vakkari, Angela Buchholz, Liqing Hao, Mika Ihalainen, Kerneels Jaars, Kajar Köster, Viet Le, Pasi Miettinen, Arya Mukherjee, Saara Peltokorpi, Iida Pullinen, Stefan J. Siebert, Olli Sippula, Markus Somero, Lejish Vettikkat, Annele Virtanen, Pasi Yli-Pirilä, Arttu Ylisirniö, and Pieter G. van Zyl

Fire is an integral part of savanna and grassland biomes and globally approximately half of landscape fire emissions originate from savannas and grasslands. Emissions of trace gases and aerosol particles from landscape fires are characterised by emission factors (EFs), which denote the amount of emitted substance per mass of combusted biomass. EFs vary depending on both the biomass that is consumed in the fire and the combustion characteristics of the fire, i.e. the ratio of flaming to smouldering combustion. However, emission inventories tend to use only one average EF for each biome.

Here, we use a set of 27 laboratory experiments to characterise the effect of combustion characteristics on submicron aerosol EFs from savanna and grassland biomass acquired from South Africa as well as boreal forest floor samples from Finland. Combustion experiments were carried out at the ILMARI facility in Kuopio, Finland from May to June 2022 under an open stack mimicking natural burning and dilution. Sample was injected into a 29 m3 environmental chamber for ageing studies. Chemical and physical properties of both fresh and aged smoke were observed with a host of instruments including e.g. AMS, FIGAERO-CIMS, VOCUS, SP2 and SMPS. The ratio of flaming to smouldering combustion was characterised by modified combustion efficiency (MCE), i.e. CO2/(CO2+CO).

The increase of organic aerosol EF with increasing smouldering fraction (i.e. decreasing MCE) was very similar for both the grassland and savanna combustion experiments. Surprisingly, also the boreal forest floor EFs closely follow the same trend, where smouldering-dominated combustion EFs are more than 10 times higher than EFs for flaming combustion. We observed also that the submicron aerosol particle size distribution shifts towards larger sized particles with increasing smouldering fraction. Furthermore, both the number and the mass of the size distribution cannot be fully characterised with a single log-normal size distribution, which needs to be considered when converting mass emissions into number size distribution in simulations.

How to cite: Vakkari, V., Buchholz, A., Hao, L., Ihalainen, M., Jaars, K., Köster, K., Le, V., Miettinen, P., Mukherjee, A., Peltokorpi, S., Pullinen, I., Siebert, S. J., Sippula, O., Somero, M., Vettikkat, L., Virtanen, A., Yli-Pirilä, P., Ylisirniö, A., and van Zyl, P. G.: Effect of combustion conditions on aerosol particle emissions from savanna and grassland fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17593, https://doi.org/10.5194/egusphere-egu24-17593, 2024.

EGU24-17935 | Posters on site | BG1.1

The FLARE Workshop perspective on Fire’s Role in the Carbon Cycle 

Chantelle Burton, Stephen Plummer, Noah Liguori-Bills, Morgane Perron, Douglas Kelley, Miriam Morrill, Boris Vannière, Joanne Hall, Stijn Hantson, Matthias Forkel, Christoph Völker, Kebonye Dintwe, Cristina Santin, Jessie Thoreson, Benjamin Poulter, Matthew Jones, and Douglas Hamilton

Fire substantially influences and modulates the global carbon cycle through numerous processes, interactions, and feedbacks. Fires are also strongly intertwined with human activities; people act both as drivers of change through ignitions, suppression, land-cover change, prescribed burning, and climate change, and are affected in return by changes in fire regimes. 

Despite fire’s many complex interactions throughout the Earth System, it is often viewed only as a destructive process, and one that solely acts as a source of atmospheric carbon. In terms of fire’s carbon budget, the release of carbon only represents the very initial stages of the process, missing the drivers and complex ways in which fire shapes plant species evolution and ecosystem trajectories, nutrient cycling and redistribution, carbon allocation, deposition and sequestration over different spatiotemporal scales. Therefore, there is a clear need to fully understand the role of fire in the Earth System holistically. However, different aspects of fire’s role in the carbon cycle are often studied by different communities and disciplines, hindering this much-needed integrated understanding. 

Through the Fire Learning AcRoss the Earth Systems (FLARE) workshop (September 2023) we brought together fire scientists across multiple disciplines to facilitate transdisciplinary discussion. We propose that the visualization of fire processes as carbon colours across the Earth System can be a thematic tool for unifying disciplines. It explores all aspects of fire and smoke implications for living systems and opens questions about fire’s role in carbon budgets, afforestation, and climate change and related mitigation strategies. We also identified several scientific challenges for the community where, by working together, we can address some fundamental questions for fire’s role in the carbon cycle, such as: What is the contribution of fire and of individual fire events to the global carbon cycle? How do changes in fire regimes influence ecosystem stability across different timescales? How do future changes in fire regimes influence global climate, allowable emissions and carbon budgets, and temperature mitigation ambitions? In this presentation, we explore how we can bring a more interdisciplinary approach to fire science to address these fundamental questions.

How to cite: Burton, C., Plummer, S., Liguori-Bills, N., Perron, M., Kelley, D., Morrill, M., Vannière, B., Hall, J., Hantson, S., Forkel, M., Völker, C., Dintwe, K., Santin, C., Thoreson, J., Poulter, B., Jones, M., and Hamilton, D.: The FLARE Workshop perspective on Fire’s Role in the Carbon Cycle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17935, https://doi.org/10.5194/egusphere-egu24-17935, 2024.

EGU24-18169 | ECS | Posters on site | BG1.1 | Highlight

What makes a fire grow extremely large? 

Rebecca Scholten, Tirtha Banerjee, Yang Chen, Ajinkya Desai, Tianjia Liu, Douglas Morton, Sander Veraverbeke, and James Randerson

Wildfires are an important disturbance in global ecosystems and are a critical driver of trends in the land carbon budget. Fire is an extreme phenomenon, with the largest burned area often occurring during extreme fire seasons generating large fires. Days with fire conditions conducive to fire ignition and spread are increasing in a warming climate in many regions of the world, contributing to increases in fire occurrence and annual burned area. However, the climate, fuel, and weather conditions that lead to extremely large fires in different biomes are poorly understood.

Here, we explore the temporal evolution of extremely large fires in temperate and boreal regions using new satellite-derived fire event tracking datasets optimized to match higher resolution time series of fire progression from aircraft and other sources. We aimed to understand the specific environmental conditions required for the development of a large fire. Our analysis revealed a disproportionate impact of multiple fire ignitions in creating large fires through merging. Our findings suggest that the largest fires in both biomes may be commonly created through multiple fires growing together. We hypothesize that a combination of physical and anthropogenic factors may accelerate merging, making these fires extremely difficult to contain and more robust to environmental controls regulating extinction. In our analysis, we use the Fire Events Database, the Arctic-boreal Fire Atlas, and GOFER, which enable attribution of ignition sources. Our analysis may contribute to an improved understanding of the influence of large-scale lightning storms in creating extremely large and destructive fire events.

How to cite: Scholten, R., Banerjee, T., Chen, Y., Desai, A., Liu, T., Morton, D., Veraverbeke, S., and Randerson, J.: What makes a fire grow extremely large?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18169, https://doi.org/10.5194/egusphere-egu24-18169, 2024.

EGU24-18811 | Posters virtual | BG1.1

Taking advantage of satellite data, large datasets of fire records and cloud computing for modelling potential fire severity useful for better assess fire risk 

José Maria Costa Saura, Valentina Bacciu, Donatella Spano, and Costantino Sirca

Fire risk analyses, usually focused on fire hazard (i.e. the probability of fire occurrence), often neglect an important issue such as the sensitivity/vulnerability (i.e., the degree of potential damage, sensus IPCC) of different locations within the area of interest.  Such lack of consideration comes from past data processing constrains that limited fire severity studies to analyse only single or few fire events. Nowadays, online data repositories and processing platforms (e.g. Google Earth Engine) allow to easily integrate and process a vast amount of data from multiple sources that might prove useful for developing tailored tools for decision making. Here, we present an example for predicting potential fire severity based on the analysis of more than 1 000 fire events from southern France and western Italy which integrates climate, topographical and remote sensing variables. Furthermore, we assessed if the model “used” the explanatory variables under a meaningful biophysical sense.   Using the random forest algorithm and the relativized difference of the Normalized Burn Ratio (rdNBR) as proxy of fire severity, we reach to explain up to 75% of the variability in the data with most of the variables showing a clear and interpretable effect. Our results suggests that this type of approach might prove useful for better address fire risk assessments.

How to cite: Costa Saura, J. M., Bacciu, V., Spano, D., and Sirca, C.: Taking advantage of satellite data, large datasets of fire records and cloud computing for modelling potential fire severity useful for better assess fire risk, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18811, https://doi.org/10.5194/egusphere-egu24-18811, 2024.

EGU24-18894 | ECS | Posters virtual | BG1.1

Mapping open burning of agricultural residues from Earth Observations 

Eduardo Oliveira, João Gata, Diogo Lopes, Leonardo Disperati, Carla Gama, and Bárbara Silva

Agricultural residue burning is a common practice in various regions of the world, which may have several environmental impacts, including on air quality, and the potential for triggering wildfires. In Portugal, this practice is particularly prevalent during the wet season, spanning from October to April. It involves open field burning of pruning residues and extensive burning to clear shrubbery, creating pastures for livestock. This research, conducted within the framework of the PRUNING project - Mapping open burning of agricultural residues from Earth Observations and modelling of air quality impacts- aims to explore the potential for detecting such events through satellite remote sensing.

The primary focus of this study is to assess the limitations of satellite remote sensing detection, with the overarching aim of integrating these findings into a systematic monitoring framework for open burning of agricultural residues. Additionally, the study aims to predict pollutant emissions and assess their impacts on air quality, providing valuable insights for environmental management and sustainable agricultural practices.

To achieve this goal, an in-depth analysis of known burning events was conducted using infrared thermal sensors. Multiple products, including Fire Radiative Power and fire masks from various sensors (e.g., MODIS, VIIRS, and Sentinel 3), were employed to characterize these known open field burning events. The results of this work allow verifying the tradeoffs effects associated with spatial, spectral, and temporal resolutions for each sensor, elucidating their impacts on the precision and accuracy of event detections. In parallel, this study evaluated the accuracy of the MINDED-FBA method in characterizing these known events. This automatic detection method, allows incorporating data from higher spatial resolution sensors (e.g., Sentinel-1, Sentinel-2, Landsat), for determining the extent of burned areas through multiple multispectral indices. In this context, the MINDED-FBA method may also be used to validate thermal anomalies detection products. Finally, the results of this work have also been compared to a national level register database of open burning, provided by the ICNF (Institute for Nature Conservation and Forests).

How to cite: Oliveira, E., Gata, J., Lopes, D., Disperati, L., Gama, C., and Silva, B.: Mapping open burning of agricultural residues from Earth Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18894, https://doi.org/10.5194/egusphere-egu24-18894, 2024.

EGU24-18941 | Orals | BG1.1

Arctic peat fire emissions estimated from satellite observations of fire radiative power 

Johannes Kaiser, Kerstin Stebel, Philipp Schneider, and Vincent Huijnen

Exceptional wildfire activity occurred in the Arctic during the last years due to pronounced heat episodes. The Arctic has an abundance of peat and soils with organic content. When peat is burnt, the carbon flux into the atmosphere is virtually irreversible and this process may become of global significance for Arctic fires. Furthermore, smoke from smoldering fires (below-ground, peat) has a different chemical composition than smoke from flaming fires. It is therefore important to distinguish peat fires and above-ground, potentially flaming fires in fire emission estimation.

The operational Copernicus Atmosphere Monitoring Service (CAMS) is tracking global fire activity and emissions with its Global Fire Assimilation System (GFAS) as a near-real time service. GFAS uses satellite-based observations of fire radiative power (FRP), which links observed thermal radiation directly to the biomass combustion rate, i.e. amount of biomass burnt and corresponding emission of carbon into the atmosphere, based on satellite retrievals from MODIS and VIIRS. 

Here, we present a partitioning of the Arctic fire activity represented in GFAS into smoldering below-ground and potentially flaming above-ground fires using two approaches: (1) masking the fire activity maps with published peat maps and (2) analysing the observed diurnal cycles of the fire activity at all locations. We subsequently apply adapted emission factors and compare the resulting emission estimates to the standard values produced by CAMS for carbon, carbon monoxide, nitrogen dioxide and aerosols.

Furthermore, we may confront the fire emission estimates with independent atmospheric smoke observations by feeding them into IFS-COMPO, which is used to generate hindcasts of atmospheric composition, including tropospheric columns of CO and NO2. This allows an evaluation of the estimated trace gas emissions, by comparing the model simulations to satellite retrievals of carbon monoxide and nitrogen dioxide. It thus provides an independent assessment of the estimated fire emissions, and, in turn, carbon flux.

How to cite: Kaiser, J., Stebel, K., Schneider, P., and Huijnen, V.: Arctic peat fire emissions estimated from satellite observations of fire radiative power, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18941, https://doi.org/10.5194/egusphere-egu24-18941, 2024.

EGU24-18977 | Orals | BG1.1 | Highlight

Global seasonality of small-scale livelihood fire 

Matthew Kasoar, Cathy Smith, Ol Perkins, James Millington, and Jayalaxshmi Mistry

Landscape fires are increasingly represented in dynamic global vegetation models to understand impacts on carbon emissions and climate. Deliberate human fire use and management influence landscape fire characteristics, varying in space and time depending on social, economic, and ecological factors. For example, fire is used variously in rural livelihoods involving e.g., agriculture, hunting, gathering, and for other cultural practices, often depending on the time of year. Yet existing global fire models typically represent human fire use as a constant function of gridded datasets such as population density or gross domestic product.

Recently, initiatives have begun to draw together available data on global fire use from across multiple disciplines and disparate sources into coherent databases. We draw on information from one of these databases, the Livelihood Fire Database (LIFE), which includes case studies in 587 locations worldwide, to assess the availability of data on seasonality of anthropogenic fires associated with small-scale rural livelihoods. By defining seasonal cycles relative to the local variation of precipitation and evapotranspiration at each case study location, we look for patterns in the spatiotemporal nature of anthropogenic fires associated with different fire-use purposes - such as clearing vegetation for agriculture, maintaining pasture for livestock, or driving game when hunting - and consider the potential for this analysis to inform fire models.

For many fire types, especially those related to hunting, gathering, human wellbeing, and social signalling, there are limited quantitative data available, but it is possible to draw qualitative insights from case studies. Where quantitative data are available, we find some correspondence between fire seasonality and the intended fire-use purpose, suggesting that distinguishing between distinct fire-use purposes could improve the representation of human fire use in fire models, and consequently the seasonal cycle of fire emissions. Case studies demonstrate that environmental and social conditions drive variation in fire use for the same purpose, reiterating that a wide range of factors influence human behaviour and that assumptions of uniform drivers of anthropogenic fire may be misleading. Many of the fires now being revealed in global burned area data by new fine-scale remote sensing products are likely human-set; continued collection, collation, and analyses of data on human fire use globally is important to ensure appropriate anthropogenic representation in fire models.

How to cite: Kasoar, M., Smith, C., Perkins, O., Millington, J., and Mistry, J.: Global seasonality of small-scale livelihood fire, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18977, https://doi.org/10.5194/egusphere-egu24-18977, 2024.

EGU24-19223 | ECS | Posters virtual | BG1.1

Monitoring wildfires from satellite, integration in Copernicus services and characterizing atmospheric impacts from the regional to the global scales 

Dominika Leskow-Czyżewska, Stephan Bojinski, Julien Chimot, Andrea Meraner, Mark Parrington, and Federico Fierli

Satellite-borne observations offer the possibility to monitor wildfires and their impact worldwide. In addition, satellite products are increasingly used in early warning and forecasting systems for fire management. Europe is implementing a long-term and reliable observational programme and, within this frame, EUMETSAT, the European meteorological satellite operator, provides numerous observational products ranging from near-real-time wildfire identification (e.g. fire radiative power) to atmospheric impacts (e.g. major pollutants and smoke). 

Our presentation will focus on the satellite data value chain, e.g. the integration in the Copernicus Atmosphere Monitoring Service (CAMS) Global Fire Assimilation System (GFAS). To do that, we will firstly present datasets addressing wildfires (e.g. Fire Radiative Power, atmospheric composition, and smoke) currently generated at EUMETSAT and its Satellite Applications Facility (SAF). We will also introduce upcoming (based on the Flexible Combined Imager on-board the Meteosat Third Generation) and future products (Sentinel-4 and 5), with an example of potential joint use for a past intense fire case in the Mediterranean (Greece, August 2023).  

We will then show the entire value chain, including how the data is used in the Copernicus Atmosphere Monitoring Service (CAMS) Global Fire Assimilation System (GFAS), with an example on the recent intense and anomalous fire season in Canada (spring to summer 2023). This will show how distinct phases of wildfires management – from early warnings up to the impacts on yearly emissions – can be monitored with the synergy of satellite data and Copernicus forecast and analysis. Finally, we will touch also on the user support activities within EUMETSAT in this area. 

How to cite: Leskow-Czyżewska, D., Bojinski, S., Chimot, J., Meraner, A., Parrington, M., and Fierli, F.: Monitoring wildfires from satellite, integration in Copernicus services and characterizing atmospheric impacts from the regional to the global scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19223, https://doi.org/10.5194/egusphere-egu24-19223, 2024.

EGU24-19330 | Orals | BG1.1

Burned Area Mapping with Sentinel-2 based on reflectance modelling and deep learning – preliminary global calibration and validation 

Marc Padilla, Ruben Ramo, Sergio Sierra, Bernardo Mota, Roselyne Lacaze, and Kevin Tansey

Current global burned area products are available at coarse spatial resolutions (300-500 m), what leads to large amounts of errors, hindering an accurate understanding of fire-related processes. This study proposes a global calibration method for a sensor-independent burned area algorithm, previously used with 300 m Sentinel-3 Synergy data, and here implemented with 20 m Sentinel-2 MSI imagery. A binomial model that combines reflectance-based burned area predictions constrained by spatio-temporal densities derived from VIIRS active fires is calibrated using a reference dataset generated from Landsat imagery at a sample of 34 units across the globe. Preliminary leave-one-out cross-validation analyses show promisingly high accuracies (Dice of coefficient of 84.8%, commission error ratio of 13.2%, omission error ratio of 17.1% and relative bias of -4.5%), especially taking into account the mismatch of acquisition dates between reference and algorithm input data, what introduces apparent errors on the validation results.

How to cite: Padilla, M., Ramo, R., Sierra, S., Mota, B., Lacaze, R., and Tansey, K.: Burned Area Mapping with Sentinel-2 based on reflectance modelling and deep learning – preliminary global calibration and validation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19330, https://doi.org/10.5194/egusphere-egu24-19330, 2024.

EGU24-19716 | ECS | Posters on site | BG1.1

"Fire impacts in the Cerrado: Integrating LiDAR and field data to monitor vegetation structure and post-fire recovery." 

Manoela Machado, Wesley da Cruz, Maria Antonia Carniello, Emily Sturdivant, Francisco Navarro-Rosales, Marcia Macedo, Wayne Walker, and Imma Oliveras Menor

Fire is a natural disturbance capable of altering plant distributions and community assemblages, influencing species evolution through the selection of traits and strategies, and affecting biogeochemical cycles. This powerful tool of landscape transformation can negatively impact even a fire-dependent ecosystem when natural fire regimes are altered. In recent times, interactions between human activities in the Cerrado (e.g., deforestation and intentional fires used to clear land), and a hotter and drier climate (due to climate change), have altered natural fire regimes causing more frequent and intense fire events, negatively impacting biodiversity, human health, and the regional climate. These fire-disturbed areas are widespread and highly vulnerable to future degradation from compounding disturbances, but they still harbour valuable biodiversity and carbon stocks that deserve protection and restoration. Monitoring the impacts of fire disturbance on vegetation structure and the potential pathways of recovery is critical to understand and protect resilient ecosystems under a rapidly changing climate. Robust monitoring requires the integration of modelled and field-based data tools and techniques. Field inventories alone are insufficient to capture the spatiotemporal variability of impacts of fire on native vegetation and should be coupled with remotely sensed data, among which, LiDAR (light detection and ranging) is unparalleled in characterising 3-D vegetation structure. Thus, the combination of LiDAR and forest inventory data is ideally suited for scaling the impacts of fire on forest vegetation and associated carbon stocks. In this study, we are assessing key metrics of vegetation structure derived from a combination of LiDAR and field data collected at the Experimental Station Serra das Araras, Mato Grosso state, Brazil. This field site comprises Cerrado vegetation that has been subject to three experimental fire treatments: every year, every two years, and every three years beginning in 2017, as well as fire suppression for over three decades. We are investigating whether key vegetation structural metrics can capture different fire treatments and identify spatial patterns of disturbance. We are also assessing if these patterns are different when comparing LiDAR data collected with a handheld scanner versus an airborne drone. This study aims to refine our methods and improve our understanding of vegetation structure responses across a gradient of fire disturbance regimes and potential post-fire recovery trajectories, which are key not only for ecological studies but also for emerging carbon markets – one of several mechanisms aimed at achieving climate change mitigation, conservation, and sustainable development outcomes. We hope to improve the process of carbon stock mapping in disturbed ecosystems and use the outputs to drive scenarios modelling at larger scales, providing a more comprehensive assessment of what future Cerrado carbon dynamics might look like under a range of possible disturbance/recovery dynamics.

How to cite: Machado, M., da Cruz, W., Carniello, M. A., Sturdivant, E., Navarro-Rosales, F., Macedo, M., Walker, W., and Oliveras Menor, I.: "Fire impacts in the Cerrado: Integrating LiDAR and field data to monitor vegetation structure and post-fire recovery.", EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19716, https://doi.org/10.5194/egusphere-egu24-19716, 2024.

EGU24-20564 | ECS | Orals | BG1.1 | Highlight

Future global wildfire regimes under high and low climate mitigation efforts  

Olivia Haas, Colin Prentice, and Sandy P. Harrison

There is growing concern over future trajectories of burning on Earth. One the one hand, some regions have seen the emergence of large and novel wildfires, whilst satellite observations continue to show declining burnt area globally, most notably in the tropics. Quantifying the response of global wildfire regimes to future changes in especially challenging given that wildfires are driven by climate, vegetation, and human activities, and that these different factors may have contrasting and opposing effects.

Using global empirical models of burnt area, fire size and fire intensity we explore the trajectory of future fire regimes under high and low climate change mitigation efforts. The models are driven by lightning ignitions, climate, vegetation properties, topography, and human factors. Making use of a set of sensitivity analysis, we show a global shift in wildfire patterns by the end of the 21st century even with warming kept below 1.5°. Burning will generally be reduced in tropical regions but larger and more intense wildfires will occur in extra-tropical regions. Under low mitigation, increases in burnt area worldwide overwhelm the human-driven decline, with up to a 60% increase in burnt area by the end of the century. However, fire size and intensity will be increasingly limited by dryness and vegetation fragmentation.

These results suggest that even under high climate change mitigation, fire management strategies must urgently be revised as current fire-suppression policies will no longer be effective in much of the world. Regional-level fire management, led by local stakeholders, should be encouraged. Wildfire risk and management must also be incorporated into mitigation scenarios that rely on extending forest area if these mitigation scenarios want to remain realistic.

How to cite: Haas, O., Prentice, C., and Harrison, S. P.: Future global wildfire regimes under high and low climate mitigation efforts , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20564, https://doi.org/10.5194/egusphere-egu24-20564, 2024.

EGU24-2140 | ECS | Posters on site | BG1.3 | Highlight

Enhanced methane concentrations measured over the Amazon rainforest 

Linda Ort, Lenard Lukas Röder, Peter Hoor, Jos Lelieveld, and Horst Fischer

Recently, global mean methane concentrations have increased strongly. Methane is one of the most important greenhouse gases and plays a key role in atmospheric chemistry. Especially, due to its long lifetime of approx. 10 years and its significant effect on Earth’s climate change, a detailed knowledge of its source regions and their temporal evolution is crucial.

In this study, we present a unique data set of methane measured in situ over the Amazon rainforest region during the wet season in the CAFE Brazil (Chemistry of the Atmosphere Field Experiment) aircraft campaign from December 2022 to January 2023 in Manaus, Brazil. Methane was measured with an infrared quantum cascade laser absorption spectrometer on board the High Altitude and LOng-range aircraft (HALO). These observations show enhanced concentrations of methane in and above the boundary layer of the Amazon rainforest. Locally, dry air mixing ratios of up to approx. 2100 ppbv could be measured up to 4 km of altitude. Detailed analysis shows only a small contribution from anthropogenic sources. Especially over permanent wetlands and deforested areas, the methane concentrations were enhanced. Furthermore, the data has been compared to satellite measurements from the National Oceanic and Atmospheric Administration (NOAA), indicating good agreement in the free troposphere. Nevertheless, the mean levels directly above the Amazon rainforest are approx. 100 ppbv higher than the global background. Moreover, a global distribution based on airborne data from several campaigns (PHILEAS 2023, CAFE Brazil 2022/23, SouthTrac 2019, CAFE Africa 2018, WISE 2017, ATom 2016/17, OMO 2015, ESMVal 2012) shows that the methane surface concentrations over the Amazon rainforest has a local maximum. This calls for more detailed investigations of methane near the surface in the Amazon and raises an important question: Have we underestimated the Amazon rainforest as a significant source of the global methane budget?

How to cite: Ort, L., Röder, L. L., Hoor, P., Lelieveld, J., and Fischer, H.: Enhanced methane concentrations measured over the Amazon rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2140, https://doi.org/10.5194/egusphere-egu24-2140, 2024.

Land and freshwater ecosystems play a significant role in affecting the global methane budget. With future warming, the increase of methane emissions could create large positive feedbacks to the global climate system.  We have used observation data of methane fluxes from diverse land and freshwater ecosystems to calibrate and evaluate extant land and freshwater biogeochemistry models of the Terrestrial Ecosystem Model (TEM) and the Arctic Lake Biogeochemistry Model (ALBM) to quantify the global methane emissions for the past few decades and the 21st century in a temporally and spatially explicit manner. Land ecosystems could emit methane from wetlands while uplands could uptake atmospheric methane. TEM simulates that global wetlands emissions are 212 ± 62 and 212 ± 32 Tg CH4 yr−1 due to uncertain parameters and wetland type distribution, respectively, during 2000–2012. After combining the global upland methane consumption of −34 to −46 Tg CH4 yr−1, we estimate that the global net land methane emissions are 149–176 Tg CH4 yr−1 due to uncertain wetland distribution and meteorological input. During 1950–2016, both wetland emissions and upland consumption increased during El Niño events and decreased during La Niña events. For freshwater ecosystems, we find that current emissions are 24.0 ± 8.4 Tg CH4 yr−1 from lakes larger than 0.1 km2. Future projections under the RCP8.5 scenario suggest a 58–86% growth in emissions from lakes.  Warming enhanced methane oxidation in lake water can be an effective sink to reduce the net release from global lakes. Additionally, these studies identify the key biogeochemical and physical processes of controlling methane production, consumption, and transport in various hotspot emission regions.  We also highlight the need for more in situ methane flux data, more accurate wetland and lake type and their area distribution dynamics information to better constrain the quantification uncertainty of global biogenic methane emissions across the landscape.

How to cite: Zhuang, Q.: Quantifying global biogenic methane emissions from land and freshwater ecosystems across the landscape , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2178, https://doi.org/10.5194/egusphere-egu24-2178, 2024.

EGU24-2479 | ECS | Posters on site | BG1.3

The UFLUX ensemble of multiple-scale carbon, water, and energy fluxes. 

Songyan Zhu and Jian Xu

In light of the challenges posed by climate change, global governments, including the United Kingdom (UK), have committed to addressing and mitigating the impacts of climate change, emphasizing the pursuit of Net Zero objectives. The terrestrial ecosystems on a global scale, functioning as pivotal carbon reservoirs, assume a critical role in climate change mitigation, especially within the context of an imminent scenario marked by accelerated warming and drying conditions. Recognizing that the carbon sequestration capacity of ecosystems is intricately linked to their energy and water cycling dynamics, this study presents the Uniform FLUXes (UFLUX)-ensemble dataset (https://sites.google.com/view/uflux) that accurately quantifies carbon, water, and energy fluxes across ecosystems in a consistent and mutually comparable manner. The UFLUX ensemble, relying on the upscaling of in-situ eddy covariance (EC) tower measurements using satellite vegetation proxies and meteorology reanalysis, constitutes the methodological foundation of this research.

The UFLUX originated from our prior investigations into filling gaps in EC fluxes. This is due to the analogous nature of the procedures involved in flux gap-filling and upscaling, wherein both entail the interpolation/extrapolation of fluxes, albeit in the temporal and spatial domains, respectively. The fluxes in UFLUX are upscaled through the application of a uniform set of algorithms and environmental determinants, aiming to mitigate the sources of uncertainty. The UFLUX methodology has demonstrated effectiveness in capturing the global CO2 fertilization effect. Furthermore, it has exhibited resilience to agricultural management interventions and has adeptly captured flux variability at a high spatial resolution of 20 meters in southwest England. These accomplishments lay the groundwork for generating the UFLUX-ensemble dataset.

The resulting UFLUX-ensemble dataset incorporates 60 members considering specific advantages of multiple satellite and meteorology reanalysis products. Aligned with the Net Zero vision articulated by nations, and recognizing the imperative of addressing data storage requirements, the dataset is made available on three scales: 1) daily 100-m resolution for the UK, 2) half-yearly 100-m resolution for Europe, and 3) monthly 0.25°×0.25°resolution for the entire globe. This diverse data provision is designed to assist climate actions, particularly in countries grappling with specific socio-economic challenges. A rigorous technical validation underscores the merits of the UFLUX ensemble, demonstrating its ability to capture 0.8 % of the flux variability with errors amounting to 0.76 g C m-2 d-1 and 11.67 W m-2. The UFLUX-ensemble dataset serves as a valuable resource, offering insights to inform land management practices, including nature-based solutions, with the overarching objective of augmenting carbon sequestration in terrestrial ecosystems and contributing to the realization of a carbon-neutral future.

How to cite: Zhu, S. and Xu, J.: The UFLUX ensemble of multiple-scale carbon, water, and energy fluxes., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2479, https://doi.org/10.5194/egusphere-egu24-2479, 2024.

EGU24-2492 | Orals | BG1.3

Future CH4 budgets as modelled by a fully coupled Earth system model using prescribed GHG concentrations vs. interactive CH4 sources and sinks 

Ulas Im, Kostas Tsigaridis, Susanne Bauer, Sabine Eckhardt, Drew Shindell, Lise Lotte Sørensen, and Simon Wilson

We have used the NASA Goddard Institute for Space Studies (GISS) Earth system model GISS-E2.1 to study the future budgets and trends of global and regional CH4 under different emission scenarios. GISS-E2.1 is one of the few ESMs that can be driven by anthropogenic CH4 emissions, as well as interactive natural sources such as wetlands, and can simulate the tropospheric CH4 chemistry. In frame of the recent short-lived climate forcers (SLCFs) assessment by the Arctic Monitoring and Assessment Programme (AMAP), we used the GISS-E2.1 model with prescribed long-lived greenhouse gas (GHG) concentrations. In the present study, we have supplemented these simulations using the interactive CH4 sources and sinks in order to quantify the model performance and the sensitivity to CH4 sources and sinks. We have used the Current Legislation (CLE) and the Maximum Feasible Reduction (MFR) emission scenarios from the Eclipse V6b emission database to simulate the future chemical composition and climate impacts from 2015 to 2050. We have also simulated 1995-2014 in order to evaluate the model performance following the AMAP-SLCF protocol.

The prescribed GHG version underestimates the Global Atmospheric Watch (GAW) surface CH4 observations during the period between 1995 and 2023 by 1% [-8.4%-2.0%], with a correlation (r) of 0.71 [-0.41 0.99]. The largest underestimations are over the continental emission regions such as North America, Europe, and Asia, while biases are smallest over oceans. On the other hand, the simulation with interactive sources and sinks underestimates the GAW observations more than the prescribed simulation, by 18.5% [-25% -10.4%], with a lower r of 0.36 [-0.82 0.93]. Opposite to the prescribed simulation, the biases are largest over oceans and smaller over the continents, however they are still larger over land than the prescribed simulation. The interactive simulation, with large sources virtually over land and strong sink over oceans, has a land/ocean ratio larger than 1 while the prescribed simulation has this ratio equal to 1 as it distributes the global prescribed CH4 concentration equally in longitude over a given latitude. This clearly shows that the interactive sources and sinks should be represented in models in order to realistically simulate the chemical composition and the oxidative capacity of the atmosphere.

As expected, the MFR scenario simulates lower global surface CH4 concentrations and burdens compared to the CLE scenario, however in both cases, global surface CH4 and burden continue to increase through 2050 compared to present day.  In the CLE scenario, increases are largest over the equatorial belt, in particular over India and East China, while the MFR scenario shows increases over the whole Southern Hemisphere, however much smaller compared to CLE. Finally, the interactive simulation shows that the chemical CH4 sink increases in the CLE scenario, while it slightly decreases in the MFR, leading to a larger CH4 lifetime in the MFR scenario compared to in the CLE scenario.

How to cite: Im, U., Tsigaridis, K., Bauer, S., Eckhardt, S., Shindell, D., Sørensen, L. L., and Wilson, S.: Future CH4 budgets as modelled by a fully coupled Earth system model using prescribed GHG concentrations vs. interactive CH4 sources and sinks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2492, https://doi.org/10.5194/egusphere-egu24-2492, 2024.

Radiocarbon can be used as an independent and objective tracer to evaluate fossil fuel CO2 (CO2ff) emissions, because of its complete depletion in fossil fuel sources. Here, we present a study on the CO2ff emissions reduction during the COVID-19 lockdowns in 2020 based on atmospheric Δ14CO2 observation at Chinese background sites. We observed obvious enhancements (several per mill to dozens of per mill) of atmospheric Δ14CO2 during the COVID-19 lockdowns compared with that in the same period. A preliminary analysis showed that these enhancements indicate several percepts to dozens of percents CO2ff emissions reduction from Eurasia (exclude China) and different parts in China during the COVID-19 lockdowns.

How to cite: Niu, Z.: Decrease in fossil fuel CO2 emissions during COVID-19 lockdowns based on  Δ14CO2 observation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3721, https://doi.org/10.5194/egusphere-egu24-3721, 2024.

EGU24-4150 | ECS | Posters on site | BG1.3

Satellite-driven model to upscale Irish CO2 Net Ecosystem Exchange (ICONEEx) 

Wahaj Habib and John Connolly

Climate change poses a significant environmental challenge for humanity, and accurately predicting its intensity as well as its impact on terrestrial ecosystems is crucial. To achieve this, monitoring, modelling, and mapping greenhouse gas (GHG) exchanges between the biosphere and the atmosphere is essential. Monitoring is also important to achieve the European Union’s goal to achieve a balance between GHG emissions and removals by 2050 and maintain negative emissions thereafter. While in situ measurement techniques, such as the eddy covariance flux tower (ECFT), have been used for decades to measure ecosystem-level exchanges of carbon, such as Net Ecosystem Exchange (NEE) of CO2, their footprint is limited to only 1 km². To overcome this limitation, satellite remote sensing data has been used to upscale these measurements to regional and global scales, but previous work has relied on low-resolution remote sensing data, such as the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor (at 250m or 500m spatial resolution).

 

This study aims to use a combination of high-resolution remote sensing data and measurements from in situ ECFT data to model the NEE of CO2 across ~92% of Ireland's terrestrial area, covering major land covers such as wetlands (coastal and peatlands), grassland, and forestry. The model will integrate datasets from both ESA (Copernicus Sentinel-1 and 2) and NASA (MODIS PAR) with the light response curve parameters derived from the ECFT data in Ireland, to model NEE CO2 at a national scale. The results will be useful for monitoring, reporting, and verifying NEE across a range of ecosystems in Ireland. They can also be used to enhance National Inventory Reporting and national ambitions on climate, influence targeted policymaking, and verify land management decisions.

How to cite: Habib, W. and Connolly, J.: Satellite-driven model to upscale Irish CO2 Net Ecosystem Exchange (ICONEEx), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4150, https://doi.org/10.5194/egusphere-egu24-4150, 2024.

EGU24-4196 | Orals | BG1.3

Drivers of ocean carbon sink variability across spatial scales 

Galen McKinley, Amanda Fay, Dustin Carroll, and Dimitris Menemenlis

Since the preindustrial era, the ocean has removed roughly 40% of fossil CO2 from the atmosphere, and it will eventually absorb at least 80% of human CO2 emissions. While there is no doubt that the ocean is a critical player in the global carbon cycle, many uncertainties remain and the drivers and magnitude of interannual-to-decadal timescale variability remain poorly constrained. A key question is the extent to which external forcing, specifically the variability of the atmospheric pCO2 growth rate, or internal ocean variability is the dominant mechanism of variability. We use a suite of experiments from the ECCO-Darwin data-assimilative ocean biogeochemistry model to isolate and explore the impact of these two drivers. We demonstrate that at the global scale, external and internal variability equally drive ocean sink variability. However, as the spatial scale becomes more regional, internal variability becomes increasingly dominant. To diagnose the future evolution of the global-scale ocean carbon sink in response to a changing atmospheric growth rate, both skillful observation-based products and data-assimilative models will be required.   

How to cite: McKinley, G., Fay, A., Carroll, D., and Menemenlis, D.: Drivers of ocean carbon sink variability across spatial scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4196, https://doi.org/10.5194/egusphere-egu24-4196, 2024.

EGU24-4472 | Posters on site | BG1.3

Greenhouse gas emissions and their trends over the last three decades across Africa 

Mounia Mostefaoui, Philippe Ciais, Matthew Joseph McGrath, Philippe Peylin, Prabir K. Patra, and Yolandi Ernst

 A key goal of the Paris Agreement (PA) is to reach net-zero greenhouse gas (GHG) emissions by 2050 globally, which requires mitigation efforts from all countries. Africa’s rapidly growing population and gross domestic product (GDP) make this continent important for GHG emission trends. In this project we study the emissions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in Africa over 3 decades. We compare bottom-up (BU) approaches, including United Nations Convention Framework on Climate Change (UNFCCC) national inventories, FAO, PRIMAP-hist, process-based ecosystem models for CO2 fluxes in the land use, land use change and forestry (LULUCF) sector and global atmospheric inversions. For inversions, we applied different methods to separate anthropogenic CH4 emissions. The BU inventories show that, over the decade 2010–2018, fewer than 10 countries represented more than 75 % of African fossil CO2 emissions. With a mean of 1373 Mt CO2 yr−1, total African fossil CO2 emissions over 2010–2018 represent only 4 % of global fossil emissions. However, these emissions grew by +34% from 1990–1999 to 2000–2009 and by +31% from 2000–2009 to 2010–2018, which represents more than a doubling in 30 years. This growth rate is more than 2 times faster than the global growth rate of fossil CO2 emissions. The anthropogenic emissions of CH4 grew by 5 % from 1990–1999 to 2000–2009 and by 14.8 % from 2000–2009 to 2010–2018. The N2O emissions grew by 19.5 % from 1990–1999 to 2000–2009 and by 20.8 % from 2000–2009 to 2010–2018. When using the mean of the estimates from UNFCCC reports (including the land use sector) with corrections from outliers, Africa was a mean source of greenhouse gases of 2622 (min: 2186, max: 3239) Mt CO2 eq. yr−1 from all BU estimates (the min–max  indicate range uncertainties) and of +2637 (min: 1761, max: 5873) Mt CO2 eq. yr−1 from top-down (TD) methods during their overlap period from 2001 to 2017. Although the mean values are consistent, the range of TD estimates is larger than the one of the BU estimates, indicating that sparse atmospheric observations and transport model errors do not allow us to use inversions to reduce the uncertainty in BU estimates. The main source of uncertainty comes from CO2 fluxes in the LULUCF sector, for which the spread across inversions is larger than 50 %, especially in central Africa. Moreover, estimates from national UNFCCC communications differ widely depending on whether the large sinks in a few countries are corrected to more plausible values using more recent national sources following the methodology of Grassi et al. (2022). The medians of CH4 emissions from inversions based on satellite retrievals and surface station networks are consistent with each other within 2 % at the continental scale. The inversion ensemble also provides consistent estimates of anthropogenic CH4 emissions with BU inventories such as PRIMAP-hist. For N2O, inversions systematically show higher emissions than inventories, either because natural N2O sources cannot be separated accurately from anthropogenic ones in inversions or because BU estimates ignore indirect emissions and underestimate emission factors. 

How to cite: Mostefaoui, M., Ciais, P., McGrath, M. J., Peylin, P., Patra, P. K., and Ernst, Y.: Greenhouse gas emissions and their trends over the last three decades across Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4472, https://doi.org/10.5194/egusphere-egu24-4472, 2024.

EGU24-5271 | ECS | Orals | BG1.3

Peatland IPCC emission factors in the light of new EC carbon flux time series 

Nicolas Behrens, Klaus-Holger Knorr, and Mana Gharun

Peatlands are the world’s largest storage of soil organic carbon. While natural peatlands act as sinks of atmospheric carbon, drainage and disturbance (e.g., due to land use and climate change) turn peatlands into net carbon sources. Greenhouse gas (GHG) emissions from drained peatlands are therefore part of national GHG-emission reports, guided by the IPCC wetlands supplement. Herein, default emission factors (EF) are defined both for drained and rewetted peatlands, the former split into tropical and boreal/temperate wetlands, the latter further sub-categorized into nutrient poor and rich peatlands. These default emission factors are to date largely based on a limited number of static chamber-based studies, many measured over relatively short periods of time (1-3 years). As carbon flux measurements on peatlands have gained more attention, recent publications have added several new datasets to the EF calculations, significantly reducing the EF and narrowing confidence intervals. However, the final values are still almost entirely derived from chamber-based measurements with inherent limitations and uncertainties.

The Eddy-Covariance (EC) method is an alternative, established method to quantify carbon fluxes from ecosystems, spatially and temporally integrated (typically every 30 min throughout the year, representing a “flux-footprint” covering a whole ecosystem). As EC-based measurements are increasingly applied and such data are now available from several disturbed peatlands over several years, it is plausible to revise the default EFs. In this study we compile global EC time series for CO2 fluxes from disturbed peatlands of different land use categories with a focus on drained and rewetted peatlands affected by no or by  minor extensive management practices.  We investigate the diurnal, seasonal and annual variability of the fluxes. The net carbon emissions are compared to the EFs currently in use. With available ancillary data such as climate, water table depths, nutrients, ecosystem type and (succession-) state of the ecosystem we asses controlling factors for carbon fluxes. This investigation yields important context to evaluate the uncertainty and reliability of default emission factors for disturbed peatlands. Additionally, we apply a process-based model (CoupModel) to an own study-site to generate a higher-tier emission factor, including seasonality and climate variations.

How to cite: Behrens, N., Knorr, K.-H., and Gharun, M.: Peatland IPCC emission factors in the light of new EC carbon flux time series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5271, https://doi.org/10.5194/egusphere-egu24-5271, 2024.

EGU24-5576 | ECS | Orals | BG1.3

The greenhouse gas budget of terrestrial ecosystems in China since 2000 

Yuanyi Gao, Xuhui Wang, Kai Wang, Yuxing Sang, Yilong Wang, Yuzhong Zhang, Songbai Hong, Yao Zhang, Wenping Yuan, and Shilong Piao

As one of the world’s economic engine and the largest greenhouse gases (GHGs) emitter of fossil fuel in the past two decades, China has expressed the recent ambition to reduce GHG emissions by mid-century. The status of GHG balance over terrestrial ecosystems in China, however, remains elusive. Here, we present a synthesis of the three most important long-lived greenhouse gases (CO2, CH4 and N2O) budgets over China during the 2000s and 2010s, following a dual constraint bottom-up and top-down approach. We estimate that China’s terrestrial ecosystems act as a small GHG sink (-29.0 ± 207.5 Tg CO2-eq yr-1 with the bottom-up estimate and -75.3 ± 496.8 Tg CO2-eq yr-1 with the top-down estimate). This net GHG sink includes an appreciable land CO2 sink, which is being largely offset by CH4 and N2O emissions, predominantly coming from the agricultural sector. Emerging data sources and modelling capacities have helped achieve agreement between the top-down and bottom-up approaches to within 25% for all three GHGs, but sizeable uncertainties remain. 

How to cite: Gao, Y., Wang, X., Wang, K., Sang, Y., Wang, Y., Zhang, Y., Hong, S., Zhang, Y., Yuan, W., and Piao, S.: The greenhouse gas budget of terrestrial ecosystems in China since 2000, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5576, https://doi.org/10.5194/egusphere-egu24-5576, 2024.

EGU24-6021 | Orals | BG1.3

Non-intuitive differences in Ninos-driven CO2 flux variability and long-term changes in the tropical Pacific and Atlantic 

Jerry Tjiputra, Shunya Koseki, and Pradeebane Vaittinada Ayar

Both the tropical Pacific and Atlantic upwelling systems are modulated by their respective Ninos (ENSO and Atlantic Nino), which significantly affect the regional and global climate variability. Coincidentally, two of largest ocean carbon outgassing systems are also located in these domains. As a result, the interannual variability of ocean CO2 fluxes in these regions have predominant imprint on the globally integrated variations (Landschutzer et al., 2016). In contrast to the effect of anomalously cold surface temperature, the upwelling of deep-water rich in dissolved inorganic carbon is understood to be the main driver for the mean CO2 outgassing. In the tropical Pacific, El Nino (La Nina) leads to a suppressed (stronger) upwelling condition and an anomalously weaker (stronger) carbon outgassing. On the other hand, the Atlantic Nino and Nina exert considerable variability in the surface freshwater and temperature, which leads to spatially heterogeneous responses in the contemporary CO2 fluxes. In both systems, we discover a critical role of subsurface alkalinity in regulating the observed variability, primarily through altering the surface buffering capacity (Koseki et al., 2023). We show that bias in CMIP6 Earth system models in simulating the mean contemporary alkalinity state in the tropical Pacific leads to contrasting future impacts (Vaittinada Ayar et al., 2022) and could have ramifications on the climate carbon cycle feedback. 

 

References

Koseki, S., J. Tjiputra, F. Fransner, L. R. Crespo, and N. S. Keenlyside (2023), Disentangling the impact of Atlantic Nino on sea-air CO2 fluxes, Nature Communications, 14, 3649, https://doi.org/10.1038/s41467-023-38718-9.

Landschützer, P., N. Gruber, and D. C. E. Bakker (2016), Decadal variations and trends of the global ocean carbon sink, Global Bio- geochem. Cycles, 30, 1396–1417, http://doi.org/10.1002/2015GB005359.

Vaittinada Ayar, P., L. Bopp, J. R. Christian, T. Ilyina, J. P. Krasting, R. Séférian, H. Tsujino, M. Watanabe, A. Yool, and J. Tjiputra (2022), Contrasting projections of the ENSO-driven CO2 flux variability in the equatorial Pacific under high-warming scenario, Earth Syst. Dynam., 13, 1097–1118, https://doi.org/10.5194/esd-13-1097-2022.

How to cite: Tjiputra, J., Koseki, S., and Vaittinada Ayar, P.: Non-intuitive differences in Ninos-driven CO2 flux variability and long-term changes in the tropical Pacific and Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6021, https://doi.org/10.5194/egusphere-egu24-6021, 2024.

EGU24-7267 | ECS | Posters on site | BG1.3

Recent increasing trend of global CO2 growth rate due to a slowdown in terrestrial carbon uptake 

Chaerin Park and Sujong Jeong

The global atmospheric CO2 growth rate is a product of the combined effects of emissions and uptake from both anthropogenic and natural carbon sources. Therefore, an evaluation of the global CO2 growth rate should be preceded to understand the global carbon-climate process. In this study, we analyzed the long-term changes in the global CO2 growth rate from 1991 to 2020, using data from 42 global sites and model simulations to assess recent changes in the global carbon-climate feedback process. Our results indicate that the annual CO2 growth rate has increased by 0.032 ppm yr-2 since the 2000s. A comprehensive assessment of carbon cycle components contributing to atmospheric CO2 growth rate changes reveals that the strengthening of this rate is linked to a decline in terrestrial carbon absorption over the last decade. This decline is primarily associated with a slowdown in the increasing trend of Net Primary Productivity. Consequently, the reduced terrestrial carbon uptake in recent decades contributed to an approximately 3 ppm increase in global CO2 concentration by 2020. Our findings highlight that the vegetation's carbon uptake capacity can no longer offset anthropogenic CO2 emissions, underscoring the importance of achieving global carbon neutrality in climate change mitigation.

 

This work was supported by Korea Environment Industry & Technology Institute(KEITI) through Project for developing an observation-based GHG emissions geospatial information map, funded by Korea Ministry of Environment(MOE) (RS-2023-00232066)

How to cite: Park, C. and Jeong, S.: Recent increasing trend of global CO2 growth rate due to a slowdown in terrestrial carbon uptake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7267, https://doi.org/10.5194/egusphere-egu24-7267, 2024.

EGU24-7366 | Orals | BG1.3

Quantifying permafrost C-cycling by fusing process-models and observations  

Luke Smallman and Eleanor Burke

Globally permafrost soils store huge quantities of carbon (C) in dead organic matter (DOM). Currently, the permafrost region is estimated to be a small net C sink. However, as the climate warms permafrost soils have begun to thaw, making a massive quantity of DOM available for potential decomposition and likely shifting the region to a net source of C. Process-models of terrestrial ecosystems are a vital tool in evaluating our understanding of ecosystem function, but also in generating forecasts of C emissions under varied climate change scenarios in support of decision support. But different models contain competing hypothesise of ecosystem functioning, leading to divergent forecasts despite convergent estimates of contemporary net C emissions. These process-models also result in contrasting estimates of the internal C-cycling. We currently lack a consistent, rigorous observational constraint on ecosystem C-stocks and dynamics (particularly below ground) due to varied challenges across both in-situ and satellite-based Earth Observation (EO). Here, we present a Bayesian model-data fusion approach (CARDAMOM) which combines diverse observations of terrestrial ecosystems (e.g. leaf area, soil C, biomass, net C exchange) to calibrate an intermediate complexity model (DALEC). CARDAMOM generates a probabilistic estimates of DALEC parameters at pixel scale based on local information. Using these local calibrations, DALEC offers a probabilistic, data-constrained estimate of current ecosystem C-cycling including its internal dynamics, which can be used to evaluate large scale process-models. We evaluate process-model estimates of key ecosystem properties, e.g. DOM residence time, and their climate sensitivity. Through this process we can identify and exclude process-models which are inconsistent with data from forecast analyses.

How to cite: Smallman, L. and Burke, E.: Quantifying permafrost C-cycling by fusing process-models and observations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7366, https://doi.org/10.5194/egusphere-egu24-7366, 2024.

EGU24-8175 | Orals | BG1.3

Estimating methane emissions at high northern latitudes using regional data and global inverse modelling 

Luana Basso, Christian Rödenbeck, Victor Brovkin, Goran Georgievski, and Mathias Göckede

Atmospheric methane levels (the second largest contributor to climate change) have more than doubled over the last 200 years, though with highly variable trends over time. The relative contribution of different sources and sinks to the global CH4 budget remains uncertain despite ongoing efforts to improve the estimates based on various approaches, and particularly the causes for an accelerated increase in recent years remain unclear. Therefore, understanding and quantifying methane sources at global to regional scales is essential to reduce uncertainties in the global methane budget and its feedback with the climate system.

Within the Arctic region, wetlands and lakes constitute a major natural source of methane. With temperatures rising at rates at least twice the global average over the last decades, Arctic permafrost is increasingly thawing. Associated disturbance processes hold the potential to increase methane emissions, and as a consequence result in a positive feedback to climate change. However, until now neither observations nor model estimates could provide clear evidence of such a trend in emissions. As a consequence, current and possible future contributions of Arctic ecosystems to the accelerated increase in the global atmospheric methane levels remain highly uncertain.

To help reduce methane emission uncertainties in the high northern latitudes, we estimated global CH4 fluxes to the atmosphere using the Jena CarboScope Global Inversion System, with a strong focus of our analysis on the Arctic region. We used wetland flux from JSBACH model as prior and assimilated atmospheric observations from regional networks available over the last years for the region above 60°N latitude (a total of 23 towers) to quantify the methane emissions over this region between 2010 to 2020. We found a clear seasonal pattern with emission peaks during July and August. As a sensitivity test to evaluate the improvement to constrain the Arctic methane fluxes with the assimilation of the regional data, we also conducted an inversion using just the global background surface stations (a total of 30 global stations). We found higher mean annual methane flux to the atmosphere when assimilating the regional data, with the largest difference between May to August. These estimates were finally evaluated against an ensemble of inverse model estimates from Global Methane Project available for the period between 2010 to 2017.

How to cite: Basso, L., Rödenbeck, C., Brovkin, V., Georgievski, G., and Göckede, M.: Estimating methane emissions at high northern latitudes using regional data and global inverse modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8175, https://doi.org/10.5194/egusphere-egu24-8175, 2024.

EGU24-8349 | ECS | Posters on site | BG1.3

Drivers and trends in Land-use change and associated carbon emissions over Indonesia 

Ida Bagus Mandhara Brasika, Pierre Friedlingstein, Stephen Sitch, and Michael O'Sullivan

Indonesia is currently known as one of the three largest contributors of carbon emissions from land and land cover change (LULCC) globally, together with Brazil & the Democratic Republic of Congo. However, there is a limited reliable data on LULCC across Indonesia, leading to a lack of agreement on drivers and trends in carbon emissions. This can also be seen in the annual global carbon budget (GCB). Here, we assess the new satellite-based land cover dataset from Mapbiomas over Indonesia to illustrate how changes in forest and agriculture (mainly palm oil) areas across Indonesia determine trends in carbon emissions from land use change (ELUC). ELUC is simulated with a process-based Dynamic Global Vegetation Model, JULES-ES using annually varying LULCC maps from Mapbiomas as input. Our results show that the forest loss and agriculture expansion have a strong correlation and trend in the last two decades. Furthermore, palm oil plantation is the major contribution to the forest-agriculture dynamics, mainly appearing in Kalimantan & Sumatera island. This dynamic has a major impact on Indonesia ELUC with a positive trend in ELUC of 0.06 PgC/yr2 since 2000 . The use of the satellite-based dataset, Mapbiomas, is shown to improve our understanding of the LULCC dynamics over Indonesia, hopefully contributing to a reduction of the ELUC uncertainty for Indonesia and the SE Asia region.

How to cite: Brasika, I. B. M., Friedlingstein, P., Sitch, S., and O'Sullivan, M.: Drivers and trends in Land-use change and associated carbon emissions over Indonesia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8349, https://doi.org/10.5194/egusphere-egu24-8349, 2024.

EGU24-8601 | ECS | Posters on site | BG1.3

Estimation of methane emissions at European scale with a special focus on Austria 

Sophie Wittig, Anjumol Raju, Seyed Omid Nabavi, Martin Vojta, Peter Redl, Antje Hoheisel, Marcus Hirtl, Christine Groot Zwaaftink, and Andreas Stohl

In recent years, methane (CH4) has attracted increasing scientific attention as the second most abundant anthropogenic greenhouse gas (GHG) in the atmosphere. Due to the high reduction potential and the relatively short atmospheric lifetime of around 9 years, mitigation measures can become effective within a relatively short period of time. However, the current estimates of CH4 fluxes from emission inventories are still subject to uncertainties at both global and regional scale.

An effort to reduce uncertainties from those bottom-up flux estimates is given by inverse modelling, which provides a robust tool to verify GHG emissions by combining GHG observations as well as atmospheric transport modelling and statistical optimization.

In this study, we use an inverse modelling approach to estimate CH4 fluxes at European scale for the year 2022. Additionally, we use the European in-situ observation network to explore the feasibility of reducing uncertainties in CH4 fluxes in Austria, a European country with a limited availability of stationary observations. This work is part of the Austrian ASAP18 flagship project “GHG-KIT: Keep it traceable”.

Hereby, the inverse modelling tool FLEXINVERT is used, which is based on the backward simulations of the Lagrangian particle dispersion model FLEXPART (FLEXible PARTicle). In particular, we investigate to what extent prolonged backward trajectories of 50 to 100 days contribute to better constrain the CH4 fluxes. In an attempt to estimate background concentrations as accurately as possible, we use global CH4 concentration fields obtained with the chemical transport model FLEXPART (CTM).

How to cite: Wittig, S., Raju, A., Nabavi, S. O., Vojta, M., Redl, P., Hoheisel, A., Hirtl, M., Groot Zwaaftink, C., and Stohl, A.: Estimation of methane emissions at European scale with a special focus on Austria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8601, https://doi.org/10.5194/egusphere-egu24-8601, 2024.

EGU24-9459 | Posters on site | BG1.3

The methane record at the ICOS background station at Plateau Rosa: identification of source areas in Europe 

Giulia Zazzeri, Francesco Apadula, Andrea Lanza, and Stephan Henne

Methane and carbon dioxide mole fractions are measured continuously at the atmospheric station at Plateau Rosa since 2018, with a Picarro cavity ring down spectrometer G2301. The station, at 3480 meter MSL, represents an ideal location for, on one hand, measurements of background air and, on the other hand, intercepting air with recent boundary layer contact. Since 2021 the site contributes as an atmospheric station to the ICOS network.

In this study we present the methodology used to filter background data, and we provide an analysis of the continuous record of CH4 since 2018. We used Hysplit back trajectories and the FLEXPART atmospheric transport model coupled with EDGAR inventories to identify source areas in Europe. We focused our analysis on April 2022, when the CH4 increment above the baseline was consistently high.

We demonstrate how the CH4 mole fraction data measured at the station at Plateau Rosa provide information on the global CH4 trend, and that, with our continuous record, we can detect high emissions events over Europe.

How to cite: Zazzeri, G., Apadula, F., Lanza, A., and Henne, S.: The methane record at the ICOS background station at Plateau Rosa: identification of source areas in Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9459, https://doi.org/10.5194/egusphere-egu24-9459, 2024.

EGU24-9609 | ECS | Posters on site | BG1.3

Terrestrial Carbon Flux Dynamics in the Southern American Temperate Region: Insights from Dynamic Global Vegetation Models and GOSAT XCO2 Measurements   

Sanam Noreen Vardag, Lukas Artelt, Eva-Marie Metz, Sourish Basu, Martin Jung, and André Butz

Understanding terrestrial carbon fluxes is a prerequisite for accurately predicting the global biospheric uptake and release of CO2 under climate change and other environmental stressors. Terrestrial carbon fluxes in the southern hemisphere still exhibit quite large uncertainties due to limited measurements and a lack of comprehensive process understanding. This study focuses on the South American Temperate (SAT) region, employing various Dynamic Global Vegetation Model (DGVM) models (TRENDY v9) to investigate carbon flux dynamics. We find significant discrepancies between these DGVM models in terms of both phasing and magnitude. To address this, atmospheric XCO2 measurements from the Greenhouse Gases Observing Satellite (GOSAT) during the period 2009-2018 are incorporated into an atmospheric inversion using the model TM5-4DVar to obtain net CO2 fluxes. We identify DGVM models that match the inversion results, particularly showing the same phasing and similar magnitude of net ecosystem exchange (NEE) as the inversion results. The matching DGVMs show that the increase in NEE during the mid of the year is driven by an early increase in heterotrophic respiration whereas the autotrophic respiration remains in phase with the gross primary production (GPP) and is delayed with respect to heterotrophic respiration. The observed flux behavior is linked to the onset of rainfall in the semi-arid regions of SAT, resembling findings in Australia by Metz et al. (2023). We hypothesize that soil rewetting processes in semi-arid areas play an important role in constraining the global carbon budget and should be represented more accurately in global carbon cycle models to improve the estimation of the global carbon budget.  

 

Metz, E.-M., Vardag, S.N., Basu, S., Jung, M., Ahrens, B., El-Madany, T., Sitch, S., Arora, V.  K., Briggs, P. R., Friedlingstein, P., Goll, D.S., Jain, A.K.,  Kato, E., Lombardozzi, D., Nabel,J .E. M. S., Poulter, B., Séférian, R., Tian, H., Wiltshire, A., Yuan, W., Yue, X., Zaehle, S.,  Deutscher, N.M.,  Griffith, D.W.T., Butz, A. Soil respiration–driven CO2 pulses dominate Australia’s flux variability. Science, 379, 1332-1335, https://doi.org/10.1126/science.add7833, 2023. 

How to cite: Vardag, S. N., Artelt, L., Metz, E.-M., Basu, S., Jung, M., and Butz, A.: Terrestrial Carbon Flux Dynamics in the Southern American Temperate Region: Insights from Dynamic Global Vegetation Models and GOSAT XCO2 Measurements  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9609, https://doi.org/10.5194/egusphere-egu24-9609, 2024.

EGU24-10840 | ECS | Orals | BG1.3 | Highlight

A new synthesis of Arctic-boreal carbon fluxes for improved carbon budget estimates 

Anna Virkkala, Isabel Wargowsky, Judith Vogt, McKenzie Kuhn, Susan Natali, Brendan Rogers, Mathias Goeckede, Kyle Arndt, Jennifer Watts, Tiffany Windholz, and Simran Madaan

The Arctic-boreal zone and its permafrost regions have historically been sparsely measured for carbon dioxide and methane fluxes. This data sparsity has created significant uncertainties in Arctic-boreal carbon budget estimates. However, over the past decade, the availability of Arctic-boreal carbon flux data has increased substantially. Yet, it remains scattered across different repositories, papers, and unpublished sources, making it hard to estimate more accurate Arctic-boreal carbon budgets. To address this research gap, we have compiled a database of Arctic-boreal carbon fluxes (ABCFlux v2) from flux repositories, literature, and site principal investigators, which will be openly distributed. The database includes carbon dioxide fluxes of gross primary production, ecosystem respiration, and net ecosystem exchange, and plant-mediated, diffusive, ebullitive, and storage methane fluxes measured with eddy covariance and chamber techniques with supporting methodological and environmental metadata from terrestrial (including wetland) and freshwater ecosystems. It has in total over 12,000 site-months and 30,000 unique monthly flux values, therefore almost doubling earlier synthesis efforts in the region. Here, we present preliminary results on carbon flux magnitudes across key land cover types and multidecadal trends based on the in-situ data and machine-learning based upscaling. These indicate, for example, that the Arctic-boreal region has been an increasing annual terrestrial net ecosystem CO2 sink with the boreal biome primarily driving this trend. This collaborative initiative, involving contributions from over 100 researchers, serves as an important step in reducing uncertainties in Arctic-boreal carbon budgets and enhancing our understanding of climate feedbacks.

How to cite: Virkkala, A., Wargowsky, I., Vogt, J., Kuhn, M., Natali, S., Rogers, B., Goeckede, M., Arndt, K., Watts, J., Windholz, T., and Madaan, S.: A new synthesis of Arctic-boreal carbon fluxes for improved carbon budget estimates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10840, https://doi.org/10.5194/egusphere-egu24-10840, 2024.

EGU24-11622 | Orals | BG1.3

Constraining atmosphere-terrestrial-aquatic carbon cycle processes at national and ecoregional scales with radiocarbon data: Introducing the Radiocarbon Inventories of Switzerland (RICH) project 

Timothy Eglinton, Heather Graven, Frank Hagedorn, Soenke Szidat, Alexander Brunmayr, Margaux Duborgel, Dylan Geissbuehler, Thomas Laemmel, Luisa Minich, Benedict Mittelbach, Timo Rhyner, and Margot White

New constraints on carbon exchanges between atmospheric, terrestrial and aquatic systems are needed to reduce uncertainty in future predictions of the global carbon cycle and climate change. Radiocarbon is a powerful tool for studying the carbon cycle due to its to its ~5700-year half-life that sheds light on processes occuring on centennial to millenial timescales, as well as the 14C “bomb spike” resulting from above-ground nuclear weapons testing in the mid-20th Century that serves as a tracer of carbon flow among more rapidly cycling pools. The “Radiocarbon Inventories of Switzerland” (“RICH”) project is a collaborative initiative that involves undertaking a first-of-its-kind, national-scale 14C survey spanning all major carbon pools and encompassing the five different Swiss ecoregions. The project is acquiring a comprehensive “snapshot” of 14C measurements for carbon species in the atmosphere, soils and the hydrophere (e.g. 14C in atmospheric and soil-derived gas samples, 14C in bulk samples and different sub-fractions of soil, water and sediment samples), and developing historical context through 14C analysis of natural archives and of archived samples spanning the pre-bomb era to the present. The measurements are being used to study various carbon cycle processes, including turnover rates of different soil carbon fractions, budgets of riverine carbon, and anthropogenic emissions of CO2 and CH4. New, integrated atmospheric-terrestrial-aquatic carbon cycle models are being developed and calibrated, and existing models are being evaluated. This presentation will outline the goals and scope of the RICH project, and provide illustrations of the information that is now flowing from this collaborative undertaking. The project structure is envisioned to serve as template that can be  adapted in carbon cycle studies on regional to global scales, and the scientific outcomes will be relevant not only to Switzerland but also to the broader understanding of carbon cycle processes.

How to cite: Eglinton, T., Graven, H., Hagedorn, F., Szidat, S., Brunmayr, A., Duborgel, M., Geissbuehler, D., Laemmel, T., Minich, L., Mittelbach, B., Rhyner, T., and White, M.: Constraining atmosphere-terrestrial-aquatic carbon cycle processes at national and ecoregional scales with radiocarbon data: Introducing the Radiocarbon Inventories of Switzerland (RICH) project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11622, https://doi.org/10.5194/egusphere-egu24-11622, 2024.

EGU24-12156 | Posters on site | BG1.3

Constraining CO2 fluxes over Europe using FLEXINVERT and in-situ measurements 

Anjumol Raju, Sophie Wittig, Martin Vojta, Omid Nabavi, Peter Redl, Antje Hoheisel, Marcus Hirtl, Christine Groot Zwaaftink, and Andreas Stohl

Atmospheric carbon dioxide (CO2) is a significant greenhouse gas, and its concentration has increased by 51% compared to the pre-industrial value. Concerning its impact on the earth’s climate system, there is an urge to reduce CO2 emissions, hence mitigating global warming and climate change. This requires adequate knowledge of its source-sink distribution and quantification of the CO2 budget. Inverse modeling has emerged as an effective tool to constrain greenhouse gas (GHG) fluxes using the spatiotemporal pattern of atmospheric concentration measurements. In this regard, this study focuses on estimating CO2 fluxes over Europe using the Bayesian inverse modelling framework FLEXINVERT during the year 2021. In-situ CO2 concentrations were taken from various locations across Europe (World Data Centre for Greenhouse Gases, WDCGG) and data were averaged every 3 hours. The Lagrangian Particle Dispersion Model FLEXPART (FLEXible PARTicle) is employed to calculate the source-receptor relationship (SRR). The FLEXPART model has been run backward in time to trace back the particles (released from the locations of observation sites) for 10 days. Background CO2 concentrations are calculated using the sensitivity of concentration at the termination points from FLEXPART and the global 3D concentration from the FLEXible PARTicle-chemical transport model (FLEXPART-CTM). The uncertainty reduction, calculated from posterior and prior flux uncertainties, indicates how well the prior fluxes are optimized. In addition, longer backward simulations can be carried out to assess the impact of transport on background CO2 concentrations and the uncertainty reduction.

How to cite: Raju, A., Wittig, S., Vojta, M., Nabavi, O., Redl, P., Hoheisel, A., Hirtl, M., Zwaaftink, C. G., and Stohl, A.: Constraining CO2 fluxes over Europe using FLEXINVERT and in-situ measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12156, https://doi.org/10.5194/egusphere-egu24-12156, 2024.

EGU24-12441 | ECS | Posters on site | BG1.3

Estimating methane sources and sinks by assimilating satellite data in a global atmospheric inverse system. 

Nicole Montenegro, Marielle Saunois, Antoine Berchet, Adrien Martinez, Philippe Bousquet, and Isabelle Pison

Methane (CH4) is the second most important greenhouse gas, contributing to approximately 30% of the additional greenhouse effect since 1750. Its varied sources and relatively short lifetime in the atmosphere (~9 years) offer interesting mitigation opportunities. To develop practical strategies for mitigating climate change, precise quantification of methane fluxes and a better understanding of its spatial distribution and biogeochemical cycling are imperative. The observations currently used to infer methane sources and sinks face limitations affecting calculation accuracy. Surface stations measuring CH4 are sparse and notably absent in major emitting regions. In contrast, satellite-derived data, while providing broader coverage, present systematic errors and estimate atmospheric composition with an accuracy range of 1-10%. Additionally, passive satellite shortwave infrared (SWIR) measurements exhibit higher sensitivity near surface emission sources but are less effective in high latitude regions. Conversely, passive satellite thermal infrared (TIR) measurements have a higher sensitivity between the free troposphere and the stratosphere.Current worksare currently being developed to integrate TIR and SWIR to obtain consolidated CH4 information on the vertical atmospheric profile. This studyaims on improving methane flux estimates using the top-down approach, which integrates observations, flux priors, and an atmospheric chemical transport model utilizing Bayesian methodology. This will be perfomed on the inversion system developed at the LSCE (Community Inversion Framework – CIF) using the global transport model LMDz. We analyze the information provided by different observing systems (TIR, SWIR and surface network) at the global scale and for a period between June 2018 and June 2020. In a first step, the sensitivity of the fluxes to the observations is estimated. In a second step, Observing System Simulation Experiments are performed to evaluate the performance of the different observations system to retrieve the target fluxes. Considering both steps, observing systems are chosen to provide the best information in terms of sensitivity and spatial representation (vertical and horizontal).

How to cite: Montenegro, N., Saunois, M., Berchet, A., Martinez, A., Bousquet, P., and Pison, I.: Estimating methane sources and sinks by assimilating satellite data in a global atmospheric inverse system., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12441, https://doi.org/10.5194/egusphere-egu24-12441, 2024.

EGU24-12480 | ECS | Orals | BG1.3

Reassessing the pre-industrial air-sea carbon flux considering the ocean alkalinity budget 

Alban Planchat, Laurent Bopp, and Lester Kwiatkowski

Disparities in estimates of the ocean carbon sink, whether derived from global ocean biogeochemical models or from data products based on observations of surface ocean pCO2, question our ability to accurately assess ocean carbon uptake and its trend over recent decades. A potential factor contributing to the inconsistency between data products and model-based estimates is the pre-industrial air-sea carbon flux that is required to isolate the anthropogenic component from the total air-sea carbon flux estimated from observations. This pre-industrial air-sea carbon flux is thought to stem at the global scale from an imbalance between riverine carbon discharge to the ocean and sediment carbon burial.  Using a mass-balanced approach and comprehensive estimates of carbon inputs to the ocean by rivers and groundwater as well as carbon burial in marine sediments, Regnier et al. (2022) estimated that the pre-industrial ocean was outgassing 0.65 ± 0.30 petagrams of carbon per year. This updated estimation was used in the latest Global Carbon Budget (Friedlingstein et al., 2023) to derive an estimate of the ocean carbon sink over recent decades. In this study, we use a series of ocean biogeochemical pre-industrial simulations with varying assumptions related to carbon riverine input and burial to develop a theoretical framework to determine the ocean carbon outgassing and its spatial distribution. Building upon previous efforts, we integrate a carbon mass-balance approach with consideration of the ocean alkalinity budget. While conventionally assumed that the global alkalinity inventory was in equilibrium during the pre-industrial era — with riverine alkalinity discharge offset by CaCO3 burial — we demonstrate that an imbalance in the pre-industrial ocean alkalinity budget could significantly affect the carbon outgassing flux. This novel conceptual framework allows us to reestimate the pre-industrial carbon flux while considering the ocean alkalinity budget. Furthermore, it provides a simple method to reevaluate this flux in light of new assessments of carbon or alkalinity sources and sinks, while also covering their uncertainty ranges.

How to cite: Planchat, A., Bopp, L., and Kwiatkowski, L.: Reassessing the pre-industrial air-sea carbon flux considering the ocean alkalinity budget, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12480, https://doi.org/10.5194/egusphere-egu24-12480, 2024.

EGU24-12481 | Orals | BG1.3 | Highlight

Methane’s record rise 2020-2023: likely causes, impacts and consequences 

Martin R. Manning, Euan G. Nisbet, Sylvia E. Michel, Xin Lan, Ed Dlugokencky, David Lowry, Rebecca E. Fisher, and James L. France

From 2020, the atmospheric methane burden has grown at the fastest rate in the detailed observational record. This rise has been accompanied by an unprecedented plunge in d13C(CH4). The causes of recent accelerated growth are as yet uncertain but the geographic spread of growth and the rapid isotopic plunge suggest strong rises in isotopically light emissions from both Tropical and Boreal wetlands. These emissions may be due to rising precipitation and temperatures in parts of the tropics, and by rising temperatures in northern Canada, Siberia, and Europe. Over the longer period since 2007, methane’s actual growth is comparable to methane’s growth in the ‘worst case’ very high baseline emission scenario RCP8.5 (8.5 W/m2 forcing increase relative to pre-industrial). If the recent trend were to continue for more than another decade it could make the 2°C target as hard to achieve as the 1.5°C target is now. Natural feedbacks to climate warming in wetlands need to be included in future modelling and should be incorporated in climate modelling projects such as CMIP7. Methane’s recent accelerated growth also has wide implications for climate negotiations as it reduces the permissible total anthropogenic greenhouse gas emissions if the Paris Agreement is to be achieved. Strong growth in non-anthropogenic methane emissions, driven by feedback impacts on natural and quasi-natural sources, was not expected in modelling at the time of the Paris Agreement and shows the urgency of improving our understanding of the feedback impacts of climate change. The simplest way to limit methane’s growth is for all nations,  including non-signatory countries, to cut anthropogenic emissions urgently and sharply, meeting or exceeding the targets of the Global Methane Pledge.

How to cite: Manning, M. R., Nisbet, E. G., Michel, S. E., Lan, X., Dlugokencky, E., Lowry, D., Fisher, R. E., and France, J. L.: Methane’s record rise 2020-2023: likely causes, impacts and consequences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12481, https://doi.org/10.5194/egusphere-egu24-12481, 2024.

EGU24-12756 | Posters on site | BG1.3

Identifying the origins of the global carbon budget imbalance using oxygen 

Nicolas Mayot, Corinne Le Quéré, and Andrew Manning

Despite major advances in the estimation of all fluxes in the global cycles of carbon and oxygen, mathematical imbalances continue to arise when these fluxes are combined. Between 1997 and 2022, the global budget imbalances (BIM) for CO2 and O2 budgets – a quantification of the missing sources and/or sinks of CO2 and O2 – are -18 Tmol/yr and 41 Tmol/yr, respectively. The CO2 BIM has tended to become increasingly negative over the last decade, while the O2 BIM has tended to become increasingly positive. To identify the origins of the BIMs, we carried out a systematic analysis of the combination and permutation of all available individual flux estimates provided by a sub-set of contributors to the Global Carbon Budget 2023 update. We first examine the possibility that inaccuracies in the ocean air-sea fluxes contributes to the CO2 and O2 BIM. We show that the interannual variability of the air-sea O2 flux required for a reduction of the O2 BIM tends to be close to that simulated by several ocean models. An in-depth analysis of the Southern Ocean has confirmed their ability to simulate reasonable interannual variability in the air-sea fluxes of O2 and CO2. We conclude that in order to simultaneously reduce the negative trend in CO2 BIM and the positive trend in O2 BIM in the recent decade, a reduction in the increasing trend in the terrestrial CO2 sink over the last decade is most likely required.

How to cite: Mayot, N., Le Quéré, C., and Manning, A.: Identifying the origins of the global carbon budget imbalance using oxygen, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12756, https://doi.org/10.5194/egusphere-egu24-12756, 2024.

EGU24-13094 | ECS | Posters on site | BG1.3

High-Resolution Inversion Modeling of Carbon Dioxide and Methane Emissions in Europe: Assessing Accuracy and  Dynamics 

Anteneh Getachew Mengistu, Aki Tsuruta, Maria Tenkanen, Tiina Markkanen, Maarit Raivonen, Antti Leppänen, Antoine Berchet, Rona Thompson, Hannakaisa Lindqvist, and Tuula Aalto

Accurate estimation of critical greenhouse gas fluxes, particularly carbon dioxide (CO2) and methane (CH4), is vital for shaping effective climate change policies. Leveraging the state-of-the-art Community Inversion Framework (CIF), we estimate high-resolution emissions across Europe (-12°E to 37°E, 35°N to 73°N). Using the Lagrangian Particle Dispersion Model (FLEXPART) with ECMWF meteorological data, we calculate surface flux footprints at 0.2° × 0.2° resolution, enhancing comparisons with national inventories. Assimilating data from 40+ in-situ observations, including ICOS and non-ICOS stations, our 4-dimensional variational optimization refines prior high-resolution flux estimates. Diverse sources contribute to the total flux, including fossil fuel emissions, biomass burning, land emissions, air-sea exchange. Flux corrections enhance accuracy, yielding posterior estimates with reduced bias and heightened correlation. Major CH4 emitters (France, Germany, Italy, Spain, Poland, and the UK) collectively contribute 72% of total emissions. The EU27 + UK average is 16.47 ± 1.33 Tg CH4/yr. Posterior anthropogenic emissions reveal a regional mean reduction of > 5 gC/m2/month in summer compared to prior estimates, highlighting seasonal emission dynamics.

How to cite: Mengistu, A. G., Tsuruta, A., Tenkanen, M., Markkanen, T., Raivonen, M., Leppänen, A., Berchet, A., Thompson, R., Lindqvist, H., and Aalto, T.: High-Resolution Inversion Modeling of Carbon Dioxide and Methane Emissions in Europe: Assessing Accuracy and  Dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13094, https://doi.org/10.5194/egusphere-egu24-13094, 2024.

EGU24-13246 | ECS | Posters on site | BG1.3

Recent methane surges reveal heightened emissions from tropical inundated areas 

Xin Lin, Shushi Peng, Philippe Ciais, Didier Hauglustaine, Xin Lan, Gang Liu, Michel Ramonet, Yi Xi, Yi Yin, and Zhen Zhang and the Coauthors

Record breaking atmospheric methane growth rates were observed in 2020 and 2021 (15.2±0.4 and 17.6±0.5 ppb yr-1), reaching their highest level since the commencement of ground-based observations in the early 1980s. Here we use an ensemble of atmospheric inversions informed by surface or satellite methane concentration observations to infer emission changes during these two years relative to 2019. We found a global increase of methane emissions of 20.3±9.9 Tg CH4 in 2020 and 24.8±3.1 Tg CH4 in 2021. The emission rise was dominated by tropical and boreal regions with inundated areas, as a result of elevated groundwater table. Strong, synchronous, and persistent emission increases occurred in regions such as the Niger River basin, the Congo basin, the Sudd swamp, the Ganges floodplains and Southeast Asian deltas and the Hudson Bay lowlands. These regions alone contributed about 70% and 60% of the net global increases in 2020 and 2021, respectively. Comparing our top-down estimates with simulation of wetland emissions by biogeochemical models, we find that the bottom-up models significantly underestimate the intra- and inter-annual variability of methane sources from tropical inundated areas. This discrepancy likely arises from the models’ limitations in accurately representing the dynamics of tropical wetland extents and the response of methane emissions to environmental changes. Our findings demonstrate the critical role of tropical inundated areas in the recent surge of methane emissions and highlight the value of integrating multiple data streams and modeling tools to better constrain tropical wetland emissions.

How to cite: Lin, X., Peng, S., Ciais, P., Hauglustaine, D., Lan, X., Liu, G., Ramonet, M., Xi, Y., Yin, Y., and Zhang, Z. and the Coauthors: Recent methane surges reveal heightened emissions from tropical inundated areas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13246, https://doi.org/10.5194/egusphere-egu24-13246, 2024.

EGU24-13846 | Posters on site | BG1.3

Reduced Southern Ocean CO2 uptake due to the positive SAM trend 

Laurie Menviel, Paul Spence, Andrew Kiss, Matthew Chamberlain, Hakase Hayashida, Matthew England, and Darryn Waugh

While the Southern Ocean (SO) provides the largest oceanic sink of carbon, some observational studies have suggested that the SO total CO2 (tCO2) uptake exhibited large (~0.3 GtC/yr) decadal-scale variability over the last 30 years, with a similar SO tCO2 uptake in 2016 as in the early 1990s. Here, using an eddy-rich ocean, sea-ice, carbon cycle model, with a nominal resolution of 0.1°, we explore the changes in total, natural and anthropogenic SO CO2 fluxes over the period 1980-2021 and the processes leading to the CO2 flux variability.

The simulated tCO2 flux exhibits decadal-scale variability with an amplitude of ~0.1 GtC/yr globally in phase with observations. Notably, two stagnation in tCO2 uptake are simulated between 1982 and 2000 as well as since 2012, while a re-invigoration is simulated between 2000 and 2012. This decadal-scale variability is primarily due to changes in natural CO2  (nCO2) fluxes south of the polar front associated with variability in the Southern Annular Mode (SAM). Positive phases of the SAM lead to enhanced SO nCO2 outgassing due to higher surface natural dissolved inorganic carbon (DIC) brought about by a combination of Ekman-driven vertical advection and DIC diffusion at the base of the mixed layer. The pattern of the CO2 flux anomalies indicate a dominant control of the interaction between the mean flow south of the polar front and the main topographic features. While positive phases of the SAM also lead to enhanced anthropogenic CO2 (aCO2) uptake south of the polar front, the amplitude of the changes in aCO2 fluxes is only 25% of the changes in nCO2 fluxes. Due to the larger nCO2 outgassing compared to aCO2 uptake as the SH westerlies strengthen and shift poleward, the SO tCO2 uptake capability thus reduced since 1980 in response to the shift towards positive phases of the SAM.

 

How to cite: Menviel, L., Spence, P., Kiss, A., Chamberlain, M., Hayashida, H., England, M., and Waugh, D.: Reduced Southern Ocean CO2 uptake due to the positive SAM trend, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13846, https://doi.org/10.5194/egusphere-egu24-13846, 2024.

EGU24-14038 | ECS | Orals | BG1.3

Sea surface pCO2 variability on different time scales in the East China Sea based on high-frequency time-series observations 

Yaohua Luo, Zhirong Zhang, Jinshun Chen, Yi Xu, Fuqing Cao, Tao Huang, Xianghui Guo, and Minhan Dai

We examined the sub-seasonal to interannual variability and multi-year trend of sea surface CO2 partial pressure (pCO2) and air-sea CO2 flux at a coastal site of the East China Sea (31⁰N, 122.8⁰E) based on high-frequency time-series data collected by a buoy since 2013. Seasonal average sea surface pCO2 was highest in autumn, but the lowest value can appear in winter or spring, depending on the biological productivity in spring. The seasonal amplitude of pCO2 was up to 123 μatm. Based on property-property relationships and a simple mass budget model, we found that temperature change, biological activity, water mixing and air-sea CO2 exchange all made significant contributions to the seasonal variation of pCO2. From winter to summer, seasonal warming and atmospheric CO2 uptake elevated the pCO2, while net biological production, weakened vertical mixing and the retreat of the Yellow Sea Coastal Water (YSCW) lowered the pCO2. Conversely, from summer to winter, seasonal cooling and CO2 emission lowered the pCO2, while respiration, enhanced vertical mixing and the YSCW intrusion raised them up. Over short-term timescale, biological production and respiration frequently drew down or elevated the pCO2 by 150-400 μatm within 5-10 days during warm months. When biological activity was suppressed during cold months, such short-term variations were dominated by water mixing with a smaller pCO2 amplitude of 5-60 μatm within 2-6 days. This site was a sink of atmospheric CO2 in winter and spring, but a CO2 source in summer and autumn. Annually, it was a moderate CO2 source in 2014 (air-sea CO2 flux was 2.88 ± 11.02 mmol m2 d1), a weak CO2 sink in 2016 (-0.21 ± 12.23 mmol m2 d1), and a weak CO2 source in the combined year of the first half of 2017 and the second half of 2018 (0.40 ± 9.11 mmol m2 d1). The relatively high CO2 source in 2014 was likely due to the weaker biological production in spring and more typhoon passage in autumn. From 2013 to 2019, the wintertime sea surface pCO2 didn’t follow the increasing trend of the atmospheric pCO2, leading to an enhancing carbon sink in winter.

How to cite: Luo, Y., Zhang, Z., Chen, J., Xu, Y., Cao, F., Huang, T., Guo, X., and Dai, M.: Sea surface pCO2 variability on different time scales in the East China Sea based on high-frequency time-series observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14038, https://doi.org/10.5194/egusphere-egu24-14038, 2024.

EGU24-14545 | ECS | Posters on site | BG1.3

Soil CH4 and N2O fluxes from drained and undrained peatland forests in the Baltic region. 

Muhammad Kamil Sardar Ali, Thomas Schindler, Hanna Vahter, Ain Kull, Ülo Mander, Andis Lazdiņš, Ieva Līcīte, Arta Bārdule, Aldis Butlers, Dovilė Čiuldienė, Egidijus Vigricas, Jyrki Jauhiainen, Raija Laiho, and Kaido Soosaar

Peatland ecosystem degradation and changes made in hydrology by artificial drainage may affect the biogeochemistry of peatlands and, together with projected global warming, may lead to significant changes in greenhouse gas (GHG) fluxes. Drainage of peatlands increases organic matter's aerobic decomposition, changes native vegetation, and may decrease the storage of C. The vegetative characteristics of forest ecosystem types may change a net GHG sink peatland to a source in drained organic soils.

However, soil CH4 and N2O fluxes in peatlands are spatially and temporally (interannual, seasonal) variable, and detailed data from drained nutrient-rich organic soils in the hemiboreal zone is lacking. We conducted a study spanned over two years comprising drained (n=18) and undrained (n=7) peatland forests with dominant tree species of Scots pine (Pinus sylvestris), Norway spruce (Picea abies), birch (Betula sp.), and black alder (Alnus glutinosa) spread across Estonia, Latvia, and Lithuania. Instantaneous fluxes of CH4 and N2O were measured monthly for the whole year using the manual static chamber method. Environmental parameters in soil, such as soil water level (WTL), moisture, and temperatures at depths (0-40 cm), were monitored continuously, and detailed soil chemical analyses were conducted. To constrain the factors regulating temporal fluxes of various environmental conditions and differentiate annual emissions between land use in the Baltic region.

The results show that all drained forest soils were annual CH4 sinks (−37.0 ± 4.5 μg C m−‍2 h−‍1), while undrained forests were emitters on average 388.5 ± 142. Mean annual CH4 uptake is significantly higher in deep-drained soils −45.5 ± 3.6 μg C m−‍2 h−‍1 (WTL > −50cm) than in poorly drained soils (p<0.05), regardless of dominant tree species. The in situ and annual CH4 fluxes statistically correlated with soil water level and temperature. Most of the drained sites emitted N2O (49.4 ± 17.8 μg N m−‍2 h−‍1); drained wet forest sites were higher emitters (84.7 ± 32.4) than drier sites (23.67 ± 15.6) in comparison to tree species. The instantaneous N2O fluxes were directly controlled by soil surface temperature and oxygen concentration of soil water, whereas variability in annual N2O emissions was associated with soil water content. Moreover, soil nutrient status regulated by specific ground vegetation functional groups has significantly impacted the emissions of nutrient-rich organic soils.

This research was supported by the LIFE programme project "Demonstration of climate change mitigation potential of nutrients-rich organic soils in the Baltic States and Finland" (2019-2023, LIFE OrgBalt, LIFE18 274CCM/LV/001158).

How to cite: Sardar Ali, M. K., Schindler, T., Vahter, H., Kull, A., Mander, Ü., Lazdiņš, A., Līcīte, I., Bārdule, A., Butlers, A., Čiuldienė, D., Vigricas, E., Jauhiainen, J., Laiho, R., and Soosaar, K.: Soil CH4 and N2O fluxes from drained and undrained peatland forests in the Baltic region., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14545, https://doi.org/10.5194/egusphere-egu24-14545, 2024.

EGU24-14672 | Orals | BG1.3

Multiple approaches for quantifying fuels, combustion dynamics, and regional fire emissions in the Amazon and Cerrado 

Matthias Forkel, Christine Wessollek, Niels Andela, Jos de Laat, Vincent Huijnen, Daniel Kinalczyk, Christopher Marrs, Dave van Wees, Ana Bastos, Philippe Ciais, Dominic Fawcett, Johannes W. Kaiser, Erico Kutchartt, Carine Klauberg, Rodrigo Vieira Leite, Wei Li, Carlos Silva, Stephen Sitch, Jefferson Goncalves De Souza, and Stephen Plummer

Fires in the Amazon are of great concern because they threaten the integrity of the tropical forest biome, the carbon cycle, and air quality. Fire emissions depend on the burning behaviour of vegetation biomass, woody debris, and litter. However, the effects of fuels on the combustion process and on the composition of fire emissions are simplified in current fire emission inventories and models. Several new fire emission approaches have recently been developed to better quantify fire emissions by either making use the improved spatial resolution of modern satellite observations or by developing new modelling approaches. 

Here we compare several current and novel approaches to quantify fuel consumption and fire emissions for the Amazon and Cerrado for the fire season in 2020. The approaches include the widely used GFAS, a top-down approach based on Sentinel-5p observations (KNMI.S5p), a bottom-up approach based on active fire observations from VIIRS (GFA.S4F), two bottom-up approaches based on MODIS burned area data (500-m version of GFED, REFIT.AC), a data-model fusion approach with dynamic emission factors that integrates several Earth observation products (TUD.S4F), and three dynamic global vegetation models in diagnostic mode with prescribed burned area. The different approaches to estimate fire emission show that forest and deforestation fires dominate the regional total fire emissions. However, large differences exist in the very high emissions of individual fires that mainly contribute to the regional total fire emissions. We found a higher agreement in estimated CO and NOx emissions between approaches for savannah fires (normalised RMSE < 20%) than for forest and deforestation fires (nRMSE 30%). We estimate that only 10% of all fire events contribute between 85% and 97% of the regional total fire emissions. By using the TUD.S4F data-model fusion approach with dynamic emission factors, we show that most fire CO emissions originate from the burning of woody debris, which burns with low combustion efficiency and hence has higher emission factors for CO. Comparisons with regional field-based investigations show, however, large differences in estimates of surface fuel loads and fuel consumption. Our results demonstrate the advantage of exploring several complementary fire emission approaches to better understand the underlying processes and to account for regional to global fire emissions and their uncertainties.

How to cite: Forkel, M., Wessollek, C., Andela, N., de Laat, J., Huijnen, V., Kinalczyk, D., Marrs, C., van Wees, D., Bastos, A., Ciais, P., Fawcett, D., Kaiser, J. W., Kutchartt, E., Klauberg, C., Leite, R. V., Li, W., Silva, C., Sitch, S., Goncalves De Souza, J., and Plummer, S.: Multiple approaches for quantifying fuels, combustion dynamics, and regional fire emissions in the Amazon and Cerrado, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14672, https://doi.org/10.5194/egusphere-egu24-14672, 2024.

EGU24-14775 | ECS | Orals | BG1.3

Global coastal ocean CO2 trends over the 1982–2020 period 

Alizee Roobaert, Pierre Regnier, Peter Landschützer, and Goulven G. Laruelle

The development of high-quality controlled databases of sea surface partial pressure of CO2 (pCO2) combined with robust machine learning-based mapping methods that fill pCO2 gaps in time and space, enable us to quantify the oceanic air-sea CO2 exchange and its spatiotemporal variability only based on in-situ observations (pCO2-products). However, most existing pCO2-products do not explicitly include the coastal ocean or have a spatial resolution that is too coarse (e.g., 1°) to capture the highly heterogeneous spatiotemporal dynamics of pCO2 in these regions thus limiting our ability to resolve long-term trends and the interannual variability of the coastal air-sea CO2 exchange (FCO2).

To address this limitation, we updated the global coastal pCO2-product of Laruelle et al. (2017) using a 2-step machine learning interpolation technique (relying on Self Organizing Maps and a Feed Forward neural Network) combined with the most extensive monthly time series for coastal waters from the Surface Ocean CO2 Atlas (SOCAT), spanning from 1982 to 2020 to reconstruct monthly high spatial resolution (0.25°) continuous coastal pCO2 maps. This updated coastal pCO2-product is then used to reconstruct the temporal evolution of the global coastal FCO2 based on observations.

Our results show that since 1982, the extended coastal ocean, covering an area of 77 million km² in this study, has been acting as an atmospheric CO2 sink, removing -0.4 Pg C yr-1 (-0.2 Pg C yr-1 with a narrower coastal domain roughly equivalent to continental shelves) from the atmosphere. Moreover, the intensity of this CO2 sink has been increasing over time at a rate of 0.1 Pg C yr-1 per decade (0.03 Pg C yr-1 decade-1 in the narrower domain). The long-term change in the air-sea CO2 flux is largely driven by the air-sea pCO2 gradient, dominated by the sea surface pCO2, however wind speed and sea-ice coverage play significant roles, regionally. This new coastal pCO2-product provides a valuable constraint for understanding the strengthening of the global coastal ocean CO2 sink, fill the coastal gap in synthesis studies such as the Global Carbon Budget and serves as a benchmark for evaluating emerging results of ocean biogeochemical models.

How to cite: Roobaert, A., Regnier, P., Landschützer, P., and Laruelle, G. G.: Global coastal ocean CO2 trends over the 1982–2020 period, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14775, https://doi.org/10.5194/egusphere-egu24-14775, 2024.

EGU24-15244 | Orals | BG1.3

A consistent budgeting of terrestrial carbon fluxes  

Julia Pongratz, Lea Dorgeist, Clemens Schwingshackl, and Selma Bultan

As the remaining carbon budget to limit global warming in line with the Paris Agreement is rapidly shrinking, accurate estimates of the emissions from land-use and land cover change (ELUC) and the terrestrial natural CO2 sinks (SLAND) are crucial. In current carbon budgeting approaches, the ELUC and SLAND estimates are conceptually not consistent, since they stem from two different model families that differ in how CO2 fluxes are attributed to environmental or land-use changes. Consequently, anthropogenic and natural budget terms are not fully distinguished. ELUC is estimated by bookkeeping models, which typically use time-invariant carbon densities representing contemporary environmental conditions. They thus assume a steady environmental state and neglect changes in environmental conditions preceding or succeeding a land-use change event, e.g., denser growing forests in response to rising atmospheric CO2 concentrations, which emit more when cleared for agricultural land. SLAND is estimated by dynamic global vegetation models, which account for environmental changes but assume that the land cover distribution remained at its pre-industrial state. They thus include carbon sinks in forests that in reality were cleared decades ago. Here we suggest an approach for consistent budgeting of ELUC and SLAND by integrating the response of vegetation and soil carbon to environmental changes, derived from dynamic global vegetation models, into a spatially explicit bookkeeping model (BLUE). A set of dedicated simulations allows us to disentangle and re-attribute environmental and land-use components of the land-atmosphere CO2 exchange. Our results show that land is a cumulative net source of CO2 since 1850, which contrasts current global carbon budgets indicating a net sink. The underlying reason is both a higher estimate of ELUC than previously suggested as well as a smaller land sink: The implementation of environmental changes increases global ELUC over time (14% compared to current estimates for 2012-2021) mainly due to increased emissions from deforestation and wood harvest, which are only partly offset by increased sinks through reforestation/afforestation and other regrowing vegetation. Our SLAND estimate calculated under actual land cover amounts to 3.0 GtC yr-1 for 2012-2021, which is substantially lower both globally and regionally compared to estimates assuming pre-industrial land cover: we find a SLAND is smaller by 0.7 GtC yr-1 in 2012-2021, i.e., 19% lower as compared to the conventional approach using pre-industrial land cover. The overestimate of SLAND under pre-industrial land cover is particularly pronounced in regions with strong ecosystem degradation, such as Southeast Asia, Brazil, and Equatorial Africa. The consistent estimation of terrestrial carbon fluxes is thus essential not only to provide a tangible estimate to monitor the progress of net-zero emission commitments and the remaining carbon budget, but also to highlight the need to protect remaining natural ecosystems for climate regulation. Our approach provides greater consistency with atmospheric inversions and provides a finer split of anthropogenic and natural fluxes useful for a direct comparison of global carbon cycle models to national greenhouse gas inventories.

How to cite: Pongratz, J., Dorgeist, L., Schwingshackl, C., and Bultan, S.: A consistent budgeting of terrestrial carbon fluxes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15244, https://doi.org/10.5194/egusphere-egu24-15244, 2024.

EGU24-16495 | Orals | BG1.3

Mean, Seasonal Cycle, Trends, and Storage of the Southern Ocean carbon cycle in the RECCAP2 assessment (1985-2018) 

Lavinia Patara, Judith Hauck, Luke Gregor, Cara Nissen, Mark Hague, Precious Mongwe, Seth Bushinsky, Scott C. Doney, Nicolas Gruber, Corinne Le Quéré, Manfredi Manizza, Matthew Mazloff, and Pedro M. S. Monteiro

The Southern Ocean has long been known to be an important region for ocean CO2 uptake, and one which is especially sensitive to changes in the overlying climate. Here we assess the Southern Ocean CO2 uptake (1985–2018) using data sets gathered in the REgional Carbon Cycle Assessment and Processes Project Phase 2 (RECCAP2). These include global ocean biogeochemical models (GOBMs), surface ocean pCO2-products, data-assimilated models, and interior ocean biogeochemical observations. Over this period the Southern Ocean acted as a sink for CO2, with magnitudes which are roughly half of those reported by RECCAP1 for the same region and timeframe. Close agreement is found between GOBMs and pCO2-products, partly due to some compensation of seasonal and regional differences. Seasonal analyses revealed agreement in driving processes in winter (with uncertainty in the magnitude of outgassing), whereas discrepancies are more fundamental in summer, when GOBMs exhibit difficulties in simulating the balance of non-thermal processes of biology and mixing/circulation. The data sets emphasize strong latitudinal variations in the mean and seasonality of the CO2 flux and asymmetries in the mean and amplitude of the CO2 flux between Atlantic, Pacific and Indian sectors. The present-day net uptake is to first order a response to rising atmospheric CO2. This drives large amounts of anthropogenic CO2 (Cant) into the ocean, thereby overcompensating the loss of natural CO2 to the atmosphere driven by the changing climate. The GOBMs show, however, a 20% spread and an overall underestimate of Cant storage in the ocean interior. An apparent knowledge gap is the increase of the sink since 2000, with pCO2-products suggesting a growth that is more than twice as strong and uncertain as that of GOBMs. This is despite nearly identical pCO2 trends in GOBMs and pCO2-products when both products are compared only at the locations where pCO2 was measured.

How to cite: Patara, L., Hauck, J., Gregor, L., Nissen, C., Hague, M., Mongwe, P., Bushinsky, S., Doney, S. C., Gruber, N., Le Quéré, C., Manizza, M., Mazloff, M., and Monteiro, P. M. S.: Mean, Seasonal Cycle, Trends, and Storage of the Southern Ocean carbon cycle in the RECCAP2 assessment (1985-2018), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16495, https://doi.org/10.5194/egusphere-egu24-16495, 2024.

EGU24-16630 | ECS | Posters on site | BG1.3

Methane emissions from Dutch peatlands measured by a national eddy covariance network 

Alexander Buzacott, Bart Kruijt, Laurent Bataille, Hanne Berghuis, Jan Biermann, Quint van Giersbergen, Christian Fritz, Reinder Nouta, Merit van den Berg, Ype van der Velde, and Jacobus van Huissteden

Drained peatlands need to be rewetted to reduce carbon dioxide (CO2) emissions caused by microbial peat oxidation and to limit soil subsidence. Raising groundwater levels will subsequently increase the chance of methane (CH4) emissions, a much more potent greenhouse gas (GHG) gas than CO2. While intact peatlands are long-term carbon sinks and have a net cooling effect, despite the CH4 emissions, how disturbed peatlands will respond to rewetting is less certain. There are several rewetting strategies outside of returning the land to unproductive uses, such as paludiculture (agriculture on inundated soils) and installing water infiltration systems (WIS) in pastures.

In the Netherlands, more than 85% of the peatlands are used for agriculture and have been extensively drained. Rewetting these peatlands is necessary to reduce CO2 emissions, however the effect this will have on CH4 emissions needs to be understood such that optimal rewetting strategies can be chosen to minimise GHG emissions. In this presentation, we report our efforts into monitoring CH4 emissions across Dutch peatlands with a network of eddy covariance (EC) systems since 2020 for the Netherlands Research Programme on Greenhouse Gas Dynamics in Peatlands and Organic Soils (NOBV) project. Fluxes of CO2 and CH4 have been observed across 20 field sites that cover the current Dutch peatland extent using a combination of permanent and mobile (alternating between two paired sites) EC towers that measured the land uses of paludiculture, semi-natural, pastures with WIS, pastures with high and low groundwater levels, and a lake. We focus on the main drivers of CH4 emissions in Dutch peatlands, evaluate the impact of land use on annual CH4 emissions, and emission upscaling.

How to cite: Buzacott, A., Kruijt, B., Bataille, L., Berghuis, H., Biermann, J., van Giersbergen, Q., Fritz, C., Nouta, R., van den Berg, M., van der Velde, Y., and van Huissteden, J.: Methane emissions from Dutch peatlands measured by a national eddy covariance network, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16630, https://doi.org/10.5194/egusphere-egu24-16630, 2024.

EGU24-18116 | Orals | BG1.3

Reviewing differences and uncertainties in land-use CO2 flux estimates 

Wolfgang Obermeier, Clemens Schwingshackl, Raphael Ganzenmüller, Ana Bastos, Philippe Ciais, Giacomo Grassi, Ingrid Luijkx, Stephen Sitch, and Julia Pongratz

CO2 fluxes from land use and land-use change (FLUC) are a major source of carbon to the atmosphere. They are composed of gross emissions, mainly from deforestation, peat burning, and peat drainage, and gross removals, mainly from re- and afforestation. The importance of FLUC for climate change mitigation strategies is increasing due to the potential of storing large carbon amounts via re- and afforestation, harvested wood products, and other vegetation-based carbon dioxide removal methods, such as bioenergy with carbon capture and storage. Yet, FLUC estimates remain largely uncertain and show substantial discrepancies between different quantification methods, which makes it challenging to provide reliable projections of their potential future evolution.

 

Here, we review the main characteristics, uncertainties, and discrepancies of individual methods used to estimate FLUC, and we highlight promising steps to reduce FLUC uncertainties and to harmonize the various FLUC estimates. Differences between the approaches are mainly due to differing definitions and assumptions, such as the definition of anthropogenic fluxes and managed land (leading to a gap in FLUC of ~1.8 GtC/yr in 2000-2020 between FLUC estimates by bookkeeping models used in the Global Carbon Project and inventory-based estimates reported by countries to the United Nations Framework Convention on Climate Change) and the inclusion of environmental effects on carbon stocks (leading to a gap of ~0.4 GtC/yr in 2000-2020 between FLUC estimates from dynamic global vegetation models and bookkeeping models). Furthermore, the individual estimation methods have large uncertainties, mainly arising from the usage of differing land-use forcing data, missing observational constraints, differences in how models implement individual processes, and the degree of implementation of land use practices in models.

 

To improve the confidence in the individual FLUC estimates, we argue for a systematic model evaluation and an improved parametrization of models, in particular regarding land-use forcing data, carbon densities of vegetation and soils, and the represented processes. Alongside, remaining framework inconsistencies, such as a precise and consistent definition of FLUC and the consideration of transient C densities need to be resolved. This undertaking requires developments in several directions. Earth observations may provide data on carbon densities in vegetation and soil at high spatial resolution, improved estimates of forest regrowth rates as well as impacts of forest management. Models need to be further improved to consider all relevant land-use processes and provide more fine-granular output to guarantee that the different estimates are comparable and/or translatable into each other.

 

Providing harmonized and more accurate FLUC estimates is essential to improve the stocktake of countries' land use-related CO2 emissions, to provide an accurate budget of the global carbon cycle, and to effectively plan and monitor land-based carbon dioxide removal methods.

How to cite: Obermeier, W., Schwingshackl, C., Ganzenmüller, R., Bastos, A., Ciais, P., Grassi, G., Luijkx, I., Sitch, S., and Pongratz, J.: Reviewing differences and uncertainties in land-use CO2 flux estimates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18116, https://doi.org/10.5194/egusphere-egu24-18116, 2024.

EGU24-19922 | Posters on site | BG1.3

Ocean biogeochemical reconstructions to estimate historical ocean CO2 uptake 

Raffaele Bernardello, Valentina Sicardi, Vladimir Lapin, Pablo Ortega, Yohan Ruprich-Robert, Etienne Tourigny, and Eric Ferrer

Given the role of the ocean in mitigating climate change through CO2 absorption, it is important to improve our abil ity to quantify the historical ocean CO2 uptake, including its natural variability, for carbon budgeting purposes. In this study we present an exhaustive intercomparison between two ocean modelling practices that can be used to reconstruct the historical ocean CO2 uptake. By comparing the simulations to a wide array of ocean physical and biogeochemical observational datasets, we show how constraining the ocean physics towards observed temperature and salinity results in a better representation of global biogeochemistry. We identify the main driver of this improvement to be a more realistic representation of large scale meridional overturning circulation together with improvements in mixed layer depth and sea surface temperature. Nevertheless, surface chlorophyll was rather insensitive to these changes, and, in some regions, its representation worsened. We identified the causes of this response to be a combination of a lack of robust parameter optimization and limited changes in environmental conditions for phytoplankton. We conclude that although the direct validation of CO2 fluxes is challenging, the pervasive improvement observed in most aspects of biogeochemistry when applying data assimilation of observed temperature and salinity is encouraging; therefore, data assimilation should be included in multi-method international efforts aimed at reconstructing the ocean CO2 uptake.

How to cite: Bernardello, R., Sicardi, V., Lapin, V., Ortega, P., Ruprich-Robert, Y., Tourigny, E., and Ferrer, E.: Ocean biogeochemical reconstructions to estimate historical ocean CO2 uptake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19922, https://doi.org/10.5194/egusphere-egu24-19922, 2024.

EGU24-20295 | Orals | BG1.3

A water mass transformation method applied to diagnosing ocean carbon uptake 

Neill Mackay, Jan Zika, Taimoor Sohail, Tobias Ehmen, and Andrew Watson

The ocean is a strong sink for anthropogenic CO2, absorbing around a quarter of emissions since the industrial era. Quantifying the ocean carbon sink is necessary for constraining the global carbon budget; however, discrepancies remain between estimates of the ocean carbon sink over the last 30 years from observation-based data products and those from numerical models. Moreover, larger regional uncertainties highlight the need for a better understanding of the drivers of ocean carbon sink variability, to help improve models and to better constrain future climate projections. A comprehensive understanding of the sink must include knowledge of (1) the air-sea flux of CO2, (2) the accumulation of carbon in the ocean interior, and (3) how it is redistributed within the ocean by changes in the physical circulation. This characterisation is typically achieved using numerical models, which are constrained by resolution and the need to parameterise processes including physical mixing at the sub-grid scale.

We present a novel method for characterising the ocean carbon sink from a combination of oceanographic datasets, and for reconciling our knowledge of the ocean’s uptake of CO2 with that of interior carbon storage rates. Our Optimal Transformation Method (OTM) uses a water mass framework to diagnose the transport and mixing of tracers such as heat, salt, and carbon consistent with observed interior changes and estimates of boundary forcings. The water mass framework has the advantage that the transport and mixing of conservative tracers are diagnosed exactly, with no need for parameterisation. We validate OTM using outputs from a data-assimilating biogeochemical ocean model and demonstrate its ability to recover the model’s ‘true’ air-sea CO2 fluxes when initialised with biased priors. OTM reduces root-mean-squared errors between diagnosed air-sea CO2 fluxes and the model truth from prior to solution by up to 71%, while simultaneously estimating inter-basin transports of heat, freshwater, and carbon consistent with the model. Following successful validation, we apply OTM to a combination of observational data products to diagnose estimates of the ocean’s uptake and redistribution of carbon since 1990, utilising reanalyses of air-sea heat and freshwater fluxes, interior temperature and salinity, air-sea CO2 fluxes, and machine-learning reconstructions of interior ocean carbon.

How to cite: Mackay, N., Zika, J., Sohail, T., Ehmen, T., and Watson, A.: A water mass transformation method applied to diagnosing ocean carbon uptake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20295, https://doi.org/10.5194/egusphere-egu24-20295, 2024.

EGU24-20413 | Posters on site | BG1.3

Quantifying unaccounted greenhouse gas emissions due to the war in Ukraine – driver analysis, emission estimation, and implications to emission reporting 

Rostyslav Bun, Gregg Marland, Tomohiro Oda, Linda See, Enrique Puliafito, Zbigniew Nahorski, Matthias Jonas, Vasyl Kovalyshyn, Iolanda Ialongo, Orysia Yashchun, and Zoriana Romanchuk

Quantifying greenhouse gas (GHG) emissions is a critical task for climate monitoring and mitigation actions.  Under the Paris Agreement, for example, accounting and reporting of GHG emissions are mandatory for Parties.  Reported emissions are often calculated using activity data approaches.  The robustness of the activity data collection is a key for obtaining accurate emission estimates; however, in a period of open conflict or war, the systems for data collection can be desperately damaged and destroyed and thus the ability of achieving robust GHG estimates and transparent reporting can be significantly hampered.  Also, military emissions, which are thought to be often poorly quantified, should increase significantly than peace times. 

We attempted to quantify GHG emissions during the first 18 months of the 2022/2023 full-scale war in Ukraine.  We first identified major, war-related, emission drivers and processes from the territory of Ukraine.  We analyzed publicly available data and used expert judgment to estimate emissions from (1) the use of bombs, missiles, barrel artillery, and mines; (2) the consumption of oil products for military operations; (3) fires at petroleum storage depots and refineries; (4) fires in buildings and infrastructure facilities; (5) fires on forest and agricultural lands; and (6) the decomposition of war-related garbage/waste.  Those sources are often not covered by current GHG inventory guidelines, and thus are not likely to be included in national inventory reports. 

Our estimate of the war-related emissions of carbon dioxide (CO2), methane, (CH4) and nitrous oxide (N2O) for the first 18 months of the war in Ukraine is 77 MtCO2-eq. with a relative uncertainty of ±22 % (95 % confidence interval).  It is important to note that these emissions are considered to be emissions from Ukraine in reporting because the emissions occurred within the territory of Ukraine.  The current emission accounting system (e.g. UNFCCC) is not designed to account war/conflict time emissions adequately.  The uncertainties due to the unaccounted emissions are also aliasing to our global and regional carbon budget calculations.

How to cite: Bun, R., Marland, G., Oda, T., See, L., Puliafito, E., Nahorski, Z., Jonas, M., Kovalyshyn, V., Ialongo, I., Yashchun, O., and Romanchuk, Z.: Quantifying unaccounted greenhouse gas emissions due to the war in Ukraine – driver analysis, emission estimation, and implications to emission reporting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20413, https://doi.org/10.5194/egusphere-egu24-20413, 2024.

EGU24-20466 | Orals | BG1.3 | Highlight

Fire-precipitation interactions control biomass carbon and net biome production across the world’s largest savanna 

Mathew Williams, David Milodowski, Smallman Luke, Iain McNicol, Kyle Dexter, Casey Ryan, Mike O'Sullivan, Aude Valade, Gabi Hegerl, and Stephen Sitch

Miombo woodlands are the world’s largest savanna, covering 2-3 M km2, and are the dominant land cover in the dry tropics of southern Africa. Here we quantify the dynamics of the miombo region carbon cycle, diagnosing stocks and fluxes and their interactions with climate and disturbance, and evaluate their representation in Trendy land surface models (LSMs). We produce a constrained multi-year analysis (2006-2017) using earth observation time series of total wood C (Cwood) and leaf area index to calibrate an intermediate complexity ecosystem model forced with observed climate, deforestation and burned area. Statistical analyses determine the relationships between carbon cycling, environmental and disturbance variables, and evaluate LSMs. The analysis suggests that the regional net biome production is neutral, 0.0 Mg C ha-1 yr-1 (95% Confidence Interval -1.7 - 1.6), with fire emissions contributing ~1.0 Mg C ha-1 yr-1 (95% CI 0.4-2.5). Spatial variation in biogenic fluxes and C pools is strongly correlated with mean annual precipitation. Burned area is also positively correlated with these pools and fluxes. Areas that are more frequently burned tend to have greater precipitation, and shorter residence time of Cwood. Fire-related mortality from Cwood to dead organic matter likely exceeds fire-related emissions from Cwood to atmosphere, and likely exceeds natural rates of Cwood mortality. LSMs match the biogenic fluxes of the analysis, but diverge on C stocks, timings of heterotrophic respiration and magnitude of fire emissions. The analysis suggests that climate, through precipitation, drives spatial variability in Cwood and GPP across the region. Fire disturbance is the major driver of losses from Cwood. Larger annual precipitation is correlated with both greater GPP and greater fire disturbance. These factors have opposing but unbalanced impacts on Cwood, but the precipitation-GPP effect dominates. Patterns of C cycling across the region are a complex outcome of climate controls on production, and vegetation-fire interactions.

How to cite: Williams, M., Milodowski, D., Luke, S., McNicol, I., Dexter, K., Ryan, C., O'Sullivan, M., Valade, A., Hegerl, G., and Sitch, S.: Fire-precipitation interactions control biomass carbon and net biome production across the world’s largest savanna, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20466, https://doi.org/10.5194/egusphere-egu24-20466, 2024.

It has been advocated that nitrogen (N) availability plays an essential role in mediating plant and microbial growth in cold environment, and could thus regulate the direction and magnitude of permafrost carbon (C)-climate feedback. However, compared to widely concerned N, little is known about soil phosphorous (P) availability and its biological acquisition strategies in permafrost environment. Here we explored soil microbial P acquisition strategies using shotgun metagenomics across the Tibetan permafrost area, encompassing a large scale survey spanning 1,000 km. In contrast to the traditional opinion that microorganisms in cold area usually obtain P mainly through mineralization process, our results revealed that the P cycling genes responsible for solubilization, mineralization and transportation were widespread, illustrating multiple microbial strategies for acquiring P in permafrost regions. Moreover, the higher gene abundance related to solubilization and mineralization as well as an increased ration of MAGs carrying these genes were detected in the active layer, while the greater abundance of low affinity transporter gene (pit) and proportions of MAGs harbouring pit gene were observed in permafrost deposits, reflecting a stronger potential for P activation in active layer but an enhanced P transportation potential in permafrost deposits. Taken together, these results highlight that besides microbial P mineralization, multiple P-related acquisition strategies and their differences among various soil layers should be considered simultaneously to improve model prediction for the responses of biogeochemical cycles in permafrost ecosystems to climate change.

How to cite: Wang, L. and Yang, Y.: Divergent microbial phosphorous acquisition strategies between active layer and permafrost deposits, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2973, https://doi.org/10.5194/egusphere-egu24-2973, 2024.

EGU24-3208 | ECS | Orals | BG1.4 | Highlight

Seagrasses' role as a reverse sedimentary phosphate pump 

Neta Soto, Gilad Antler, and Avner Gross

Seagrasses are marine-flowing plants that form an important coastal ecosystem. Although occupying less than 0.2% of the ocean’s surface, seagrasses store over 15% of the accumulated global carbon storage in the ocean’s sediments. Thus, Seagrass meadows play a pivotal role in mitigating climate change by carbon sequestration. Seagrasses are widely distributed in oligotrophic tropical waters despite the low nutrient levels in the water column due to their ability to absorb nutrients from the sediment porewater. Moreover, seagrasses can actively mobilize unavailable nutrients e.g., iron and phosphorus in the rhizosphere via multiple biogeochemical interactions. This provides them with an important advantage over pelagic photoautotrophs, which are limited by the availability of nutrients in the water column. Despite their ability to transport nutrients from sinks e.g., sediments to the water column where they can be recycled trough grazing or decomposition, the potential role of seagrass as a revers sedimentary phosphate pump remains unclear. The aim of this study is to examine the effect of seagrass disappearance on phosphate flux in marine coastal environments. In a series of incubation experiments, the change in the phosphate release was examined in different tissues of seagrass Halophila stipulacea. The results showed that the while the highest decomposition rate of the rhizomes was the fastest, the highest phosphate release rate was measured in the leaves, despite having similar phosphate content. Since the leaves mostly decompose in the water column, the released phosphate is made available to planktonic photoautotrophs and further enhances more carbon fixation. Overall, we suggest that in oligotrophic environments seagrasses act as a reverse phosphate pump by accessing phosphate in the sediment and later translocating it to the aboveground parts and releasing in the water column, thus fertilizing planktonic photoautotrophs and enhancing further carbon sequestration.

How to cite: Soto, N., Antler, G., and Gross, A.: Seagrasses' role as a reverse sedimentary phosphate pump, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3208, https://doi.org/10.5194/egusphere-egu24-3208, 2024.

EGU24-3472 | Orals | BG1.4

Elevated atmospheric CO2 increased soil plant available and soil organic phosphorus in a mature temperate oak (Quercus robur L.) forest 

Amin Soltangheisi, Adam Pinder, Keegan Blazey, Robert T. Grzesik, Miles Marshall, Angeliki Kourmouli, Carolina Mayoral, Kris M. Hart, Sami Ullah, Iain P. Hartley, A. Robert MacKenzie, and Andy R. Smith

Enhanced productivity of forest ecosystems in response to rising levels of anthropogenically generated atmospheric carbon dioxide (CO2) has the potential to mitigate against climate change by sequestering carbon in woody biomass and soils. However, the physiological response of trees to elevated atmospheric CO2 may be constrained by the availability of soil nutrients, predominantly nitrogen and phosphorus (P). Here, we assess the impact of elevated atmospheric CO2 on P cycling in a temperate 180-year-old oak (Quercus robur L.) forest exposed to free-air CO2 enrichment (ambient + 150 ppm) for six years. Soil cores were collected to a depth of 1 m in July 2023 and separated into three horizons and three layers (O, A, B, 30-50, 50-70, 70-100 cm) before analysis using the Hedley1 sequential P fractionation and the DeLuca2biological based P extraction techniques. Plant available P in soil pore water and total organic P from the O horizon increased by 84 and 128%, respectively, whilst organic P extracted with phosphatase increased by 62% under elevated CO2. Total organic P in soil horizons beyond the B horizon (> 15 cm) decreased under elevated CO2 in comparison with ambient CO2. As soil organic P is derived from the turnover of both vegetation and microbial biomass, increased soil organic P in the O horizon may be due to the faster turnover of organic matter or an increase in the net primary productivity of the forest. Soil P cycling in this forest ecosystem appears to be predominantly influenced by biological rather than chemical processes, since elevated CO2 only affected the organic P and not inorganic P fractions. Forest productivity may be constrained by P limitation in future elevated CO2 environments, if there is faster organic matter turnover which is probably the case in our study.

1Hedley, M. J., Stewart, J. W. B., & Chauhan, B. (1982). Changes in inorganic and organic soil phosphorus fractions induced by cultivation practices and by laboratory incubations. Soil Science Society of America Journal, 46(5), 970-976.

2DeLuca, T. H., Glanville, H. C., Harris, M., Emmett, B. A., Pingree, M. R., de Sosa, L. L., Cerdá-Moreno, C. & Jones, D. L. (2015). A novel biologically-based approach to evaluating soil phosphorus availability across complex landscapes. Soil Biology and Biochemistry, 88, 110-119.

How to cite: Soltangheisi, A., Pinder, A., Blazey, K., Grzesik, R. T., Marshall, M., Kourmouli, A., Mayoral, C., Hart, K. M., Ullah, S., Hartley, I. P., MacKenzie, A. R., and Smith, A. R.: Elevated atmospheric CO2 increased soil plant available and soil organic phosphorus in a mature temperate oak (Quercus robur L.) forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3472, https://doi.org/10.5194/egusphere-egu24-3472, 2024.

EGU24-4491 | Posters on site | BG1.4

Silicone availability and NaCl water type enhances the phosphorus release from sediments in coastal forest catchments in Akita, Japan 

Atsushi Hayakawa, Yuka Kuroe, Ayumi Kawata, Kazuya Nishina, Yuichi Ishikawa, and Tadashi Takahashi

[Background] Phosphorus (P) availability in soils and sediments is a critical parameter influencing primary production in terrestrial and aquatic ecosystems, controlled by both P chemical fractions in solid phase and solution composition. A recent study using Arctic soils reported that the addition of Si to the soil released P bound to Fe(II) compounds, but reports on other soils and sediments are limited. In our previous study, we detected higher P concentrations in stream water and iron-bound P content in river sediments in the marine sedimentary rock catchments of the Akita coastal area compared to catchments in the adjacent igneous rock area. Furthermore, high-P stream waters were NaCl water type with relatively lower Ca2+ and higher SiO2 concentrations. In this study, we evaluated the effects of different solution compositions and amorphous Si addition on P solubilization in sediments using river sediments from marine sedimentary and igneous rock regions. [Method] We tested each five river sediments (<2 mm) in the headwaters of western Akita Prefecture, Japan, where the surface geology is composed of marine sedimentary rocks and igneous rocks. Available Si (easily water-soluble Si) was measured by a long-term flooded incubation in distilled water at 30°C for 30 days. In the P dissolution incubation, four types of treatment solutions (distilled water, 1 mM NaCl and NaHCO3 solutions, and 0.5 mM CaCl2 solution) were added to 0.5 g sediment and in the Si addition treatment, amorphous Si (hydrophilic fumed silica, AEROSIL300) was also added. SRP, DOC and pH in the solution were measured after shaking for 48 hours. A statistical analysis was performed using a linear mixed model (LMM) with SRP, DOC and pH in the liquid phase as objective variables. The surface geology, four types of solutions, and the Si addition as explanatory variables. Additionally, each five sediment was treated as a random effect. [Results and discussion] Easily water-soluble Si content in sediments was significantly higher in marine sedimentary rock areas (p < 0.001), indicating that the easily soluble Si causes higher SiO2 concentration in stream water. The incubation results showed Si addition significantly increased P concentration in the liquid phase (p < 0.001), and combined Si addition with NaHCO3 treatment further increased P concentration. Conversely, CaCl2 treatment significantly decreased the liquid-phase P concentration. The influence of surface geology on extracted P concentration was not significant. Si addition did not affect pH (p = 0.58) and DOC (p = 0.90), while the effects of solution composition on pH and DOC were also significant; NaHCO3 solution increased pH and DOC while CaCl2 solution decreased pH and DOC. In conclusion, in marine sedimentary rock areas in coastal Akita with NaCl water type where Ca2+ concentration is relatively low and sediments have higher easily soluble Si, P release from sediments easily occurs and a high P concentration keeps in the liquid phase.

How to cite: Hayakawa, A., Kuroe, Y., Kawata, A., Nishina, K., Ishikawa, Y., and Takahashi, T.: Silicone availability and NaCl water type enhances the phosphorus release from sediments in coastal forest catchments in Akita, Japan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4491, https://doi.org/10.5194/egusphere-egu24-4491, 2024.

EGU24-6352 | ECS | Posters on site | BG1.4

Phosphorous in the seabed sediments of the Gulf of Riga, Baltic Sea: Fe-Mn concretions as main carriers of mobile phosphorous  

Markus Ausmeel, Martin Liira, Päärn Paiste, Aivo Lepland, and Sten Suuroja

Baltic Sea is a geologically young semi-enclosed brakish-water body which water exchange with the ocean has been gradually declining. Approximately 85 million people live in the Baltic Sea's catchment area, resulting in significant human impact on the basin's ecosystem. Eutrophication due to anthropogenic discharge of nutrients is considered to be the most serious environmental problem which leads to a greater growth of phytoplankton and algae, deterioration of water quality, and lack of oxygen in near-bottom water masses. As a result of recent large-scale input of nutrients, phosphorus has accumulated in the seabed sediments from where it can be remobilized and released into the water column under favorable conditions (hypoxic or anoxic). Marine sediments contain phosphorus in various components i.e. fractions, but not all of them are affected by remobilization. Therefore, knowing how phosphorus fractions are distributed in seabed sediments is important.

One part of the Baltic Sea that has received little attention, but will significantly affect the entire Baltic Sea in the future, is the Gulf of Riga. The Gulf of Riga accounts for less than 5% of the total area of the Baltic Sea and less than 2% of the total water volume. Due to its shallowness and limited connection with the open Baltic Sea, the Gulf of Riga is strongly influenced by riverine input. Intense agriculture, rapid development of industry, and urbanization have resulted in high loads of nutrients into the Gulf of Riga already since the 1960s.

Phosphorus fractions and their vertical distribution were studied from the sea-bottom sediments from the Gulf of Riga and other coastal areas of western Estonia. The amount of potentially mobile phosphorus stored in the surface sediments of the Gulf of Riga is several times higher than in other accumulation areas of the Baltic Sea, with concentrations as high as 980 mg/kg(dw). A strong correlation between Mn and mobile phosphorus concentration suggests that Fe-Mn concretions control the amount of phosphorus in the sediments of the Gulf of Riga. Although the bottom waters of the Gulf of Riga are currently predominantly oxic, a decreasing trend of deep-layer oxygen concentrations and more frequent hypoxia in the Gulf of Riga during previous decades have been documented. Considering the large amount of potentially mobile phosphorus in the sediments of the Gulf of Riga, surpassing the annual total phosphorus input to the Baltic Sea, a substantial release of phosphorus could be inevitable, possibly impacting the entire Baltic Sea ecosystem.

How to cite: Ausmeel, M., Liira, M., Paiste, P., Lepland, A., and Suuroja, S.: Phosphorous in the seabed sediments of the Gulf of Riga, Baltic Sea: Fe-Mn concretions as main carriers of mobile phosphorous , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6352, https://doi.org/10.5194/egusphere-egu24-6352, 2024.

EGU24-7212 | ECS | Orals | BG1.4

Vivianite verified in early Cambrian strata in northwestern China: Implications for phosphorus recycling in ancient anoxic oceans 

Xuyang Cao, Pengcheng Ju, Yigui Han, Lihui Lu, and Dong Shao

In modern low sulfate and anoxic (euxinic) waters, the precipitation of mineral vivianite (an easily oxidized hydrated ferrous-iron phosphate) has played a crucial role in restraining the limiting nutrient element phosphorus (P) recycling back to the water column and consequently decreasing primary productivity. Although such low sulfate and anoxic conditions were widespread in ancient coastal oceans, vivianite has not been directly discovered in the paleo-sediments, which hampers the understanding of P cycling in ancient anoxic environments. Here, we combined techniques of scanning electron microscopy-energy dispersive X-ray spectroscopy, focused ion beam-transmission electron microscopy and P K-edge X-ray absorption near edge structure spectroscopy to analyze samples of P-bearing siliceous rocks and shales from the early Cambrian Yurtus Formation in the Tarim Craton, northwest China. Our results have demonstrated that micron- to nano-scale vivianite crystals are well preserved in the rocks and the vivianite dominates the P phase in some samples. The cherty matrix of the rocks most likely increased the chances of preservation of the oxidation-sensitive vivianite. In light of recent advances, we suggest that vivianite was a crucial P phase in ancient continental margin sediments, spanning most time from the Neoarchean to the early Cambrian. During this interval, the precipitation of vivianite was likely aided by the prevalent dynamic ocean euxinic conditions linked with the seawater sulfate reservoir and the flux of organic matter settling. We propose a negative feedback mechanism in which vivianite precipitation from ancient euxinic waters restricted P availability for biota, reduced marine primary productivity, and possibly abated the rate of Earth's oxygenation and associated evolution of life. This work was financially supported by NSFC projects (grants 42072264, 41730213) and Hong Kong RGC GRF (17307918).

How to cite: Cao, X., Ju, P., Han, Y., Lu, L., and Shao, D.: Vivianite verified in early Cambrian strata in northwestern China: Implications for phosphorus recycling in ancient anoxic oceans, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7212, https://doi.org/10.5194/egusphere-egu24-7212, 2024.

EGU24-9578 | ECS | Posters on site | BG1.4

Lithology-constrained phosphorus (P) releasement 

Shenghui Ouyang

Phosphorus (P), as an indispensable nutrient element in Earth’s biological system, exerts a pivotal role on the burial of organic carbon over million-year time scales. By producing oxygen and consuming carbon dioxide, organic carbon burial may have paved the path for multicellular organisms by reforming the anoxic atmosphere to an oxic one. Organic carbon burial, on long time scales, is ultimately limited by continental P influx released by chemical weathering of P-bearing minerals. As crystalline rocks characterized by prominent discrepancy in P-bearing mineral composition undergoing various dominant weathering forces on surficial environment, P availability for organic carbon burial could be controlled by lithology. To decipher the conundrum of P releasement, a catchment scale case study was conducted, encompassing a series of lithologies following the crystalline rock order. Preliminary data suggests that the P release efficiency is lithology-constrained, indicating an enhanced P releasement in felsic catchment. The result gives us a hint that felsic crust would export more P to the ocean and promote the organic carbon burial, the lithology-constrained P releasement also enlightens us a new perspective to understand the coevolution among crust, atmosphere and life.

How to cite: Ouyang, S.: Lithology-constrained phosphorus (P) releasement, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9578, https://doi.org/10.5194/egusphere-egu24-9578, 2024.

EGU24-9674 | ECS | Orals | BG1.4

Linking phosphorus research to impact: advances and challenges in mapping soil phosphorus pools 

Julian Helfenstein, Bruno Ringeval, Federica Tamburini, Daniel S. Goll, Xianjin He, Vera Mulder, Yingping Wang, Edwin Alblas, and Emmanuel Frossard

Improved management of phosphorus (P) is essential for achieving a range of Sustainable Development Goals (SDGs), including maintaining food security, preserving water quality, and mitigating climate change. This requires an integration of comprehensive mechanistic understanding with accurate spatial data. In this interdisciplinary review, we combine insights from empirical P research, digital soil mapping, biogeochemical modeling, and environmental law to critically examine the current state, pinpoint challenges and propose novel pathways for desperately needed P maps. We first elucidate the relevance of spatial data on P for different SDGs. Subsequently, we summarize the current efforts in mapping P pools at regional to global scales, and discuss the challenges of mapping “available P” due to substantial local scale variability and poor correlation with predictors relative to other soil properties. The practical applicability of these recently published maps is tested by evaluating them with independent measurement data. Finally, we outline ways forward to enhance the accuracy and reliability of P maps, as a basis for science-informed management of P resources.

How to cite: Helfenstein, J., Ringeval, B., Tamburini, F., Goll, D. S., He, X., Mulder, V., Wang, Y., Alblas, E., and Frossard, E.: Linking phosphorus research to impact: advances and challenges in mapping soil phosphorus pools, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9674, https://doi.org/10.5194/egusphere-egu24-9674, 2024.

EGU24-14368 | Orals | BG1.4

Phosphorus Cycling and Transport in Phosphorus Saturated Soils of the Chesapeake Bay Watershed, USA 

Gurpal Toor, Jesse Radolinski, Emileigh Lucas, Charles Burgis, Bradley Kennedy, Fajun Sun, and Patricia Steinhilber

Long-term application of organic products (manure, biosolids, other wastes) and inorganic phosphatic fertilizers have created hot spots of phosphorus (P) saturated soils in intensive animal production regions worldwide. In such regions, P losses from P-saturated (i.e., legacy P) soils continue to plague efforts to improve water quality. Understanding the P cycling and fluxes from these P-saturated soils is critical to advancing our knowledge and developing strategies to manage P in soils and curb P losses. This presentation will discuss P cycling and transport in agricultural catchments (with Maize-Soybean rotation) from the lenses of P chemistry in soils and hydrologic responses from soils to further advancements in managing the P cycle in the soil-plant-water continuum for agricultural sustainability and environmental protection.

How to cite: Toor, G., Radolinski, J., Lucas, E., Burgis, C., Kennedy, B., Sun, F., and Steinhilber, P.: Phosphorus Cycling and Transport in Phosphorus Saturated Soils of the Chesapeake Bay Watershed, USA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14368, https://doi.org/10.5194/egusphere-egu24-14368, 2024.

EGU24-14436 | ECS | Orals | BG1.4

Balancing crop production, water quality and the use of finite P reserves by using the soil P sorption capacity in revised fertilizer recommendations 

Maarten van Doorn, Debby van Rotterdam-Los, Gerard H. Ros, and Wim de Vries

Phosphorus (P) is an essential nutrient for plant growth and is applied to agricultural soils in the form of organic manure or inorganic fertilizer. To guide farmers in achieving optimal crop yields, P fertilizer recommendations are in place with the rationale to bring soils to a “target soil P status” following the classic build-up and maintenance approach. The target soil P status where crop yield is not limited by P deficiencies is generally operationalized as the soil P status at which 90-99% of the potential crop yield is found in long-term fertilization field experiments. Though these fertilizer recommendations allow for an economic optimization of crop yield versus P inputs, environmental objectives are barely considered. In our research, we revised the classic build-up and maintenance approach to balance crop production, water quality and the use of finite P reserves. This revision requires insights into the P sorption capacity of soils (PSC) and its saturation with P. We identify the oxalate extraction method as a key component of this approach since it quantifies the PSC from the combined measurement of amorphous iron- and aluminium-(hydr)oxides and the total pool of reversibly bound P. For the Netherlands, we show the implications of the approach for P fertilizer use. We quantified soil amorphous iron- and aluminium(hydr)oxides contents at a 25m resolution across the soil depth profile using a Digital Soil Mapping approach and used these predictions to translate agronomic soil P data to new insights to optimize P fertilizer use. We finally argue that agronomic P target levels should be lowered in soils with a low PSC to decrease the risk of P leaching and in soils with a high PSC to ensure judicious use of finite P reserves.

How to cite: van Doorn, M., van Rotterdam-Los, D., Ros, G. H., and de Vries, W.: Balancing crop production, water quality and the use of finite P reserves by using the soil P sorption capacity in revised fertilizer recommendations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14436, https://doi.org/10.5194/egusphere-egu24-14436, 2024.

EGU24-16417 | ECS | Orals | BG1.4

31P NMR Reveals Predominance of Small Molecules in Organic Phosphorus within NaOH-EDTA Soil Extracts 

Lenny Haddad, Andrea Vincent, Reiner Giesler, and Jürgen Schleucher

Organic phosphorus (P) plays a crucial role in maintaining the health and productivity of soils. Understanding the composition of organic phosphorus in soils is thus relevant to a range of disciplines, spanning from agricultural sciences to ecology. Over the past few decades, efforts have been directed towards characterizing and quantifying various soil organic P compounds and determining their turnover rates. Despite these efforts, the precise nature of soil organic P remains unclear, particularly that of orthophosphate monoesters, which dominate 31P NMR spectra of NaOH-EDTA extracts globally.

Typically, the monoester region of 1D 31P NMR spectra appears as a series of sharp signals "sitting" on a broad background where the broad background can account for a substantial part of the monoester region. This is prompting questions about how to integrate and identify these signals and to what extent this fraction may be ecologically important. To investigate this monoester background, we employed 1D 31P NMR and 2D 1H-31P NMR1, along with 31P transverse relaxation (T2)2 measurements to calculate intrinsic linewidths. We related this linewidth to molecular weight to unveil the nature of the observed background. Analysing seven soils from different ecosystems, we observed linewidths ranging from 0.5 to 3 Hz for both resolved monoester signals and the background. This suggests that the background comprises numerous, possibly exceeding 100, sharp signals associated with small (<1.5 kDa) organic P molecules.

Organic P in the form of nucleic acids, phospholipids, P-containing metabolites, and phosphorylated proteins dominate the P content of live leaves, leaf litter and microbial tissues. Furthermore, P-containing metabolites are exuded by roots and are present in a vast array of organisms. Evidence that the background potentially can contain a large number of small metabolites is thus not surprising and may account for an important part of the organic P pool given that the background accounts for about 55% of the monoester region. Our findings warrant further research specifically addressing to what extent this pool may play for plant and microbial P nutrition.

We provide recommendations for treating 31P NMR spectra to accurately quantify phosphomonoester species, representing a crucial step in linking observed P speciation to its bioavailability. Our findings align with previous 31P NMR studies detecting background signals in soil-free samples and new evidence suggesting that alkali-soluble soil organic matter consists of self-assemblies of small organic compounds mimicking large molecules.

1Vestergren, J.; Vincent, A. G.; Jansson, M.; Persson, P.; Ilstedt, U.; Gröbner, G.; Giesler, R.; Schleucher, J. High-Resolution Characterization of Organic Phosphorus in Soil Extracts Using 2D 1H–31P NMR Correlation Spectroscopy. Environmental Science & Technology 2012, 46 (7), 3950–3956. https://doi.org/10.1021/es204016h.

2Vincent, A. G.; Schleucher, J.; Gröbner, G.; Vestergren, J.; Persson, P.; Jansson, M.; Giesler, R. Changes in Organic Phosphorus Composition in Boreal Forest Humus Soils: The Role of Iron and Aluminium. Biogeochemistry 2012, 108 (1), 485–499. https://doi.org/10.1007/s10533-011-9612-0.

How to cite: Haddad, L., Vincent, A., Giesler, R., and Schleucher, J.: 31P NMR Reveals Predominance of Small Molecules in Organic Phosphorus within NaOH-EDTA Soil Extracts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16417, https://doi.org/10.5194/egusphere-egu24-16417, 2024.

EGU24-16549 | ECS | Posters on site | BG1.4

A meta-analysis of global soybean plant growth and yield improvement in response to phosphorus addition 

Hannah Walling, Mariana Rufino, Jose Rotundo, Lucas Borras, Shane Rothwell, John Quinton, and Phil Haygarth

Application of phosphorus (P) fertiliser to soybean accounts for a large proportion of the global consumption of P as an agricultural fertiliser. Despite this key a knowledge gap exists surrounding the mechanisms of P fertiliser uptake and how it interacts with nitrogen fixation processes and yield improvements.

This paper aims to improve the understanding of P cycling in global cropping systems and will present a global meta-analysis of published data quantifying the effect of P fertiliser application on soybean above- and below-ground plant response variables. 790 paired observations (P fertiliser treatment and control treatment) were synthesised from 81 peer-reviewed articles that reported soybean response, including seed yield and nodulation, to P addition under a range of different environmental conditions.

We tested the hypothesise that:

  • soybean productivity will increase following P addition, with this response being driven by below-ground processes;
  • environmental conditions, particularly soil chemical properties would explain the variance in the observed response.

Analysis of these observations showed an overarching increase in soybean plant response following P addition. We found that several environmental and experimental conditions, particularly soil phosphorus status and phosphorus fertiliser rate influence the response of soybean to phosphorus addition, highlighting the complexities of sustaining P use across such a globally cultivated crop.

We recommend further experimental work needs to be conducted, which controls for such factors and allows for the improved mechanistic understanding of below-ground processes, to inform better use of finite P resources.

How to cite: Walling, H., Rufino, M., Rotundo, J., Borras, L., Rothwell, S., Quinton, J., and Haygarth, P.: A meta-analysis of global soybean plant growth and yield improvement in response to phosphorus addition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16549, https://doi.org/10.5194/egusphere-egu24-16549, 2024.

EGU24-17700 | ECS | Posters on site | BG1.4

Vivianite as a phosphorus sink in estuarine systems: The case study of the Brillantes mudflat, Loire, France 

Mohammed Barhdadi, Aurélia Mouret, Christine Barras, Guillaume Morin, Grégoire Maillet, Matthieu Durand, Meryem Mojtahid, Eric Bénéteau, Nicolas Dubosq, and Edouard Metzger

Phosphorus (P) is a key nutrient controlling primary production in aquatic systems. In coastal systems, the P cycle involves dynamic interactions between terrestrial, aquatic and sedimentary compartments. Over the last century, human activities such as deforestation, intensive agricultural practices and the disposal of municipal and industrial wastes have increased P inputs to coastal ecosystems. As a result, this increase in P inputs has led to an increase in the occurrence of algal blooms and higher oxygen demand in estuaries. In the Loire estuary, dissolved oxygen deficits have been a recurrent and worrying issue for several decades despite the improvement of water quality over the last 30 years due to reduced wastewater discharge and better effluent treatment. In this context, the burial of bioavailable P may influence the recovery of waters from eutrophication. The major P burial phases are apatite, organic P and iron-bound P. The results of sequential chemical extraction and pore water analysis carried out over a 5m-long sediment core from the intertidal Brillantes mudflat in the Loire estuary indicated a greater abundance of the iron-bound P compared to other phases. Iron-bound P occurs in two different forms: phosphorus bound to iron oxides and in the iron phosphate mineral known as vivianite. Vivianite is a ferrous iron phosphate mineral formed under reducing and low sulphate conditions in sediments where organic matter serve as electron donor for ferric iron reduction. Results of sequential chemical extraction of freeze-dried sediment samples combined with pore water data and scanning electron microscope–energy dispersive x-ray spectroscopy (SEM-EDXS) on resin-embedded sediment samples indicated that vivianite-type minerals may act as an important sink for P at the studied site. Authigenic vivianite crystals were found below the shallow sulphate/methane transition zone (SMTZ) at 94 cm depth and contain significant amounts of manganese, as observed in freshwater sediments. We therefore hypothesise that anthropogenic over-fertilization of coastal regions in the last century may have increased the importance of vivianite authigenesis in surface sediments. Consequently, vivianite is likely to be an important sink for P in estuarine systems worldwide.

This study is part of a PhD financed by the European Project Life REVERS’EAU.

How to cite: Barhdadi, M., Mouret, A., Barras, C., Morin, G., Maillet, G., Durand, M., Mojtahid, M., Bénéteau, E., Dubosq, N., and Metzger, E.: Vivianite as a phosphorus sink in estuarine systems: The case study of the Brillantes mudflat, Loire, France, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17700, https://doi.org/10.5194/egusphere-egu24-17700, 2024.

EGU24-19011 | Orals | BG1.4

Microbial phosphorus limitiation with soil age along a chronosequence on the Galapagos Islands 

Katharina Maria Keiblinger, Sebastian Socianu, Maria Rechberger, Martin Gerzabek, and Franz Zehetner

The Galápagos archipelago, a volcanic island chain, is comprised of a series of progressively older islands with increasingly weathered soils away from the volcanic hotspot. Volcanic soils are known for their high phosphate sorption capacity. In this study, we explore differences in soil microbial abundance and activity across a soil age gradient (1.5 to 1070 ka) to understand how soil microorganisms are affected by soil development, shifting soil characteristics and P sorption over extensive periods.

Basal respiration, substrate-induced respiration and microbial biomass P decreased with soil development, suggesting increasing nutrient limitation for soil microbes. Also, soil enzymatic stoichiometry revealed a limitation driven mainly by P and not by N or C. C- and N-acquiring exoenzyme activities peaked at 26 ka with lower activities in younger and older soils. Phosphatase activity increased with soil age, indicating microbial P limitation in the older soils. This is only partly in line with  P sorption-desorption characteristics along the studied weathering sequence. Phosphate sorption capacity was high in the 4.3 ka soils likely due to amorphous soil constituents. A change towards 2:1-type crystalline clays after 26 ka of soil weathering led to weaker P sorption and stronger desorption, and acidification and increased P occlusion in Al and Fe (hydr)oxides became an important factor for microbial P limitation in the older soils.

Our results reveal striking differences in soil properties on the Galápagos Islands, suggesting relatively little nutrient constraints for soil microbes, despite strong P sorption, in the younger volcanic soils but growing P limitation in the older, highly weathered soils. These observations have important bearings on nutrient cycling and may therefore also affect the evolution of plant and animal species on this unique archipelago.

How to cite: Keiblinger, K. M., Socianu, S., Rechberger, M., Gerzabek, M., and Zehetner, F.: Microbial phosphorus limitiation with soil age along a chronosequence on the Galapagos Islands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19011, https://doi.org/10.5194/egusphere-egu24-19011, 2024.

EGU24-20517 | Posters on site | BG1.4

A spatial perspective on internal phosphorus cycling in morphologically complex eutrophic lakes: the importance of stratification 

Tom Jilbert, Siqi Zhao, Jussi Vesterinen, and Juha Niemistö

Many eutrophic lakes suffer from long term accumulation of legacy phosphorus (P) in sediments. Repeated cycling of P between sediments and water column leads to delayed recovery from eutrophication even after abatement of external loading. Moreover, in complex multi-basin lake systems, legacy P can be internally redistributed over time, leading to spatial heterogeneity in regeneration and burial of P and consequent impacts on water quality. Few studies have attempted to map such internal variability in individual lakes in the context of understanding long term recovery from eutrophication. Here we use a combination of sediment trap deployments through one full stratification cycle (May-October 2021), sediment core biogeochemical analyses, and mass balance calculations, to quantify P cycling in Lake Hiidenvesi, a dimictic lake with 5 sub-basins in southern Finland. We show that exchange of P between sediments and water column is more intense in shallow (approximately 0-10 m depth) non-stratified sub-basins, due to both sediment resuspension and diffusive fluxes across the sediment-water interface. In contrast, deeper stratified sub-basins serve as P sinks by promoting sedimentation in relatively quiescent conditions. Due to lateral exchange of water and suspended materials between sub-basins, P is shuttled towards long term burial in deeper, downstream sub-basins. Budget calculations show that net sediment P burial exceeds external loading on the whole-lake scale, indicating a long-term trend towards recovery from eutrophication. However, temporary retention and repeated recycling of legacy P in the shallower upstream sub-basins continues to impact negatively on water quality, despite external loading reductions. The results have implications for understanding the timescales of recovery and for targeting restoration actions aimed at modifying internal P cycling to improve water quality.

How to cite: Jilbert, T., Zhao, S., Vesterinen, J., and Niemistö, J.: A spatial perspective on internal phosphorus cycling in morphologically complex eutrophic lakes: the importance of stratification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20517, https://doi.org/10.5194/egusphere-egu24-20517, 2024.

EGU24-20917 | Posters on site | BG1.4

Controls on global patterns of dissolved organic phosphorus utilisation in the surface ocean 

Bei Su, Xianrui Song, Solange Duhamel, Claire Mahaffey, Clare Davis, Ingrid Ivančić, Shuo Zhou, and Jihua Liu

          Utilisation of dissolved organic phosphorus (DOP) by marine microbes as an alternative phosphorus (P) source when phosphate is scarce can help sustain non-Redfieldian carbon:nitrogen:phosphorus ratios and efficient ocean carbon export. Alkaline phosphatase (AP) is an important enzyme group that facilitates the remineralisation of DOP to phosphate and thus its activity is a promising proxy for DOP-utilisation, particularly in P-stressed regions. In order tounderstand the global spatial patterns and rates of microbial DOP utilization and their environmental controls, we compiled a Global Alkaline Phosphatase Activity Dataset (GAPAD) with 4083 measurements collected from 79 published manuscripts and one database and further investigated the possible mechanisms controlling global ocean APA. We find that DOP concentration, salinity, excess phosphate (P*), and chlorophyll a concentrations are critical factors in predicting global patterns of APA, which together explain as much as 39% of the variance in the observed APA dataset. Among all environmental factors, DOP concentration explains the most variance in the observed APA data and is negatively correlated with APA. P* is negatively correlated with APAwhile chlorophyll a concentration is positively correlated.  Moreover, wind speed, dust iron deposition rate, and zinc concentration are also possible important environmental factors controlling APA. Using structural equation modeling, DOP and P* concentrations have a total negative effect on APA of -0.36. and -0.2 respectively, while chlorophyll a concentration and salinity have a total positive effect of 0.16 and 0.24. Via a set of numerical competition experiments between an AP-producing phytoplankton and a non AP-producing competitor, AP-producing phytoplankton are found to have an advantage in regions with low P*, but only alongside sufficiently high DOP and DIN concentrations. This trend arises due to the trade-off between P acquisition and N allocation to AP synthesis and is not affected by varying the model assumptions regarding nutrient supplies, N-demand, and key physiological traits.  Extending our results to the global ocean using DIN, DIP, and DOP datasets enables us to pinpoint key regions where optimal conditions for DOP-utilisation are prevalent. These findings align closely with the patterns illuminated by our APA dataset. Our results show that on a global scale, when phosphate limitation is severe, plankton utilize DOP through producing AP, and this will help understand the biogeographical shift of different microbial groups in response to future climate change. Further work is needed to include the parallel role of the trace metal co-factors iron and zinc in driving AP synthesis and its spatial distribution in our modelling experiments.

How to cite: Su, B., Song, X., Duhamel, S., Mahaffey, C., Davis, C., Ivančić, I., Zhou, S., and Liu, J.: Controls on global patterns of dissolved organic phosphorus utilisation in the surface ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20917, https://doi.org/10.5194/egusphere-egu24-20917, 2024.

EGU24-21673 | Posters on site | BG1.4

Beyond “Redfield ratio”: Oxygen exchange between water and phosphate can provide insights into carbon dynamics in soils 

Federica Tamburini, Maja Siegenthaler, and Chiara Pistocchi

Phosphorus (P) is essential for cellular metabolism. Many metabolic pathways and processes depend on it, including energy production through ATP, DNA and RNA synthesis, and protein phosphorylation during post-translational signaling adaptation.

In marine sediments and oceanic water, the stoichiometric ratio between carbon and phosphorus has been found to vary with latitude, but in algae and phytoplankton, which are responsible for primary production and CO2 uptake from the atmosphere, this ratio is relatively constant. This constant ratio is known as the Redfield ratio and  it is often used as a constraint in modeling.

In soils, where microorganisms control nutrient cycling and consequent carbon sequestration, the C:P is more variable both in soil and microbial biomass. First, microorganisms exhibit a wide range of metabolic adaptations to environmental pressure, and the physical and mineralogical properties of the soil play a significant role in nutrient control, e.g. through sorption/desorption reactions. Due to these complexities, using nutrient ratios for modeling soil organic carbon dynamics and predicting the impact of anthropogenic influences on global changes is challenging. Is it possible to find a connection between carbon and phosphate that encompasses the "Redfield" ratio and reflects their tight link in cellular metabolism?

By examining the oxygen isotope composition in inorganic phosphate (δ18O-Pi), we can determine the extent of oxygen exchange between water and phosphate, which is controlled by biological processes. Intracellularly, this exchange occurs through phosphoryl transfer, a fundamental process in cellular phosphate cycling. 

During the last 10 years, we conducted a series of incubation experiments where we measured CO2 respiration and δ18O in resin and microbial cytosolic phosphate in soils from different environments. These incubations were performed with waters of varying 18O isotopic composition. By analyzing δ18O in microbial cytosolic phosphate at the beginning and end of the incubation, we could measure the level of oxygen exchange between water and phosphate.

Comparing the results from these incubations, we observed a significant correlation between the percentage of oxygen exchange and the cumulative CO2 respired during the incubation. This correlation was consistent  through different soil ages, mineralogy, phosphate levels, and incubation length. When normalizing the percentage of oxygen exchange to moles of oxygen exchanged per moles of carbon respired, it appears that for every mole of oxygen exchanged due to phosphoryl transfer, there is a nearly fixed amount of carbon respired. This suggests that the moles of oxygen exchanged through phosphoryl transfer recorded in soil microbial phosphate can provide information about metabolic carbon expenditure.

This finding would provide new insights on the link between P and C in soil microbial biomass. The controlled nature of the incubation experiments may not fully reflect the biological activity in soil environments, so it would be necessary to perform field-based incubation experiments to confirm the link between carbon respiration and phosphorus microbial cycle. This information could potentially improve our understanding of carbon dynamics and be used for further modeling purposes.

How to cite: Tamburini, F., Siegenthaler, M., and Pistocchi, C.: Beyond “Redfield ratio”: Oxygen exchange between water and phosphate can provide insights into carbon dynamics in soils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21673, https://doi.org/10.5194/egusphere-egu24-21673, 2024.

EGU24-21972 | Posters on site | BG1.4

Exploring spatial distribution and characterization of inorganic and organic phosphorus in temperate soils using NanoSIMS  

Kaiyu Lei, Franziska Barbara Bucka, Carmen Höschen, Yahan Hu, and Ingrid Kögel-Knabner

For a comprehensive understanding of the phosphorus (P) storage and cycling in temperate soils, it is necessary to explore further the bonding pathways of organic P (Po) and inorganic P (Pi) to mineral surfaces and soil organic matter (SOM), and their interconnections with organic carbon (OC) at a micro-scale other than conventional bulk analysis. In the past decade, nanoscale secondary ion mass spectrometry (NanoSIMS) has been increasingly recognized as a promising imaging technique to understand soil biogeochemical processes, particularly in exploring organo-mineral associations in soils at the microscale (Mueller et al., 2023). However, its application in studying P, and the identification and distinction of Po and Pi remains challenging, hindering a comprehensive understanding of the P cycling in soils.

In our study, four temperate soil types, including Cambisol, Luvisol, Phaeozem and Fluvisol, were taken from Bavarian Forest in South-East Germany. The pH of these soils ranges from 5.4 to 6.3, with poor to medium P stocks but distinct Po stocks in fine fractions (<20 μm). Previous bulk studies have hinted at different pathways in P bonding to mineral surfaces and SOM. NanoSIMS was employed to further explore and visualize these bonding pathways. Recent advancements in NanoSIMS technology, particularly improved O- sources for cation detection and the capability for 31P- and 31P16O2- detection enable us to identify and distinguish Po and Pi at a microscale by 31P16O2-/31P- ratio, in which a lower ratio in specific areas corresponds to a more dominant presence of Po, and vice versa.

From NanoSIMS images, preliminary results reveal that a proportion of Po associates with either clay minerals or Fe (hydr)oxdies without assimilating into SOM. This Po fraction is suspected to originate from highly decomposed SOM, where N has either been assimilated by microorganisms or leached away, and Po is stabilized to mineral surfaces due to strong bonding strength. In contrast, the Po assimilated into SOM is associated with various cations, including Ca, Al and Fe, which may suggest the origin from particulate organic matter. Interestingly, the fine plant residue is depleted in Po in the fine fraction.

In conclusion, our study provides valuable insights into distinguishing different bonding pathways of these P forms within clay minerals, Fe (hydro)oxides, and SOM by using advanced NanoSIMS data, and emphasizes the interconnection with OC and Po and Pi in the fine fraction.

Reference: Mueller, C. W., Hoeschen, C., Koegel-Knabner, I., 2023. Understanding of soil processes at the microscale—Use of NanoSIMS in soil science. Encyclopedia of Soils in the Environment (Second Edition). Elsevier. 10.1016/B978-0-12-822974-3.00045-8

How to cite: Lei, K., Bucka, F. B., Höschen, C., Hu, Y., and Kögel-Knabner, I.: Exploring spatial distribution and characterization of inorganic and organic phosphorus in temperate soils using NanoSIMS , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21972, https://doi.org/10.5194/egusphere-egu24-21972, 2024.

EGU24-22214 | Orals | BG1.4

Heterogeneous Dissolved Organic Phosphorus Composition and Bioavailability in Marine Systems 

Sonya Dyhrman, Kathleen Ruttenberg, Danielle Hull, and Sherril Leon Soon

The critical role of Dissolved Organic Phosphorus (DOP) in supporting primary production has spurred efforts to characterize DOP composition so that insight may be gained into its bioavailability and cycling in aquatic systems. The degree to which DOP is bioavailable to primary producers will determine, in part, the extent of carbon uptake and sequestration.  Ascertaining DOP composition has proven to be an analytically challenging endeavor.  As a consequence, the DOP pool remains poorly characterized, and our predictive power relative to DOP-bioavailability, and coupled carbon cycling, remains limited. Analytical impediments to characterizing DOP composition in natural waters include its low concentration, requiring pre-concentration before compositional features can be probed via spectroscopy, and the fact that organic phosphorus compounds are not easily amenable to standard organic geochemical approaches, such as chromatographic or mass spectrophotometric methods, particularly in salt water. While 31-Phosphorus Nuclear Magnetic Resonance (31P-NMR) spectroscopy has provided intriguing information on the distribution of the 2 major DOP compound types (phosphoesters, phosphonates), the crucial question of DOP bioavailability cannot be addressed by this method. We present novel DOP molecular weight distribution and bioavailability data, generated using a coupled sequential ultrafiltration-bioavailability approach from a marine water column depth profile and locations across a gradient in phosphate concentration in the Atlantic and Pacific Oceans.  There is substantial compositional variability in the marine DOP pool, both in the pattern of DOP molecular weight distribution at different sites, as well as the distribution of bioavailable mono- and diesters of phosphate across molecular weight fractions.  In some cases, a substantial fraction of DOP in different molecular weight size classes is non-reactive to the two enzymes used to assay potential bioavailability, raising the interesting possibility of non-bioavailable DOP. The significance of recognizing that the oceanic DOP pool is compositionally heterogeneous, and variably bioavailable, lies in that fact that such information is a prerequisite to building ecosystem models that capture the influence of P biogeochemistry on primary production and carbon cycling in aquatic systems.

How to cite: Dyhrman, S., Ruttenberg, K., Hull, D., and Leon Soon, S.: Heterogeneous Dissolved Organic Phosphorus Composition and Bioavailability in Marine Systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22214, https://doi.org/10.5194/egusphere-egu24-22214, 2024.

Biogenic volatile organic compounds (BVOCs) are carbon compounds released by plants through secondary metabolism. In the global background of nitrogen (N) deposition, plants respond to environmental changes by altering BVOCs and photosynthetic strategies. However, there is very little research on the release and photosynthetic characteristics of BVOCs in bamboo in response to N deposition. Therefore, we took Pleioblast amarus as a research object and conducted pot experiments to set up four different nitrogen deposition levels (referred to as "N deposition") (0 kg N hm-2-a-1(N0), 30 kg N hm-2 a-1(N1), 60 kg N hm-2 a-1(N2), and 90 kg N hm-2 a-1(N3)) to explore the effects of different N deposition levels on the release and photosynthetic characteristics of BVOCs in leaves, and analyzed the correlation between the indicators. The results showed that: (1) the percentage of isoprene emission from Pleioblast amarus bamboo leaves increased with the increase of N deposition level (significantly positively correlated), but the N deposition level did not significantly affect the total number of BVOCs; (2) the increase of N deposition level significantly increased the net photosynthetic rate and isoprene (ISO) emission rate of leaves, with the highest ISO emission rate under N3 treatment, which was 80. 39%, 75.07%, and 50.84% higher than N0, N1, and N2, respectively; (3) ISO emission rate and total BVOCs emission of Sanming bitter bamboo were significantly positively correlated with net photosynthetic rate and photosynthetic effective radiation of leaves, but ISO emission rate and total BVOCs emission were significantly negatively correlated with chlorophyll b and total chlorophyll content (P≤0.05). In conclusion, the increase in nitrogen deposition led to a remarkable increase in isoprene emissions from Sanming bitter bamboo leaves. 

How to cite: Li, L. and Liu, X.: Effects of nitrogen deposition on volatile organic compounds composition, isoprene emissions and photosynthetic characteristics of Pleioblast amarus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2236, https://doi.org/10.5194/egusphere-egu24-2236, 2024.

EGU24-2534 | Posters on site | BG1.6

Rice cultivation under continuous flooding vs alternate wetting and drying: implications for biomass, nitrogen cycling and greenhouse gas flux 

Sami Ullah, Megha Kaviraj, Yafei Guo, Gianni Micucci, and Fotis Sgouridis

Rice uses 34-43% of the global irrigation water and is responsible for the usage of 24-30% of the world's total freshwater. More than 75% of rice produced in India is cultivated using the traditional continuous flooding (CF) irrigation method, which is a labour-intensive, time, water and energy-consuming process and a key source of global methane emissions. Alternate Wetting and Drying (AWD) is a popular water-saving approach trailed in Asia including India to reduce water use and methane emissions, whilst sustaining rice production. AWD is a method of periodic soil saturation followed by drying compared to CF. The objective of this research was to evaluate greenhouse gas (GHG) fluxes and internal and external nitrogen cycling processes as influenced by AWD and CF management regimes. A mesocosm experiment was set up in the laboratory using imported Indian paddy soil where Jasmine rice (var KDML 105) was grown. Our results depicted that plant biomass (52.57%), root biomass (28.57%), height (24.77%), effective tiller number (45.15%), stem sheath diameter (53.38%) and stomatal conductance (66.49%) were significantly (p<0.05) higher in CF compared to AWD treatment. A similar trend was observed in rice leaf chlorophyll (Chl a, b and total chl) contents. Interestingly, the chlorophyll a and b ratio observed was higher (1.63) in AWD compared to CF (1.03) conditions. This was likely during the process of chlorophyll b degradation and conversion to Chl a, thus resulting in the increase of a to b ratio to cope with the stress by maintaining the leaf photosynthetic efficacy. Soil enzyme activity revealed that β-glucosidase (BG), β-N-acetyl-glucosaminidase (NAG), and acid phosphatase (AP) were higher in AWD, whereas leucine aminopeptidase (LAP) activity was significantly higher in CF. Higher LAP activity might be a response to limited nutrient availability, as LAP helps to release amino acids that serves as a source for N mineralization and N supply. The 15N isotope tracing study revealed that denitrified N2O flux was significantly (p<0.05) higher in CF compared to AWD where source partitioning (% N2O denitrified) was 99.32% in CF and 27.01% in AWD. Higher gross mineralization was observed under AWD (3.92 ± 0.31µg-1 g-1 d-1) due to the promotion of aerobic microbial activity compared to CF (1.31 ± 0.31µg-1 g-1 d-1). A similar trend was observed for the consumption and immobilization of NH4+ and gross nitrification rates. GHG emissions rate viz., CH4-C, CO2-C, and N2O-N emissions were significantly higher under CF by 61, 3 and 72.%, respectively. Moreover, the global warming potential projected was higher under CF averaging at 10.92 mg kg-1 soil compared to 2.19 mg COkg-1 soil under AWD. Reduced GHG emissions under AWD provides for a significant negative feedback to global warming potential and future initiatives should keep emphasizing the optimization of this practice for its significant contribution to both climate change mitigation and sustainable agriculture.

How to cite: Ullah, S., Kaviraj, M., Guo, Y., Micucci, G., and Sgouridis, F.: Rice cultivation under continuous flooding vs alternate wetting and drying: implications for biomass, nitrogen cycling and greenhouse gas flux, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2534, https://doi.org/10.5194/egusphere-egu24-2534, 2024.

EGU24-2749 | ECS | Posters on site | BG1.6

Molecular transformation of organic nitrogen in Antarctic penguin guano-affected soil 

Libin Wu, Ming Sheng, Xiaodong Liu, and Pingqing Fu

Organic nitrogen (ON) is an important participant in the Earth’s N cycle. Previous studies have shown that penguin feces add an abundance of nutrients including N to the soil, significantly changing the eco-environment in ice-free areas in Antarctica. To explore the molecular transformation of ON in penguin guano-affected soil, we collected guano-free weathered soil, modern guano-affected soil from penguin colonies, ancient guano-affected soil from abandoned penguin colonies, and penguin feces from the Ross Sea region, Antarctica, and Fourier transform ion cyclotron mass spectrometry (FT-ICR MS) was used to investigate the chemical composition of water-extractable ON. By comparing the molecular compositions of ON among different samples, we found that the number of ON compounds (>4,000) in weathered soil is minimal, while carboxylic-rich alicyclic-like molecules (CRAM-like) are dominant. Penguin feces adds ON into the soil with > 10,000 CHON, CHONS and CHN compounds, including CRAM-like, lipid-like, aliphatic/ peptide-like molecules and amines in the guano-affected soil. After the input of penguin feces, macromolecules continue to degrade, and other ON compounds tend to be oxidized into relatively stable CRAM-like molecules, this is an important transformation process of ON in guano-affected soils. We conclude the roles of various forms of ON in the N cycle are complex and diverse. Combined with previous studies, ON eventually turns into inorganic N and is lost from the soil. The lost N ultimately returns to the ocean and the food web, thus completing the N cycle. Our study preliminarily reveals the molecular transformation of ON in penguin guano-affected soil and is important for understanding the N cycle in Antarctica.

How to cite: Wu, L., Sheng, M., Liu, X., and Fu, P.: Molecular transformation of organic nitrogen in Antarctic penguin guano-affected soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2749, https://doi.org/10.5194/egusphere-egu24-2749, 2024.

EGU24-3699 | Posters on site | BG1.6 | Highlight

Nitrite stimulates HONO and NOx but not N2O emissions in Chinese agricultural soils during nitrification 

Dianming Wu, Yaqi Song, Yuanchun Yu, and Peter Dörsch

The long-lived greenhouse gas nitrous oxide (N2O) and short-lived reactive nitrogen (Nr) gases such as ammonia (NH3), nitrous acid (HONO), and nitrogen oxides (NOx) are produced and emitted from fertilized soils and play a critical role for climate warming and air quality. However, only few studies have quantified the production and emission potentials for long- and short-lived gaseous nitrogen (N) species simultaneously in agricultural soils. To link the gaseous N species to intermediate N compounds [ammonium (NH4+), hydroxylamine (NH2OH), and nitrite (NO2)] and estimate their temperature change potential, ex-situ dry-out experiments were conducted with three Chinese agricultural soils. We found that HONO and NOx (NO + NO2) emissions mainly depend on NO2, while NH3 and N2O emissions are stimulated by NH4+ and NH2OH, respectively. Addition of 3,4-dimethylpyrazole phosphate (DMPP) and acetylene significantly reduced HONO and NOx emissions, while NH3 emissions were significantly enhanced in an alkaline Fluvo-aquic soil. These results suggest that ammonia-oxidizing bacteria (AOB) and complete ammonia-oxidizing bacteria (comammox Nitrospira) dominate HONO and NOx emissions in the alkaline Fluvo-aquic soil, while ammonia-oxidizing archaea (AOA) are the main source in the acidic Mollisol. DMPP effectively mitigated the warming effect in the Fluvo-aquic soil and the Ultisol. In conclusion, our findings highlight the important role of NO2 in stimulating HONO and NOx emissions from dryland agricultural soils. In addition, subtle differences of soil NH3, N2O, HONO, and NOx emissions indicated different N turnover processes, and should be considered in biogeochemical and atmospheric chemistry models.

How to cite: Wu, D., Song, Y., Yu, Y., and Dörsch, P.: Nitrite stimulates HONO and NOx but not N2O emissions in Chinese agricultural soils during nitrification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3699, https://doi.org/10.5194/egusphere-egu24-3699, 2024.

EGU24-4369 | ECS | Orals | BG1.6

Constraining the denitrification process in conventional and regenerative agriculture 

Gianni Micucci, Fotis Sgouridis, Stefan Krause, Iseult Lynch, Niall P. McNamara, Felicity Roos, Leake Jonathan, and Sami Ullah

In this study, we aimed to constrain and characterize the dynamics of denitrification in three different fields: one conventional arable and two types of pasture (“leys”). During a one-year field campaign, denitrification was measured using our newly developed method combining the application of 15N tracer and artificial atmosphere for the incubation of soil cores under field conditions (Micucci, 2022), while total N2O emissions were measured using static flux chambers during parallel incubations. Our objectives were to determine the best way to upscale soil core denitrification measurements and trace the fate of applied synthetic nitrogen fertilizer via denitrification in conventional agriculture in comparison to pastures under regenerative agriculture practices.

We determined that the best way to derive field-scale fluxes of denitrification was to use the core method to calculate the source partitioning coefficient (SPC) and product ratio (PR) and use these metrics in combination with static chamber data. The SPC is defined as the proportion of total N2O emissions that originates from denitrification while the product ratio measures the proportion of denitrification product emitted as N2O rather than N2.

During the field campaign, we estimated that 22 kgN ha-1 were lost via denitrification in the arable field, amongst which 15.17 were attributed to fertilizer application, representing around 8% of the 200 kgN ha-1 applied. Furthermore, 9 % of the denitrified fertilizer was emitted as N2O rather than N2. On the other hand, the unfertilized ley emitted only 2.6 kgN ha-1 via denitrification annually. Overall, the total N2O emissions in the fertilizer arable field were responsible for around 2 t eqCO2 ha-1 year-1 compared to 0.15 in the unfertilized ley, highlighting the importance of land management in strategies of greenhouse gas emission reduction.

How to cite: Micucci, G., Sgouridis, F., Krause, S., Lynch, I., McNamara, N. P., Roos, F., Jonathan, L., and Ullah, S.: Constraining the denitrification process in conventional and regenerative agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4369, https://doi.org/10.5194/egusphere-egu24-4369, 2024.

EGU24-4706 | ECS | Orals | BG1.6

How does nitrogen control soil organic matter composition? – A theory and model 

Chun Chung Yeung, Harald Bugmann, Frank Hagedorn, and Olalla Díaz-Yáñez

Current soil biogeochemical models have difficulties matching the observed composition of soil organic matter (i.e., the relative proportions of deadwood, raw litter, organic horizon, particulate organic carbon, and mineral-associated organic carbon). In reality, nitrogen (N) controls microbial decomposition and physiological processes, whereas in most models it is merely considered a plant nutrient. In addition, many N fertilization studies have shown that N exerts different effects on different C pools via changing exoenzyme activities, microbial growth, and necromass production via microbial turnover. These divergent effects control SOM composition and have C-cycle consequences.

We expanded the CENTURY model by incorporating multiple hypothesized microbial responses to nitrogen availability, including 1) decomposition reduction of recalcitrant substrates when N is in excess; 2) decomposition stimulation of high C:N substrates when N limitation is alleviated; 3) microbial adaptation of turnover rate; 4) microbial adaptation of CUE; and 5) secondary feedback to decomposition via changes in microbial biomass in response to N. We systematically tested multiple model variants using two sets of simulations, one along a natural N gradient in Swiss forests, and another one with artificially increased N input (i.e., simulating an N-fertilization experiment). We evaluated the simulated outputs using data on soil organic matter fraction stocks, their relative proportions, and temporal responses under N addition.

From the simulation results, we identified the necessary processes to explain the temporal response pattern of different C pools to N addition, in accordance with findings from meta-analyses. In addition, we identified patterns of SOM composition over a natural gradient of N supply (no artificial N addition), which can again be explained by the N-driven processes we implemented. We conclude that considering the direct effects of nitrogen as a key additional constraint on microbial processes is essential to improve the realism and accuracy of soil biogeochemistry models.

How to cite: Yeung, C. C., Bugmann, H., Hagedorn, F., and Díaz-Yáñez, O.: How does nitrogen control soil organic matter composition? – A theory and model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4706, https://doi.org/10.5194/egusphere-egu24-4706, 2024.

EGU24-5161 | ECS | Orals | BG1.6

On the Contribution of Atmospheric Nitrogen Deposition to Nitrogen Burden in an Eutrophic Lake in Eastern China 

Weikun Li, Xia Wang, Zhongyi Zhang, Xiaodong Liu, and Lei Geng

Atmospheric deposition of natural and anthropogenic sourced reactive nitrogen (Nr, mainly including NH3, NH4+, NOx, NO3- and etc.) has substantial influence on terrestrial and aquatic ecosystems, driving global nutrient imbalances and increasing risks to human health. Although it has been demonstrated that atmospheric Nr deposition has a substantial impact on nitrogen pools in remote and/or sensitive lakes, there is a scarcity of systematic evaluations regarding atmospheric Nr deposition's impact on the nitrogen burden in eutrophic lakes with riverine input as the primary source. Utilizing a regional chemical transport model, combined with observations of riverine nitrogen input, we investigate the contribution of atmospheric Nr deposition to a eutrophic Lake Chaohu in eastern China. The results indicate that riverine total nitrogen (TN) input to the lake was 11553.3 t N yr-1 and atmospheric TN deposition was 2326.0 t N yr-1 in the year of 2022. For Nr species which are directly available for the biosphere supporting algae and plant growth, riverine NH4+ input was 1856.1 t N yr-1 and atmospheric NHx (NH3 and NH4+) deposition was 824.5 t N yr-1. The latter accounts for ~ 1/3 of total NHx input to the lake. For NOy (HNO3 and NO3-) species, atmospheric deposition was estimated to also contributes a similar amount to the NHx species. The results suggest that even in regions with dense human activities with primary riverine N input, atmospheric deposition of Nr could also contribute significantly to the bio-available nitrogen in lake systems, and addressing eutrophication in Lake Chaohu and other eutrophic lakes will also need to consider the reduction of NH3 and NOx (i.e., NO + NO2, the precursor of NOy) emissions, in addition to the mitigation of riverine N input.

How to cite: Li, W., Wang, X., Zhang, Z., Liu, X., and Geng, L.: On the Contribution of Atmospheric Nitrogen Deposition to Nitrogen Burden in an Eutrophic Lake in Eastern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5161, https://doi.org/10.5194/egusphere-egu24-5161, 2024.

EGU24-5244 | ECS | Posters on site | BG1.6

Surges in global N2O fluxes from saltmarshes are driven by increasing porewater nitrate and ammonium concentrations 

Devon Collier-Woods, Sami Ullah, and Sophie Comer-Warner

Saltmarshes have the potential to sequester large amounts of carbon, however, the value of stored carbon may be partially offset by emissions of the potent greenhouse gas nitrous oxide (N2O). Increased nutrients [NO3- and NH4+] have been shown to increase N2O emissions from saltmarshes, however, a global-scale analysis of this relationship has not been performed. Here, we present a global meta-analysis to investigate the relationship between N2O fluxes and porewater nitrogen and determine the relative importance of porewater NO3- and NH4+ as key drivers of enhanced saltmarsh N2O fluxes. Both porewater NO3- and NH4+ were significantly, positively correlated with N2O fluxes (p < 0.01), explaining 25 and 18% of the variation in fluxes, respectively. We estimate a global saltmarsh N2O flux of 0.012 Tg N2O yr-1, which is six times higher than the current estimate (0.0021 Tg N2O yr-1), representing an offset of 19% of the estimated global saltmarsh carbon burial. Using predicted future increases in riverine DIN export, our meta-analysis suggests that 17-31% of the estimated global saltmarsh carbon burial could be offset by a surge in N2O emissions under chronic mineral N pollution. This meta-analysis indicates the importance of reducing nutrient inputs into saltmarshes to reduce N2O fluxes and maximise their negative radiative forcing.

How to cite: Collier-Woods, D., Ullah, S., and Comer-Warner, S.: Surges in global N2O fluxes from saltmarshes are driven by increasing porewater nitrate and ammonium concentrations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5244, https://doi.org/10.5194/egusphere-egu24-5244, 2024.

EGU24-5701 | ECS | Orals | BG1.6

Regionalized nitrogen balances of Switzerland 

Anina Gilgen, Simon Baumgartner, Ernst Spiess, and Frank Liebisch

For the agri-environmental monitoring of Switzerland, nitrogen balances on farm level for all Swiss farms were calculated and aggregated in order to obtain regionalized nitrogen balances. This monitoring attempts to incorporate as much existing data as possible to minimize multiple data collections from farmers. Data from the agricultural policy information system of Switzerland was used as basis for the calculation. This database contains information on livestock numbers, the crops grown, and the direct payments received for each farm. This information was supported with different data sources from federal offices, cantons, agricultural associations, and research institutions. Balances were calculated as a soil-surface balance according to the OECD method, which includes N input via organic and mineral fertilizers, biological N-fixation, atmospheric N-deposition, and seedlings as well as N outputs via plant yields.

The regional balances showed a high variability, resulting in an average N surplus of around 105 kg N per hectare of utilized agricultural area in cantons with highly intensive livestock farming and around 16 kg N in cantons with more extensive farming practices, i.e. in mountain regions. On national scale, highest N input occurred via organic fertilizers, whereas mineral fertilizers and biological N-fixation account for around 15% of the total input each.

Our approach of calculating N balances on farm level for the whole Swiss farming system has some limitations, which are mainly due to missing or incomplete data sources.  As an example, the use of mineral fertilizers had to be estimated by application data of a rather small sample of farms (~300 farms). Nevertheless, the obtained results show that this methodology is a promising tool to gain a regional overview of the environmental status of Swiss farms. Over the years, this approach will be refined and new data (e.g. additional administrative data, satellite data) can be incorporated in order to better estimate the N balances of Swiss farms.

How to cite: Gilgen, A., Baumgartner, S., Spiess, E., and Liebisch, F.: Regionalized nitrogen balances of Switzerland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5701, https://doi.org/10.5194/egusphere-egu24-5701, 2024.

EGU24-5728 | ECS | Orals | BG1.6

Advances in measuring low N2O fluxes by a portable gas analyser and manual chambers 

Nathalie Ylenia Triches, Maija Marushchak, Anna Virkkala, Timo Vesala, Martin Heimann, and Mathias Göckede

Nitrous oxide (N2O) is one of the most important greenhouse gases with a global warming potential of about 298 times stronger than carbon dioxide (CO2) over a period of 100 years. From 1800 to 2023, the atmospheric concentration of N2O has increased from 273 to 336 ppbv, whereby more than half of this rise is due to the addition of fertilisers and manure on agricultural soils. Whilst these managed, nutrient-rich soils have been relatively well studied, little is known about N2O fluxes in nutrient-poor ecosystems (e.g., the Arctic).

Since many Arctic soils contain very low amounts of available nitrogen, in the past it has been generally assumed that Arctic soils are not a significant source of N2O. Only recently, several studies have reported significant N2O emissions from organic-rich Arctic soils; however, due to methodological challenges, extensive investigations on N2O fluxes in Arctic soils have been limited. As a result, the importance of N2O fluxes from this region to the global budget remains highly uncertain. 

With the recent advances in portable GHG analyser technology, extensive manual chamber measurements based on in-situ N2O concentration measurements can provide novel information to close this knowledge gap. However, guidelines on measuring techniques (e.g., chamber closure time) and data quality (e.g., no flux vs. low flux) are still lacking. In this study, we provide new insights on N2O fluxes in a nutrient-poor ecosystem and give general practical guidelines for measuring low N2O fluxes with a portable gas analyser and manual chambers. In May, July, and September 2023, we used a portable N2O/CO2 analyser to measure N2O fluxes in a thawing sub-Arctic permafrost peatland in northern Sweden. Recommendations on practical use in the field are given to support future N2O research with portable gas analysers. 

How to cite: Triches, N. Y., Marushchak, M., Virkkala, A., Vesala, T., Heimann, M., and Göckede, M.: Advances in measuring low N2O fluxes by a portable gas analyser and manual chambers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5728, https://doi.org/10.5194/egusphere-egu24-5728, 2024.

EGU24-5816 | ECS | Orals | BG1.6

2152 

Meng Yao and Ronghua Kang

It has been recognized recently that trees can assimilate NO2 directly through leaf stomata. Both laboratory and field studies have measured the foliar NO2 deposition velocity, which could be determined by some environmental factors, e.g. light irradiation intensity, ambient NO2 concentration, and leaf characteristics. However, the NO2 uptake capacity and allocation of foliar uptake NO2 under these environmental factors remain unclear. To clearly understand the foliar NO2 uptake process and refine the forest NO2 uptake models, we conducted a dynamic 15NO2 fumigation experiment.

We selected Fraxinus mandshurica (F. mandshurica), Pinus koraiensis (P. konraiensis), Quercus mongolica (Q. mongolica), and Larix gmenilii (L. gmenilii) saplings, four dominant tree species in temperate forests of northeastern China, as our experimental materials. Meanwhile, we chose a pair of broad-leaved and coniferous tree species (F. mandshurica and P. konraiensis) to perform fumigation experiment under dark/light irradiation and another pair (Q. mongolica and L. gmenilii) to perform fumigation experiment with soil N addition. All saplings were dynamically fumigated with 50 ppb 15NO2 for 8 h and destructively sampled immediately after fumigation. We rinsed the samples surface with purified water, dried and grinded all samples, then measured the 15N abundance in leaves, twigs, stems and roots with EA-IRMS.

The results showed that tree saplings can absorb NO2 under both dark and light irradiation treatments. The total 15N recovery ranged between 30 to 80% under the light condition in all species. Under the dark condition, the total 15N recovery were (29.8±9.16) % and (1.1±0.47) % for F. mandshurica and P. konraiensis, which were significantly lower than under the light condition, (59.6±5.2) % and (8.8±2.5) %, respectively. With the soil N addition, the total 15N recovery in Q. mongolica ((56.2±8.8) %) were significantly larger than non-N addition ((27.6± 4.8) %), while L. gmenilii showed the opposite result that the total 15N recovery ((31.7±7.8) %) significantly decreased, compared to that without N addition ((73.6±4.3) %). These results are likely attributed to different amount of N demand for different tree species, more N needed for Q. mongolica than L. gmenilii. Moreover, coniferous species could assimilate more N through foliar uptake than broad-leaved species, probably due to bigger leaf surface areas of coniferous trees. After 8 h fumigation, the largest proportion of 15NO2 was recovered in leaves in all species and treatments, accounting for 60-97%, which indicates that NO2 stays in leaves in a short-term period after foliar assimilation. However, further studies are needed to explore the transformation of foliar incorporated NO2 to other organs in a long-term scale.

This study quantified the foliar NO2 uptake capacity of different tree species and figured out the effects of light irradiation and soil nitrogen availability on foliar NO2 uptake. Our results would provide references for the model estimation of canopy NO2 uptake magnitude at a regional scale.

How to cite: Yao, M. and Kang, R.: 2152, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5816, https://doi.org/10.5194/egusphere-egu24-5816, 2024.

EGU24-6942 | ECS | Orals | BG1.6

Improving Agricultural Nitrogen Use Efficiency to Reduce Air Pollution in China 

Biao Luo and Amos P. K. Tai

Chinese agriculture has long been characterized by low nitrogen use efficiency (NUE) associated with substantial ammonia (NH3) loss, which contributes significantly to fine particulate matter (PM2.5) pollution. However, the knowledge gaps in the spatiotemporal patterns of NH3 emissions and the states of nitrogen management of agricultural systems render it challenging to evaluate the effectiveness of different mitigation strategies and policies. Here we explored the NH3 mitigation potential of various strategies and its subsequent effects on PM2.5 pollution, and their effectiveness in improving NUE of Chinese agricultural systems. We developed and used a nitrogen flow model for evaluating NUE of different crop and livestock types at a provincial scale in China. We then used the bottom-up NH3 estimates to drive an air quality model (GEOS-Chem High Performance, GCHP) to provide an integrated assessment of four improved nitrogen management scenarios: improving NUE of crop systems (NUE-C), increasing organic fertilizer use (OUR), improving NUE of livestock systems (NUE-L) and combined measures (COMB). The total agricultural NH3 emission of China was estimated to be 11.2 Tg NH3 in 2017, of which 46.24% and 53.76% are attributable to fertilizer use and livestock animal waste, respectively, and emission hotspots can be identified in the North China Plain. Our results show that grain crops have higher NUE than fruits and vegetables, while high livestock NUE can be found in pork and poultry, and NUE for the entire crop and livestock systems are both better in Northeast China than the rest of China. We also found that agricultural NH3 emissions can be reduced from 11.2 Tg to 9.1 Tg, 9.3 Tg, 9.9 Tg and 6.8 Tg, and consequently annual population-weighted PM2.5 reductions are estimated to be 1.8 µg m–3, 1.6 µg m–3, 1.3 µg m–3 and 4.1 µg m–3 under NUE-C, OUR, NUE-L and COMB scenarios, respectively. Our results are expected to provide decision support policy making concerning agricultural NH3 emissions.

How to cite: Luo, B. and Tai, A. P. K.: Improving Agricultural Nitrogen Use Efficiency to Reduce Air Pollution in China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6942, https://doi.org/10.5194/egusphere-egu24-6942, 2024.

EGU24-9564 | ECS | Posters on site | BG1.6

Progressive decline in topsoil nitrogen pool upon decadal warming in a permafrost ecosystem 

Bin Wei and Yuanhe Yang

Nitrogen (N) plays an important role in mediating many aspects of permafrost carbon cycle, such as plant productivity, soil organic matter decomposition and the production of greenhouse gases. In contrast to the well-recognized effects of climate warming on soil organic carbon stocks and vulnerability, the fates and pools of soil N has received little attention in permafrost ecosystems.

Here, based on a decadal warming experiment in a permafrost ecosystem on the Tibetan Plateau, we assessed changes in soil N stocks over a 10-year time-scale, and in situ measured the majority of N-cycling processes involving biological N fixation and soil N transformation, and the preferential plant uptake of different N forms, and above- and belowground litter decomposition and N release, and N leaching losses as well as high-resolution nitrous oxide (N2O) flux during the growing season.

Our results showed that experimental warming progressively reduced topsoil N stocks but had no effect in the deeper soils on a 10-year time-scale. The observed decline in topsoil N pools could be due to the fact that decadal warming enhanced plant N uptake and intensified N leaching and gaseous losses. Specifically, warming treatment had a negligible effect on ecosystem biological N fixation rate, but increased the above- and belowground plant N pools. Meanwhile, simulated warming accelerated belowground litter N release and soil N transformation rate, and enhanced plant uptake of organic N. However, warming intensified the topsoil inorganic N leaching losses and N2O flux during the growing season.

These findings highlight that progressive N limitation could occur in permafrost ecosystems under continuous climate warming due to the re-allocation of N pool from soils to plants and the losses of N through leaching and gases flux, which would make the future trajectory of permafrost carbon cycle and its feedback to climate warming more complex than previously thought.

How to cite: Wei, B. and Yang, Y.: Progressive decline in topsoil nitrogen pool upon decadal warming in a permafrost ecosystem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9564, https://doi.org/10.5194/egusphere-egu24-9564, 2024.

EGU24-10360 | ECS | Posters on site | BG1.6

Mitigation measures of crop cultivation to reduce climate-impacting emissions from denitrification 

Jaqueline Stenfert Kroese, Caroline Buchen-Tschiskale, Johannes Cordes, Rene Dechow, Klaus Dittert, Bryan Dix, Kathrin Fuchs, Andreas Gattinger, Jörg-Michael Greef, Balazs Grosz, Michael Hauschild, Jarrah Mahboube, Johannes Kühne, Henrike Mielenz, Thade Potthoff, Clemens Scheer, Franz Schulz, Conor Simpson, Benjamin Wolf, and Reinhard Well

The joint project 'Measures to reduce direct and indirect climate-impacting emissions caused by denitrification in agricultural soils - MinDen' addresses the topics of reducing nitrous oxide emissions and improving nitrogen efficiency through modeling, the evaluation of possible mitigation measures and the evaluation of denitrification on spatial scale. Gaseous emissions from denitrification cause N losses relevant to crop cultivation and cause direct N2O emissions from crop cultivation. Climate protection measures in crop production in the areas of fertilization, soil cultivation and crop rotation have hardly been researched with regard to the role of denitrification. Crop management that optimizes N efficiency and minimizes N emissions at the same time has therefore not yet been reliably defined. The overall objective of the present project is to identify practicable crop management measures to minimize N2 and N2O emissions from denitrification for arable cropping systems in Germany by improving the knowledge on denitrification-related N losses through field and laboratory studies and using it for parameterization, validation and application of simulation models. Our objectives are as follows:

  • Regionalization of N losses due to denitrification in Germany based on existing models
  • Determination of the effect of crop protection measures on N2 and N2O losses on field scale
  • Testing of mitigation options on the model, laboratory and field scale, taking into account the topsoil and subsoil for different soils
  • Further development of denitrification models to improve the mapping of mitigation measures using existing and new field data
  • Testing of mitigation options for Germany using the improved models, taking into account yield, economic efficiency, technology requirements, N2O emissions, N efficiency, fertilizer requirements, NH3 emissions and nitrate leaching.

We provide an overview of the approach and the current status of the joint project, which started at the beginning of 2023.

How to cite: Stenfert Kroese, J., Buchen-Tschiskale, C., Cordes, J., Dechow, R., Dittert, K., Dix, B., Fuchs, K., Gattinger, A., Greef, J.-M., Grosz, B., Hauschild, M., Mahboube, J., Kühne, J., Mielenz, H., Potthoff, T., Scheer, C., Schulz, F., Simpson, C., Wolf, B., and Well, R.: Mitigation measures of crop cultivation to reduce climate-impacting emissions from denitrification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10360, https://doi.org/10.5194/egusphere-egu24-10360, 2024.

Title: Drought and eCO2 Effects on Oak Seedlings Growth, Soil Fertility, and Greenhouse Gases Fluxes

 

Authors: Rehab Al Mutairi, Nicholas Kettridge and Sami Ullah

 

Objective/Purpose:

This study explores the impact of water stress legacy and elevated CO2 on oak seedlings' growth, stomatal conductance, soil nutrient availability, and greenhouse gas (GHGs) fluxes. The research aims to unravel the intricate interplay of these factors under controlled glasshouse conditions.

 

Methods/Approach:

The experiment, conducted from mid-May to August 2023 at the University of Birmingham campus, involved oak seedlings grown under ambient CO2 and elevated CO2 chambers, subjected to two soil volumetric moisture levels (10% for drought, 30% for non-drought). Various parameters, including oak growth, stomatal conductance, soil nutrient availability, and GHGs flux, were measured and recorded throughout the three-month period. Additional analyses, including biomass, soil extracellular enzyme activities, microbial biomass of N and C, and net N mineralization, were conducted at the experiment's conclusion.

 

Key Findings/Results:

The study revealed compelling insights into the response of oak seedlings to drought stress and elevated CO2 conditions. Under drought scenarios, both under ambient and elevated CO2  environments, oak biomass and growth were notably diminished. Particularly, the roots exhibited a substantial increase in biomass, suggesting a coping strategy in search of water and nutrient resources of the seedlings. Stomatal conductance exhibited a decline under elevated carbon dioxide (eCO2), indicating a water-saving mechanism employed by plants. Additionally, extracellular enzyme activities were impacted by environmental conditions: a reduction was observed under drought stress. This reduction in enzyme functions aligns with a concurrent decrease in nutrient availability, highlighting a correlation between nutrient levels and enzyme activity reduction during drought conditions.

 

Conclusion/Implications:

The findings underscore the vulnerability of oak seedlings to drought stress, highlighting the importance of soil moisture management for their optimal growth. Additionally, the differential response between ambient and elevated CO2  levels emphasizes the need for nuanced considerations in future climate change scenarios. These insights contribute to our understanding of ecosystem responses to concurrent drought and elevated CO2 conditions.

 

Keywords:

Oak seedlings, Drought stress, Elevated CO2, Soil fertility, Greenhouse gas fluxes, Stomatal conductance, Biomass, Microbial biomass, Net N mineralization.

 

 

 

 

 

How to cite: Almutairi, R.: Drought and eCO2 Effects on Oak Seedlings Growth, Soil Fertility, and Greenhouse Gases Fluxes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11614, https://doi.org/10.5194/egusphere-egu24-11614, 2024.

EGU24-12116 | Orals | BG1.6

Examining the natural nitrogen biogeochemical cycling and impacts across South African ecosystems 

Rebecca M. Garland, Mogesh Naidoo, Katye Altieri, Phesheya Dlamini, Gregor Feig, Kerneels Jaars, Lerato Sekhohola, Pieter van Zyl, Nomsa Muthelo, Jabulile Leroko, Pelenomi Sakwe, Tamryn Hamilton, Tiaan van Niekerk, Pedro Bixirao Neto Marinho, and Kathleen Smart

The biogeochemical nitrogen (N) cycle in South Africa is influenced by, and in turn influences a number of crucially important global change processes. However, the natural N cycling in South Africa is not well-understood. The “Emissions, deposition, impacts - Interdisciplinary study of N biogeochemical cycling (EDI-SA)” project is working to improve our baseline understanding of the natural biogeochemical cycling of N in non-industrialized ecosystems across South Africa. This includes quantifying N fluxes from emissions through to deposition, identifying linkages between N cycling and related species such as sulphur (S) and ozone, and evaluating ecosystem impacts. Previous work has focused on the impact of atmospheric deposition of N and S species on ecosystems at sites almost exclusively on the industrialized Highveld. This has left large gaps of knowledge in the biogeochemical cycling and ecosystem impacts, particularly within the diverse natural ecosystems found across South Africa. In order to address this gap, EDI-SA is applying a more holistic approach using measurements (from two South African Research Infrastructures; EFTEON and BIOGRIP) and modelling to investigate multiple linkages within the biogeochemical cycling of N with a focus on improving the understanding of the natural cycling. The project is applying a variable resolution sampling approach to investigate processes which occur at multiple spatial scales, and applying multiple measurement techniques including atmospheric measurements, stable isotope analysis of aerosol particles, rainwater and soil, and analysis of soil chemistry and biology. This contribution will detail the approach of this interdisciplinary project, highlight results from the first soil and air sampling campaigns, as well as the atmospheric composition modelling that assesses the relative importance and impacts of N emissions from soil across South Africa. This baseline understanding will allow future research to assess the potential changes to N biogeochemical cycling into the future in a changing climate.  

How to cite: Garland, R. M., Naidoo, M., Altieri, K., Dlamini, P., Feig, G., Jaars, K., Sekhohola, L., van Zyl, P., Muthelo, N., Leroko, J., Sakwe, P., Hamilton, T., van Niekerk, T., Bixirao Neto Marinho, P., and Smart, K.: Examining the natural nitrogen biogeochemical cycling and impacts across South African ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12116, https://doi.org/10.5194/egusphere-egu24-12116, 2024.

Nitrogen is a fundamental plant nutrient and the most important fertilizer in modern agriculture. At the same time nitrate based nitrogen loss from agroecosystems becomes an increasing environmental problem in ground- and surface waters. The lysimeter station Brandis in Saxony, Germany, provides detailed observations of water and solute fluxes under representative agricultural landuse since 1981. Despite substantial efforts and success in regulation and assessment of fertilizer needs and the reduction of fertilization excess, the seepage water analysis reveals increasing or stagnating levels of nitrate concentration in groundwater recharge in a broad range of soil types. This apparent decoupling between input and output is evident in all soil types under investigation and raises some important questions concerning the nitrate loss in agricultural soils:

  • Which part of the soil N-cycle contributes to the seepage water nitrate export?
  • What are the main drivers of nitrate loss in agricultural soils?
  • Can residence times of mineral fertilizer nitrogen be estimated?
  • Will reduced fertilization excess lead to timely reductions in nitrate loss to the groundwater?

We investigated these questions with long-term solute balances and state-of-the-art isotope methods. Analysis of source δ 15N ratios in soil, atmospheric deposition and fertilizer in combination with a 5-year campaign of δ15N and δ18O analysis of seepage water nitrate allows a source identification with dual-isotope plots and mixing models. The results clearly show that the main source of nitrate loss with the seepage water is the soil organic matter pool in all investigated soils. Analysis of the long-term nitrogen balances and the soil samples show furthermore a substantial accumulation of fertilization excess within the upper meter of agricultural soils and indicate that the residence time of nitrogen in the lysimeters might be substantially longer than water residence times. Isotope analysis in combination with mixing model analysis suggest that the nitrate loss is mainly driven by nitrification of this nitrogen legacy in the post-harvest period. Thus, the results hold an explanation why the current regulation efforts have not yet led to the desired reductions in nitrogen loadings of seepage water fluxes. Furthermore, the apparent decoupling between nitrogen input in agricultural soils and the seepage water output makes a timely reduction of nitrate concentrations, by reductions in fertilization excess alone, in groundwater recharge unlikely.

How to cite: Werisch, S., Alexandra, T., and Diana, B.: Insights into nitrogen dynamics and nitrate loss from agricultural soils based on long-term lysimeter observations and a 5-year isotope measurement campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12647, https://doi.org/10.5194/egusphere-egu24-12647, 2024.

EGU24-13239 | ECS | Orals | BG1.6

Resolving nitrogen gaseous pathways in the atmosphere-plant-microbial-soil continuum in the NOAA/GFDL Earth System Modeling Framework 

Maureen Beaudor, Elena Shevliakova, Sergey Malyshev, and Minjin Lee

Representing plant-microbe-soil organic matter interactions and their coupling with land surface processes are critical to understanding of ecosystem responses to climate change. More specifically, microbes play an important role in the nitrogen (N) cycle by providing acquisition pathways for plants and overcoming N limitation through mycorrhizal symbiosis and bacterial fixation. Even though biological nitrogen fixation acts as a primary N source for the organisms, ecosystem N availability is still strongly affected by N losses, including atmospheric volatilization.

One of the major challenges to accurately representing N availability in Earth System Models (ESM) is the representation of the atmospheric losses that are not necessarily controlled by the organisms. For instance, the conversion of soil ammonium into gaseous ammonia (i.e., volatilization) is driven by ambient environmental conditions and not directly controlled by the biological demand of plants and soil microbes. Thus, rapid losses of N via volatilization (e.g., after precipitation events) could induce feedback on soil microbial activity and plant growth by impeding biological assimilation.

Even though the representation of ammonia emissions is progressively integrated into ESMs, the focus has been mainly on parameterizing losses from agricultural or managed ecosystems. However, ammonia volatilization from natural soils occurs worldwide and can reach 9 TgN/yr, a non-negligible source, especially in alkaline drylands. Up to now, no proper representation of emissions of ammonia, applicable to unmanaged lands, has been included in ESMs and challenged by observations. In the future, these emissions are likely to follow the rising trends of nitrogen deposition and increasing precipitation due to climate change.

Here we describe a mechanistic parameterization of ammonia emissions in natural ecosystems with explicit treatment of microbes and vegetation dynamics in the fully integrated terrestrial component of the GFDL ESM, LM4.2-GIMICS-N. We apply observational constraints, including measurements of soil 15N isotope and estimates of nitrogen fluxes (BNF, nitrification, mineralization, and ammonia exchange) at different sites to reduce uncertainty in the model simulations. Finally, we examine the main drivers of ammonia volatilization across various ecosystems by considering aridity, soil pH, and nitrogen deposition as well as the key environmental conditions such as precipitation, temperature, and soil moisture.

How to cite: Beaudor, M., Shevliakova, E., Malyshev, S., and Lee, M.: Resolving nitrogen gaseous pathways in the atmosphere-plant-microbial-soil continuum in the NOAA/GFDL Earth System Modeling Framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13239, https://doi.org/10.5194/egusphere-egu24-13239, 2024.

EGU24-15243 | Posters on site | BG1.6

A Sphagnum incubation study using 15N-labelled atmospheric N2 reveals contrasting potential for biological N2 fixation at three medium-polluted Central European peat bogs 

Marketa Stepanova, Martin Novak, Bohuslava Cejkova, Frantisek Buzek, Ivana Jackova, Eva Prechova, Frantisek Veselovsky, and Jan Curik

Microbial N2-fixation helps to sustain carbon accumulation in pristine peatlands and to remove CO2 from the atmosphere. Recent work has provided evidence that this energetically costly process is not completely downregulated at sites with higher availability of reactive nitrogen (Nr). We studied nitrogen (N) cycling at three high-elevation, mainly rain-fed, Sphagnum-dominated peat bogs in the northern Czech Republic receiving medium to high amounts of reactive nitrogen (Nr) via atmospheric deposition. 15N/14N isotope ratios were determined in Nr deposition, along vertical peat profiles, and in a laboratory incubation study using fresh Sphagnum and 15N-enriched atmospheric N2. Our objective was to assess the potential for biological N2-fixation at the selected study sites in light of various biogeochemical parameters. Historically, all the peat bogs experienced similar changes in atmospheric Nr (mainly NO3--N and NH4-N) inputs. Nr depositions at all three sites peaked between 1980 and 1990. During that time period, the highest annual depositions were close to 10 kg ha-1 yr-1 at the slightly more polluted site Uhlirska (UHL) than at Male mechove jezirko (MMJ) and Brumiste (BRU). Since ca. 1990, atmospheric deposition of Nr has been steadily decreasing. Living Sphagnum had variable N concentrations with similar means for all three sites (1.1, 1.0 and 0.9 wt. % at MMJ, BRU and UHL, respectively). Downcore, peat density remained nearly constant at MMJ but increased at BRU and UHL. Ash contents were below 10 wt. % at least to the depth of 20 cm. With an increasing peat depth, both N concentration and δ15N values generally increased, while C/N ratios tended to decrease. At depths > 10 cm, N/P ratio was lower at UHL than at the other two sites and remained nearly constant downcore. N/P ratio at MMJ increased from ~10 to ~20 with an increasing depth, whereas the N/P ratio exhibited a zigzag vertical pattern at BRU, reaching a value of 40 in deeper segments. The potential for biological N2-fixation was investigated using a replicated laboratory incubation of fresh Sphagnum in a closed system following an application of 98 % enriched atmospheric N2. The experiment lasted for 7 days. The control Sphagnum samples had δ15N values of -4.0 ‰ (BRU and UHL) and -3.7 ‰ (MMJ). At the end of the incubation, the δ15N significantly increased only in MMJ moss reaching + 70 ‰, while it remained unchanged in BRU and UHL moss. Biological N2 fixation was thus recorded at only at MMJ, a site with the lowest N/P ratio in the topmost 2-cm thick sections. Potential N2 fixation rates at MMJ were similar to values previously reported for Finland (Leppänen et al. 2015) but ~7 times lower than at sites located in Patagonia, Chile (Knorr et al. 2016).

References

Leppänen et al., 2015. Plant and Soil, 389, 185-196.

Knorr et al., 2016, Global Change Biology 21, 2357–2365.

How to cite: Stepanova, M., Novak, M., Cejkova, B., Buzek, F., Jackova, I., Prechova, E., Veselovsky, F., and Curik, J.: A Sphagnum incubation study using 15N-labelled atmospheric N2 reveals contrasting potential for biological N2 fixation at three medium-polluted Central European peat bogs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15243, https://doi.org/10.5194/egusphere-egu24-15243, 2024.

EGU24-15470 | Orals | BG1.6

Long-term soil warming causes acceleration of soil nitrogen losses in a temperate forest studied by 15N isotope fractionation 

Wolfgang Wanek, Michaela Bachmann, Ye Tian, Steve Kwatcho Kengdo, Jakob Heinzle, Erich Inselsbacher, Werner Borken, and Andreas Schindlbacher

Climate warming was shown to strongly affect the biogeochemical cycles in global forests, reducing soil carbon storage and accelerating soil nitrogen (N) and phosphorus cycling. In a long-term soil warming experiment in a temperate old-growth forest in Achenkirch, Austria, we recently showed faster root turnover and growth, decreases in microbial biomass, carbon use efficiency and soil carbon storage, increases in ecosystem phosphorus limitation, and varied responses of the soil N cycle in warmed plots (+4 ° C above ambient for 14 years). In this study we therefore employed natural stable isotope techniques to better understand ecosystem-level responses of the N cycle in Achenkirch, studying the abundance of 15N and 14N (expressed as δ15N values) in a wide range of soil nitrogen pools (bulk soil N, root N, microbial biomass N, extractable organic N, ammonium, nitrate) and employed isotope fractionation models to explain the patterns found dependent on soil warming. Specific N cycle processes such as mineralization, nitrification and denitrification cause substantial isotope fractionation (against the heavy stable isotope 15N), leading to 15N enrichment of the residual substrates and 15N depletion of the cumulative products, depending on the fraction on substrates consumed and the isotope fractionation factor of that process. Other processes such as diffusion, (de)sorption and depolymerization exert negligible isotope fractionation. We found a significant warming effect on the isotopic signatures of root N and the soil ammoniumpool, i.e. a 15N enrichment in these pools. 15N enrichment of tree fine roots, considered to be isotopic integrators of the plant available N pool, suggest increased soil N cycling and greater soil N losses in warmed plots causing a 15N enrichment of the soil inorganic N pool (ammonium and nitrate). The increased 15N enrichment in ammonium of warmed soils highlights an increased activity of nitrifiers, with greater fractions of ammonium oxidized to nitrate causing the observed 15N enrichment of ammonium. However, soil nitrate did not show the expected 15N depletion imparted by nitrifiers but matched or even exceeded δ15N values of soil ammonium. Isotope fractionation calculations indicated that >50% of the soil nitrate produced was lost, particularly through denitrification promoting gaseous N losses in the form of NO, N2O and/or N2 and less through nitrate leaching. Natural 15N abundance studies thereby hold great potential for evaluating the status quo of the complex N cycle in terrestrial ecosystems and to monitor in situ responses to climate change with minimal invasion and improved time integration.

How to cite: Wanek, W., Bachmann, M., Tian, Y., Kwatcho Kengdo, S., Heinzle, J., Inselsbacher, E., Borken, W., and Schindlbacher, A.: Long-term soil warming causes acceleration of soil nitrogen losses in a temperate forest studied by 15N isotope fractionation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15470, https://doi.org/10.5194/egusphere-egu24-15470, 2024.

EGU24-15569 | Posters on site | BG1.6 | Highlight

The anaerobic soil volume as a controlling factor of denitrification  

Steffen Schlüter, Maik Lucas, Balazs Grosz, Olaf Ippisch, Jan Zawallich, Hongxing He, Rene Dechow, David Kraus, Sergey Blagodatsky, Mehmet Senbeyram, Alexandra Kravchenko, Hans-Jörg Vogel, and Reinhard Well

Denitrification is a major component of the nitrogen cycle in soil that returns reactive nitrogen to the atmosphere. Denitrification activity is often concentrated spatially in anoxic microsites and temporally in ephemeral events, which presents a challenge for modelling. The anaerobic fraction of soil volume can be a useful predictor of denitrification in soils. Here, we provide a review of this soil characteristic, its controlling factors and its estimation from basic soil properties.

The concept of the anaerobic soil volume and its link to denitrification activity has undergone several paradigm shifts that came along with the advent of new oxygen and microstructure mapping techniques. The current understanding is that hotspots of denitrification activity are partially decoupled from air distances in the wet soil matrix and are mainly associated with particulate organic matter (POM) in the form of fresh plant residues or manure. POM fragments harbor large amounts of labile carbon that fuels local oxygen consumption and, as a result, these microsites differ in their aeration status from the surrounding soil matrix.

Current denitrification models link the anaerobic soil volume fraction to bulk oxygen concentration in different ways but take almost no account of microstructure information, such as the distance between POM and air-filled pores. Based on meta-analyses, we derive new empirical relationships to estimate conditions for the formation of anoxia at the microscale from basic soil properties and we outline how these empirical relationships could be used in the future to improve prediction accuracy of denitrification models at the soil profile scale.

How to cite: Schlüter, S., Lucas, M., Grosz, B., Ippisch, O., Zawallich, J., He, H., Dechow, R., Kraus, D., Blagodatsky, S., Senbeyram, M., Kravchenko, A., Vogel, H.-J., and Well, R.: The anaerobic soil volume as a controlling factor of denitrification , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15569, https://doi.org/10.5194/egusphere-egu24-15569, 2024.

Direct emission of the greenhouse gases methane and nitrous oxide (N2O) constitute a significant fraction of the overall carbon footprint of wastewater treatment. Measurement methods to identify emission sources and to quantify emissions are key in mitigating these direct emissions. Nitrous oxide is formed in biological nitrogen removal process units, which are the main source of N2O emission from wastewater treatment.

Liquid phase sensors (LPS) have recently been developed and installed at various Danish wastewater treatment plants to measure N2O concentrations in the liquid phase of biological nitrogen removal tanks. These sensors can be used to implement adjustments on the operation of the plant (for example duration of aeration), which affects N2O emission. In addition, LPS can be utilized to calculate N2O emission through mass transfer modelling. However, there is a need for validation of liquid-based modelled emission rates against measurement methods, which measure direct N2O emission rates. In this study, emission rates determined by two remote sensing methods, the tracer gas dispersion method (TDM) and Eddy covariance method (EC) were compared to LPS derived N2O emission rates.

TDM relies on continuous, controlled release of a gaseous tracer at the source combined with downwind measurements of concentration of target gas (N2O here) and tracer gas (often acetylene - C2H2).  This method is well-established, validated, and has been used to quantify fugitive emissions from various sources such as landfills, composting plants, biogas plants, etc. EC is a stationary method, which relies on high-frequency measurements of N2O concentration and wind vector on a tower near the source. EC can be set up for continuous monitoring, while TDM as applied here is a discrete measurement method.

In the study, N2O emission rates were measured over a period of 1.5 years at a relatively large wastewater treatment plant in the greater Copenhagen area. TDM measurements were conducted on 15 measurement days covering both periods of relatively high and low N2O emission rates. TDM measurements were compared to LPS derived emission rates, where N2O emission was measured using sensors in four of eight process units for biological nitrogen removal. Overall, daily average emission rates between approximately 0.38 and 13.4 kg N2O h-1 were measured. High emission rates of 120 kg N2O h-1 were observed on a day, where plant maintenance is believed to be the cause of unusual high emission. Emission rates from simultaneous TDM measurements and LPS derived values (n=43) showed good correlation (R2=0.70). On average, emission rates from TDM were 35% higher than LPS rates. The model implementation to derive LPS determined emission rates was further developed during the study, and the listed results were the final values after some correction. Several factors can explain the difference – including liquid sensor drift, which for the specific sensors tends towards lower N2O concentration readings than actual concentrations. Continuous EC measurements showed the same emission dynamics as measured by the liquid sensors located inside the footprint of the station.

How to cite: Fredenslund, A., Kissas, K., and Scheutz, C.: Comparison of liquid phase and remote sensing measurements of nitrous oxide emission from biological nitrogen removal at a wastewater treatment facility, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16147, https://doi.org/10.5194/egusphere-egu24-16147, 2024.

EGU24-16927 | ECS | Posters on site | BG1.6

In-situ treatment of nitrate polluted groundwater by chemoautotrophic denitrification: flow-through tank experiments 

Adrian Simon Seeholzer, Anja Wunderlich, Ruben Steib, and Florian Einsiedl

Nitrate in groundwater can be converted microbially into N2. However, the lack of anoxic conditions (oxygen concentrations < 50 μmol/L) in the aquifer linked with the limitation of microbial available organic and inorganic electron donors may lead to insufficient denitrification in aquifers and nitrate concentration above the drinking water limit of 50 mg/L can be observed. In view of the increasing drinking-water scarcity associated with climate change and the continuing increase in nitrate concentrations in near-surface aquifers, it is urgently necessary and prudent to develop practicable and cost-effective methods to reduce nitrate to harmless N2.
Faced with the increasing nitrate pollution in groundwater, we want to develop a new cost-effective in-situ remediation technology by hydrogen/methane coupled denitrification. We hypothesize that the simultaneous injection of the two water soluble electron donors H2 and CH4 into groundwater may significantly enhance the rate of nitrate consumption by activation of denitrifying chemolithoautotrophic microorganisms that are already present in the groundwater.
Here we show the experimental set-up of the 2D-model aquifer (6 m x 1,8 m), the sampling strategy and show first results of the methane injection experiment. Measurements are performed along the flow direction and at several depths. Concentration profiles and stable isotope composition of methane (δ13C) and nitrate (δ15N) linked with oxygen concentrations shed light on the hydrogen-methane coupled denitrification potential in the model aquifer.

How to cite: Seeholzer, A. S., Wunderlich, A., Steib, R., and Einsiedl, F.: In-situ treatment of nitrate polluted groundwater by chemoautotrophic denitrification: flow-through tank experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16927, https://doi.org/10.5194/egusphere-egu24-16927, 2024.

EGU24-17028 | Orals | BG1.6

Quantifying tree canopy nitrification across European forests 

Rossella Guerrieri, Joan Joan, Stefania Mattana, Emilio Casamayor, Josep Peñuelas, and Maurizio Mencuccini and the Collaborators at the ICP Forests sites

Fluxes and chemical composition of precipitation is substantially changed after passing through tree canopies, particularly in the case of atmospheric nitrogen compounds, with important implications on forest nitrogen cycling. The causes of these changes, however, have mostly focused on the passive role of foliar surfaces to scavenge pollutants from the atmosphere and to ion exchange processes, while biological processes involving microbes hidden in the phyllosphere have been less investigated. We combined triple oxygen isotopes approach and molecular analyses with the aim of quantifying canopy nitrification and identify microbes responsible for it, respectively. Ten sites included in the European ICP Forests monitoring network, chosen along climate and nitrogen deposition gradients, were selected to include the two most dominant tree species in Europe (Fagus sylvatica L. and Pinus sylvestris L.). Specifically, in this study we: 1) estimated the relative contribution of nitrate derived from biological canopy nitrification vs. atmospheric deposition by using δ18O and Δ17O of nitrate collected in water samples, i.e., in the open field (bulk deposition) and underneath tree canopies (throughfall); 2) quantified the functional genes related to nitrification for the two dominant tree species in European forests by using next-generation sequence analyses. Based on the isotope approach, we found that up to 80% of the nitrate reaching the soil via throughfall derived from biological transformations in the phyllosphere, equivalent to a flux of gross canopy nitrification of up to 5.76 kg N ha-1 y-1. The fraction of microbiologically derived nitrate increased with raising nitrogen deposition, thus suggesting that the process can be substrate limited. Molecular analyses confirmed the presence on foliar surfaces of bacterial and archaeal autotrophic ammonia oxidisers and bacterial autotrophic nitrite oxidisers across the investigate European forests. Our study demonstrates the potential of integrating stable isotopes with molecular analyses to advance our understanding on key processes underpinning forest nitrogen cycling, which should no longer exclude microbial processes occurring in the phyllosphere.

How to cite: Guerrieri, R., Joan, J., Mattana, S., Casamayor, E., Peñuelas, J., and Mencuccini, M. and the Collaborators at the ICP Forests sites: Quantifying tree canopy nitrification across European forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17028, https://doi.org/10.5194/egusphere-egu24-17028, 2024.

EGU24-17096 | ECS | Orals | BG1.6

Co-application of organic amendments and urea-N in a loamy soil reduced the N2O emission factor but substantial amounts of organic C were lost as CO2. 

Georgios Giannopoulos, Elpida Pasvadoglou, Georgios Kourtidis, Lars Elsgaard, George Zanakis, and Ioannis Anastopoulos

Under the framework of Circular Economy, EU Green Deal, and UN Sustainable Development Goals the addition of organic amendments to agricultural soils is highly promoted as a cost-efficient solution to improve soil quality and agrosystem sustainability. Nonetheless, their agronomic use comes with an uncertainty of their potential to release ample plant-available N, and to emit soil greenhouse gases.

This mesocosm study investigated short-term (90 d) soil N dynamics of a loamy soil receiving four organic amendments (50 t ha-1) (i) cow manure compost (CMC), (ii) food waste compost (FWC), (iii) used digestate substrate (UDS) and (iv) municipal sewage sludge (MSS), without and with N fertilization (160 kg N ha-1; urea). An unamended soil mesocosm was included as a control (C). During the incubation soil NO2-, NO3-, NH4+, N2O and CO2 were regularly monitored.

During the incubation, org. amendments did not affect NH4+ availability (AUC) compared to unamended soil, except MSS treatment which had 5.7x more NH4+ than C. The co-application of urea increased available NH4+ by 2.9x, 4.1x, 4.4x, 4.6x, and 5.9x for MSS, UDS, CMC, FWC, and C, respectively. There was no difference in available NO2- among org. amendment treatments and the C, except MSS (2.4x). There was a substantial and temporal accumulation of NO2- (2.4x to 3.6x) when urea was co-applied with org. amendments. Co-application of urea with org. amendments increased AUC NO3- in all treatments ranging to 2.7x from 13.6x, except MSS. Considering cum. CO2 we did not observe any differences between org. amended treatments without and with urea. However, org. amendments increased cum. N2O emission by 1.4x, 1.6x, and 3x, for UDS, FWC, and MSS, and reduced by 0.6x for CMC relative to C, respectively. The co-application of urea increased cum. N2O emissions for MSS, UDS, and CMC by 6%, 65%, and 90%, respectively, and reduced by 58% for FWC, compared to the corresponding org. treatment without urea.

Interestingly, co-application of urea with org. amendments reduced N2O emission factor (EF) by 4x, 6x, 6x, and 9x, relative to org. amendments without urea, for CMC, MSS, UDS and FWC, respectively. However, the EF N2O exceeded 1% in most cases. Treatments with urea lost substantial amounts of org. C as CO2-equivalent emissions, for instance, UDS+U and MSS+U lost 22% and 68%, respectively.  

In conclusion, our preliminary results indicate that the co-application of org. amendments with urea-N could potentially fuel soil N2O emissions, thus offsetting any favorable aspects of the aforementioned policies. Org. amendment, urea-N, and their interaction were significant factors (p≤0.05) driving CO2 and N2O emissions. The quality and composition of the amendments may stimulate soil microbial N transformations, and further investigation will elucidate the intrinsic role of soil microbes and their dynamics in regulating CO2 and N2O emissions from soils.

The research project was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “2nd Call for H.F.R.I. Research Projects to support Post-Doctoral Researchers”; Project #01053 awarded to P.I. Dr Georgios Giannopoulos. This project was co-implemented with industrial partner Corteva Agriscience Hellas SA.     

How to cite: Giannopoulos, G., Pasvadoglou, E., Kourtidis, G., Elsgaard, L., Zanakis, G., and Anastopoulos, I.: Co-application of organic amendments and urea-N in a loamy soil reduced the N2O emission factor but substantial amounts of organic C were lost as CO2., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17096, https://doi.org/10.5194/egusphere-egu24-17096, 2024.

EGU24-17469 | Orals | BG1.6

Evaluating temporal patterns in wood δ15N in Swedish forests as an indicator of changing N limitation 

Michael Gundale, Kelley Bassett, Lars Östlund, Jonas Fridman, Steven Perakis, and Sandra Jämtgård

Boreal forests play an important role in the global carbon (C) cycle, and their productivity is strongly limited by nitrogen availability.  Thus, understanding whether nitrogen availability in boreal forests is changing has important implications for understanding past, present, and future trends of forest growth. We utilized a unique archive of tree cores collected by the Swedish National Forest Inventory, to evaluate temporal patterns (1950-2017) of wood δ15N, which is commonly used as an indicator of N limitation. First, we focused on an area of ca. 55,000 sq. km in central Sweden to evaluate how sensitive the wood δ15N approach is to tree age and two alternative sampling methodologies: a) analysis of single trees sampled in the present, versus b) tree chronologies constructed from multiple trees of the same age sampled during different decades.  By analysing 1038 woods samples, and covering two key boreal tree species (Picea abies and Pinus sylvestris), we found strong trends of declining δ15N through time, suggestive of progressive N limitation.  We further found that temporal patterns were highly sensitive to method choice, where the multiple tree approach supported by the tree core archive showed much stronger temporal patterns than reliance on more conventional contemporary sampling approaches, where N mobility appeared to obscure temporal patterns.  We further found that temporal trends were relatively insensitive to tree age class. Using the more powerful Multiple Tree Approach, we further evaluated δ15N values from an additional 1000 P. abies and P. sylvestris wood samples covering the entire forested area of Sweden and spanning the same time period, to investigate how temporal patterns in wood δ15N varied in areas with historically high N deposition (Southern Sweden) versus low N deposition (Northern Sweden).  These data help address current debates regarding whether temporal patterns in δ15N are indicative of oligitrophication (i.e. progressive N limitation), or are instead the result of changing δ15N signatures from nitrogen deposition inputs.  

How to cite: Gundale, M., Bassett, K., Östlund, L., Fridman, J., Perakis, S., and Jämtgård, S.: Evaluating temporal patterns in wood δ15N in Swedish forests as an indicator of changing N limitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17469, https://doi.org/10.5194/egusphere-egu24-17469, 2024.

EGU24-17865 | ECS | Posters on site | BG1.6

The effect of nano fertilizers on wheat vegetative characters 

Thanawan Buacharoen, Yafei Guo, Eugenia Valsami - Jones, and Sami Ullah

The effect of nano fertilizers on Wheat vegetative characters

Thanawan Buacharoen1, Yafei Guo1, Eugenia Valsami-Jones1*, and Sami Ullah1

*Authors to whom correspondence should be addressed.

1School of Geography, Earth and Environmental Science, College of Life and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK

Wheat is the primary staple cereal in the world. It was the highest cultivation in 2018. According to the British Survey of Fertilizer Practice, total nitrogen use in Great Britain was reduced between 2021 and 2022. At the same time, the total phosphate did not change. Meanwhile, the usage of the total potash has increased compared to last year.  
Conventional fertilizer, which consists of nitrogen, phosphorous, and potassium nutrients, will release Greenhouse gas emissions. The other option to solve this problem is the nano fertilizer. Plants can easily absorb a tiny particle of nano fertilizer, reducing greenhouse gas emissions into the air. Therefore, this study focused on nano fertilizers' effect on plant growth. 

The first set of 30-day-old wheat plants was treated with amorphous calcium phosphate (nano - ACP), a potassium-bearing variant of the ACP (nano ACP - NPK) and a urea and potassium-bearing variant of the ACP (nano - UNPK). Moreover, three conventional fertilizers, which have the same nutrient quantity as same as nano fertilizers, were applied to the second set of plants to be a positive control. On the other hand, blank treatment was used to be a negative control. After harvesting the wheat plants, the shoot length and fresh weight were measured. Also, the ammonium concentration in the soil was examined with the colorimetric method. Maximum root weight was found in the wheat treated with nano–ACP (Average± SD. = 0.39±0.20). The nano ACP - NPK gave the highest value of shoot weight (Average ± SD. = 0.9 ± 0.10), number of seeds (84 seeds) and shoot length (Average ±SD.= 63.33 ± 4.29). However, the maximum ammonium concentration was found in the soil treated with nano ACP. All treatments' seed weight and shoot length differ at the P – value of less than 0.5. Our finding suggests that the nano fertilizers had enhanced vegetative characteristics compared with the conventional fertilizers.

Key word; amorphous calcium phosphate (nano - ACP), potassium-bearing variant of the ACP (nano ACP - NPK) and urea and potassium-bearing variant of the ACP (nano - UNPK)        

How to cite: Buacharoen, T., Guo, Y., Valsami - Jones, E., and Ullah, S.: The effect of nano fertilizers on wheat vegetative characters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17865, https://doi.org/10.5194/egusphere-egu24-17865, 2024.

EGU24-19499 | ECS | Orals | BG1.6

Increased irrigation frequency reduces N2O, but not overall denitrification losses (N2O+N2) from an intensively managed pasture following ruminant urine deposition and nitrogen fertilisation. 

Johannes Friedl, Daniele De Rosa, Clemens Scheer, Michael Fitzgerald, Peter R. Grace, and David W. Rowlings

Intensively managed pasture systems receive large inputs of nitrogen (N) in the form of fertiliser and through the  deposition of ruminant urine, creating hot-spots for denitrification which results in variable amounts of nitrous oxide (N2O) and dinitrogen (N2) emitted. Here we investigated the potential of increased  irrigation frequency to reduce N2O and N2 emissions from an intensively managed pasture in the subtropics after ruminant urine deposition. Irrigation volumes were estimated to replace evapotranspiration and were applied either once (Low-Frequency) or split into four applications (High-Frequency). This irrigation schedule was applied 3 times over the 60 day monitoring period, and fluxes of N2O and N2 were  measured using the 15N gas flux method. In line with farming practice, simulated urine patches (equivalent of 80 g N m-2 applied) were also fertilised three times with 2 g urea N m-2 to show the combined effects of urinary and fertiliser N on N2O and N2 emissions. Highest N2O emissions of up to 60 mg N2O-N m-2 day-1 were observed briefly after urine deposition, decreasing thereafter, resulting in cumulative N2O losses of 169.9 mg N2O-N m-2 from the Low-Frequency treatment. Denitrification was dominated by N2, accounting for more than 89% of  N2O+N2 emitted. Irrigation treatments had no effect on cumulative N2 losses of more than 2700 mg N2-N m-2. However, High frequency irrigation reduced cumulative N2O losses by 35%. Our findings suggest that under conditions of high N availability, increased irrigation frequency can reduce the environmental impact (N2O) of denitrification, but not overall N losses via this pathway. The response of N2O emissions may further indicate that less frequent, but more intense rainfall events will shift the product ratio of denitrification towards N2O, increasing environmentally harmful N losses from intensively managed pasture systems.

How to cite: Friedl, J., De Rosa, D., Scheer, C., Fitzgerald, M., Grace, P. R., and Rowlings, D. W.: Increased irrigation frequency reduces N2O, but not overall denitrification losses (N2O+N2) from an intensively managed pasture following ruminant urine deposition and nitrogen fertilisation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19499, https://doi.org/10.5194/egusphere-egu24-19499, 2024.

EGU24-20301 | ECS | Orals | BG1.6

Browning and mining increase the nitrous oxide production in sediments of large boreal lakes during winter 

Carlos Palacin-Lizarbe, Stefan Bertilsson, Henri J. Siljanen, Moritz Buck, Lukas Kolh, Dhiraj Paul, Marion Maréchal, Hannu Nykänen, Tong Liu, Mikko Kiljunen, Sanni L. Aalto, Antti J. Rissanen, Christina Biasi, Anssi Vainikka, and Jukka Pumpanen

There is limited knowledge on the N (nitrogen) cycling in winter, on the role of organic matter quality on N cycling, and on the microbes involved.

We studied Lake Viinijärvi and Lake Höytiäinen, large boreal lakes in Finland, each lake with clear-water and brown-water sides. Viinijärvi has an additional side affected by mining activities in the catchment showing higher nitrate and sulphate levels. During winter of 2021 we sampled 5 sites at the beginning and at the end of the ice-covered period. Using the Isotope Pairing Technique we incubated sediment cores with 15NO3- and quantified the products of 1) complete denitrification (N2), 2) truncated denitrification (nitrous oxide, N2O), and 3) dissimilatory nitrate reduction to ammonium (DNRA, NH4+) to infer the process rates. We characterized the DOM using FT-ICR MS. We explore the genetic potential (DNA) of the sediment microbiome by using several sequencing techniques.

During winter the sediment-water interface is an active compartment. The top sediment microbiome has heterotrophic bacteria with flexible metabolism, breaking-down OM during winter despite most of the DOM is recalcitrant. Impacts of browning and mining with major differences between sites. The genetic potential of the sediment microbiome indicates more DNRA and N2O consumption in clear-waters, while in the mining-impacted site and brown-water sites the dominant pathway depends on the sediment layer with truncated denitrification in top layer, and methanogenesis and N-fixation in sub-top layer. The N2O production (d14), that fits the genetic potential, is highest in the mining-impacted site (35-43 µmol N/m2/d), followed by the brown-water sediments (6-11 µmol N/m2/d), with the lowest rates in the clear-water sediments (0-1 µmol N/m2/d).

How to cite: Palacin-Lizarbe, C., Bertilsson, S., Siljanen, H. J., Buck, M., Kolh, L., Paul, D., Maréchal, M., Nykänen, H., Liu, T., Kiljunen, M., Aalto, S. L., Rissanen, A. J., Biasi, C., Vainikka, A., and Pumpanen, J.: Browning and mining increase the nitrous oxide production in sediments of large boreal lakes during winter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20301, https://doi.org/10.5194/egusphere-egu24-20301, 2024.

One of the most pressing issues in intensive agriculture is how we can reduce post-harvest losses of nitrogen (N) on agricultural land. In terms of N use efficiency, the focus so far has been on optimizing the amount and timing of N fertilization, including spatially targeted application (precision agriculture). However, we must be aware that this will not be sufficient to solve the problem of N surplus. The mineralization of crop residues and soil organic matter, especially after harvest, can lead to very high mineral N concentrations in the soil, which ultimately result in high N losses, mainly in the form of nitrate leaching, but also as nitrous oxide (N2O) if the excess N is not immobilized before winter. In crop rotations that do not allow the cultivation of a catch crop, e.g. before winter cereals, the N immobilization potential is by far not high enough to immobilize the available mineral N. In this case, a different approach than plant N immobilization is required to immobilize the excess N before winter.

Here, we present results from laboratory incubations and field trials with different soils under a wide range of conditions based on the stimulation of microbial biomass growth by readily available organic soil amendments. They show that effective immobilization of mineral N in large quantities (almost 100 % reduction of nitrate concentration in the soil) is possible for several months, even under winter conditions. A consistent picture emerges from the results, suggesting that the optimal and longest-lasting effect of N immobilization can be achieved with nitrogen-free organic compounds that are moderately available to microorganisms (i.e., within several weeks rather than a few days). If the microorganisms are offered compounds that are too readily available (extreme case: glucose), a rapid stimulating effect can be triggered, which, however, does not last long enough to immobilize N for several months due to too early remineralization. If too recalcitrant organic compounds are introduced into the soil, the utilization of the additional carbon source takes too long to lead to effective N immobilization. We can therefore say that we have taken a significant step forward in understanding the mechanisms and timing of microbial N immobilization and remobilization, which may prove key to solving the N surplus problem in agriculture. However, the extent to which such management measures can be implemented in agricultural practice also depends on the political framework conditions that make them economically feasible.

How to cite: Brüggemann, N., Zhao, K., and Reichel, R.: How can we reduce post-harvest nitrogen losses on agricultural land? Evaluating the potential of easily degradable, nitrogen-free organic soil additives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20772, https://doi.org/10.5194/egusphere-egu24-20772, 2024.

EGU24-21470 | Orals | BG1.6

Off-target effects of biological nitrification inhibitors on soil microbial substrate use and enzyme activity in an agricultural soil  

Iris Karbon, Konstanze Madani, Judith Prommer, Paula Rojas, Andrew Giguere, Christopher Sedlacek, Taru Sandén, Heide Spiegel, Petra Pjevac, and Lucia Fuchslueger

High nitrification rates and substantial nitrogen (N) losses through nitrate leaching and N2O emissions make current agricultural practices unsustainable, contributing to greenhouse gas emissions and environmental pollution. Synthetic nitrification inhibitors (SNIs) can be amended with N-fertilizers to reduce the conversion of ammonia to nitrate by soil nitrifiers. SNIs aim to increase agricultural nitrogen use efficiency (NUE), but they have several disadvantages (e.g., costs, ineffectiveness in the field, possible accumulation in the food chain). The use of biological nitrification inhibitors (BNIs), naturally occurring in plant root exudates, could become an alternative to SNIs. Potential BNIs should be highly specifically targeting nitrification, but for most known BNIs it is unclear if and how they affect other soil microorganisms and biogeochemical processes.

This study aimed to investigate possible off-target effects of BNIs in agricultural soils. We tested the effect of two candidate BNIs (Methyl 3-(4-hydroxyphenyl)propionate and DL-limonene) in slurry assays on soil microbial communities from a typical Austrian agricultural field (Linz, pH 6.89±0.12, fertilized with 120 kg N ha-1 yr-1), and compared them to a known SNI (nitrapyrin), and two further nitrification inhibitors (phenylacetylene and octyne). The slurries were incubated for eight days and CO2 production, pH, as well as nitrate- and N2O accumulation were measured. At the end of the incubation, we analyzed fluorescence-based enzyme activity, as well as microbial substrate use efficiency using ‘Biolog©’ assays to test the influence on general microbial activity, selected microbial soil processes, and the effectiveness of nitrification inhibition, respectively.

Our results showed that both tested BNIs significantly reduced net nitrification rates, but also affected other biogeochemical processes, even though limonene lost some effectiveness during the incubation. MHPP was heavily respired by heterotrophic microorganisms, leading to a drop in pH and heterotrophic competition for the remaining ammonium, therefore likely acting as an indirect nitrification inhibitor. Extracellular enzymes were also affected: MHPP led to increased potential β-glucosidase activity, while nitrapyrin led to a decrease in potential phosphatase activity. General soil microbial substrate use diversity seemed to be unaffected by the input of either BNIs or SNIs. Whether or not the observed off-target effects are positive and what they mean for the large-scale application of BNIs in the agricultural industry remains to be further investigated.

How to cite: Karbon, I., Madani, K., Prommer, J., Rojas, P., Giguere, A., Sedlacek, C., Sandén, T., Spiegel, H., Pjevac, P., and Fuchslueger, L.: Off-target effects of biological nitrification inhibitors on soil microbial substrate use and enzyme activity in an agricultural soil , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21470, https://doi.org/10.5194/egusphere-egu24-21470, 2024.

EGU24-5418 | Orals | BG1.8

AmazonFACE – A large-scale Free Air CO2 Enrichment Experiment in the Amazon rainforest  

Anja Rammig and David Lapola and the AmazonFACE Team

Tropical rainforests play an important role in the global carbon cycle. They store massive amounts of biomass in their trees and soils, and contribute to climate mitigation by removing carbon from the atmosphere through photosynthesis. It is assumed that plant responses to rising atmospheric CO2 concentrations may have induced an increase in biomass and thus, increased the carbon sink in forests worldwide. Rising CO2 directly stimulates photosynthesis (the so-called CO2-fertilization effect) and tends to reduce stomatal conductance, leading to enhanced water-use efficiency, which may provide an important buffering effect for plants during adverse climate conditions and also have implications for water resources by reducing the loss of soil moisture through transpiration. For these reasons, current global climate simulations consistently predict that undisturbed tropical forests will continue to sequester more carbon in aboveground biomass. However, several lines of evidence point towards a decreasing carbon sink strength of the Amazon rainforest in the coming decades, potentially driven by nutrient limitation, droughts or other factors. Mechanistically modelling the effects of rising CO2 in the Amazon rainforest are hindered by a lack of direct observations from ecosystem scale CO2 experiments. To address these critical issues, we are currently building a free-air CO2 enrichment (FACE) experiment in an old-growth, highly diverse, tropical forest in the Brazilian Amazon and we here present our main hypotheses that underpin the AmazonFACE experiment.  We focus on possible effects of rising CO2 on carbon uptake and allocation, phosphorus cycling, water-use and plant-herbivore interactions, and discuss relevant ecophysiological processes, which need to be implemented in dynamic vegetation models to estimate future changes of the Amazon carbon sink. We give an update on the state of the experiment construction, present the sampling strategy and discuss our approach to upscale tree-level responses to stand scale. 

How to cite: Rammig, A. and Lapola, D. and the AmazonFACE Team: AmazonFACE – A large-scale Free Air CO2 Enrichment Experiment in the Amazon rainforest , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5418, https://doi.org/10.5194/egusphere-egu24-5418, 2024.

EGU24-5862 | Posters on site | BG1.8

Landscape-scale And Spatially Explicit Representation of vegetation dynamics and ecosystem carbon stocks in a hyperdiverse tropical forest ecosystem (LASER) 

Florian Hofhansl, Peter Hietz, Werner Huber, Anton Weissenhofer, and Wolfgang Wanek

Tropical vegetation dynamics and ecosystem carbon (C) stocks typically vary with local topography and forest disturbance history. Yet, neither remote sensing nor vegetation modeling captures the underlying mechanistic processes determining ecosystem functioning and therefore the resulting estimates often do not match field observations of vegetation C stocks, especially so in hyperdiverse tropical forest ecosystems. This mismatch is further aggravated by the fact that multiple interacting factors, such as climatic drivers (i.e., temperature, precipitation, climate seasonality), edaphic factors (i.e., soil fertility, topographic diversity) and diversity-related parameters (i.e., species composition and associated plant functional traits) in concert determine ecosystem functioning and therefore affect tropical forest C sink-strength.

Here, we propose a novel framework designed for integrating in-situ observations of local plant species diversity with remotely sensed estimates of plant functional traits, with the goal to deduce parameters for a recently developed trait- and size-structured demographic vegetation model. Plant-FATE (Plant Functional Acclimation and Trait Evolution) captures the acclimation of plastic traits within individual plants in response to the local environment and simulates shifts in species composition through demographic changes between coexisting species, in association with differences in their life-history strategies.

Our framework may be used to project the functional response of tropical forest ecosystems under present and future climate change scenarios and thus should have crucial implications for assisted restoration and management of tropical plant species threatened by extinction.

How to cite: Hofhansl, F., Hietz, P., Huber, W., Weissenhofer, A., and Wanek, W.: Landscape-scale And Spatially Explicit Representation of vegetation dynamics and ecosystem carbon stocks in a hyperdiverse tropical forest ecosystem (LASER), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5862, https://doi.org/10.5194/egusphere-egu24-5862, 2024.

EGU24-7786 | ECS | Posters on site | BG1.8

Using Landsat composites to document temporal change within Amazonian forest vegetation 

Rajit Gupta, Kalle Ruokolainen, and Hanna Tuomisto

Deforestation of the Amazon rainforest biome has been of considerable international concern, as extensive forest loss has negative impacts on global carbon storage, hydrological cycles and biodiversity. Ongoing climatic change is predicted to make these effects worse, as climatic models suggest that increasing temperatures will often be accompanied by decreasing precipitation. Such change would put the continued existence of the rainforest biome at risk, as moisture-demanding species would be replaced by more drought-resistant ones. Field observations already indicate that even those Amazonian forests that are not directly affected by deforestation have started to change, and that they grow faster, store less carbon and contain more lianas than before. However, field measurements can only be carried out in a limited number of sites, and these only cover a minute part of the entire Amazon biome. To get a more complete understanding of the changes within the remaining Amazonian forests, we are carrying out broad-scale analyses using Landsat imagery. We first did pixel-based compositing using all image acquisitions within a 10-year time window in order to obtain a clean cloud-free reflectance surface. Two such composites were produced for different time periods (2000-2009 and 2013-2022) in order to identify potential changes across the forested landscape. The results are expected to identify areas where significant but non-obvious changes in the structure and/or function of the forest could be happening, and thereby to facilitate in assessing the degree of threat to the ecosystem

How to cite: Gupta, R., Ruokolainen, K., and Tuomisto, H.: Using Landsat composites to document temporal change within Amazonian forest vegetation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7786, https://doi.org/10.5194/egusphere-egu24-7786, 2024.

EGU24-8693 | ECS | Orals | BG1.8

Vertical Variability in Leaf Traits and Environmental Conditions: Implications for Evapotranspiration and Net Ecosystem Exchange above the Amazon Rainforest 

Raquel González Armas, Daniël Rikkers, Hugo de Boer, Vincent de Feiter, Sebastiaan de Haas, Oscar Hartogensis, Wouter Mol, Martin Janssens, Bert Heusinkveld, Chiel van Heerwaarden, Hella van Asperen, Luiz Machado, Cléo Quaresma, Eric Bastos Görgens, and Jordi Vilà Guerau de Arellano

Land-surface representations in weather and climate models simplify the characterization of vegetation as a single layer with bulk environmental conditions. This approach overlooks the vertical variability in leaf traits and environmental conditions within the canopy. This research explores the vertical variability of plant ecophysiology and environmental measurements within the Amazon tropical rainforest during daytime, specifically at the ATTO site, during the late dry season.

To characterize the canopy and its vertical variability, we categorized the canopy into three layers: the top layer (approximately the upper third of the canopy, 18-27 m), the medium layer (approximately the medium third of the canopy, 9-18 m), and the low layer (approximately the lower third of the canopy, 0-9 m) where leaf gas exchange measurements were conducted. Utilizing these layers, we developed a multi-layer model representation that calculates water and CO2 fluxes based on within canopy on-site observations. We conducted sensitivity analyses of the rainforest multi-layer representation to discern the significance of capturing vertical variability in leaf traits and environmental conditions for deriving net fluxes of water and CO2 of the forest.

Current results show that measured leaf traits exhibit vertical variation within the canopy, indicating larger productivity in the top layer compared to the medium and low layers. Environmental conditions, such as incoming radiation in the top layer, fluctuate due to cloud presence. Temperature peaks in the top layer and reaches a minimum at mid-canopy. This results in a non-uniform mixing of the canopy air, maintaining a stable layer within the forest canopy that can potentially affect the distribution of scalars within the canopy. Ongoing analyses explore the similarities and differences between the CO2 exchange between the multi-layer representation and CO2 fluxes from eddy covariance systems, as well as the sensitivity of the former to vertical variability in leaf traits and environmental conditions. By doing so, we aim to gain knowledge on the relevance (or irrelevance) of characterizing vertical variability in land-surface representations and on important processes that may not be well captured yet by land-surface representations.

How to cite: González Armas, R., Rikkers, D., de Boer, H., de Feiter, V., de Haas, S., Hartogensis, O., Mol, W., Janssens, M., Heusinkveld, B., van Heerwaarden, C., van Asperen, H., Machado, L., Quaresma, C., Bastos Görgens, E., and Vilà Guerau de Arellano, J.: Vertical Variability in Leaf Traits and Environmental Conditions: Implications for Evapotranspiration and Net Ecosystem Exchange above the Amazon Rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8693, https://doi.org/10.5194/egusphere-egu24-8693, 2024.

EGU24-10409 | ECS | Orals | BG1.8 | Highlight

The Blind Spot in active tropical forest restoration: unknown impacts on soil carbon 

Nadine Keller, Andrea Jilling, Jun Ying Lim, Lian Pin Koh, Elia Godoong, and Mark A. Anthony

Restoring formerly degraded ecosystems is a promising nature-based solution to mitigate climate change and ensure the provisioning of ecosystem services. Consequently, ecosystem restoration is prominent on both governmental and private agendas (e.g., the Bonn Challenge, airline carbon off-sets by planting trees). Two opposing strategies are employed to promote forest restoration: active versus passive (e.g. natural regeneration) restoration. Assessing how these two approaches influence biodiversity hot spots such as tropical rainforests is uniquely important, but the benefits and limitations of these two techniques have not been thoroughly compared.

Among all tropical moist forests globally, forests of Asia-Oceania have experienced the highest disturbance rates in the past three decades, among which Sabah, Malaysian Borneo, contains forests with past managements to strategically assess long-term forest recovery following active and passive restoration strategies.

How overall forest carbon balance, including carbon storage in the soil, is affected by active versus passive restoration, remains a blind spot not only at this site, but also globally. Given that up to half of the total carbon stored in secondary tropical rainforests can be stored belowground, and that this carbon has slower turn-over rates than above-ground vegetation, Sabah is a perfect testing ground to examine how common forest restoration influences below-ground carbon dynamics and total forest carbon balance.

To address this, we collected soil samples in 15 actively restored and 15 naturally regenerating forest plots in INFAPRO, a restoration project in Sabah. This site was severely, selectively logged for two decades and then actively restored by planting (mainly) Dipterocarpacaea (i.e., diptertocarps) seedlings more than 20 years ago. These trees associate with ectomycorrhizal fungi that mediate important soil biochemical cycles as root-inhabiting tree symbionts.

At this restoration site, active restoration enhanced tree diversity, promoted rare species, and increased above-ground carbon density in living vegetation in comparison to natural regeneration. We hypothesize that active restoration, including the planting of diptertocarps, further enhances the presence of ectomycorrhizal fungi, leading to a suppression of free-living microbial decomposition of plant litter inputs (i.e., the Gadgil effect), and an increase in total soil carbon storage. While this may increase total soil carbon storage, the more persistent fraction that is mineral-associated may decrease. This is due to slowed plant litter decomposition and thus less production of compounds that absorb onto mineral surfaces in addition to less microbial necromass inputs sticking to minerals due to the lower growth efficiency by ectomycorrhizal fungi compared to free-living microbes.

This knowledge on soil carbon storage and its persistence is a much needed contribution to holistic assessments of active restoration compared to natural regeneration. Empirical results on soil carbon analyses will be generated by the time of the EGU conference.

How to cite: Keller, N., Jilling, A., Lim, J. Y., Koh, L. P., Godoong, E., and Anthony, M. A.: The Blind Spot in active tropical forest restoration: unknown impacts on soil carbon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10409, https://doi.org/10.5194/egusphere-egu24-10409, 2024.

EGU24-10719 | ECS | Posters on site | BG1.8

Multiple plant root strategies improve phosphorus acquisition under elevated CO2 in the Amazon rainforest 

Nathielly Martins and the AmazonFACE team

The impact of elevated atmospheric CO2 concentrations on forest productivity depends on the capacity of plants to balance the additional CO2 with the demand for additional nutrients. One hypothesis states that plants may allocate the extra carbon belowground in producing and maintaining fine roots to alleviate nutrient limitation. In the Amazon basin, where approximately 60% of the forest is on old and weathered soil, the litter layer is an important nutrient source. In some regions, root mats growing in the litter layer can be observed, where the roots intercept the newly mineralized nutrients before they reach the soil and may bind to the mineral matrix. To improve their nutrient uptake capacity, trees can either modify their root morphology to a ‘do-it-yourself” strategy, increasing root length and branching intensity or alternatively, they can outsource the same function by investing in symbioses with mycorrhizal fungi. Additionally, fine roots can stimulate microbial decomposition of recalcitrant substrates (e.g., wood debris) by exuding low molecular weight organic compounds (LMWO) and increasing P mobilization by phosphatase activity without changing decomposition. These strategies could also vary depending on the growing depth of roots due to the different physical conditions between the organic upper and mineral layers. However, little is known about the role of trait differences in roots under higher CO2 concentrations.

To increase our understanding of belowground responses of understory plants to elevated CO2 concentrations, we set up an Open-Top Chamber experiment in a lowland forest in the Central Amazon. We observed that under eCO2, root productivity did not change in the litter layer but showed a decreased pattern in the soil layer. Moreover, plants intensified root foraging in the litter layer by increasing their specific root length more than threefold under elevated CO2. In contrast, roots in the soil mineral layer followed an “outsourcing” strategy by increasing arbuscular mycorrhizal colonization by 117%. In addition, our results showed a decrease in the organic P in litter without a change in C decomposition under higher CO2 concentrations, suggesting a direct P mobilization.

Our results suggest that plants may plastically adjust resource acquisition strategies to increase nutrient uptake efficiency and be able to directly affect P mobilization from the litter layer. We conclude that this ability of plants to adapt their P acquisition strategies in response to eCO2 by tackling different sources within the litter-soil continuum and maximizing nutrient acquisition represents an important mechanism to support the CO2 fertilization effect and might affect the resilience of the Amazonian rainforest to climate change, and thus global carbon balance.

How to cite: Martins, N. and the AmazonFACE team: Multiple plant root strategies improve phosphorus acquisition under elevated CO2 in the Amazon rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10719, https://doi.org/10.5194/egusphere-egu24-10719, 2024.

EGU24-10823 | Posters on site | BG1.8

Seasonal variation of water isotopes in different forest ecosystems in the Central Amazon  

Flavia Durgante, Jochen Schöngart, Maria Teresa Fernandez Piedade, Susan Trumbore, Sam P. Jones, Didier Gastmans, Shujiro Komiya, Rafael Oliveira, Gerd Gleixner, Jost Lavric, Heiko Moossen, Heike Geilmann, Bianca Weiss, Maira Macedo, Lorena Maniguage Rincon, Priscila Amaral de Sá, and Florian Wittmann

The Central Amazon comprises mosaics of forest ecosystems with different water dynamics and soil characteristics. The water dynamics from each ecosystem affect the evaporation signal seasonally expressed in the water isotopes (δ18O and δD). The recognition of the evaporative signal from different forest segments is essential for the development of hydrological and eco-hydrological studies in the complex Amazon biome. In this study, we used stable isotopes to evaluate how the water dynamics of different forest ecosystems affect seasonal water evaporative signals in each environment. We monitored water isotope signals from 2018-2020 in different compartments (precipitation, soil, stream, groundwater, river, lake, and flooded areas) of two non-flooded forests (clay soils - “plato” and sandy soils – “campinarana”) and three flooded forests (pristine igapó, disturbed igapó and várzea). We found that the soil water sampled by lysimeters in the upland forest seasonally expresses the isotope signal from the rainwater (Local Meteorical Water Line-LMWL) without a strong evaporative overprint. The water isotope signal from flooded forests is more variable. The isotopic composition of pristine rivers has an overlapping signal from the rain isotope signal (LMWL). However, water from the river downstream from the very large hydropower dam (Balbina) has a strong evaporative signal. During the flooded period, the water within the flooded forests has a more evaporated signal than the signal from the source (such as the river or lakes). During the non-flooded period, the water isotope signal from the soil inside the flooded forest corresponds to the rainwater signal. To the best of our knowledge, these represent the first description of the water isotope signals from the compartments in different Central Amazonian forest ecosystems. They illustrate and identify the high variation of the evaporative signal from the complex Amazon biome, knowledge that is essential to understanding how different forest ecosystems influence water recycling in the Amazon hydrological cycle.

How to cite: Durgante, F., Schöngart, J., Piedade, M. T. F., Trumbore, S., Jones, S. P., Gastmans, D., Komiya, S., Oliveira, R., Gleixner, G., Lavric, J., Moossen, H., Geilmann, H., Weiss, B., Macedo, M., Rincon, L. M., Sá, P. A. D., and Wittmann, F.: Seasonal variation of water isotopes in different forest ecosystems in the Central Amazon , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10823, https://doi.org/10.5194/egusphere-egu24-10823, 2024.

EGU24-11089 | ECS | Orals | BG1.8

Seasonal drought reduces microbial diversity and functional richness in the Amazon 

Jessica Finck, Dan Frederik Lange, Beto Quesada, Bruno Takeshi Tanaka Portela, Sávio José Filgueira Ferreira, Fernando Dini Andreote, Erika Kothe, and Gerd Gleixner

Tropical rainforests such as the Amazon are of high importance as a global carbon sink. Due to its well-known nutrient limitation, the Amazon rainforest relies heavily on rapid microbial decomposition of biomass to release freshly available nutrients for plant growth. Despite the fundamental importance of decomposers for this ecosystem, little is known about the biodiversity of such microbiomes, their functional activity, and spatial and seasonal variability. We used 16S rDNA and ITS rDNA sequencing to analyze the microbial communities of the Amazon’s terra firme and the much drier white-sand ecosystems during the dry and wet seasons in 2022. Bacterial microbiomes differed significantly between seasons, displaying lower bacterial species richness and diversity in response to seasonal drought. In contrast, fungal richness and diversity differed strongly between sites, but were less affected by seasonal variation, suggesting their hyphae network and associations with plants as potential protectors against drought effects. Fungal and bacterial communities alike showed lower abundance of taxa involved in organic matter decomposition following seasonal drought. These changes were also reflected at the functional level, with samples collected during the dry season and at white-sand sites featuring lower abundances of decomposition and denitrification pathways. Soil hydro-chemical data also emphasizes how prolonged drought may limit soil nutrient supply via local microbiomes. Our results suggest that the reduced nutrient availability and soil connectivity during drought and within the white-sand ecosystem lower microbial activity and functional redundancy, henceforth demonstrating a strong impact of ecosystem type and drought on tropical microbiomes and their functional capacities. Our results further highlight that the observed increase in droughts in the Amazon rainforest may additionally limit nutrient supply through the microbial community, limiting carbon sequestration in the ecosystem with negative consequences for the global climate system.

How to cite: Finck, J., Lange, D. F., Quesada, B., Portela, B. T. T., Ferreira, S. J. F., Andreote, F. D., Kothe, E., and Gleixner, G.: Seasonal drought reduces microbial diversity and functional richness in the Amazon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11089, https://doi.org/10.5194/egusphere-egu24-11089, 2024.

EGU24-11932 | ECS | Posters on site | BG1.8 | Highlight

Attributing future Amazon forest loss to land-use change and climate change 

Selma Bultan, Sebastian Bathiany, Niklas Boers, Raphael Ganzenmueller, Gergana Gyuleva, Yiannis Moustakis, and Julia Pongratz

The Amazon rainforest is of vital importance for biodiversity, regional climate, as well as global water and carbon cycling. However, over the past decades, ecosystem functions of the Amazon rainforest have diminished through a combination of increasing anthropogenic pressure in form of land-use change and intensifying natural disturbances. Recent studies suggest that unabated deforestation and climate change could tip large parts of the Amazon towards a different, savanna-like vegetation state. Although such a scenario could lead to severe impacts on the climate system from regional to global scales, a holistic assessment of the risk of large-scale Amazon forest loss due to land-use change and climate change in the 21st century is currently lacking. 

Here, we use data from multiple CMIP6 Earth System Models under two low climate mitigation scenarios to attribute Amazon forest loss until 2100 to land-use change and climate change, applying a novel ensemble member approach. We find that around 1 mio. km2 of forest will diminish by 2100, corresponding to a loss of around one fifth of the pre-industrial forest area. Historically and over the first half of the 21st century, land-use change is the main driver of forest loss, whereas forest loss due to climate change increases non-linearly beyond 2°C global warming and even exceeds forest loss caused by land-use change by the end of the century in some models. We further find a consistent increase in the probability of abrupt (rather than gradual) forest loss with progressing deforestation and climate change. 

Overall, our results highlight that under plausible low mitigation socio-economic pathways 1) the Amazon rainforest will substantially diminish due to anthropogenic climate and land-use change and 2) the risk of forest loss due to climate change increases significantly beyond 2°C global warming. This stresses the urgent need for increased efforts to reduce deforestation and forest degradation through forest protection, conservation and sustainable land-use practices and for climate mitigation efforts in line with the Paris Agreement.

How to cite: Bultan, S., Bathiany, S., Boers, N., Ganzenmueller, R., Gyuleva, G., Moustakis, Y., and Pongratz, J.: Attributing future Amazon forest loss to land-use change and climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11932, https://doi.org/10.5194/egusphere-egu24-11932, 2024.

EGU24-12275 | ECS | Posters virtual | BG1.8

Plant nutrient resorption efficiency in a Central Amazon rainforest 

Julyane Santos, Sabrina Garcia, Laynara Lugli Lugli, Izabela Aleixo, Tomas Domingues, Bruno Takeshi, Ana Oliveira, Juliane Menezes, David Lapola, and Carlos Quesada

Nutrient resorption efficiency (RE) occurs before leaf abscission, with nutrients being actively transported via phloem through abscission zones from senescent leaves to be used in other parts of the plant. It is an essential nutrient conservation strategy for tropical plants growing on soils depleted of P (phosphorus) and other rock-derived elements (K; potassium, Ca; calcium, and Mg; magnesium), influencing nutrient cycling in these ecosystems. The environment heavily influences resorption; therefore, a better understanding of nutrient resorption processes in tropical trees, which act as a carbon sink, is important when facing the rapid climatic changes. Thus, our objective was to investigate the resorption of five macro elements (C; carbon, N; nitrogen, P, K, Ca, and Mg) and three micronutrients (Fe; iron, Zn; zinc, and Mn; manganese), and the effects of leaf longevity, foliar nutrient concentration, and canopy position in RE in a lowland forest tree community in Central Amazon. The study was conducted in two experimental plots at the AmazonFACE Program (Free-Air CO2 Enrichment) in Manaus, Amazonas, Brazil. Two 40 m scaffolding towers in the center of the plot granting access to the canopy of the twelve tree species studied. Young, mature, and senesced leaves were collected, totaling 188 leaves, from 2018 to 2019 for nutrient laboratory analysis. We found that K, P, and N were the most resorbed nutrients (42%, 33%, and 7%, respectively), while Zn, Fe, and Ca were the most accumulated (-65%, -27%, and -21%, respectively). Additionally, we found that C, N, P, Fe, and Zn resorption positively correlated with their concentration in leaves. Likewise, P, N, Mg, K, and C resorption positively correlated with leaf longevity. On the other hand, canopy position influenced the resorption of three elements: C, K, and Zn resorption. Our results suggest that P was the scarcest nutrient stored in leaves; the higher resorption efficiencies for K and P than for N suggest higher plant internal nutrient recycling of K and P, likely due to their scarcity in the soil during leaf senescence, species with longer leaf life span are often assumed to have higher nutrient resorption efficiency than species with short leaf life span to reduce nutrient loss, species in the community studied can optimize leaf anatomy and physiology to make the best use of the variable light encountered regarding of its position on the forest vertical profile. These trends suggest that nutrient resorption from senescent leaves may be a general adaptive strategy for conserving nutrients by plants in tropical forests growing on nutrient-poor soils, which should be considered when predicting future scenarios.

How to cite: Santos, J., Garcia, S., Lugli, L. L., Aleixo, I., Domingues, T., Takeshi, B., Oliveira, A., Menezes, J., Lapola, D., and Quesada, C.: Plant nutrient resorption efficiency in a Central Amazon rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12275, https://doi.org/10.5194/egusphere-egu24-12275, 2024.

EGU24-12352 | Posters on site | BG1.8

Tropical forests: a source of CO! 

Hella van Asperen, Thorsten Warneke, Alessandro Carioca de Araújo, Bruce Forsberg, Sávio José Filgueiras Ferreira, Thomas Röckmann, Carina van der Veen, Sipko Bulthuis, Shujiro Komiya, Sam P Jones, Santiago Botía, Leonardo Ramos de Oliveira, Thiago de Lima Xavier, Jailson da Mata, Marta de Oliveira Sá, Paulo Ricardo Teixeira, Julie Andrews de França e Silva, Justus Notholt, and Susan Trumbore

CO is an indirect greenhouse gas because it reacts with OH, therefore increasing the lifetime of methane: its possible indirect radiative forcing has been estimated as larger than that of N2O. Previous studies have indicated that temperate and boreal forests act as a net sink for CO, but the role of tropical rain forest ecosystems has not been investigated. We present the first CO flux measurements from tropical forest and forest soils, and can show that tropical rain forests are a net source of CO to the atmosphere.

During two intensive field campaigns at tropical rain forest fieldsite ZF2 (Manaus, Brazil), soil CO fluxes were determined by use of flux chambers. In addition, nighttime vertical CO concentration profiles were measured and different micro-meteorological techniques were applied to estimate ecosystem CO fluxes. Furthermore, we performed nocturnal CO concentration measurements in a seasonally inundated valley, which was hypothesized as a potential hotspot for ecosystem CO emissions.

Soil CO fluxes ranged from -0.19 (net soil uptake) to 3.36 (net soil emission) nmol m-2 s-1, averaging ∼1 nmol CO m-2 s-1. Fluxes varied with season and topographic location, with highest fluxes measured in the dry season in a seasonally inundated valley. Nocturnal canopy air profiles show consistent decreases in CO mixing ratios with height, which requires positive surface fluxes between 0.3 and 2.0 nmol CO m-2 s-1. Similar fluxes are derived using a canopy layer budget method, which considered the nocturnal increase in CO over time (1.1 to 2.3 nmol CO m-2 s-1). Using wet season concentration profiles of CO, the estimated valley ecosystem CO production exceeded the measured soil valley CO fluxes, indicating a potential contribution of the valley stream to overall CO emissions.

Based on our field observations, we expect that tropical rain forest ecosystems are a net source of CO. Extrapolating our first observation-based tropical rain forest soil emission estimate of ∼1 nmol m-2 s-1, a global tropical rain forest soil emission of ∼16.0 Tg CO yr-1 is suggested. Total ecosystem CO emissions might surpass this estimate, considering that valley streams and inundated areas could serve as local CO emission hotspots. To further improve tropical forest ecosystem CO emission estimates, more in-situ tropical forest soil and ecosystem CO flux measurements are essential.

How to cite: van Asperen, H., Warneke, T., Carioca de Araújo, A., Forsberg, B., José Filgueiras Ferreira, S., Röckmann, T., van der Veen, C., Bulthuis, S., Komiya, S., P Jones, S., Botía, S., Ramos de Oliveira, L., de Lima Xavier, T., da Mata, J., de Oliveira Sá, M., Ricardo Teixeira, P., Andrews de França e Silva, J., Notholt, J., and Trumbore, S.: Tropical forests: a source of CO!, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12352, https://doi.org/10.5194/egusphere-egu24-12352, 2024.

EGU24-13403 | Posters on site | BG1.8

Understanding the role of temperature in forest edges: a remote sensing approach in the Brazilian Amazon 

Skye Hellenkamp, Paulo Brando, and Bela Starinchak

Land surface temperature (LST) is a dominant influence on the health and productivity of ecosystems. Deforestation in the Brazilian Amazon has led to extensive land-use transitions from forests to pastures and industrialized agriculture. This has resulted in elevated land surface temperatures, with impacts on the energy, water, and carbon cycles. Forest fragmentation increases the area of forest edges, where exposure to sunlight, wind, and bordering land-uses alters the forest microclimate. While the changes in forest edge temperature due to bordering land-use transitions is acknowledged, the magnitude of these changes between specific agricultural land management practices has yet to be determined. This case study uses a remote sensing approach to investigate forest edge temperatures in Mato Grosso, Brazil, with a primary goal of discerning how distinct agricultural practices, such as cover cropping or double cropping, can potentially mitigate adverse temperature impacts on forest edges. These findings will strengthen the understanding of forest edge temperatures, with a focus on the potential of sustainable land management, contributing to broader conservation efforts in the Amazon Rainforest. 

How to cite: Hellenkamp, S., Brando, P., and Starinchak, B.: Understanding the role of temperature in forest edges: a remote sensing approach in the Brazilian Amazon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13403, https://doi.org/10.5194/egusphere-egu24-13403, 2024.

EGU24-14471 | Orals | BG1.8

Constraining uncertainty in terrestrial tropical carbon flux dynamics requires capturing local biogeochemical influences on structure and function 

Elsa Ordway, Gregory Asner, David Burslem, Stuart Davies, Simon Lewis, Mohamad Mohiza, Nilus Reuben, O'Brien Michael, Phillips Oliver, Qie Lan, Sabrina Russo, Xiangtao Xu, Marcos Longo, and Paul Moorcroft

Spatial heterogeneity in tropical forest productivity and resulting rates of carbon uptake and storage emerge from variation in ecosystem structure and functional traits reflecting differences in climate, edaphic conditions, evolutionary history, and natural and anthropogenic disturbance histories. Yet, models poorly represent this heterogeneity. Remote sensing data provide landscape-scale measures of tropical forest heterogeneity in structure and functional traits that can be used to advance terrestrial biosphere models. To examine whether forest functional traits related to photosynthetic capacity can be used to improve predictions of tropical biomass dynamics and carbon fluxes, we parameterized the Ecosystem Demography model version 2.2 (ED2.2) using canopy traits derived from visible to shortwave infrared (VSWIR) airborne imaging spectroscopy data across an edaphic gradient in Borneo. We find significant site-level differences in relationships between SLA and foliar nutrient concentrations, suggesting that remotely sensed foliar traits can be used to capture variation in photosynthetic capacity at large, edaphically varying spatial scales. We further show that plant functional types parameterized with site-constrained trait values yield more accurate predictions of canopy demography, forest productivity and above-ground biomass dynamics than simulations that depend solely on parameterization of edaphic conditions. However, the most substantial improvements result from allowing for site-level variation in background disturbance rates in the model. Our study reveals the importance of capturing tropical forest heterogeneity in terrestrial biosphere models, particularly as it relates to nutrient availability and disturbance processes. 

How to cite: Ordway, E., Asner, G., Burslem, D., Davies, S., Lewis, S., Mohiza, M., Reuben, N., Michael, O., Oliver, P., Lan, Q., Russo, S., Xu, X., Longo, M., and Moorcroft, P.: Constraining uncertainty in terrestrial tropical carbon flux dynamics requires capturing local biogeochemical influences on structure and function, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14471, https://doi.org/10.5194/egusphere-egu24-14471, 2024.

EGU24-14707 | Orals | BG1.8 | Highlight

Do local-scale climate tipping points exist in Amazon forests, and can they warn of impending basin-scale tipping point vulnerability? 

Scott Saleska, Natalia Restrepo-Coupe, Kleber Silva Campos, Luciana Alves, Valeriy Ivanov, Marcos Longo, Raimundo de Oliveira Jr., Rodrigo Silva, Marielle Smith, Raphael Tapajos, and Tyeen Taylor

The risk of a tipping point for Amazon forests — a perturbation threshold beyond which abrupt, irreversible (or difficult to reverse) changes in forest function and large-scale tree die-off occur — motivates much recent Amazon forest science and policy work to understand and reduce the risk. However, virtually all the science to date focuses on tipping points as a basin-wide phenomenon. To understand how large-scale tipping points may be triggered, we urgently need to study mechanisms of tipping point onsets at local-scales in pivotal forests.

 Here, we used 12+ years of observations (spread over two decades from 2001-2020) of water and energy fluxes from eddy covariance measurements, and associated ecological and meteorological observations in the eastern Amazon basin, to investigate the potential for hydrological extremes to induce a “local scale” tipping point.  We focused on forest transpiration capacity (the capacity of vegetation to convert available energy into latent heat, quantified as the ratio of transpiration to incoming radiation, T/R) because transpiration in eastern Amazon forests is the basis for precipitation recycling on which forests to the west depend.

Our observations encompassed two strong El Niño droughts, in 2002-2003 and in 2015-2016. Both events were characterized by similarly reduced rainfall; however, the 2015 El Nino was further amplified by an ongoing warming trend, which made for a hotter drought with higher atmospheric vapor demand, exacerbating the drought effects on the forest. 

This amplification of drought by warming was apparently sufficient to cause widely divergent responses to the two droughts.  The forest responded positively to the 2002 drought, with increases in canopy conductance (Gs) and in evapotranspiration, consistent with a stable forest transpiration capacity (T/R) that saw proportional increases in T in response to higher R. By contrast, the transpiration capacity (sustained through two decades of previous dry seasons and the 2002 El Nino drought) collapsed during the 2015 drought.  Notably, the forest’s ability to transpire did not return with the rain as the drought ended, but remained low for several years. Thus, we concluded that the difference between the 2002 and 2015 El Nino’s was sufficient to push the forest past a “tipping point” threshold in forest transpiration function, into an alternate state of reduced function in which it remained trapped until the forest could regenerate the canopy with new leaves.  

This discovery of the phenomenon of local-scale short-term tipping point dynamics in forest canopy function opens the door to investigating and understanding how basin-scale tipping points may emerge from local phenomena, and how careful local observations may provide early warnings of impending larger-scale forest vulnerability.

How to cite: Saleska, S., Restrepo-Coupe, N., Silva Campos, K., Alves, L., Ivanov, V., Longo, M., de Oliveira Jr., R., Silva, R., Smith, M., Tapajos, R., and Taylor, T.: Do local-scale climate tipping points exist in Amazon forests, and can they warn of impending basin-scale tipping point vulnerability?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14707, https://doi.org/10.5194/egusphere-egu24-14707, 2024.

EGU24-14880 | Orals | BG1.8 | Highlight

Biodiversity-mediated ecosystem functioning in the Amazon: a remote sensing approach 

Maria J. Santos and Diego Villamaina

The megadiverse system of the Amazon contributes to many local and global ecosystem processes with potential to trigger an irreversible shift in the functioning of our planet. Yet, Amazon’s biodiversity is complex and remains mostly understudied. Biodiversity distribution patterns likely affect the functioning of this crucial system, yet large scale systematic assessments are still lacking. Herein we examine how can optical remote sensing contribute to understanding biodiversity patterns in the Amazon. We use the spectral diversity approach to map the heterogeneity of spectral signatures as a proxy for heterogeneity in canopy composition using Sentinel-2 imagery over the entire basin. Our map is able to reproduce patterns of primary, secondary and deforested areas, and within the forest areas, the patterns of spectral richness and spectral turnover resemble those expected for the Amazon system, with rapid turnover in species composition closer to the waterways and more stable plant community compositions away from the waterways. We then examine whether the locations with higher or lower spectral variability correspond to different community and trait compositions. We examine the relationship between spectral richness and turnover and the presence of hyperdominant trees in the Amazon. We also examine the multivariate trait space including Specific leaf area (SLA), Leaf dry matter content (LDMC), Leaf nitrogen content (LNC), and Leaf Phosphorous content (LPC) along the gradient of spectral variability to find that trait syndromes vary along the gradient of spectral diversity. These results show that biodiversity biodiversity gradients among the Amazon may explain differences in ecosystem functioning and that approaches such as the spectral heterogeneity may start to shed some light into such relationships, especially over entire and important ecosystems like the Amazon. Further examinations of these processes and relationships are therefore required and will contribute to our better understanding of the feedbacks between biodiversity and earth system processes.

How to cite: Santos, M. J. and Villamaina, D.: Biodiversity-mediated ecosystem functioning in the Amazon: a remote sensing approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14880, https://doi.org/10.5194/egusphere-egu24-14880, 2024.

EGU24-15363 | ECS | Posters on site | BG1.8

Fire trends on ATTO footprint over the last two decades 

Gisela Dajti, David Urquiza, Hella van Asperen, Sam Jones, Shujiro Komiya, Jost Lavric, Stijn Hantson, and Santiago Botía

The Amazon Tall Tower Observatory is located in the central Amazon (S 02 08.9°, W 059 00.2°) inside the Uatumã Sustainable Development Reserve and has been monitoring continuously the atmospheric composition since 2013. The site is set up with two measurement towers of 80 meters and a tall tower of 325 meters for continuous monitoring of trace gases and aerosols. The surface influence (hereafter footprint) of the research station covers a large area to the east and northeast with the fetch extending for hundreds of kilometres, overlapping with the main branch of the Amazon River reaching the city of Belém (during the dry season) and large swaths of primary forest over the Amapá state (during the wet season).  We have analysed trends in fire counts (using MODIS thermal anomalies) and burned area (GFED4 and GFED5, Global Fire Emission Database 4th and 5th version) over the last two decades (2000-2023) inside the ATTO footprint and found that both show increasing and significant trends for the months of June (14,68 fire counts/year) July (42,23 fire counts/year), August (59,6 fire counts/year) and September (148,6 fire counts/year). Spatially, fires are located on easternmost part of the footprint and there is no evidence of a spatial trend approaching ATTO. Interestingly, in October the mean longitude of the fire counts over the period of interest shows a trend migrating from -56°W to -54°W, but with no significant trend in fire counts. We complement these results by analysing mole fractions of carbon monoxide (a proxy for biomass burning) at ATTO for an overlapping period (2013-2023). In addition, we provide links to the environmental drivers explaining these trends and spatial patterns. Observing biogenic greenhouse gases enhances our understanding of the Amazonian rainforest’s carbon budget, influenced by climatic conditions, land use alteration and other anthropogenic impacts.  

How to cite: Dajti, G., Urquiza, D., van Asperen, H., Jones, S., Komiya, S., Lavric, J., Hantson, S., and Botía, S.: Fire trends on ATTO footprint over the last two decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15363, https://doi.org/10.5194/egusphere-egu24-15363, 2024.

EGU24-16499 | ECS | Posters on site | BG1.8

NO and O3 mixing ratios above the canopy in the rainforest 

Carolina Monteiro, Anywhere Tsokankunku, Hartwig Harder, and Stefan Wolff

Nitrogen oxides (NOx = NO and NO2) are chemical compounds that affect and control the abundance of ozone (O3) and hydroxyl radicals (OHx = OH and HO2), the main oxidizing agents in the atmosphere. In pristine environments, these oxidizers react with biogenic volatile organic compounds (BVOCs), such as isoprenes, to produce oxidized secondary organic products. Further reaction with NOx leads to the formation of nitrates. Nitrates deposit on surfaces and grow aerosol particles which eventually act as cloud condensation nuclei. This makes NOx an important atmospheric component, even in low concentrations. Therefore, NOx measurements are being made at the Amazon Tall Tower Observatory (ATTO) research site in the central Amazon forest basin, a pristine region.

Here we present the measurements of NO, O3 and meteorological parameters collected at the Walk-up tower, at a height of approximately 40 m, just above the canopy.  

How to cite: Monteiro, C., Tsokankunku, A., Harder, H., and Wolff, S.: NO and O3 mixing ratios above the canopy in the rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16499, https://doi.org/10.5194/egusphere-egu24-16499, 2024.

EGU24-18326 | ECS | Posters on site | BG1.8

Mapping Phosphorus Forms in the Pan-Amazon Region: A Machine Learning Approach 

Joao Paulo Darela-Filho, Anja Rammig, Katrin Fleischer, Tatiana Reichert, Laynara F. Lugli, Carlos A. Quesada, Luis Carlos C. Hurtarte, Mateus D. de Paula, and David M. Lapola

Phosphorus (P) is a key driver of terrestrial productivity. However, the lack of spatial data on various P forms in soils hinders the large-scale application of process-based vegetation models. To address this, we used a model selection approach based on Random Forest regression models to predict different P forms (total, available, organic, inorganic, and occluded P) in the pan-Amazon region. Our models were trained and tested using data from 108 sites of the RAINFOR network, including soil group and textural properties, geolocation, nitrogen (N) and carbon (C) contents, terrain elevation and slope, soil pH, and mean annual precipitation and temperature. The models were then applied to several spatially explicit datasets to predict the target P forms. The resulting maps depict the distribution of total, available, organic, inorganic, and occluded P forms in the topsoil profile (0 - 30 cm) at a spatial resolution of 5 arcminutes. Our models achieved a good level of mean accuracy (77.37 %, 76,86 %, 75.14 %, 68.23 %, and 64.62% for the total, available, organic, inorganic, and occluded P forms, respectively). Our results reveal a clear gradient of soil development and nutrient content, with the mapped area generally exhibiting very low total P concentration status. Total N was the most important variable for predicting all target P forms. Despite some gaps in the training and testing data, most of the area could be mapped with a good level of accuracy. Our maps can aid in the parametrization and evaluation of process-based terrestrial ecosystem models and promote the testing of new hypotheses about P availability and soil-vegetation feedbacks in the pan-Amazon region.

How to cite: Darela-Filho, J. P., Rammig, A., Fleischer, K., Reichert, T., Lugli, L. F., Quesada, C. A., Hurtarte, L. C. C., de Paula, M. D., and Lapola, D. M.: Mapping Phosphorus Forms in the Pan-Amazon Region: A Machine Learning Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18326, https://doi.org/10.5194/egusphere-egu24-18326, 2024.

EGU24-18954 | Posters on site | BG1.8 | Highlight

Amazonian understory response to elevated CO2 

Tomas Domingues, Amanda Damasceno, Sabrina Garcia, Izabela Aleixo, Juliane Menezes, Iokanam Pereira, Martin De Kauwe, Vanessa Ferrer, Katrin Fleischer, Thorsten Grams, Flávia Santana, Iain Hartley, Bart Kruijt, Laynara Lugli, Nathielly Martins, Richard Norby, Bruno Portela, Anja Rammig, Carlos Quesada, and David Lapola and the AmazonFACE team

The response of plants to increasing atmospheric CO2 concentration depends on several factors such as life history of specific species, availability of water, nutrients and light, and the ecological context that the plants are found. Although several experiments with elevated CO2 (eCO2) have been done worldwide, none was performed in the Amazon forest understory focusing in a community growing naturally. The understory of the central Amazon is limited by both light and phosphorus. Understanding how such ecosystem responds to eCO2 is important to foresee how the forest will function in the future. Also, quantifying the response of this forest compartment helps to constrain Ecosystem Models that compute carbon and water fluxes.

For this study, we used the open-top chamber (OTC) approach, with a CO2 enrichment of +250 ppm above the ambient concentration. Eight OTC were installed (4 with ambient CO2 and another 4 with eCO2) in the understory of a natural forest in the Central Amazon, approximately 70 km from Manaus city. The eCO2 experiment started in November 2019 and, after 120 days, we quantified the average community response of the following photosynthetic parameters: light saturated carbon assimilation rate (Asat), stomatal conductance (gs), transpiration rate (E), intrinsic water use efficiency (iWUE), apparent quantum yield (Φ), light compensation point (LCP), maximum carboxylation capacity (Vcmax), maximum electron transport rate (Jmax). After 240 days of treatment, we quantified mean individual leaf production and accumulated leaf production, leaf area (Lfarea). After 300 days, we quantified the increment in base diameter (BD), height (Ht) and relative growth rate (RGR).

Under eCO2, we observed increases in Asat (67%), Jmax (19%), Φ (56%), and iWUE (78%), in agreement with the hypothesis that plants near the light compensation point respond strongly to eCO2. We also detected an increase in Lfarea (51%) and BD (65%), indicating that the extra primary productivity was not allocated to growth in height, but to supporting more light intercepting organs (leaf and conducting tissues). No detectable changes were observed for the other variables.

Apart from the expected increase in assimilation rates, understory plants in Central Amazon responded positively to eCO2 by increasing their ability to capture and use light (leaf size, Φ, and Jmax). The increment in leaf area while maintaining E rates signifies that this forest compartment will increase its contribution to the whole forest water fluxes to the atmosphere. That might be related to the prevailing acquisitive strategy necessary for competing for phosphorus brought by water flow through plants. As a possible consequence, this forest might be less resistant to extreme drought associated with El Niño years.

Funding: Coordination for the Improvement of Higher Education Personnel - CAPES (grants 312589/2022-0) and São Paulo Research Foundation-FAPESP processes numbers (2022/07735-5) and (2015/02537-7). 

How to cite: Domingues, T., Damasceno, A., Garcia, S., Aleixo, I., Menezes, J., Pereira, I., De Kauwe, M., Ferrer, V., Fleischer, K., Grams, T., Santana, F., Hartley, I., Kruijt, B., Lugli, L., Martins, N., Norby, R., Portela, B., Rammig, A., Quesada, C., and Lapola, D. and the AmazonFACE team: Amazonian understory response to elevated CO2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18954, https://doi.org/10.5194/egusphere-egu24-18954, 2024.

EGU24-19868 | ECS | Orals | BG1.8

Assessing the relative importance of soil moisture and temperature on the nighttime CO2 flux: two contrasted ecosystems study cases in West Africa 

Renaud Koukoui, Ossénatou Mamadou, Djideme Franck Houénou, Bernard Heinesch, Jean-Martial Cohard, Mamadou Bousso, Christophe Peugeot, and Basile Kounouhéwa

In the context of global warming and rapid increase of population particularly in West Africa where forest ecosystems are threatened by land use conversion, understanding the biophysical variables influencing the ecosystem respiration (Reco) becomes vital for predicting the carbon balance in response to climate change. Using the Eddy Covariance method, and without an automatic chamber system, a key step to determine Reco is to use nighttime Net Ecosystem Exchange (NEE) data to establish a functional relationship using Reco main driver’s as an input.  However, to ensure that the input variable(s) used in this relationship is the most relevant governing this process, especially in tropical regions where both data and studies are scarce, it remains therefore an important prerequisite to examine the relative importance of potential drivers. This prior analysis is especially needed because: (1) the main driver may differ according to the climate and locations; (2) collinearity between some potential drivers could be a complex issue in identifying the main one; (3) the scale of influence of these drivers on the nighttime CO2 emission at some sites is still unknown. In our study, we therefore investigated the relative importance and scale of influence of soil moisture (Hsoil) and temperature (Tsoil) at different depths on the nighttime NEE. Since variations of the net CO2 flux exchanged can differ from one site to another, in this study we used data acquired from 2008 to 2017 above two contrasted ecosystems: a mixed culture (Nalohou, lat. 9.74°N, long. 1.60°E) and an open clear forest (Bellefoungou, lat. 9.79°N, long.1.72°E) located in Sudanian climate, Northern Benin. Both sites belong to the AMMA-CATCH (African Monsoon Multidisciplinary Analysis-Coupling of the Tropical Atmosphere and Hydrological Cycle) observatory. Two methods have been then deployed: the first one which is the Mutual Information, was used to identify the relative importance of Hsoil and Tsoil in controlling the nighttime NEE; the second one, the wavelet transform allows determining the scales of influence of these variables on nighttime NEE. We found that periodicity of nighttime NEE response to the two variables differs according to the season.  Soil moisture appears as the most important variable in the nighttime NEE variation whatever ecosystems and seasons analyzed. During wet seasons, nighttime NEE response to soil moisture exhibits a periodicity lower than 64 nights with synchronization every 07 nights, while this synchronization can extend from 12 to 14 nights during the dry season. This fast response of nighttime CO2 emissions to soil moisture during the wet season results from a significant increase in precipitation. During the dry seasons, without precipitation, soil moisture decreases, and this reduces the water available to plant growth and microorganism activity, thus reducing the amount of CO2 emitted. Moreover, sporadic rainfall events rewet the soil, leading to spontaneous CO2 emissions. Soil temperature is secondary in importance, but its impact can vary; it is less relevant during the dry season, or more redundant in the wet season, for both sites. It is also out of phase with nighttime CO2 emissions regardless of the season.

How to cite: Koukoui, R., Mamadou, O., Houénou, D. F., Heinesch, B., Cohard, J.-M., Bousso, M., Peugeot, C., and Kounouhéwa, B.: Assessing the relative importance of soil moisture and temperature on the nighttime CO2 flux: two contrasted ecosystems study cases in West Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19868, https://doi.org/10.5194/egusphere-egu24-19868, 2024.

EGU24-19990 | ECS | Posters on site | BG1.8

Quantifying the photosynthetic capacity of dominant tree species in a humid lowland tropical forest of the Congo Basin 

Thomas Sibret, Marc Peaucelle, Felicien Meunier, Marijn Bauters, David Ellsworth, Kristine Crous, Pascal Boeckx, and Hans Verbeeck

The Congo basin is home to the second largest tropical forest in the world Therefore, it plays a crucial role in the global carbon cycle. Yet very few field based data on related processes exist. Gaining knowledge on a species level is also crucial for understanding these ecosystems. Leaf chamber measurements allow to measure photosynthetic capacity on a leaf level and by so, quantify the photosynthetic capacity of individual species. Moreover, they allow to quantify a plant´s reaction to environmental parameters such as light, atmospheric CO2 concentration and temperature. Such data is crucial to improve the calibration and robustness of global vegetation models. These models are key tools to estimate the global carbon budget and ecosystem responses to climate change as a part of the Intergovernmental Panel on Climate Change exercises.

To date, no such data exists for the forests of the Congo Basin which prevents us to properly understand forest dynamics and resilience to global changes.In this research, we quantify leaf level carbon uptake and its response to light, CO2 and Temperature for dominant tree species within the footprint of the CongoFlux tower in Yangambi (DR Congo).

As such, we deliver the first in-field leaf-level photosynthetic parameters dataset for a lowland tropical forest of the Congo Basin. Doing this, we explore the controls of interspecific variation in photosynthetic capacity including plant guild, species and vertical canopy position. Our study takes place at the research site of CongoFlux, Yangambi (DR Congo).

How to cite: Sibret, T., Peaucelle, M., Meunier, F., Bauters, M., Ellsworth, D., Crous, K., Boeckx, P., and Verbeeck, H.: Quantifying the photosynthetic capacity of dominant tree species in a humid lowland tropical forest of the Congo Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19990, https://doi.org/10.5194/egusphere-egu24-19990, 2024.

EGU24-20160 | Orals | BG1.8 | Highlight

Investigating the impact of lianas on global tropical forests 

Hans Verbeeck, Sruthi Moorthy Krishna Moorthy, Kim Calders, and Félicien Meunier

Lianas (woody vines) are an iconic feature of tropical forests as they represent on average 25% of all woody stems. Lianas are structural parasites that use the stems of self-supporting plants to reach the top of the canopy. From there, they strongly compete with trees for above- (light) and below-ground (water nutrients) resources. Despite their importance, lianas are completely neglected by terrestrial models. To fill this gap, we developed the first mechanistic representation of lianas in a state-of-the-art vegetation model, the Ecosystem Demography model version 2 (ED2.2). Model simulations revealed the critical role of liana for forest biogeochemical cycles (e.g., tree gross and net productivity decreases when lianas are present with the magnitude of the reduction varying with liana abundance) but also for the energy balance (e.g., lianas increase forest albedo and buffer the microclimate of forest understorey). 

 

In addition, we used a combination of terrestrial lidar scanning and a meta-analysis of field and drone observations of tree shape and structure to evaluate the impacts of lianas on tree allometries. In total, we gathered 45,000+ observations of individual tree height, 1.000+ observations of tree crown areas and 150+ tree quantitative structure models over more than 40 sites spread over the tropics, together with liana infestation levels. Those datasets converged to identify a key role of lianas on the shape and structure of tree in tropical forests, independently of the tree species. Liana heavy infestation was responsible for a strong reduction of tree height (-10.7%), crown area (-12.6%), branch length (-45.9%), and overall aboveground carbon stocks (-19.6%). We estimated the global potential liana impact on aboveground tree carbon stocks to be 13.5 Tg over the tropics, or about 7% of the total tropical forest biomass.

 

How to cite: Verbeeck, H., Krishna Moorthy, S. M., Calders, K., and Meunier, F.: Investigating the impact of lianas on global tropical forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20160, https://doi.org/10.5194/egusphere-egu24-20160, 2024.

EGU24-20858 | Posters virtual | BG1.8 | Highlight

GhanaFLUX: Meauring carbon fluxes in an African Rainforest 

Frederick Otu-Larbi, Caleb Mensah, Nana Agyemang Prempeh, Naomi Kumi, and Richard Kyere-Boateng

A new carbon flux tower has been established in the tropical rainforest of Ghana to measure carbon fluxes as well as emissions of biogenic volatile organic compounds. African tropical forests constitute about 20% of Global Tropical Forest cover but have been understudied due to a lack of in-situ observations. The establishment of GhanaFLUX in the Bia-Tano forest reserve in western Ghana will help to fill this gap, allowing in-depth assessments of carbon sequestration and storage in African forests. Here, we present a snapshot of the facilities available at GhanaFLUX, and measurements taken in the first year of operation. We show time series analysis of carbon dioxide and meteorological datasets obtained from GhanaFLUX, highlighting the seasonal variations in these observations. We also share some of our experiences and challenges during the establishment and operation of the flux site to guide researchers who are planning to set up new sites in challenging environments like rainforests. 

How to cite: Otu-Larbi, F., Mensah, C., Agyemang Prempeh, N., Kumi, N., and Kyere-Boateng, R.: GhanaFLUX: Meauring carbon fluxes in an African Rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20858, https://doi.org/10.5194/egusphere-egu24-20858, 2024.

EGU24-416 | ECS | Posters on site | BG1.10

The dissolution pattern of the flattened otolith of Pacific cod using the stepwise acid dissolution method 

Keito Aonuma, Yusuke Yokoyama, Yosuke Miyairi, Masayuki Chimura, Tomonori Hamatsu, Osamu Sakai, and Guido Plaza

The inner ear of fish contains calcium carbonate (CaCO3)-based crystals called otoliths, which play an essential role in hearing and balance. During otolith formation, new calcium carbonate is deposited in layers on the surface of the existing part and the part is no longer affected by metabolism. This feature means that each layer of the otolith retains the trace element ratios and isotope ratios it had at the time of formation. By analysing this preserved information, it is possible to make estimates about the environment and habitat at that time.

The stepwise acid dissolution method has been used in several studies as a technique for analysing the radiocarbon isotope ratios preserved in otoliths. In this method, phosphoric acid is used to dissolves the otolith from the outermost to the innermost layers. It has the advantage that a large amount of carbon can be collected from a single otolith, compared to the mechanical methods for the calcium carbonate sampling from each layer of the otolith.

However, this method involves dissolving the otolith in acid and the pattern of dissolution cannot be controlled minutely by the experimenter. Pacific cod (Gadus macrocephalus) otolith used by us is flattened and the dissolution pattern of such otoliths is not yet known. Furthermore, no direct observation of the otolith dissolution process has been made in relation to previous studies.

In this study, we dissolved three Pacific cod otoliths in phosphoric acid to directly confirm the process of otolith dissolution in the stepwise acid dissolution method. We removed each otolith from the acid one or more times during the dissolution process, weighed it and observed the change in the shape of the otolith and the layer structure exposed on the otolith surface. As the dissolution progressed and the otoliths became smaller, we polished them to check that the internal layered structure had not been destroyed by acid penetration.

As a result, we found that the serrated structures present on the outer edges of the otoliths are maintained when they are dissolved from the outside by acid. We also confirmed that acid dissolution from the outside does not destroy the inner layer structure, even microstructures such as daily rings. The validity of the stepwise acid dissolution method would be strengthened by these results. On the other hand, the otoliths were thinner as a result of acid dissolution, exposing the more inner layers on the flat surface. This is due to the thin vertical thickness of the flattened otoliths. This observation suggests that the collected carbon may be mixed with the carbon collected from more inner layer. This carbon mixing is able to be taken into account with future work. In addition, care should be taken when using this method near the nucleus, as the final stage of dissolution results in multiple holes in the otolith.

How to cite: Aonuma, K., Yokoyama, Y., Miyairi, Y., Chimura, M., Hamatsu, T., Sakai, O., and Plaza, G.: The dissolution pattern of the flattened otolith of Pacific cod using the stepwise acid dissolution method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-416, https://doi.org/10.5194/egusphere-egu24-416, 2024.

EGU24-815 | ECS | Orals | BG1.10

From sediments to the atmosphere: a mass spectrometry approach revealing structural dissimilarities of common NOM components 

Alexander Zherebker, Oliver Babcock, Roman Vasilevich, and Chiara Giorio

Natural organic matter (NOM) is a complex mixture of thousands of organic molecules that reflects environmental conditions and chemical transformations occurring nowadays or in the past. Fourier transform mass spectrometry (FTMS) resolves isobaric constituents and it is widely applied to obtain aquatic, terrigenous and aerosol NOM fingerprints. Traditionally, comparison of mass peak intensities is used to make a distinctive conclusion about samples behavior, but it has the limitation of omitting structural information on the corresponding ions. Due to the stochastic character of NOM synthesis, drastically different samples may appear as resembling, which hampers mechanistic study of NOM dynamics and its attribution to the source. Here we present how implementation of chemical and isotopic tagging in combination with FTMS helps to overcome this issue. The developed approach provides an upper boundary for the presence of specific structural features, e.g. functional groups, in individual NOM components. This facilitates a clear distinction between different NOM samples, which would share isobaric ions, and provides insights on isomeric complexity of these ions. The advantages of the method were demonstrated on two sets of samples. Firstly, we collected permafrost peat cores from different depths in the European Arctic region, which varied in corresponding botanical conditions, peat degradation and oxidation states. Selective deuteromethylation and bromination coupled to FTMS enabled to capture structural differences between shared ions, which differed in carboxylic functionality and aromaticity. Surprisingly, structural differences were found for ions, which abundance positively correlated with peat characteristics and geo-temporal conditions. The second set included aerosol particles collected in marine, rural and urban areas. Application of in-source H/D exchange for FTMS analysis of extracted NOM enabled to enumerate functional groups in shared ions and point molecular constituents with similar and distinct structural features. The observed trends serve to better understand aerosol formation processes and accompanied conventional formula-based statistical analysis including better understanding of Kendrick mass defect series.

How to cite: Zherebker, A., Babcock, O., Vasilevich, R., and Giorio, C.: From sediments to the atmosphere: a mass spectrometry approach revealing structural dissimilarities of common NOM components, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-815, https://doi.org/10.5194/egusphere-egu24-815, 2024.

EGU24-1109 | ECS | Orals | BG1.10

Post fire Black Carbon alteration: Rapid changes in a supposedly inert pool 

Oliver Donnerhack, Patrick Liebmann, Philipp Maurischat, and Georg Guggenberger

Forest fires are among the most influential disturbances in ecosystems and have varying effects on the soil depending on fire intensity and biomass consumption. The significant decline in biodiversity in European forests due to centuries of non-sustainable forest management, combined with worsening drought from climate change, has greatly increased vulnerability to wildfires. Incomplete combustion during fires leads to the formation of black carbon (BC), a group of substances known for their persistence in soil. However, studies suggest that medium-condensed BC species may have lower chemical and spatial stability and are therefore potentially more mobile and consequently only serve as temporary carbon sinks.

In order to assess the mobilization of BC, we investigate short-term changes in BC under field conditions, particularly of the low-condensed BC, and call into question the established concept of the general stability of BC pools. We investigated the dynamics of BC alterations during the post-fire period within one winter, following a late summer forest fire. We selected two comparable sites featuring spruce-dominated forest stands with different geologic parent material and weather conditions, particularly with respect to the amount of precipitation during the observation period. We sampled soil profiles down to 40 cm depth shortly after the fire event in late summer and after a 6-month period in late spring. After performing density fractionation to separate the mineral associated organic matter (MAOM) from particulate organic matter (POM), we analysed the BC content in the MAOM fraction using benzene polycarboxylic acids (BPCA) analysis.

The results show a high content of low to medium condensed BPCAs directly after fire, which decreased, especially the medium condensed BPCA marker, during the observation period. Taking into account the fast change in medium BPCA values in the MAOM fraction, we conclude that the general assumption that BC is in principle a stable, long-term carbon sink needs to be addressed more carefully.

How to cite: Donnerhack, O., Liebmann, P., Maurischat, P., and Guggenberger, G.: Post fire Black Carbon alteration: Rapid changes in a supposedly inert pool, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1109, https://doi.org/10.5194/egusphere-egu24-1109, 2024.

EGU24-1180 | ECS | Orals | BG1.10

Net CO2 release during chemical weathering in the north-western Himalaya: A dominant role of pyrite oxidation 

Rakesh Kumar Rout, Gyana Ranjan Tripathy, Satyabrata Das, and Santosh K. Rai

Oxidation of pyrites plays a key role in global chemical and climatic cycles. In particular, interaction of sulfuric acid produced through this process with carbonates releases CO2 to the atmosphere. This CO2 source counterbalances the CO2 consumed during silicate weathering in river basins, and hence, may influence earlier-suggested linkage between silicate weathering and global cooling events. In this study, we have investigated the dissolved major ions and sulfur isotopes of Indus headwaters to quantify the net effect of sulfide oxidation on the CO2 budget. This research is an attempt to evaluate the coupling between global Cenozoic cooling event and Himalaya weathering - ­a hypothesis which overlooked the CO2 supply via sulfide and organic oxidation. Towards this, we have employed sulfur isotopes (δ34S) as a proxy for riverine sulfate sources, mainly due to its distinct composition for the two major end-members [pyrite (~ -12 ‰) and gypsum (~ 17 ‰); [1]]. The average sulfate concentrations for the Indus headwaters are found to be higher than the regional rainfall, global average for rivers, and other major Himalayan rivers (e.g., Ganga and the Brahmaputra). Consistently, the mean δ34S for the Indus headwaters is also depleted with respect to that reported for the Ganga (~ 2 ‰) and Brahmaputra (~ 4 ‰) outflows [1-5]. Also, the sulfur isotopic values for the Indus headwaters are systematically depleted by 3 to 4 ‰ than that reported earlier for Indus mainstream [3]. These lighter δ34S values for the headwaters hint at relatively higher sulfide oxidation in the northwestern (NW) Himalaya compared to central and eastern Himalayas. Also, these processes are found to be more intense in the mountainous regions than in the floodplains. These observations are consistent with the basin lithology dominated by Paleozoic carbonates and organic-rich shales, and higher glacial coverage. Estimation of sulfide-derived cations from carbonate weathering and silicate-derived cations indicate that the chemical weathering in the Indus headwaters serve as a net source of CO2 to the atmosphere. This finding is in contrast with previous suggestion of significant CO2 removal during the Himalaya weathering and hence, challenges the role of land surface processes in the NW Himalaya in regulating the Cenozoic cooling event.

 

 

References

[1] Burke et al., (2018), Earth Planet. Sci. Lett., 496, 168-177.

[2] Chakrapani et al., (2009), J. Asian Earth Sci., 34, 347-362.

[3] Karim and Veizer, (2000), Chem. Geol., 170, 153-177.

[4] Kemeny et al., (2021), Geochim. Cosmochim. Acta, 294, 43-69.

[5] Turchyn et al., (2013), Earth Planet. Sci. Lett., 374, 36-46.

How to cite: Rout, R. K., Tripathy, G. R., Das, S., and Rai, S. K.: Net CO2 release during chemical weathering in the north-western Himalaya: A dominant role of pyrite oxidation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1180, https://doi.org/10.5194/egusphere-egu24-1180, 2024.

EGU24-1546 | Posters on site | BG1.10

Soil chemistry and hydrophobicity caused by four 2021-22 western U.S. megafires. 

Vera Samburova, Eric Schneider, Christopher Rüger, Brad Sion, Lukas Friederici, Yasaman Raeofy, Markus Berli, Palina Bahdanovich, Hans Moosmüller, and Ralf Zimmermann

In the past decade, the size, frequency, and severity of wildfires have increased around the world, especially in forests of the western United States, where ecosystems are dominated by dry conifer forests. It is known that fires can greatly affect not only air quality, climate, forest, and fauna, but also soil. The heat from fires can alter soil chemistry and change soil water repellency (SWR). SWR can reduce soil infiltration, which can increase surface runoff, erosion, and the potential for flooding and mud and debris slides. The increased frequency and intensity of western U.S. wildfires due to the rapidly changing climate poses an important question: What are the short- and long-term effects of wildfires on soil’s hydrologic responses, including SWR, and what is the role of fire-induced chemistry in SWR?

In the summer and fall of 2021 and 2022, there were four mega-wildfires (Caldor, Dixie, Beckwourth Complex, and Mosquito) in the Eastern Sierra Nevada mountains (California, USA). These wildfires provided us an opportunity to collect post-fire soil and ash samples and study the effects of fires on the physical and chemical properties of soils. We collected over 80 samples and performed multiple water-droplet penetration time (WDPT) tests in the field and, in the laboratory, apparent contact angle (ACA) measurements with the goniometer technique. For all four fires, a significant increase in SWR was observed between unburned and burned soils, with WDPT increasing from <1 s to 600 s (maximum measured value) and ACA values increasing between 1.1 and 9 times (p-value < 0.001). Our WDPT and ACA measurements of the samples collected 6 months and 1 year after the 2021 megafires (Dixie, Caldor, and Beckwourth Complex megafires) showed no significant changes in SWR for unburned and burned soils. The chemical analysis of organic constituents of unburned and burned soils with ultra-high-resolution mass spectrometry (thermogravimetry atmospheric pressure photoionization in combination with Fourier transform ion cyclotron resonance mass spectrometry or TG APPI FT-ICR MS) suggests that burned soils became water-repellent due to the formation and/or deposition of aromatic organic species (e.g., polycyclic aromatic hydrocarbons or PAHs) on the soil surface during fires. We found a positive correlation (R2 = 0.813) between the ACA values of analyzed fire-affected samples and aromaticity derived from the TG APPI FT-ICR MS spectra.

These results of our research highlight the importance of future research on the chemical composition of post-fire soils and the need to study the long-term effects of fires on soil properties.

How to cite: Samburova, V., Schneider, E., Rüger, C., Sion, B., Friederici, L., Raeofy, Y., Berli, M., Bahdanovich, P., Moosmüller, H., and Zimmermann, R.: Soil chemistry and hydrophobicity caused by four 2021-22 western U.S. megafires., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1546, https://doi.org/10.5194/egusphere-egu24-1546, 2024.

EGU24-1595 | ECS | Posters virtual | BG1.10

Hyperspectral Reflectance of Pre- and Post-Fire Soils: Toward Remote Sensing of Fire-Induced Soil Hydrophobicity 

Yasaman Raeofy, Vera Samburova, Markus Berli, Brad Sion, and Hans Moosmüller

Recently, wildfire activity and intensity in the western U.S. have greatly increased, mainly due to a warming climate, population growth, land use changes, and fuel accumulation. Disastrous effects during fires include loss of human lives and infrastructure, ecosystem disturbances, and emissions of carbon dioxide and air pollutants. In addition, wildfires modify physical and chemical soil properties and can cause Fire-Induced Soil Hydrophobicity (FISH), which reduces water infiltration into the soil and accelerates runoff during precipitation events. This may induce cascading disasters including flooding, landslides, and deterioration of water quality. To predict and mitigate such disasters, FISH is generally quantified at a few fire-affected locations using a manual infiltration test. However, this limited spatial coverage poorly represents FISH on a watershed scale as needed for prediction and mitigation purposes.

Watershed-wide, high-resolution monitoring of FISH is only practical using airborne or satellite-based remote sensing, for example utilizing solar reflectance spectra to characterize and monitor physical and chemical properties of fire-affected soils. Such spectra depend on light scattering and absorption at the soil surface. For this study, we have sampled ash, burned, and unburned soils, fresh (0 month), 1 year, and 2 years after three recent California (US) megafires: the Dixie (2021, 3,890 km2), Caldor (2021, 897 km2), and Beckwourth Complex (2021, 428 km2) fires. We studied the optical, chemical, and physical properties of all our samples. Optical hyperspectral reflectance spectra (350–2,500 nm) were obtained using natural solar (blue sky) illumination and a spectroradiometer (ASD FieldSpec3), operated in reflectance mode.  For all three fires, the results show that 700 nm wavelength reflectance of ash samples collected 1 and 1.5 years after the fire decreased between 36% and 76% compared to that of samples collected right after the fires. Additionally, significantly higher visible reflectance has been found for unburned compared to burned soil samples in each fire region that was studied. Fourier-transform infrared (FTIR) measurements were used to characterize the carbonate content of soil and ash samples demonstrating a positive relationship between carbonate content and visible reflectance, indicating a possible contribution of carbonate to the reflectance of soil/ash samples.

How to cite: Raeofy, Y., Samburova, V., Berli, M., Sion, B., and Moosmüller, H.: Hyperspectral Reflectance of Pre- and Post-Fire Soils: Toward Remote Sensing of Fire-Induced Soil Hydrophobicity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1595, https://doi.org/10.5194/egusphere-egu24-1595, 2024.

EGU24-1957 | ECS | Orals | BG1.10

Bacterial decomposition of dissolved organic matter: including the colloidal perspective 

Erika Andersson, Lars Tranvik, Marloes Groeneveld, Anders Tunlid, Per Persson, and Ulf Olsson

Dissolved organic matter (DOM) is a major carbon pool and considered the most bioavailable and most mobile fraction of organic matter. DOM is generally defined as the organic matter passing a filter pore size of 0.2 or 0.45 µm, and this size cut off means that DOM not only contains dissolved molecules but also colloidal objects and aggregates up to a few hundred nanometres. The properties of this colloidal DOM fraction, such as for example size, shape, and surface charge, will affect its actual bioavailability and mobility in the environment. Although previously not well studied, there has recently been a growing interest in this colloidal fraction of DOM.

We have studied DOM extracted by water from a boreal spruce forest soil, filtered through a 0.2 µm pore size. By using a combination of spectroscopy techniques, such as NMR, and light (SLS, DLS), X-ray (SAXS) and neutron (SANS) scattering techniques, we can access chemical and physical information on both the molecular and colloidal fractions of DOM.

Our results show that the colloidal DOM has a homogenous chemical composition, and that carbohydrates is the dominating chemical component in both the colloidal and molecular DOM. The colloids have a mass fractal structure which does not change upon dilution and they are electrostatically stabilised against aggregation. In a lab scale study, we investigated the bacterial decomposition of this DOM during a two-month incubation. The molecular fraction of DOM was quickly decomposed. However, no change was observed for the colloidal DOM, constituting ca. 50% of the carbon, indicating that it persisted bacterial decomposition.

Our results suggest that colloidal properties could be an important but hitherto overlooked aspect to the central question of what dictates organic matter reactivity and persistency in different environments and across different time scales. Our current work extends from soil solution to aquatic ecosystems, to assess the ubiquity of the colloidal fraction of DOM.

How to cite: Andersson, E., Tranvik, L., Groeneveld, M., Tunlid, A., Persson, P., and Olsson, U.: Bacterial decomposition of dissolved organic matter: including the colloidal perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1957, https://doi.org/10.5194/egusphere-egu24-1957, 2024.

EGU24-2117 | Orals | BG1.10

Biochar enhanced microbial carbon use efficiency, while reducing mineralization of added and native soil organic carbon 

Kristiina Karhu, Subin Kalu, Aino Seppänen, Kevin Mganga, Outi-Maaria Sietiö, and Bruno Glaser

Biochar can increase long-term soil organic carbon (SOC) storage due to its polyaromatic structure. In addition to the recalcitrant carbon (C) contained in the biochar itself, biochar can also increase SOC storage by adsorption or organic matter on its surfaces, and reduced decomposition rate of native SOC (negative priming). Limited number of studies have looked at how biochar affects decomposition and stabilization of fresh C inputs, and native SOC decomposition. To fill this knowledge gap, we conducted a laboratory incubation study, where we followed the fate of added 13C-labeled glucose in a fine-textured agriculturally used soil (Stagnosol) amended with two different biochar levels corresponding to 15 and 30 Mg ha-1 in field conditions. Biochar addition reduced mineralization of SOC and added 13C glucose, while increasing microbial biomass and microbial carbon use efficiency (CUE). Most of the added biochar, as well as remaining 13C were found in the free particulate organic matter (POM) fraction after 6 months, indicating that added 13C glucose was preserved within the biochar particles. Our closer study of 13C amino sugar fraction extracted from the biochar particles revealed that the microbes that had efficiently grown on the added 13C glucose in the presence of biochar, were retained as dead microbial residues inside the biochar pores. This microbial route could provide a way for additional formation of rather recalcitrant C in the form of microbial residues in the presence of biochar, which could with time contribute to building SOC stock in biochar amended soils beyond the C present in biochar itself. We found that biochar also increased the portion of occluded POM in the treatments without 13C glucose addition, demonstrating that increased soil occlusion following biochar addition reduced SOC mineralization. The effects were found to be dose-dependent, i.e. higher biochar application rate resulted in lower mineralization rate of native SOC and of added 13C-glucose.

How to cite: Karhu, K., Kalu, S., Seppänen, A., Mganga, K., Sietiö, O.-M., and Glaser, B.: Biochar enhanced microbial carbon use efficiency, while reducing mineralization of added and native soil organic carbon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2117, https://doi.org/10.5194/egusphere-egu24-2117, 2024.

Elevated concentration levels of geogenic ammonium in groundwater arise from the mineralization of nitrogen-containing natural organic matter in various geological settings worldwide, especially in alluvial-lacustrine and coastal environments. However, the difference in enrichment mechanisms of geogenic ammonium between these two types of aquifers remains poorly understood. To address this knowledge gap, we investigated two representative aquifer systems in central Yangtze (Dongting Lake Plain, DTP) and southern China (Pearl River Delta, PRD) with contrasting geogenic ammonium contents. The use of optical and molecular characterization of DOM combined with hydrochemistry and stable carbon isotopes has revealed differences in DOM between the two types of aquifer systems and revealed contrasting controls of DOM on ammonium enrichment. The results indicated higher humification and degradation of DOM in DTP groundwater, characterized by abundant highly unsaturated compounds. The degradation of DOM and nitrogen-containing DOM was dominated by highly unsaturated compounds and CHO+N molecular formulas in highly unsaturated compounds, respectively. In contrast, the DOM in PRD groundwater was more biogenic, less degraded, and contained more aliphatic compounds in addition to highly unsaturated compounds. The degradation of DOM and nitrogen-containing DOM was dominated by aliphatic compounds and polyphenols and CHO+N molecular formulas in highly unsaturated compounds and polyphenols, respectively. As DOM degraded, the ammonium production efficiency of DOM decreased, contributing to lower ammonium concentrations in DTP groundwater. In addition, the CHO+N(SP) molecular formulas were mainly of microbial-derived and gradually accumulated with DOM degradation. In this study, we conducted the first comprehensive investigation into the patterns of groundwater ammonium enrichment based on DOM differences in various geological settings.

How to cite: Xiong, Y.: Characteristics of Dissolved Organic Matter Contribute to Geogenic Ammonium Enrichment in Coastal versus Alluvial-lacustrine Aquifers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3292, https://doi.org/10.5194/egusphere-egu24-3292, 2024.

EGU24-3355 | Posters on site | BG1.10

NOM quality differences in sediments of land based aquacultures – insights by liquid chromatography-high resolution mass spectrometry 

Peter Herzsprung, Carolin Waldemer, Matthias Koschorreck, and Oliver Lechtenfeld

Natural organic matter (NOM) was widely investigated in natural waters, sea water, river water, lake water, groundwater. The highest molecular resolution of NOM can be achieved by Fourier-transform ion cyclotron resonance mass spectroscopy (FT-ICR-MS). This analytical tool generates molecular formulas (MF) for thousands of NOM components. By coupling liquid chromatography to FT-ICR-MS insights into the polarity (hydrophilic versus hydrophobic) of NOM compounds can be achieved.

Anthropogenic inputs have an imprint on NOM and it changes its overall composition. Aquaculture is one of the fastest growing sectors of food production by covering over 8 Mio ha. The consequences of fish farming for the organic matter quality in fish pond waters and sediments are poorly understood. Here we investigated the stages of pollution by comparison the water extractable organic matter (WEOM) in the sediment at the main site of fish feed application and open water sediments at different distances (transect) to the feeding site.

Full profile HPLC-FTICR-MS chromatograms were segmented into approx. one-minute wide segments between 10 and 15 Min (five segments), the main eluting region of WEOM. MF were calculated for the mass range 150 - 1000 Da with an error threshold of 1 ppm using in-house software considering the following carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and sulphur (S) elements: 12C0–60, 13C0–1, 1H0–122, 16O0–40, 14N0–8, 32S0–3, and 34S0–1.

For all retention times, N3, N4, N5, N6, N7 (CHNO) MF with 0.2 < O/C < 0.5 and 1.5 < H/C < 2.0 showed relative higher intensities in the feeding center compared to the distant sites. For some MF like C20H37N5O7, C22H39N5O7, C24H42N6O10 the intensity was more than five times higher in the center compared to open water site. Such components can be suggested to be oligopeptides (Leu-Asn-Thr-Ile, Glu-Pro-Lys-Ile, Leu-Leu-Asp-Ser-Gln as possible isomeric solutions). The sediment in the feeding center exhibited a prevalence of CHNOS and CHOS2 MF, whereas N1, N2, CHOS1, and CHO displayed relatively uniform intensities along the transect, with some instances of slightly higher intensities observed away from the feeding site. The number and abundance of CHNOS MF decreased with increasing retention time (decreasing polarity). Notably, these compounds appear to be inherently hydrophilic, characterized by predominantly low molecular weights (< 400 Da).

The results obtained suggest the following biogeochemical processes: Initially, the protein-rich fish feed undergoes hydrolysis, leading to the formation of oligopeptides. Subsequent partial desamination of these molecules facilitates their interaction with inorganic sulphides, resulting in the formation of CHNOS MF. Notably, the component C8H13N1O3S1, exhibiting a five-fold intensity at the feeding site, appears to correspond to one of the possible metabolites (Sulfanylpropanoyl-proline).

The results indicate a potential overfertilization with easily biodegradable protein-rich substances. The WEOM quality seems highly affected by additional input of CHNO, CHNOS and CHOS.

How to cite: Herzsprung, P., Waldemer, C., Koschorreck, M., and Lechtenfeld, O.: NOM quality differences in sediments of land based aquacultures – insights by liquid chromatography-high resolution mass spectrometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3355, https://doi.org/10.5194/egusphere-egu24-3355, 2024.

EGU24-3667 | ECS | Orals | BG1.10

Rapid lateral transport of fresh dissolved organic matter to the deep ocean in the NE Atlantic 

Bingbing Wei, Michael Seidel, Gesine Mollenhauer, Hendrik Grotheer, Jenny Wendt, Thorsten Dittmar, and Moritz Holtappels

Deepwater formation in the North Atlantic Ocean is a major gateway for dissolved organic matter (DOM) transport into the deep ocean. Despite focusing on vertical mixing, lateral transport of DOM from productive shelf regions is underexplored. Previous research suggested substantial offshore DOM transport on the Irish and Hebrides Margin via the bottom Ekman Drain. Our in-depth bottom water DOM analyses of carbon isotopes in combination with ultrahigh-resolution mass spectrometry (FT-ICR-MS) indicated that downwelling in this region leads to higher DOM concentrations (by 7–11 μM) and younger radiocarbon ages (by 190–330 yrs) compared to DOM of the central Northeast Atlantic at similar depths. During downslope transport, conservative mixing shapes the molecular composition of recalcitrant DOM, while minor particulate organic matter degradation contributes to producing less-refractory DOM with terrigenous signals. Consequently, the bottom Ekman transport emerges as a rapid and efficient channel for transporting fresh DOM into the deep North Atlantic Ocean, acting as a crucial carbon sink for atmospheric CO2.

How to cite: Wei, B., Seidel, M., Mollenhauer, G., Grotheer, H., Wendt, J., Dittmar, T., and Holtappels, M.: Rapid lateral transport of fresh dissolved organic matter to the deep ocean in the NE Atlantic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3667, https://doi.org/10.5194/egusphere-egu24-3667, 2024.

EGU24-3890 | ECS | Posters on site | BG1.10

Carbon cycling in coexisting marine ecosystems: Cold seeps and coral reefs in Northern Norway 

Muhammed Fatih Sert, Knut Ola Dølven, Sebastian Petters, Timo Kekäläinen, Janne Jänis, Jorge Corrales-Guerrero, and Bénédicte Ferré

Cold seeps and cold water corals (CWCs) coexist on Northern Norway's continental shelf at the Hola trough between Lofoten and Vesterålen. Here, cold seeps release methane from the seabed, yet only a limited amount reaches the atmosphere. The remaining methane dissolves and disperses in nearby seeps. Methane is unreactive for most microorganisms in the water column, yet it is a unique energy and carbon source for methane-oxidizing bacteria (MOB). MOBs metabolize methane and release carbon dioxide as the end product of oxidation. Increasing carbon dioxide may constrain pH-sensitive CWCs in the region. We investigated the biogeochemistry of carbon, carbon isotopes, nutrients, dissolved organic matter (DOM) compositions and microbial diversity through water column profiles and water samples collected in June 2022. Preliminary results indicated that elevated methane increases dissolved inorganic carbon concentrations and modifies carbon isotopic compositions. Additionally, DOM compositions implied a positive correlation between prokaryotic diversity and protein-like DOM components at cold seeps and the entire water column near CWCs, suggesting analogous microbial modifications. Our preliminary conclusion suggests cold seeps and CWCs symbiotically coexist in Northern Norway continental shelves; however, enhanced water temperatures and consequent increase in methane release at cold seeps may mitigate the functioning of CWCs in future.

This study is supported by the Research Council of Norway, project number 320100, through the project EMAN7 (Environmental impact of Methane seepage and sub-seabed characterization at LoVe-Node 7).

How to cite: Sert, M. F., Dølven, K. O., Petters, S., Kekäläinen, T., Jänis, J., Corrales-Guerrero, J., and Ferré, B.: Carbon cycling in coexisting marine ecosystems: Cold seeps and coral reefs in Northern Norway, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3890, https://doi.org/10.5194/egusphere-egu24-3890, 2024.

EGU24-5444 | ECS | Orals | BG1.10

Efficiency of Biological Carbon Pump: Insights from Compound-Specific Amino Acid δ15N 

Chen Li, Zhimin Jian, and Haowen Dang

As a vital component of the global carbon cycle, the ocean’s biological carbon pump determines the amount of carbon fixed by primary production in the surface waters. The efficiency of this biological pump is closely interconnected with the nitrogen cycle, which regulates nutrient inventory and primary productivity rates. Additionally, the structure of the upper ocean ecosystem influences the efficiency of the biological pump by determining how much fixed carbon is exported to the deep ocean. Compound-specific nitrogen isotope (δ15NAA) is a novel proxy that could provide valuable insights into both aspects of these questions. The δ15NAA could unravel isotopic information of source nitrogen and show δ15N changes associated with trophic processes. This study generates sedimentary δ15NAA, as well as bulk sediment δ15N and organic δ15N records from a western equatorial Pacific site (MD10-3340) covering the last 140 kyr. Our results demonstrate an overall agreement among three proxies, all indicating distinct precessional variations in source nitrate δ15N and potential changes in nutrient inventory. More importantly, the δ15NAA signatures suggest an inverse relationship between animal trophic activity in the surface water and the degradation of organic matter precipitating through the water column. Higher ecosystem trophic position is found during glacial periods, accompanied by inactive organic matter recycling, which implies a greater potential for carbon burial in deep reservoirs. Together, we suggest that the δ15NAAsignatures can provide a detailed picture of carbon cycle coupled with nitrogen cycle.

How to cite: Li, C., Jian, Z., and Dang, H.: Efficiency of Biological Carbon Pump: Insights from Compound-Specific Amino Acid δ15N, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5444, https://doi.org/10.5194/egusphere-egu24-5444, 2024.

EGU24-5586 | Orals | BG1.10

Temporal and spatial changes in DOM revealed by FT-ICR MS 

Catherine Moody, Nicholle Bell, Logan Mackay, and Ezra Kitson

DOM from peatlands is a collection of complex molecules, but also a significant source of carbon to aquatic pathways. It has a wide impact on aquatic ecosystems, providing an energy source for microbes and buffering capacity for water chemistry changes. The composition of DOM in drinking water reservoirs also impacts on chemical and energy demands of treatment processes, and is an area of growing concern for UK drinking water providers.

DOM was extracted from water collected from peatland headwater streams and reservoirs in the UK. The DOM was analysed with elemental analysis and FT-ICR MS to determine how the composition changes as water moves through the catchment. A combination of spatial and temporal sampling strategies allowed seasonal and catchment characteristics to be investigated (from 2018-2021, and 53-61°N).

There were significant trends in DOM composition metrics across a north/south gradient, with higher lipid content, and lower carbohydrate and peptide content in northern sites than southern sites. Samples collected in 2021 had several significant composition differences to other years. Monthly sampling showed the largest changes in DOM composition coincided with the end of the growing season (September in the UK).

These results show variable DOM in headwaters can be, and how reservoirs act to buffer the most extreme changes, resulting in more stable DOM compositions in reservoirs. Understanding how DOM composition is impacted by season, climate and catchment characteristics will have important ramifications for drinking water providers, and will help catchment managers plan land use changes and timing of water draw-off from peatland reservoirs.

How to cite: Moody, C., Bell, N., Mackay, L., and Kitson, E.: Temporal and spatial changes in DOM revealed by FT-ICR MS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5586, https://doi.org/10.5194/egusphere-egu24-5586, 2024.

EGU24-6501 | Orals | BG1.10

Variations in binding properties of dissolved organic matter along river-ocean continuum 

Pablo Lodeiro, Joao C. A. Macedo, Calin David, Carlos Rey-Castro, Jaume Puy, María Martínez-Cabanas, Roberto Herrero, Manuel E. Sastre de Vicente, and José L. Barriada

The binding properties of dissolved organic matter (DOM) play a crucial role in the biogeochemical cycles of trace metals and carbon. The composition of DOM is anticipated to exert influence over the magnitude and distribution of the intrinsic ion binding affinities that occur over a continuum of values, referred to as the affinity spectra. These spectra encompass many different organic acid groups that contribute to the nuanced binding characteristics of DOM. The total proton binding capacity represents the maximum sites available for other chemical species that may compete with protons for the same DOM binding sites, particularly in the case of metals. Consequently, the study of proton binding by DOM becomes the initial step to investigate deeper into metal binding mechanisms. Here, we research the variability in proton binding exhibited by DOM extracted from the Ebro and Mero Rivers (NNE and NW of Spain), and at the Atlantic Ocean and Mediterranean Sea. Our approach combines the non-ideal competitive adsorption (NICA) isotherm, offering insights into chemical binding on heterogeneous ligands, with the Donnan electrostatic model, which accounts for polyelectrolytic effects, i.e., the non-specific binding. This methodology enables us to pinpoint potential shifts in DOM binding affinities and derive a comprehensive set of intrinsic binding parameters for DOM. Importantly, these parameters are thermodynamically consistent and remain independent of the specific conditions of the samples, enhancing the extrapolation to future environmental changes.

 

Acknowledgements: Authors thank Agencia Española de Investigación for the financial support through the research projects PID2020-117910GB-C21 and -C22/AEI/10.13039/501100011033. P.L. acknowledges current support from the Ministerio de Ciencia, Innovación y Universidades of Spain and University of Lleida (Beatriz Galindo Senior award number BG20/00104)

References:

[1] Lodeiro, P., Rey-Castro, C., David, C., Humphreys, M. H., Gledhill, M., 2023. Proton Binding Characteristics of Dissolved Organic Matter Extracted from the North Atlantic. Environmental Science & Technology 57, 21136–21144.

[2] Waska, H., Brumsack, H.-J., Massmann, G., Koschinsky, A., Schnetger, B., Simon, H., Dittmar, T., 2019. Inorganic and organic iron and copper species of the subterranean estuary: Origins and fate. Geochimica et Cosmochimica Acta 259, 211–232.

[3] Heerah, K. M.,  Reade, H. E., 2023. Towards the identification of humic ligands associated with iron transport through a salinity gradient. Scientific Reports 12:15545.

How to cite: Lodeiro, P., Macedo, J. C. A., David, C., Rey-Castro, C., Puy, J., Martínez-Cabanas, M., Herrero, R., Sastre de Vicente, M. E., and Barriada, J. L.: Variations in binding properties of dissolved organic matter along river-ocean continuum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6501, https://doi.org/10.5194/egusphere-egu24-6501, 2024.

EGU24-6516 | ECS | Posters on site | BG1.10

Spatio-temporal dimensions of organic carbon-mineral interactions in a source-to-sink system 

Nora Gallarotti, Bernhard Peucker-Ehrenbrink, Sophia Johannessen, Lisa Bröder, Reto Wijker, Britta Voss, Negar Haghipour, and Timothy Eglinton

Rivers play a key role in the global carbon cycle by transferring organic carbon (OC) from the terrestrial biosphere to marine sediments, which act as an important long-term carbon sink. Associations between biospheric OC and mineral phases can alter OC stability and hydrodynamic properties, thereby influencing its transport and storage patterns within a river basin and dictating the fate of terrestrial biospheric OC discharged to the ocean. While research has mainly investigated the formation of these associations within soils, open questions remain on how these interactions evolve over space and time.

The Fraser River Basin in British Columbia, Canada drains regions with distinctive lithological and climatic gradients allowing the simultaneous study of leaf-wax-specific isotopic compositions (δ2H, δ13C) and inorganic geochemical signatures (εNd) of sediments as tracers of the provenance of biospheric OC and detrital mineral phases, respectively. In addition, bulk radiocarbon (D14C) serves as a tool to constrain biospheric OC residence times. Here, to investigate seasonal variations in the geochemical signatures of OC and its mineral host in sediments exported by the Fraser River to the Strait of Georgia using samples from a time-series sediment trap deployed cover the course of a year adjacent to the river mouth.

Both εNd and D14C follow a seasonal pattern by which aged OC (-176 to -140‰) is mostly transported during high discharge events such as the freshet in June and heavy rainstorms occurring in the upper basin in fall. During the former event, the geochemical signature (εNd: -9.2 to -7.2) points towards the Coastal Range affecting the detrital mineral composition more strongly, which shifts towards a greater proportion of Rocky Mountains-sourced sediment (εNd: -11.7 to -9.1) during the second high discharge event. Biomarker specific δ2H will further elucidate the extent to which the provenance of biospheric OC coincides with the mineral detrital load. Further, comparison with geochemical signatures of fluvial sediments within the Fraser basin, together with corresponding signatures in river-proximal sediments deposited in the Strait of Georgia allow for OC-mineral interactions to be assessed from a source-to-sink perspective.

This coupled investigation of organic and inorganic tracers provides new insights into terrestrial organic carbon export and the role of organo-mineral interactions on riverine organic carbon dynamics. These findings also have important ramifications for the interpretation of sedimentary archives.

How to cite: Gallarotti, N., Peucker-Ehrenbrink, B., Johannessen, S., Bröder, L., Wijker, R., Voss, B., Haghipour, N., and Eglinton, T.: Spatio-temporal dimensions of organic carbon-mineral interactions in a source-to-sink system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6516, https://doi.org/10.5194/egusphere-egu24-6516, 2024.

EGU24-6629 | ECS | Orals | BG1.10

Different dissolved organic matter (DOM) sources sustain microbial life in beach subterranean estuary 

Grace Abarike, Simone Brick, Bert Engelen, and Jutta Niggemann

Dissolved organic matter (DOM) is diverse in composition and serves as substrate for microbial metabolism. Within subterranean estuaries (STEs), DOM is introduced from different sources along the groundwater flow paths. These different DOM sources make it challenging to disentangle degradation pathways, especially in high-energy beaches with dynamic porewater advection and changing redox conditions. We performed sediment incubations in flow-through reactors (FTRs) to investigate how DOM from different sources is transformed by STE microbial communities. We used sediment and groundwater from the STE of a high-energy beach on Spiekeroog Island (Germany). Intertidal beach sediments were incubated for 13 days in FTRs with groundwater of low (~1.6) and high salinity (~29.1) as marine and terrestrial endmember, respectively, in triplicate setups, and additional control FTRs with artificial seawater of respective salinities. The FTRs ran under oxic conditions with recirculating advective flow. Porewater samples were taken daily for quantification of dissolved organic carbon (DOC) and nutrient concentrations, and samples from the start and the end of the incubation were taken for the analysis of microbial community composition, microbial cell numbers, and DOM composition. DOM samples were isolated through solid phase extraction and molecularly characterized via ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry. Over the course of the incubation, DOC concentrations increased, presumably from sediment leaching and potentially also by primary production in light-exposed parts of the setup, as oxygen concentrations also increased. The DOM composition of the porewater samples at start and end of the incubation was highly diverse, with a total of up to 2900 different molecular formulae detected in each sample. As expected, the low salinity porewater had a more terrestrial DOM signature with a higher proportion of aromatic compounds compared to the DOM in the high salinity porewater. In all setups, the DOM composition changed significantly from start to end. We observed an increase in DOM lability in both endmember setups indicating the mobilization of fresh DOM from sediments and/or microbial activity, including primary production. Interestingly, the changes observed were similar for both DOM endmembers. Our results indicate that the microbial communities of the high-energy beach STE thrive on a similar fraction of DOM, independent of its source.

How to cite: Abarike, G., Brick, S., Engelen, B., and Niggemann, J.: Different dissolved organic matter (DOM) sources sustain microbial life in beach subterranean estuary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6629, https://doi.org/10.5194/egusphere-egu24-6629, 2024.

EGU24-7088 | ECS | Posters on site | BG1.10

Using a novel N-15 natural abundance approach to quantify soil nitrogen transformations in biochar-treated vineyard soils. 

Kate Kingston, Zhihong Xu, Chris Pratt, Brendan Mackey, Paul Petrie, and Yihan Li

The increased frequency and intensity of climate extremes challenges vineyards to adapt and mitigate to ensure the survival of grape vines (Vitis vinifera) to meet the growing demand for quality wine.  Regenerative Viticulture (RV) is a novel approach with a strong focus on increasing soil carbon (C) stocks to regenerate vineyard soil that is largely degraded and in poor health.  When soil health and fertility is low, this impacts vine health and reduces its ability to fight disease and pests and withstand extreme climatic events. We hypothesised that biochar would increase nitrogen (N) cycling and retention and that these would differ in relation to the distinct physiochemical properties of the two vineyard soils.   Conscious of contributing to a sustainable circular economy, we utilised viticulture industry waste to produce biochar’s to compare with standard pine biochar.  Biochar was produced with three feedstocks at different pyrolysis temperatures, grape marc (475°C), vine pruning (450°C) and pine (600°C).  Soil (0 - 10 cm depth) was collected from under vines from vineyards at the South Burnett (heavy texture) and Granite Belt (sandy texture) regions in Queensland, Australia. We used a novel 15N natural abundance approach in a laboratory incubation experiment to investigate the potential of using biochar, a C-dense material produced by high temperature pyrolysis of organic materials in limited oxygen conditions as a suitable climate smart RV method for vineyard soils.  A short three-day laboratory incubation followed by microdiffusion was conducted to quantify the impacts of the three biochars on N transformations in the two soils.  Soil moisture was controlled at 60% and 90% water holding capacity (WHC) and biochar applied at 0% and 10% (w/w), with samples harvested on incubation days 0 and 3. Preliminary results indicate that in the short term for both experimental soils, biochar stimulated microbial activity, increased N availability and water use efficiency and reduced N loss through denitrification.  The results indicate that fungicides use in vineyards impacted the underlying soil health and microbial communities and influencing N cycling.  For the long term impact, the potential to use biochar for increase biodiversity and ecosystem recovery as a climate smart RV method in vineyards needs to be trialled in the field.  This is to establish the long-term effects of C accumulation and improved N cycling on soil health, biodiversity, vine resilience under extreme natural weather events, and on wine grape quality and quantity.

How to cite: Kingston, K., Xu, Z., Pratt, C., Mackey, B., Petrie, P., and Li, Y.: Using a novel N-15 natural abundance approach to quantify soil nitrogen transformations in biochar-treated vineyard soils., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7088, https://doi.org/10.5194/egusphere-egu24-7088, 2024.

EGU24-7317 | ECS | Orals | BG1.10

Reactivity of hydrogen sulfide toward organic compounds with sulfur-sulfur bonds 

Irina Zweig and Alexey Kamyshny

The presence of organic molecules containing sulfur-sulfur bonds was identified in both water columns and sediments of natural aquatic systems. While processes leading to formation of these compounds were intensively studied during recent decades, the kinetics and mechanisms of reactions responsible for their decomposition remain poorly understood. This study focuses on the kinetics and products of the reactions of dimethyl disulfide, dimethyl trisulfide, and cyclic polysulfide lenthionine (1,2,3,5,6-pentathiepane) with hydrogen sulfide at the pH and temperature ranges typical of environmental conditions. The findings reveal that under environmental conditions (pH≥5), the overall reaction rates are primarily controlled by the reaction of bisulfide anion (HS-) rather than hydrogen sulfide. The activation energy and the order of the reaction with respect to bisulfide anion is dimethyl disulfide < dimethyl trisulfide < lenthionine, while the order of the reaction with respect to organosulfur compounds is lenthionine < dimethyl trisulfide < dimethyl disulfide. The rates of the reactions between linear dimethyl polysulfides with bisulfide anion were found to be higher than the rates of their reactions with cyanide and hydroxyl anions, but lower than the rates of their photodecomposition. These results suggest that rapid decomposition of organosulfur compounds in sulfidic aphotic natural aquatic systems should be controlled by HS- decomposition pathway. Products of the decomposition of dimethyl disulfide and dimethyl trisulfide include methanethiol, higher dimethyl polysulfides, and inorganic polysulfides. The cyclic polysulfides were shown to be more stable than their linear analogs, resulting in their preferential preservation during the maturation process.

How to cite: Zweig, I. and Kamyshny, A.: Reactivity of hydrogen sulfide toward organic compounds with sulfur-sulfur bonds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7317, https://doi.org/10.5194/egusphere-egu24-7317, 2024.

EGU24-7593 | Posters on site | BG1.10

Towards an online ramped oxidation approach for thermal dissection and serial radiocarbon measurement of complex organic matter 

Marco A. Bolandini, Daniele De Maria, Negar Haghipour, Lukas Wacker, Jordon D. Hemingway, Timothy I. Eglinton, and Lisa Bröder

Radiocarbon (14C) measurements provide a powerful tool to deconvolute sources and dynamics of organic matter in the environment. However, interpretation of conventional bulk-level 14C data is challenging due to the myriad components comprising organic matter in soils and sediments. Thermally ramped oxidation provides one approach for overcoming this limitation, and involves subjecting a sample to gradually increasing temperatures, serially oxidizing the OC to CO2. Collected over prescribed temperature ranges ('thermal fractions'), this CO2 is then analyzed for 14C content using accelerator mass spectrometry (AMS). While effective, current ramped oxidation methods are mostly 'offline', involving manual collection and subsequent AMS analysis of evolved CO2, hindering sample throughput and reproducibility.

Here, we introduce a compact, online ramped oxidation (ORO) setup in which CO2 from discrete thermal fractions is directly collected and measured for 14C by AMS equipped with a gas ion source. The setup comprises two modules: (i) an ORO unit with two sequential furnaces - the first, ramped from room temperature to 900 °C, holds the sample; the second, maintained at 900 °C, includes a catalyst ensuring complete oxidation to CO2; and (ii) a dual-trap interface (DTI) collection unit with two parallel molecular sieve traps alternately collecting and releasing CO2 from a given fraction for direct injection into the AMS.

Preliminary results indicate reproducible data, evident in both thermograms and F14C results. Analysis of natural reference samples reveals that measured 14C values and their associated uncertainties align with those reported in the literature using conventional “off-line” ramped oxidation methods, affirming the utility of the new ORO-DTI-AMS setup.

Our goal is to apply this new method for comprehensive investigation of a range of natural samples, with a particular focus on the improved understanding of the fate of OC held in permafrost soils in the context of on-going climate and carbon cycle change in high latitude ecosystems.

How to cite: Bolandini, M. A., De Maria, D., Haghipour, N., Wacker, L., Hemingway, J. D., Eglinton, T. I., and Bröder, L.: Towards an online ramped oxidation approach for thermal dissection and serial radiocarbon measurement of complex organic matter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7593, https://doi.org/10.5194/egusphere-egu24-7593, 2024.

Subterranean estuaries underlying high-energy beaches are efficient turnover sites for dissolved organic matter (DOM) and nutrients from marine and terrestrial waters. In addition, leaching of beach wrack during tidal inundation and precipitation can contribute to DOM and nutrient loads. However, the combined impact of diverse environmental settings on the release of DOM and nutrients from beach wrack has so far not been studied, although e.g., salinity oscillations and temporary exposure to sunlight are common in high-energy beach subterranean estuaries. Here, we present the results of an extensive beach wrack leaching experiment taking beach wrack type, age, sunlight exposure, and leaching matrix into consideration. A combination of UVA irradiation, advanced wrack age, and leaching by low-salinity artificial rainwater resulted in high dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) releases of mmoles- to moles per kg dry weight in the macroalga Fucus sp. Furthermore, jellyfish wrack released millimoles of TDN in artificial seawater incubations. Ultra-high-resolution analyses of DOM revealed a prevalence of molecular formulae resembling biochemical building blocks such as sugars, amino acids, and vitamins, indicating that the released DOM could be of substantial nutritional value for the heterotrophic microbial communities on and near beach wrack. An interesting finding was the high abundance of aromatic and humic-like DOM released from macroalgal beach wrack, which may impact typically used marine and terrestrial source- and sink proxies. As such, beach wrack DOM and nutrients could further complicate biogeochemical distribution patterns in the subterranean estuary.

How to cite: Waska, H. and Banko-Kubis, H.: Experimental comparison of dissolved organic matter and nutrients leached from beach wrack by sea- and rainwater: A nutritional boost for the sandy beach subterranean estuary, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8750, https://doi.org/10.5194/egusphere-egu24-8750, 2024.

EGU24-10047 | Orals | BG1.10

Carbonate-associated organic matter: A form of “dissolvable” organic matter? 

Mary Zeller, Bryce Van Dam, Amy McKenna, Christian Lopes, Christopher Osburn, James Fourqurean, Kominoski John, and Michael Böttcher

Carbonate-associated organic matter (CAOM) is the organic matter associated with carbonate minerals, and a survey of carbonate-rich surface sediments suggests that it is incorporated at a consistent amount scaling with the internal surface area of the carbonate grains. As the carbonate sediment is sensitive to changes in saturation state due to benthic biogeochemical processing, we predicted that CAOM could exhibit interesting biogeochemical cycling, based on its potential to bridge particulate and dissolved pools of organic matter. Here, we report on a study in a seagrass meadow in central Florida Bay, USA. We utilize a combination of inorganic stable isotope (C, S, O) and high resolution mass spectrometry (21T FT ICR-MS) techniques to explore the carbon and sulfur cycles here, with a particular emphasis on dissolved organic matter (DOM) characterization. CAOM is examined similar to standard solid phase extraction (SPE-DOM) methods, after first washing carbonate sediment and dissolving it incompletely under a mild hydrochloric acid treatment. The δ34S and δ18O of sulfate, as well as the δ13C of dissolved inorganic carbon (DIC), suggest that the promotion of sulfide oxidation in the seagrass rhizosphere drives rapid carbonate dissolution and re-precipitation cycles. Sulfide oxidation, as well as elevated sulfide concentration, promotes sulfurization of CAOM, which is more sulfurized than porewater and surface water, as 42% of CAOM formulas vs 28% of surface water are sulfurized. Furthermore, a substantial quantity of molecular formulas present in the overlaying surface waters (90% of formulas, 97% by relative abundance) are also present in CAOM. Despite the CAOM sample containing nearly twice the number of formulas compared to surface water, due in part to its higher dissolved organic carbon concentration, these shared formulas make up 75% of the abundance of CAOM formulas. We argue that repeated coupled sulfur and inorganic carbon cycles, intensified by seagrasses, leads to increased sulfurization and release of CAOM, affecting DOM quality in the broader aquatic system. We estimate that approximately 9% of the particulate organic carbon (POC) stored in the sediments of this site are CAOM. Our results suggest that CAOM here is a form of “dissolvable” organic carbon which cycles much more rapidly than POC more broadly.

How to cite: Zeller, M., Van Dam, B., McKenna, A., Lopes, C., Osburn, C., Fourqurean, J., John, K., and Böttcher, M.: Carbonate-associated organic matter: A form of “dissolvable” organic matter?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10047, https://doi.org/10.5194/egusphere-egu24-10047, 2024.

EGU24-10209 | ECS | Posters on site | BG1.10

Apparent Aging and Rejuvenation of Terrestrial Organic Carbon Along the River-Estuary-Coastal Ocean Continuum 

Meng Yu, Timothy Eglinton, Pengfei Hou, Negar Haghipour, Hailong Zhang, Zicheng Wang, and Meixun Zhao

The balance between remineralization and sedimentary burial of terrestrial organic carbon (OCterr) in large river-dominated marginal seas influences atmospheric CO2 inventory on a range of timescales. Here we systematically investigate the evolution of OCterr along the river-estuary-coastal ocean continuum for three fluvial systems discharging to the Chinese marginal seas. The 14C-depleted characteristics of bulk OC and molecular components of riverine suspended sediments and marine sediments suggest that the Chinese marginal seas are a significant sink of pre-aged OCterr. Lower plant-wax fatty acid 14C contents suggest selective degradation of labile OC within estuaries, resulting in apparent aging of OCterr, followed by an apparent rejuvenation in OCterr in shelf sediments, the latter likely reflecting inputs from proximal sources that contribute younger OCterr. This selective degradation, aging and rejuvenation of OCterr along the continuum confounds the use of plant wax lipid 14C to constrain lateral transport times, and sheds light on more complex OCterr dynamics in marginal seas.

How to cite: Yu, M., Eglinton, T., Hou, P., Haghipour, N., Zhang, H., Wang, Z., and Zhao, M.: Apparent Aging and Rejuvenation of Terrestrial Organic Carbon Along the River-Estuary-Coastal Ocean Continuum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10209, https://doi.org/10.5194/egusphere-egu24-10209, 2024.

EGU24-11112 | ECS | Orals | BG1.10

Exploring CO2 Cycling in Karst Critical Zones: Lessons from Milandre Cave 

Sarah Rowan, Marc Leutscher, Sönke Szidat, and Franziska Lechleitner

We know that the concentrations of CO2 and DIC in the subsurface are often magnitudes higher than in the soil zone, and therefore we need to understand this reservoir and its vulnerability to change. Understanding the critical zone in the context of CO2 input, cycling dynamics, and export is essential as this carbon is particularly vulnerable to changes in water table rise which may result in rapid release of CO2 into the atmosphere. Cave environments provide an accessible natural window into the critical zone as they connect meteoric water, soils, the unsaturated vadose zone, and saturated zone. We conducted a two year monitoring campaign at Milandre cave in northern Switzerland, analyzing pCO2, d13CO2, and 14CO2 at various environmental interfaces, including the soil zone, within the epikarst, and in the cave itself. Forest soils maintained stable, modern 14C signatures and low d13C indicating year-round contribution of CO2 from C3 tree and plant root respiration. Conversely, meadow soils exhibited notable seasonality in F14C, suggesting a dominance of respiration from older soil pools in the winter months. Distinct variations in CO2 concentrations were observed within the cave, influenced by temperature driven ventilation dynamics. Keeling plot analysis revealed a consistent contributing endmember of C3 vegetation. However, similarities between the F14C of the meadow soils and cave CO2 suggests a significant contribution of meadow soil CO2 into the cave. These findings offer vital insights into the nuanced dynamics of CO2 sources and cycling processes within the critical zone of Milandre Cave, shedding light on the influences of seasonal variation and ecological influences of critical zone carbon and the export of carbon from terrestrial ecosystems.

How to cite: Rowan, S., Leutscher, M., Szidat, S., and Lechleitner, F.: Exploring CO2 Cycling in Karst Critical Zones: Lessons from Milandre Cave, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11112, https://doi.org/10.5194/egusphere-egu24-11112, 2024.

EGU24-11285 | Orals | BG1.10

Global expression of bomb radiocarbon in Earth's surface carbon reservoirs 

Timothy Eglinton and the Bomb-spike team

The Earth’s carbon cycle encompasses myriad processes that connect different reservoirs containing diverse forms of carbon that turnover and exchange on a wide range of spatial and temporal scales. Increased atmospheric CO2 from anthropogenic perturbation of the carbon cycle associated with fossil fuel combustion and land-use change reflects the release of carbon from stable, slow-cycling reservoirs.  Much current research seeks to quantify carbon transfer from slow to fast cycling reservoirs, as well as the ability of different carbon reservoirs, particularly the terrestrial biosphere and the oceans, to compensate for these increased CO2 emissions through carbon uptake and storage. Determination of the turnover time and rate of transfer of carbon between reservoirs is crucial in this regard. Radiocarbon, 14C, represents a powerful tool to address this question by virtue of its ~ 5700-year half-life that allows processes occurring on centennial to millennial timescales to be resolved. Superimposed on natural abundance 14C variations, above-ground nuclear weapons testing during the mid-20th Century created an abrupt spike in atmospheric radiocarbon (“bomb spike”) that has subsequently permeated into and moved through various Earth surface carbon reservoirs, serving as a useful tracer of carbon cycle processes occurring on annual to decadal timescales. Numerous studies have exploited this signal for assessment of turnover or transit times within and through carbon pools, atmospheric and oceanic circulation, ecosystem functioning and source attribution. However, much 14C data currently tends to be compartmentalized, with a focus on specific reservoirs or geographic locations.

In this study, we evaluate the global expression of the radiocarbon bomb spike across the different Earth surface active carbon reservoirs (terrestrial biosphere, soils, freshwater aquatic systems, and marine carbon reservoirs). We compile 14C data from existing and nascent databases as well as new measurements, including direct observations and records from natural archives spanning the pre-bomb period to the present, to develop an overview of the general features of 14C (timing, amplitude and character of the bomb peak) within each reservoir over this time interval.  In addition to using this information to refine our understanding of the interactions between different reservoirs, this study seeks to (i) identify gaps and biases in data with a view to motivating further 14C studies, (ii) underline the value of systematic data reporting, as well as careful archiving of samples for future 14C analysis, (iii) inform isotope-enabled carbon cycle and earth system models, and (iv) serve as benchmark against which to gauge future carbon cycle changes.

How to cite: Eglinton, T. and the Bomb-spike team: Global expression of bomb radiocarbon in Earth's surface carbon reservoirs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11285, https://doi.org/10.5194/egusphere-egu24-11285, 2024.

EGU24-11446 | ECS | Orals | BG1.10

Pyrogenic Carbon production in eucalypt forests: implications for the carbon cycle in fire-prone ecosystems 

Minerva García-Carmona, Cristina Santín, and Stefan Doerr

Wildfires play an important role in the carbon cycle, influencing both atmospheric carbon concentrations and terrestrial carbon storage. Pyrogenic carbon (PyC) derived from incomplete biomass combustion during wildfires is currently considered a relevant carbon sink at the global level. In order to assess the quantitative importance of PyC production, accurate data on PyC generation in different ecosystems and under a range of fire conditions are needed. In this study, we focus on the fire-prone continent of Australia, specifically on eucalypt forests, which are the most common type of native forests. Eucalypt forests, subjected frequently to both wildfires and human-prescribed fires, provide an important context for understanding PyC dynamics.
We conducted comprehensive pre-fire and postfire fuel inventories and quantified all pyrogenic materials generated in three representative eucalypt forests in Sydney, Melbourne, and Perth. Experimental fires, simulating low to medium-severity wildfires, were used to quantify PyC conversion rates in the main fuel components: forest floor, understory, down wood, and overstory (comprising only tree bark as these fires did not affect the crowns).
Our results show an average pyrogenic carbon conversion rate of 24% for eucalypt forests. This translates to 9 t C ha-1 of the carbon affected by the fire being emitted to the atmosphere, while 3 t C ha-1 is transformed into PyC, underscoring the relevance of PyC in carbon budgets from eucalypt forest fires. The conversion rates varied substantially among fuel components, with the bark component exhibiting the highest conversion rate, at approximately 40%, and the down wood component displaying the lowest rate at around 15%. Intermediate conversion values were reported for forest floor and understory components. 
Given the recurrent nature of fires in eucalypt forests in Australia, both naturally and under human-prescribed conditions, our findings suggest that PyC production plays a significant role in the carbon cycle, of sufficient magnitude to be considered in global carbon budget estimations.

How to cite: García-Carmona, M., Santín, C., and Doerr, S.: Pyrogenic Carbon production in eucalypt forests: implications for the carbon cycle in fire-prone ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11446, https://doi.org/10.5194/egusphere-egu24-11446, 2024.

EGU24-11885 | Orals | BG1.10

Radiocarbon measurements of archived fish scales reconstruct past carbon cycle changes in a peri-alpine lake 

Margot White, Benedict Mittelbach, Timo Rhyner, Negar Haghipour, Thomas Blattmann, Martin Wessels, Nathalie Dubois, and Timothy Eglinton

Climate change and other anthropogenic impacts such as nutrient pollution result in perturbations to freshwater systems that alter aquatic carbon cycling. In the alpine Rhine basin, for example, long-term monitoring over the past four decades has documented increasing water temperatures that cause a decrease in the solubility of CO2. However, this same dataset records a small increase in the concentration of dissolved inorganic carbon (DIC) over the same period. This requires increasing inputs of DIC to aquatic systems and an acceleration of the carbon cycle, but the source of this additional carbon is not clear. Possible explanations include increased weathering of bedrock or increased soil organic matter respiration, with sharply contrasting implications for carbon storage and turnover. Radiocarbon (14C) is an ideal tool to distinguish between these different scenarios, as bedrock weathering will contribute 14C-depleted (fossil) DIC whereas increased soil respiration will contribute DIC that is more 14C-enriched (younger). Furthermore, large changes in the atmospheric radiocarbon content over the past century resulting from the testing of nuclear weapons provide a strong signal with which to track the exchange between aquatic and atmospheric carbon pools by examining how lake water DI14C changes through time. Here we focus on Lake Constance, a large peri-alpine lake fed mostly by the alpine Rhine River. We measured natural abundance radiocarbon in archived fish scales collected from Lake Constance over the past 100 years to reconstruct changes in lake water DI14C. These fish scales come from young fish caught in the lake who feed primarily on phytoplankton and thus reflect the 14C of the lake DIC pool. Preliminary measurements of fish scales from the pre-bomb period were 0.78 to 0.79 Fm, reflecting the addition of 14C dead rock-derived carbon from the dissolution of carbonate rocks within the catchment. These values are 14C-depleted compared to present day water column DIC values of 0.82 to 0.84 Fm, where the bomb spike signal persists. Results from fish scales will ultimately be compared with other archives of water column DI14C currently in development, including 14C of chlorophyll degradation products and zooplankton exoskeletons isolated from varved lake sediments. These records permit us to investigate how carbon cycling in the lake and its catchment has responded to anthropogenic perturbations such as warming and nutrient pollution over the past century, with the eventual goal of calibrating isotope enabled carbon cycle models.

How to cite: White, M., Mittelbach, B., Rhyner, T., Haghipour, N., Blattmann, T., Wessels, M., Dubois, N., and Eglinton, T.: Radiocarbon measurements of archived fish scales reconstruct past carbon cycle changes in a peri-alpine lake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11885, https://doi.org/10.5194/egusphere-egu24-11885, 2024.

EGU24-11886 | Posters on site | BG1.10

Direct radiocarbon measurements of dissolved inorganic carbon from environmental water using a gas ion source  

Negar Haghipour, Charlotte Schnepper, Thomas Blattmann, Kayley Kundig, Maxi Castrillejo, Nuria Casacuberta, Timothy I. Eglinton, and Margot E. White

An increasing demand for radiocarbon analysis of small samples has led to the development of various methods to further improve and simplify the CO2 extraction needed for accelerator mass spectrometer (AMS) measurements. Here, the performance of a direct feeding system of CO2 from dissolved inorganic carbon (DIC) from small water samples (<6 ml) and direct AMS measurement via a gas ion source coupled to a gas interface system (GIS) is presented and compared to the conventional preparation by graphitization that demands significantly larger samples (> 60 ml).

Seawater samples collected from Sargasso Sea, southeast of and lake water samples collected from Lake Constance have been prepared by both methods. The extraction of CO2 gas from samples for GIS measurement is performed using a carbonate handling system (CHS-Ionplus AG) through purging the headspace, acidifying the water, and sparging out the CO2. The preparation time is greatly reduced compared to conventional analysis that requires the labor-intensive graphitization step. The yielded 14C results from the direct CO2 measurements are in good agreement with values obtained from graphite measurements. The observed deviation between the two methods is below the uncertainty of radiocarbon gas measurement (~7‰).

This new approach will facilitate understanding of carbon cycle dynamics in many different environments and applications where a high throughput (up to 80 sample/day) is required. The new method is suitable for groundwater, pore water, seawater, freshwaters from lakes, rivers and glacial settings. Furthermore, it enables the analysis of small milliliter-scale samples and those containing low DIC concentrations.

How to cite: Haghipour, N., Schnepper, C., Blattmann, T., Kundig, K., Castrillejo, M., Casacuberta, N., Eglinton, T. I., and White, M. E.: Direct radiocarbon measurements of dissolved inorganic carbon from environmental water using a gas ion source , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11886, https://doi.org/10.5194/egusphere-egu24-11886, 2024.

EGU24-12192 | Posters on site | BG1.10

There to remain? Pyrogenic carbon production of savanna fires 

Cristina Santin, Carmen Sánchez-García, Minerva García-Carmona, Tercia Strydom, Philippa Ascough, and Stefan H. Doerr

Southern African savanna fires account for ~30% of the annual global carbon (C) emissions from vegetation fires, but their impact on the global C cycle extends beyond direct emissions During fire, part of the C burnt is converted to pyrogenic carbon (PyC), which is more resistant to degradation than original biomass and acts as a buffer to global fire C emissions when stored in soils or sediments. Despite its recognized importance for the C cycle, how much PyC is produced and how much of it stays in savanna ecosystems is still not well known, with no information yet for Southern African savannas. To address this research gap, we quantified how much PyC was produced during four fires in Kruger National Park (South Africa) and how much PyC was stored in surface soils. We also characterized the chemical and thermal recalcitrance of this PyC. Our results will be discussed in the broader context of C emissions from savanna fires as well as the role PyC plays as a C sequestration mechanism through its accumulation in soils, redistribution and ex-situ transport.

How to cite: Santin, C., Sánchez-García, C., García-Carmona, M., Strydom, T., Ascough, P., and Doerr, S. H.: There to remain? Pyrogenic carbon production of savanna fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12192, https://doi.org/10.5194/egusphere-egu24-12192, 2024.

EGU24-12381 | ECS | Posters on site | BG1.10

Assessing the biodegradability of dissolved organic carbon in freshwater systems: A method evaluation study 

Danielle Green, Fereidoun Rezanezhad, Scott Smith, Stephanie Slowinski, and Philippe Van Cappellen

Dissolved organic carbon (DOC) is an important contributor to both carbon cycling and other biogeochemical processes in aquatic ecosystems. The biodegradable fraction of DOC can be microbially degraded over time, producing carbon dioxide (CO2), a greenhouse gas. In addition, microbial degradation-resistant DOC can accumulate in water bodies, causing chemical and physical changes to aquatic systems. Although biodegradable DOC (BDOC) is widely studied, there is no agreed-upon standard method for assessing its biodegradability. Here, we aimed to develop and evaluate a new method for determining BDOC in freshwater samples. Our method includes filtering water samples to below 0.22 µm, to remove existing microbial cells, prior to inoculating the samples with a concentrated microbial inoculum produced by stepwise isolation of microbial cells from a peat sample. In addition, we added solutions containing nitrogen and phosphorus (in the forms of NH4NO3 and K2HPO4, respectively) to ensure that the microbes were not nutrient-limited. The samples were then capped with foam stoppers and incubated in the dark at 25⁰C on a shaker for 28 days to allow constant aeration during BDOC degradation. When applied to five freshwater samples collected from rivers, stormwater ponds, and a lake, and a glucose control, we observed that the amount of BDOC in the natural samples ranged from 15% to 53% and was 90% in the glucose control. Rates of BDOC degradation were calculated from DOC measurements at six sampling time points between days 0 and 28. We found that the DOC trends with time were best explained by two successive phases for BDOC degradation in all of the samples: an initial, fast, phase of BDOC degradation followed by a second, slower, phase of BDOC degradation where the rate constant for the second phase was between 5.57 and 565 times slower than for the initial phase. Changes in chemical characteristics of DOC measured using absorbance and fluorescence parameters including specific ultraviolet absorbance at 254 nm (SUVA254), humification index (HIX), and parallel factor analysis (PARAFAC) at each sampling time revealed that the initial, fast, phase of BDOC degradation often represents the utilization of small, non-aromatic compounds while the later, slower, phase of BDOC degradation often represents the utilization of more complex, aromatic compounds. The presented method provides a new approach to measure and characterize BDOC degradability and degradation kinetics that can be applied to future studies on biogeochemical processes in aquatic ecosystems.

How to cite: Green, D., Rezanezhad, F., Smith, S., Slowinski, S., and Van Cappellen, P.: Assessing the biodegradability of dissolved organic carbon in freshwater systems: A method evaluation study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12381, https://doi.org/10.5194/egusphere-egu24-12381, 2024.

EGU24-12504 | ECS | Posters on site | BG1.10

Burning poop: carbon dynamics in herbivore dung during southern-African savanna fires 

Carmen Sánchez-García, Cristina Santín, Tercia Strydom, and Stefan Doerr

Herbivores play a vital role in the functioning of savanna ecosystems. They ingest plants, modifying the vegetation cover, and disperse nutrients across the landscape in the form of dung. Fire in savanna is also a key nutrient recycling pathway, making elements readily available through the resultant ash and smoke. Wildfire ash, known for its susceptibility to be transported by wind and water, plays a key role in redistributing pyrogenic organic matter and nutrients across the landscape. However, our level of understanding of ash characteristics from burnt dung is very low. In addition, and due to its high carbon content, dung also adds to the wildland fuels for fires, alongside vegetation. Given that savannas are the dominant source of global Cemissions from fires, assessing the role of burnt dung in C dynamics is, therefore, also crucial for more accurate estimations of the overall C released during savanna fires.

We quantified C losses from dung combustion during fire in four savanna sites burnt by experimental fires in Kruger National Park (South Africa). We also analysed chemical properties, including major nutrients and metals, of dung and dung-derived ash. The studied dung came from large herbivores (zebra, elephant, giraffe, buffalo and wildebeest). The concentration of carbon and nitrogen in burnt dung was significantly lower than unburnt dung (carbon: 41 and 4.1%, nitrogen: 1.1 and 0.3% in unburnt and burnt dung, respectively). The carbon released from dung burning accounted for up to 6% of the carbon released from vegetation burning, emphasizing the substantial role of dung in carbon emissions during savanna fires. Our results also highlight burnt dung as a hotspot for minerals and nutrients with chemical characteristics different to those found in vegetation ash (e.g., phosphorus: 9,195 and 6,158 mg kg-1, copper: 55.8 and 28.1 mg kg-1 in dung-derived and vegetation ash respectively). This is likely to affect local soil physical and chemical properties and hence enhance ecosystem diversity.

How to cite: Sánchez-García, C., Santín, C., Strydom, T., and Doerr, S.: Burning poop: carbon dynamics in herbivore dung during southern-African savanna fires, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12504, https://doi.org/10.5194/egusphere-egu24-12504, 2024.

EGU24-13692 | ECS | Posters on site | BG1.10

Unveiling the role of soil water: Identifying primary sources of dissolved organic matter in surface waters 

Livia Vieira Carlini Charamba, Tobias Houska, Klaus Kaiser, Klaus-Holger Knorr, Stephan Krüger, Tobias Krause, Huan Chen, Pavel Krám, Jakub Hruška, and Karsten Kalbitz

Dissolved organic matter (DOM) is crucial for various ecological processes, playing essential roles in carbon and nutrient cycling. In forested catchments, litter input contributes to soil organic matter, influencing DOM composition in surface waters. The transition of DOM from soil organic matter to the dissolved state significantly impacts ecological balance and highlights the role of specific soil horizons in the catchment for stream water. DOM fingerprints, reflecting variations and similarities, act as valuable indicators for identifying primary DOM sources. The increasing trend in dissolved organic carbon (DOC) concentrations in surface waters underscores the urgency to understand contributing sources comprehensively. This study aims to characterize DOM along the terrestrial-aquatic continuum, identifying sources in stream water.

Soil, soil water, and stream water samples were collected biweekly for approximately two years at various depths in the Sosa drinking water reservoir catchment (Ore Mountains, Saxony, Germany). Two sub-catchments (one with a significant peatland component and one with predominantly mineral soils) were considered, each with two streams. The soil and soil water samples included four different soil types that characterize the entire catchment, i.e., intact and degraded peatland, cambisol, podzol. Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) was employed to characterize DOM in both solid and aqueous samples. Rstudio was used as a semiautomatic data processing aiming to achieve consistent compound identification. A principal component analysis (PCA) and cluster analysis were used to identify DOM sources in stream water.

PCA results showed a clear distinction between solid and aqueous samples. Overlaps were observed among soil water and stream water samples, revealing shared organic compound sources and potential transfer pathways. Fluctuations and degradation patterns were noted across seasons, especially for soil water samples. Cluster analysis revealed that soil water DOM from peat horizons predominantly influenced upstream stream water DOM in peatland-dominated areas. Downstream, the DOM composition changed and was influenced by soil water from the cambisol and the podzol (mineral soils). Concerning the sub-catchment composed mainly of mineral soils, stream water reflected DOM of deep mineral horizons of cambisols and podzols. Forest floor soil water from cambisol had no to very little effect in both sub-catchments, however, soil water of the podzol forest floor slightly contributed to the streams located in the mineral soil-dominated sub-catchment. Thus, the results show that the primary source of DOM in the Sosa catchment came from soil water of deep mineral soil horizons and that stream proximity was a primary factor influencing the influx of allochthonous DOM into stream water.

The research emphasized that DOM composition in the four streams closely resembled soil water DOM and analyzing the composition of the solid organic soil horizons did not help to identify the potential DOM source of the streams. Therefore, although recognizing intrinsic stream processes is important, successful source identification requires analysis of DOM in soil water from major catchment soil types. Proximity to stream water played a critical role as the predominant factor contributing to the introduction of allochthonous DOM into stream water.

How to cite: Vieira Carlini Charamba, L., Houska, T., Kaiser, K., Knorr, K.-H., Krüger, S., Krause, T., Chen, H., Krám, P., Hruška, J., and Kalbitz, K.: Unveiling the role of soil water: Identifying primary sources of dissolved organic matter in surface waters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13692, https://doi.org/10.5194/egusphere-egu24-13692, 2024.

EGU24-14728 | Orals | BG1.10

Transformations of soil organic matter induced by volatile organic compounds 

Laura Meredith, Juliana Gil Loaiza, Adrian Castro, Antonette DiGuiseppe, Gemma Purser, Zhaoxin Zhang, Qunli Shen, Kolby Jardine, Romy Chakraborty, Eoin Brodie, and Malak Tfaily

Volatile organic compounds (VOCs) are diverse and prevalent metabolites exchanged in microbial systems but are often overlooked as vectors of soil organic matter (SOM) transformations. Roots, litter, aboveground vegetation, and microbial metabolism are all sources of VOCs to soil; however, little is known about how they can contribute to soil carbon (C) cycling. VOCs have been shown to contribute to key soil C pools including microbial biomass, dissolved organic matter, particulate organic matter, and mineral-associated organic matter (MAOM), suggesting that they can participate in critical soil C stabilization pathways such as the microbial necromass conduits to MAOM. Yet, we still lack an understanding of the specific VOC-induced transformations in SOC, hindering the characterization of this process across soil and volatile compounds.

 

To address this research gap, we conducted a soil incubation study to evaluate the contributions of VOCs to SOM composition. We hypothesized that VOCs would impact SOM composition and soil carbon pool magnitudes. We evaluated whether the diversity and quality of soil metabolites change in response to weekly additions of five individual VOCs over a 3-month period: methanol, acetone, acetaldehyde, isoprene, and alpha-pinene. In our study, we utilized soil matrices from a semi-arid agroecosystem, alongside sterile (irradiated) soil controls and silica controls, enabling us to distinguish between biotic and abiotic interactions. We monitored CO2 concentrations regularly as a proxy for microbial activity. Destructive triplicate samples were harvested each month for metabolite extraction and high-resolution SOM analysis by Fourier-transform ion cyclotron resonance mass spectrometry (FTICRMS). We found that VOCs stimulated SOM transformations and generally increased the number of lipids and amino sugars—markers of microbial biomass. VOCs a-pinene, acetaldehyde, and methanol had the most unique compounds, suggesting that these VOCs may support biomass production and its transformation, while isoprene and acetone had no unique compounds and may have predominantly been used for catabolic, CO2-producing processes. With this study, we aim to grow understanding of the role of VOCs in soil C cycling and their contribution to soil ecological and metabolic interactions related to carbon stabilization.

How to cite: Meredith, L., Gil Loaiza, J., Castro, A., DiGuiseppe, A., Purser, G., Zhang, Z., Shen, Q., Jardine, K., Chakraborty, R., Brodie, E., and Tfaily, M.: Transformations of soil organic matter induced by volatile organic compounds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14728, https://doi.org/10.5194/egusphere-egu24-14728, 2024.

EGU24-15386 | ECS | Posters on site | BG1.10

Dissolved Organic Matter from Coastal Vegetated Ecosystems Through the Lens of Carbon Sequestration 

Dariya Baiko, Thorsten Dittmar, Philipp Böning, and Michael Seidel

Coastal vegetated ecosystems (CVEs) are highly productive habitats whose role in coastal biogeochemical cycles cannot be understated. The high productivity of salt marshes, seagrass meadows, and mangrove forests is channeled into the sediments and into the sea in form of particulate and dissolved organic matter (DOM). While labile DOM is degraded within a short time frame, recalcitrant DOM compounds can remain in the oceanic water column for hundreds to thousands of years. However, so far, DOM has received little consideration in carbon sequestration approaches. In sulfidic porewater of CVEs, DOM can undergo abiotic sulfurization, producing dissolved organic sulfur (DOS), which may render it resistant to biodegradation. Thus, the formation of DOS in CVEs can act as a link between labile and recalcitrant pools of DOM and provide the means of carbon transport across and beyond ecosystem boundaries. We analyzed DOM as well as inorganic nutrients in samples from temperate (German) and tropical (Malaysian) mesotidal CVEs. Unprecedentedly high porewater DOC concentrations were found in both temperate salt marshes as well as in tropical mangroves. High proportions of DOS in the DOM pool demonstrated accumulation of sulfurized compounds in the porewater. Molecular DOM patterns deduced from ultrahigh-resolution mass spectrometry (FT-ICR-MS) analysis indicated that up to 50% of the several thousand molecular formulas identified were characteristic of the analyzed CVEs. Adjacent habitats shared a substantial proportion of DOM molecular formulas indicating lateral transfer of organic material. This emphasizes that the potential for carbon dioxide removal of CVEs extends beyond the areas with above-ground biomass.

How to cite: Baiko, D., Dittmar, T., Böning, P., and Seidel, M.: Dissolved Organic Matter from Coastal Vegetated Ecosystems Through the Lens of Carbon Sequestration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15386, https://doi.org/10.5194/egusphere-egu24-15386, 2024.

EGU24-15535 | ECS | Orals | BG1.10

The climate control of soil organic carbon dynamics inferred from speleothem radiocarbon ages 

Gang Xue, Yanjun Cai, Peng Cheng, Franziska Lechleitner, Haiwei Zhang, Yanhong Zheng, Yingying Wei, Shouyi Huang, Ling Yang, Xing Cheng, Yanbin Lu, Jie Zhou, Le Ma, Hai Cheng, and Lawrence Edwards

The complexity of processes affecting soil organic carbon (SOC) turnover on spatio-temporal scales often hinders the extrapolation of results from specific sites to larger scales. This study presents Holocene speleothem U-Th ages paired with 14C ages of carbonate and dissolved organic carbon (DOC) through three caves located on a north-south transect through China. The deviations of speleothem 14CDOCages from the U-Th ages show clearly spatial variability, and they are positively correlated with mean ages of modern SOC and soil turnover time, suggesting that deviations can be used to infer the SOC turnover. We further demonstrate that slow SOC turnover (large deviation) was associated with weak monsoon (low temperature/less precipitation) on temporal scales. Our findings reveal that climate dominates the speleothem 14CDOCages and SOC turnover. As global warming likely will intensify, the accelerated turnover of SOC, particularly at higher latitude areas, may partially offset the existing soil carbon stock. 

How to cite: Xue, G., Cai, Y., Cheng, P., Lechleitner, F., Zhang, H., Zheng, Y., Wei, Y., Huang, S., Yang, L., Cheng, X., Lu, Y., Zhou, J., Ma, L., Cheng, H., and Edwards, L.: The climate control of soil organic carbon dynamics inferred from speleothem radiocarbon ages, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15535, https://doi.org/10.5194/egusphere-egu24-15535, 2024.

EGU24-15782 | ECS | Posters on site | BG1.10

Lambda-Miner: Enhancing Reproducible Natural Organic Matter Data Processing with a Semi-Automatic Web Application  

Johann Wurz, Anika Groß, Kai Franze, and Oliver Lechtenfeld

As the volume and complexity of data in environmental sciences continue to grow, the need for data management and reproducible processing methods becomes increasingly crucial. In the specific research domain of natural organic matter (NOM), there is currently no standardized tool for data processing, particularly for the management of data and its respective metadata. We developed and present the Lambda-Miner - a semi-automatic web application for data processing of ultrahigh-resolution mass spectrometry data of NOM. The platform provides an end-to-end data processing pipeline and supersedes manual steps via standardized data and metadata management. It empowers users to execute interactive workflows for mass spectra calibration, assignment of molecular formulas by specific rules to peak masses, and validation of these formulas according to specific sets of rules. Peak data as well as sample and measurement metadata are stored in a relational database management system (RDBMS). The Lambda-Miner thus facilitates reproducible, standardized data processing which builds a common repository for mass data, metadata (such as sample type and geolocation), intermediate, and final results in a format suitable for subsequent analyses. The combination of this information in one place enables meta-analyses such as long-term quality control studies and software optimization assays. The Lambda-Miner supports domain-specific requirements for research data management and contributes to achieving FAIR data principles in the domain of NOM analytics. The Lambda-Miner allows researchers to process their ultrahigh-resolution mass spectrometry data of NOM within minutes and linking it to features such as extraction efficiency, accumulation time, and relation of total assigned current to total ion current. Processed data can be downloaded in an interoperable format, facilitating individual data processing or visualization. The current implementation of the Lambda-Miner is designed for studying NOM with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) allowing formula assignments with widely used elemental compositions of NOM in the mass range from 0 to 1000 Da. But its modular structure makes it easy to adjust and extend the implementation for other kind of analyses or instrumentations. With its adaptability and focus on reproducibility, the Lambda-Miner introduces a valuable tool for advancing standardized data storage, processing, and analysis in the study of Natural Organic Matter.

How to cite: Wurz, J., Groß, A., Franze, K., and Lechtenfeld, O.: Lambda-Miner: Enhancing Reproducible Natural Organic Matter Data Processing with a Semi-Automatic Web Application , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15782, https://doi.org/10.5194/egusphere-egu24-15782, 2024.

EGU24-16215 | ECS | Orals | BG1.10

Detection and exclusion of false molecular formula assignments via mass error distributions in ultrahigh resolution mass spectra from natural organic matter. 

Shuxian Gao, Elaine Jennings, Limei Han, Boris Koch, Peter Herzsprung, and Oliver Lechtenfeld

Ultrahigh resolution mass spectrometry (UHRMS) routinely detects and identifies thousands of molecular formulas (MFs) in natural organic matter (NOM). However, multiple assignments (MultiAs) occur when the several chemically plausible MFs are assigned to one single mass peak. MultiAs for a mass peak consist of one common core MF but different “formula residuals”, or replacement pairs, and increase as more heteroatoms and isotopes are being considered during the assignment process. This poses a major problem for the reliable interpretation of NOM composition in a biogeochemical context. A number of approaches have been proposed to rule out false assignments based on structural constraints or isotopologue detection and intensity ratios. But this becomes increasingly challenging for low abundance mass peaks or when stable isotope labeling (e.g. with 15N, 2H) is employed. Here, we present a new approach based on mass error distributions for the identification of true and false-assignments among MultiAs. An automatic workflow was developed for the detection and exclusion of false assignments in MultiAs based on their recurring replacement pairs and Kendrick mass defect values. The workflow can validate MFs for mass peaks that are close to detection limit or where naturally occurring isotopes are rare (e.g. 15N) or absent (e.g. P, F), substantially increasing the reliability of MFs assignments and broadening the applicability of UHRMS in characterization of NOM, e.g. for organic nitrogen and organic phosphorus in different environmental compartments, which are key components for global elemental cycles.  

How to cite: Gao, S., Jennings, E., Han, L., Koch, B., Herzsprung, P., and Lechtenfeld, O.: Detection and exclusion of false molecular formula assignments via mass error distributions in ultrahigh resolution mass spectra from natural organic matter., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16215, https://doi.org/10.5194/egusphere-egu24-16215, 2024.

EGU24-16483 | ECS | Orals | BG1.10

Radiocarbon signatures of dissolved black carbon in early winter water masses from the Beaufort Sea 

Linn Speidel, Negar Haghipour, Thomas Blattmann, Lisa Bröder, Julie Lattaud, Alysha I. Coppola, and Timothy I. Eglinton

Black carbon (BC) is a fraction of organic carbon resulting from the incomplete combustion of biomass and fossil fuels. The production and fate of BC is a topic of great interest in the context of ongoing climate change, as the intensity and severity of fires is increasing. The recalcitrant nature enables BC to buffer these changes by removing biomass-derived carbon into longer cycling pools. BC is mainly produced on land and a portion is transported in both particulate and dissolved form by the rivers to the oceans. Dissolved BC (DBC) cycles on millennial timescales, thereby storing BC as fraction of Dissolved Organic Carbon (DOC) in the marine DOC pool before deposition to sediments or complete degradation. However, there is currently limited information on the cycling, transport and evolution of modern riverine DBC, and how it contributes to the deep ocean DOC pool.
The arctic and boreal regions are well recognized as a nexus for climate change, given amplified rates of change in average temperatures and summer precipitation, which exacerbate carbon cycle feedbacks, including enhanced BC production by intensified wildfire seasons. The Beaufort Sea in the Arctic Ocean is composed of different water masses, with Pacific water masses entering from the Chukchi Sea, and arctic rivers - in particular the Mackenzie River - being the major source of freshwater that delivers both terrestrial DOC and DBC. Presently, information on the sources and fate of BC in the Arctic Ocean remains sparse.
Here, we report DBC concentrations and Δ14C values in the Beaufort Sea during early winter conditions. Distinct water masses were sampled, including the outflow of the Mackenzie River and the Pacific water jet on the shelf break, during two cruises in 2021 and 2022 that spanned the coast of north Alaska to the Amundsen Gulf. Preliminary radiocarbon results show that DBC on the shelf break is up to five millennia old. We discuss our findings in the context of regional hydrography and carbon cycle processes.

How to cite: Speidel, L., Haghipour, N., Blattmann, T., Bröder, L., Lattaud, J., Coppola, A. I., and Eglinton, T. I.: Radiocarbon signatures of dissolved black carbon in early winter water masses from the Beaufort Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16483, https://doi.org/10.5194/egusphere-egu24-16483, 2024.

EGU24-16551 | ECS | Orals | BG1.10

Prediction of soil pyrogenic carbon contents from Rock-Eval® thermal analysis: a machine-learning based model 

Johanne Lebrun Thauront, Severin Luca Bellè, Marcus Schiedung, Amicie Delahaie, Marija Stojanova, François Baudin, Pierre Barré, and Samuel Abiven

Pyrogenic carbon (PyC) is a continuum of aromatic and condensed organic molecules. It represents about 15 % of organic carbon in soils and sediments1. However, there is a discrepancy in the literature regarding quantification of PyC: different methods that are currently considered as reference differ largely in their results1,2. Indeed, most methods used to quantify PyC are based on different operational principles (e.g. chemical, thermal or physical stability of PyC, molecular markers) and consequently, they do not cover the same range of the PyC continuum2. In addition, most of them are expensive and/or time consuming. Here, we propose a new PyC quantification method based on Rock-Eval® thermal analysis, thought to be rapid, inexpensive and comparable to the previous methods toolbox. Rock-Eval® thermal analysis has been successfully introduced to the field of soil carbon analysis in the last two decades and allowed to distinguish between various pools of soil carbon (inorganic carbon, stable and active organic carbon) using a single analysis of combined pyrolysis and thermal oxidation3,4. In this study, we formulate the hypothesis that Rock-Eval® thermal analysis in combination with predictive modelling is suitable to quantify PyC in soil matrices.

To build and validate such a model, we chose soil samples originating from contrasting climate zones and parent material and with varying properties including clay content and mineralogy, iron oxide speciation and content, pH, cation-exchange capacity and organic carbon content. We measured PyC using a set of established methods (i.e. CTO-375, BPCA and HyPy) and acquired Rock-Eval® thermograms. Then, we identified the relevant features for PyC quantification in the thermograms by applying several machine-learning approaches. This work adds a new soil carbon pool to the ones already accessible from Rock-Eval® thermal analysis and allows an efficient and rapid quantification of PyC in soils, which is needed for large-scale studies of soil carbon pools.

(1) Reisser, M.; Purves, R. S.; Schmidt, M. W. I.; Abiven, S. Pyrogenic Carbon in Soils: A Literature-Based Inventory and a Global Estimation of Its Content in Soil Organic Carbon and Stocks. Front. Earth Sci. 2016, 4 (August), 1–14. https://doi.org/10.3389/feart.2016.00080.

(2) Hammes, K.; Smernik, R. J.; Skjemstad, J. O.; Schmidt, M. W. I. Characterisation and Evaluation of Reference Materials for Black Carbon Analysis Using Elemental Composition, Colour, BET Surface Area and 13C NMR Spectroscopy. Appl. Geochemistry 2008, 23 (8), 2113–2122. https://doi.org/10.1016/j.apgeochem.2008.04.023.

(3) Disnar, J. R.; Guillet, B.; Keravis, D.; Di-Giovanni, C.; Sebag, D. Soil Organic Matter (SOM) Characterization by Rock-Eval Pyrolysis: Scope and Limitations. Org. Geochem. 2003, 34 (3), 327–343. https://doi.org/10.1016/S0146-6380(02)00239-5.

(4) Cécillon, L.; Baudin, F.; Chenu, C.; Houot, S.; Jolivet, R.; Kätterer, T.; Lutfalla, S.; Macdonald, A.; Van Oort, F.; Plante, A. F.; Savignac, F.; Soucémarianadin, L. N.; Barré, P. A Model Based on Rock-Eval Thermal Analysis to Quantify the Size of the Centennially Persistent Organic Carbon Pool in Temperate Soils. Biogeosciences 2018, 15 (9), 2835–2849. https://doi.org/10.5194/bg-15-2835-2018.

How to cite: Lebrun Thauront, J., Luca Bellè, S., Schiedung, M., Delahaie, A., Stojanova, M., Baudin, F., Barré, P., and Abiven, S.: Prediction of soil pyrogenic carbon contents from Rock-Eval® thermal analysis: a machine-learning based model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16551, https://doi.org/10.5194/egusphere-egu24-16551, 2024.

EGU24-16627 | Posters on site | BG1.10

Direct analysis of marine dissolved organic matter using LC-FT-ICR MS 

Oliver Lechtenfeld, Jan Kaesler, Elaine Jennings, and Boris Koch

Marine dissolved organic matter (DOM) is an important component of the global carbon cycle, yet its intricate composition and the sea salt matrix pose major challenges for chemical analysis. The current view on marine DOM as assessed with ultrahigh resolution mass spectrometry (UHR-MS) is largely based on SPE-extracts known for its consistent underestimation of e.g. the mean nominal oxidation state of carbon (NOSC) and molecular weight as compared to bulk measurements. We introduce a direct injection, reversed-phase liquid chromatography Fourier-transform ion cyclotron resonance (FT-ICR) MS approach to analyze marine DOM without the need for solid-phase extraction. Effective separation of salt and DOM is achieved with a large chromatographic column and an extended isocratic aqueous step. Post-column dilution of the sample flow with buffer-free solvents and implementing a counter gradient reduced salt buildup in the ion source and resulted in excellent repeatability. With this method over 5,500 unique molecular formulas were detected from just 5.5 nmol of carbon in 100 µL filtered Arctic Ocean seawater. We observed highly linear detector response for variable sample carbon concentrations and a high robustness against the salt matrix. We could demonstrate the bias of SPE in marine DOM on a molecular level leading to a predominant detection of less polar DOM, while neglecting a large fraction of polar, heteroatom-rich DOM. In addition, a substantial fraction of terrestrial-derived DOM was previously overlooked in solid-phase extracted marine DOM. Overall, the direct analysis of seawater offers fast and simple sample preparation and avoids fractionation introduced by extraction. The method facilitates studies in environments, where only minimal sample volume is available e.g. in marine sediment pore water, ice cores, or permafrost soil solution. The small volume requirement also supports higher spatial (e.g. in soils) or temporal sample resolution (e.g. in culture experiments). Chromatographic separation adds further chemical information to molecular formulas, enhancing our understanding of marine biogeochemistry, chemodiversity, and ecological processes.

How to cite: Lechtenfeld, O., Kaesler, J., Jennings, E., and Koch, B.: Direct analysis of marine dissolved organic matter using LC-FT-ICR MS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16627, https://doi.org/10.5194/egusphere-egu24-16627, 2024.

EGU24-17503 | ECS | Orals | BG1.10

Sediment source and transport along the Iberian Margin 

Sara Campderrós, Leopoldo D. Pena, Jaime Frigola, Ester Garcia-Solsona, Eduardo Paredes, Negar Haghipour, Heather M. Stoll, and Isabel Cacho

The Iberian Margin is a dynamic margin, affected by complex sedimentary and oceanographic processes. The Mediterranean Outflow Water (MOW) is a prominent water mass that flows along the Iberian margin and interacts with the sediment on the slope. However, more information about how MOW interacts with sediment delivery, distribution, deposition along the margin is needed. In this study we combine Nd, Sr and Pb isotopes on fine-grained detrital sediments (< 63 μm) and 14C measurements in planktonic foraminifera (G. bulloides) in 25 coretop sediment samples collected along the entire Iberian Margin (from the Gulf of Cadiz to the “Cachucho” mount in the Cantabrian Sea). Nd, Sr and Pb isotopes were used to (i) identify the main source areas of terrigenous sediments coming from the Iberian Peninsula and (ii) trace the distribution of these sediments along the Iberian Margin. Additionally, 14C data in planktonic foraminifera were used to obtain radiocarbon ages, that allowed us to date the coretop sediments. Results from Nd, Sr and Pb isotopes allow us to identify three main terrigenous sediment source provinces in the Iberian margin, depicting a prominent south to north gradient. Moreover, large age discrepancies in coretop sediments are strongly associated with the main pathway of MOW, thus suggesting erosion and lateral transport of sediments along the main path of the MOW.

How to cite: Campderrós, S., Pena, L. D., Frigola, J., Garcia-Solsona, E., Paredes, E., Haghipour, N., Stoll, H. M., and Cacho, I.: Sediment source and transport along the Iberian Margin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17503, https://doi.org/10.5194/egusphere-egu24-17503, 2024.

EGU24-17520 | ECS | Posters on site | BG1.10

A multi-method approach to characterise and quantify pyrogenic carbon in tropical urban agroecosystems.  

Stephen Boahen Asabere, Ankit Ankit, Tino Peplau, Simon Drollinger, Christopher Poeplau, Daniela Sauer, and Axel Don

Pyrogenic carbon (PyC) is produced by the incomplete combustion of biomass. It is chemically inert and nutrient-deficient, making it relatively stable in soils. PyC can thus form an important pool of total soil organic carbon (TOC) for C preservation in soils. Despite its significance, data on the nature, level, and relative contribution of PyC to TOC in tropical urban agroecosystems is largely non-existent. In this study, we aim to determine the content and chemical composition of PyC in urban arable soils of Kumasi, a rapidly expanding city in Ghana, West Africa. PyC is likely enriched in these soils, mainly due to soot deposition from traffic, combined with widespread burning of household waste and use of charcoal for cooking.

We sampled topsoils (0–10 cm) from arable fields under four levels of urbanisation intensity (UI), from low to high UI. We employed a range of analytical techniques including visual, chemothermal, thermogravimetric, and biomarker analysis, as well as fourier transformed infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Visual assessment indicated that ≥80% of all bulk soil samples contained charred macro particles, pointing to PyC enrichment in the urban arable soils. Separating TOC into particulate organic C (POC, ≥63 µm particle size) and mineral-associated organic C (MAOC, <63 µm), chemothermal assessment revealed that PyC contributed less than 0.1% to each fraction under all urban intensity conditions. These PyC levels increased notably along with increasing UI in both TOC fractions. Thereby, median PyC levels in the MAOC fraction (7.8–20.4 mg kg-1) were markedly higher compared to those of the POC fraction (0.1–0.3 mg kg-1). This finding highlight a noticeable PyC contribution to TOC preservations in Kumasi’s tropical urban arable soils, although overall contribution is low. Ongoing thermogravimetric, FTIR spectroscopy, NMR spectroscopy, and biomarker analysis will further detail the amount and chemical composition of PyC in these soils. For instance, we will integrate diagnostic ratios of polycyclic aromatic hydrocarbons with masoccharide anhydrides in order to decouple the relative amount of PyC from biomass and that of fossil fuel.

By characterising the chemical nature of PyC with this wide range of analytical techniques, insights into the source and transformation of PyC in a tropical urban agricultural context can be provided. This will lead to better understanding of the role of PyC in the urban soil carbon cycle and its implications for urban sustainability and global C sequestration efforts.

How to cite: Asabere, S. B., Ankit, A., Peplau, T., Drollinger, S., Poeplau, C., Sauer, D., and Don, A.: A multi-method approach to characterise and quantify pyrogenic carbon in tropical urban agroecosystems. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17520, https://doi.org/10.5194/egusphere-egu24-17520, 2024.

EGU24-18669 | Orals | BG1.10

Pyrogenic carbon: Is it a sink in the global carbon cycle? And why we can’t be sure. 

Matthew Jones, Alysha Coppola, and Cristina Santín

Fires play a critical role in modulating the quantity and quality of carbon (C) stored in the terrestrial biosphere, including in aboveground vegetation and soils. Via riverine transport routes, fires also affect the quantity and quality of C delivered to the global oceans.

The mission of this talk is to set the scene on the multifaceted ways in which fire impacts the global C cycle, with a special focus on the widely-overlooked role of pyrogenic C.

We will begin by summarising how fires impact on terrestrial stores of C, starting with natural cycles of disturbance and recovery that influence total stocks of C on the terrestrial landscape. We will then demonstrate how shifting fire regimes, related to climate change and changes in land use, are perturbing the cycle of C and influencing the quantity of C stored on the landscape. Increased fire frequency and intensity generally promotes a loss of C from landscapes, especially in cases where vegetation cannot recover completely in the shortening time available between disturbance events.

Set within the broader cycle of biogenic C is a sub-cycle of highly recalcitrant ‘pyrogenic’ C – a by-product of incomplete combustion during fires. We will highlight how the special properties of this pyrogenic C promote its longevity in terrestrial stores in a manner that can offset (or ‘buffer’) losses of total C. The process of pyrogenic C storage has been widely overlooked in models of the global C cycle leading to C accounting errors, however we will highlight some recent examples of its implementation in land surface models and the lessons learned from doing so.

Due to its exceptional longevity in terrestrial pools, pyrogenic C has enhanced odds of reaching the global oceans via rivers. We will discuss the disproportionate export of pyrogenic C to the global oceans (relative to biogenic C) and how this leads to an unusual potential for long-term C sequestration.

Finally, we will provide an overview of the current understanding of the global budget of pyrogenic C, integrating best estimates for the fluxes of C to and from terrestrial stores and to and from marine stores. We will also highlight how uncertainties in the magnitude of fluxes in the C cycle lead to poor understanding of whether pyrogenic C currently acts as a sink or source of C to the atmosphere. We will underscore the particular need to constrain the decomposition rates and residence times of pyrogenic C in soils and marine stores if we are to build a complete picture of its role in the global C cycle.

How to cite: Jones, M., Coppola, A., and Santín, C.: Pyrogenic carbon: Is it a sink in the global carbon cycle? And why we can’t be sure., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18669, https://doi.org/10.5194/egusphere-egu24-18669, 2024.

EGU24-19168 | Orals | BG1.10

Molecules and microbes: monitoring peatland health below the surface 

Nicholle Bell, Ezra Kitson, Gianluca Trifiro, and Richard York

Peatlands are organic matter rich (with over 60% organic matter) ecosystems that act as ‘carbon sinks’, storing many times the carbon stored by Earth’s forests. Peatlands act as sponges storing excess water from rain events and releasing it slowly, a mechanism that not only mitigates floods but also filters drinking waters. However, peatlands can only conduct these vital services when healthy and functioning, with a near surface water table and anoxic acidic conditions below the surface. Unfortunately, 80% of UK peatlands have been assessed as damaged mainly via drainage for repurposing the land for other uses. Rewetting peatlands by installing dams is one of the most common methods to restore these damaged bogs. While there is a large amount of evidence that rewetting restores the water table, questions remain whether rewetting successfully restores peatlands to their full health. To answer this question, we need to know what is happening below the surface and examine the roles of key players in peat formation and carbon cycling, namely the microbes and the carbon-containing molecules. It is not clear which of these players is more important, or how they depend on each other. To address this question, we are using the latest technologies (DNA/RNA sequencing, NMR spectroscopy and FT-ICR mass spectrometry) to uncover who they are, how they interact and how they are impacted by drainage and rewetting. The task is not easy as peat is an uncharacterised complex mixture on a molecular and microbial level and the key players could be found in different phases (solid or liquid). In this presentation, I will provide a brief overview of what insights the technologies we are using provide for below the surface characterisation of UK peatlands.

How to cite: Bell, N., Kitson, E., Trifiro, G., and York, R.: Molecules and microbes: monitoring peatland health below the surface, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19168, https://doi.org/10.5194/egusphere-egu24-19168, 2024.

EGU24-19501 | ECS | Posters on site | BG1.10

Inorganic biogenic carbon redistribution and transport in marine sediments 

Prabodha Lakrani Hewage, Luz María Mejía, Negar Haghipour, Mariem Saavedra-Pellitero, Ben Trundley, Timothy Eglinton, David Hodell, and Blanca Ausín

Coccolithophores are calcifying marine phytoplankton whose blooms can be seen from space and play an important, yet complex, role in the global carbon cycle. On one hand, coccolithophores sequester atmospheric CO2 to the deep ocean via photosynthesis contributing to the biological pump. On the other hand, coccolithophores increase aqueous CO2 via precipitation of tiny calcite scales named coccoliths (i.e., carbonate counter pump), which are a major component of marine sediments. Coccoliths are generally in the 2-20 µm size range, and thus they can be winnowed by strong currents and transported to distal locations. Here, we show the first coccoliths radiocarbon (14C) ages and explore the influence of size-dependent coccolith sorting and transport, redistribution, and fate in marine sediments. Because the coccolith depends on the species, we have separated and 14C dated four coccolith size fractions: 8-11 µm, 5-8 µm, 3-5 µm, and 2-3 µm, in  five depth intervals on a sediment core recovered from SHAK06-5K site, off the Iberian Margin. Coccolith separation was achieved by a combination of dry sieving, microfiltration, centrifugation, and settling experiments. Energy Dispersive Spectroscopy (EDS) images of selected size fractions were used to estimate the relative contribution of coccolith and non-coccolith carbonate. A relationship between coccolith 14C age and grain size is apparent in all samples, with the smallest size class recording the youngest ages and the largest coccoliths being the oldest. The latter suggests that hydrodynamic sorting largely influences coccolith redistribution in marine sediments, where larger coccoliths result in increased mobility, as they are prone to resuspension than coccoliths in 2-3 µm size fraction that tend to show cohesive behaviour. The 14C ages of coccoliths are older than those of co-deposited planktic foraminifera, bulk organic carbon (OC), long-chain fatty acids (LCFA), and alkenones. Coccoliths within the 2-3 µm size class show 14C ages comparable to those of OC in all samples. Such a pattern indicates similar transport mechanisms for both the smallest coccoliths and OC, and that the majority of carbonate in the 2-3 µm size fraction, including the non-coccolith particles, is predominantly derived from marine primary production and thus, of biogenic origin. Our study has implications for palaeoceanographic studies using coccoliths as paleo-productivity and geochemical proxies.

How to cite: Hewage, P. L., Mejía, L. M., Haghipour, N., Saavedra-Pellitero, M., Trundley, B., Eglinton, T., Hodell, D., and Ausín, B.: Inorganic biogenic carbon redistribution and transport in marine sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19501, https://doi.org/10.5194/egusphere-egu24-19501, 2024.

EGU24-19642 | Orals | BG1.10

Insight in high alpine soil carbon dynamics from compound-specific and soil fraction radiocarbon analysis on a glacier forefield chronosequence  

Rienk Smittenberg, Valerie Schwab, Hans Sanden, Iso Christl, Frank Hagedorn, Irka Hajdas, Lukas Wacker, Negar Haghipour, Susan Trumbore, Xiaomei Xu, and Stefano Bernasconi

The ecosystem carbon balance of high latitude and high altitude ecosystems is particularly sensitive to climate change, where increasing temperatures generally lead to a rise of the ecosystem carbon storage, but also increasing carbon turnover times. In this study, we investigated the carbon dynamics of the 150-year long Damma Glacier forefield chronosequence, Switzerland. Specifically, we performed radiocarbon analysis of a range of organic matter fractions, sampled in 2007, 2017 and 2022 from soils developing on areas having been exposed for 20-150 years due to the retreat of the glacier. To characterize the age spectrum of material making up the bulk soil carbon, we isolated a range of different fractions, from supposedly 'stable' carbon pools (fine mineral-bound, and peroxide-resistant carbon), microbially ‘labile’ respired CO2, dissolved soil organic carbon (DOC), hydrophobic leaf wax-derived alkanes, and microbial-derived fatty acids. Comparison of our results with the penetration of the radiocarbon bomb spike and the increase of soil and ecosystem carbon over the both the chronosequence (space-for-time) and over the sampling period (time-for-time) allowed us to make the following inferences: (i) A small but persistent contribution of ancient carbon is present in the forefield area exposed by the glacier, which is particularly visible in the hydrophobic leaf wax 14C data. From this we conclude that this old carbon pool is at least in part a remnant of ancient soil carbon from a previous warm and glacier-free period, potentially adding to contributions of fossil-fuel derived black carbon deposition. (ii) There is a significant portion of soil carbon with a decadal-scale carbon turnover rate, and (iii) mineral-bound carbon clearly has a slower turnover time. (iv) Microbial lipids, soil CO2 and DOC 14C content reflect different carbon sources: in younger soils, relatively low 14C contents indicate a higher relative contribution of ancient carbon decomposition, while in older soils this signal is swamped by decomposition of freshly photosynthesized organic matter.

How to cite: Smittenberg, R., Schwab, V., Sanden, H., Christl, I., Hagedorn, F., Hajdas, I., Wacker, L., Haghipour, N., Trumbore, S., Xu, X., and Bernasconi, S.: Insight in high alpine soil carbon dynamics from compound-specific and soil fraction radiocarbon analysis on a glacier forefield chronosequence , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19642, https://doi.org/10.5194/egusphere-egu24-19642, 2024.

EGU24-21439 | ECS | Orals | BG1.10

Modeling microbial functional trait-environment interactions at the continental scale 

Katherine Shek, James Stegen, Alan Roebuck, Amy Goldman, Mikayla Borton, Kelly Wrighton, and Adam Wymore

Inferring linkages between microbial metabolism and dissolved organic matter (DOM) across environmental gradients is a promising avenue to improve biogeochemical predictions at large spatial scales. Despite decades of metagenomic studies identifying microbial functional trait-environment patterns at small spatial scales, general patterns at continental or global scales that may improve large-scale models remain unresolved. Recent influx of multi-omics datasets that represent diverse environmental conditions has enabled scalable analyses linking microbial metabolic niche breadths with key environmental processes, such as carbon and nutrient transformations.

Here, we leveraged publicly available microbial metagenome assembled genomes (MAGs) derived from the Worldwide Hydrobiogeochemistry Observation Network for Dynamic River Systems (WHONDRS) data paired with metabolomic (FTICR-MS) and sediment chemistry data to link microbial metabolic potential with organic chemistry. We annotated 1,384 MAGs representing 65 sites using the R tool microTrait, which categorizes functional traits under the YAS (growth yield-resource acquisition-stress tolerance) framework. Following Hutchinsonian niche theory, we modeled microbial trait combinations as n-dimensional hypervolumes and observed trait-DOM patterns at the continental scale, showing microbial functional tradeoffs along gradients of organic carbon. We expect that at the continental scale, microbial trait profiles will be distinct across climatic regions, and that niche breadth (i.e. the size of individual hypervolumes in trait space) will correlate with DOM/metabolite diversity. The results of this work will distill generalizable patterns of microbe-DOM availability and diversity at large spatial scales, thus identifying information to improve current biogeochemical models.

How to cite: Shek, K., Stegen, J., Roebuck, A., Goldman, A., Borton, M., Wrighton, K., and Wymore, A.: Modeling microbial functional trait-environment interactions at the continental scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21439, https://doi.org/10.5194/egusphere-egu24-21439, 2024.

Frequent occurrences of high-temperature records have become commonplace during the summer seasons in regions adjacent to the western Arabian Gulf, such as Bahrain, Saudi Arabia, and Qatar. On a daily basis, the fluctuation in daytime and nighttime temperatures, along with varying afternoon temperatures, poses a potential threat to organisms inhabiting intertidal and shallow water environments, whether residing above the substrate or submerged beneath. Surprisingly, there has been no prior scientific investigation into the resilience of these coastal communities, especially from a non-anthropocentric perspective, focusing on the marine calcifying organism that inhabits one of the world's most extreme marine environments. To address this gap, we aimed to determine the upper thermal limits of intertidal calcifying benthic organisms in the western Arabian Gulf region. For this purpose, we selected three representative species among the diverse inhabitants, comprising two gastropod species and one ostracod species. These specimens were subjected to controlled environmental conditions inside a thermal incubator over a short-term period (three hours), with temperature exposures ranging from 40°C to 60°C. We considered different scenarios that replicated their natural ecological conditions: full exposure, partial exposure, and full coverage/submerged underwater. Our comprehensive results revealed that different gastropod species exhibited varying levels of resilience to higher thermal exposure, depending on the scenario (heat comma temperature/HCT ranged between 39°C-48.5°C versus 42.1°C-44.1°C). In contrast, the ostracod displayed remarkable tolerance to higher temperatures than the gastropod specimens before succumbing to complete mortality or entering a comatose state (temperature range of 39.1°C-53.5°C). Furthermore, post-exposure recovery demonstrated that higher heat exposure substantially prolonged the recovery time. In the case of the gastropod specimens subjected to the highest thermal exposure, no successful recovery was observed. Our findings underscore the importance of conducting ecological experiments that involve prolonged exposure to high temperatures. However, it is imperative to recognize that even short-term periods of elevated temperatures can have fatal implications for the target organisms. This is particularly relevant in light of the ongoing warming trend and the recording of extreme temperatures in our regional area in the western Arabian Gulf, which may eventually be deemed a potential "kill zone" during the peak of summer seasons within a short timeframe.

How to cite: Prayudi, S. D., Korin, A., and Kaminski, M.: An Ecological Perspective on Short-Term Heat Exposure Experiments with Marine Calcifying Organisms from the Western Arabian Gulf Region: Insights into a Summer Heatwave Scenario, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-46, https://doi.org/10.5194/egusphere-egu24-46, 2024.

EGU24-1819 | ECS | Orals | BG1.13

The daily growth bands pattern of Tridacna - evidence from culture experiments. 

Haotian Yang, Hong Yan, and Chengcheng Liu

Biogeochemical archive such as tree rings, corals, and stalagmites have proven effective in reconstructing past paleoclimate patterns at year-month resolutions. However, they are not suitable for investigating weather changes on a day-hour scale. Tridacna, the largest bivalve in the world, which inhabits the Tropical-subtropical Pacific-Indian Ocean area, exhibits unique daily growth bands ranging from 5 to 60μm. This characteristic grants Tridacna the potential to reconstruct extreme weather events in the past, thus paving the way for paleoweather studies. Tridacna engages in symbiosis with zooxanthellae and relies on photosynthesis for energy. The growth rate and pattern of its daily growth bands correlate with diurnal alternations. Currently, the utilization of Tridacna daily growth bands and high-resolution geochemical element ratios holds potential for establishing a daily resolution biogeochemical proxy. However, the precise mechanism of the circadian rhythm during Tridacna's growth period in natural conditions remains unclear. Consequently, our comprehension of the pattern exhibited by Tridacna's daily growth bands is limited, impeding progress in the development of hourly scale paleo-weather analysis. In this study, a 30-day artificial experiment was conducted on Tridacna derasa to investigate the significance of shell daily growth bands and hourly element ratios in reflecting environmental conditions. The results of calcein labeling revealed that the wide dim areas in the daily growth bands corresponded to daytime and exhibited valley values in Sr/Ca ratio, while the narrow bright areas corresponded to nighttime and showed peak values in Sr/Ca ratio. At the daily-hourly scale, when the water temperature remained constant, the Sr/Ca daily variation showed potential for recording the light daily cycle. However, it is important to note that the influence of the light daily cycle on the Sr/Ca variation may be indirect. As a result, a hypothesis was proposed: the Sr/Ca variation is directly controlled by the internal regulation of Tridacna. During the daytime, the Sr/Ca ratio was primarily regulated by physiological activities. Due to light stimulation, the activity of certain enzymes in the inner mantle was enhanced, leading to an increase in Ca2+ concentration and a decrease in Sr/Ca ratio. During the nighttime, the Sr/Ca ratio was mainly regulated by organic matrices. In the extrapallial fluid (EPF), the presence of high Sr2+-selective organic matrices promoted the incorporation of Sr2+ into the shell, resulting in a higher Sr/Ca ratio.

How to cite: Yang, H., Yan, H., and Liu, C.: The daily growth bands pattern of Tridacna - evidence from culture experiments., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1819, https://doi.org/10.5194/egusphere-egu24-1819, 2024.

EGU24-2520 | Orals | BG1.13

Cropland Microplastics in Xinjiang: Unveiling Distribution and Impact of Mulching Film Residues 

Qingling Zhang, Shan Zhang, Wuzhou Dong, Zhipan Wang, and Zewen Mo

Microplastics, ubiquitous environmental pollutants, pose a significant threat to agricultural ecosystems and food safety. Xinjiang, a critical dryland agricultural region in China, faces a pressing issue with microplastic accumulation due to extensive use of mulching film. This study addresses this challenge by combining feild investigation, lab analysis, and remote sensing observations:

  • Developing an improved, batch-processed soil microplastics extraction method, optimizing cost and time.
  • Extracting and analyzing microplastics from typical Xinjiang cropland soil, revealing their distribution patterns and influencing factors.
  • Establishing a model linking microplastic abundance to cumulative mulching film years, providing a predictive tool.
  • Combining the model with remote sensing data to unveil the regional distribution of microplastics across Xinjiang croplands.

Our findings provide:

  • A deeper understanding of microplastic pollution dynamics in mulching film-based agriculture.
  • A robust method for assessing and predicting microplastic contamination in croplands.
  • Valuable data for informing mitigation strategies and policy decisions.

This study paves the way for effective microplastic management and for examining their environmental impacts in Xinjiang and beyond, safeguarding agricultural productivity and environmental health. Future study efforts are encouraged to examine local and remote impacts of soil microplastics in Xinjiang and beyond.

How to cite: Zhang, Q., Zhang, S., Dong, W., Wang, Z., and Mo, Z.: Cropland Microplastics in Xinjiang: Unveiling Distribution and Impact of Mulching Film Residues, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2520, https://doi.org/10.5194/egusphere-egu24-2520, 2024.

EGU24-4077 | ECS | Orals | BG1.13

Effects of biofouled plastics on phytoplankton community assembling and water chemistry: pilot study and implications for freshwater environments 

Gilberto Binda, Stefano Carnati, Margarida Costa, Vladyslava Hostyeva, Eva Leu, Birger Skjelbred, Davide Spanu, Luka Šupraha, Sara Trotta, Christian Vogelsang, and Luca Nizzetto

The presence of plastic litter and microplastics in freshwaters has raised concern about their potential transport and accumulation in water and sediments over time. However, several direct and indirect environmental consequences are still not well understood. In this study, we investigated the role of plastic as a carrier of algal species favouring their dispersal in freshwaters, and we assessed the potential effects on water biodiversity and chemical features in a pilot, laboratory-based study. We simulated an algal community using 5 algal species commonly found in freshwaters and we exposed this community to both pristine and biofouled polypropylene fragments of 5 × 5 × 0.3 mm in size. The biofouled plastic was generated by incubating similar polypropylene fragments with 2 other freshwater algal species, which were different from those in the simulated community. In addition, we evaluated the effect of the dispersal of algae from plastic without the presence of a simulated pelagic community. The experiment lasted 15 days in total. At different time intervals, we assessed: total algal growth and photosynthetic efficiency, algal community composition and the concentration of macronutrients and minor elements in the water. We observed changes in the algal community composition and marked chemical alterations driven by the presence of the biofouled plastics. The presence of pristine plastic, instead, did not show significant changes in the community composition and in the concentration of dissolved elements. The dispersal of algal species from the biofilm on plastic and competitive interactions between the plastic biofilm and the pelagic community were, therefore, likely responsible for the changes in the algal diversity. These results confirmed the hypothesis that plastic can influence dispersal and biodiversity of the algal community. Biofouled plastic from environmental samples and environmental communities selected from natural freshwater bodies will be used in future experiments. This will help to unravel the potential consequences of plastic pollution for ecosystem functioning and microbial biodiversity.

How to cite: Binda, G., Carnati, S., Costa, M., Hostyeva, V., Leu, E., Skjelbred, B., Spanu, D., Šupraha, L., Trotta, S., Vogelsang, C., and Nizzetto, L.: Effects of biofouled plastics on phytoplankton community assembling and water chemistry: pilot study and implications for freshwater environments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4077, https://doi.org/10.5194/egusphere-egu24-4077, 2024.

EGU24-5364 | Posters on site | BG1.13

Potential metal(loid)s mobilization from acid mine drainage-affected sediments under sea level rise projections 

María Dolores Basallote, Rona Giese Miranda, Martin Frank, Manuel Olías, and Carlos Ruiz Cánovas

Metals and metalloids are among the most dispersed hazardous substances released to estuarine systems, which often accumulate within the sediments, contributing to a global problem of pollution in estuaries. In this context, the projected future sea level rise predict the inundation of metal-polluted sediments in littoral areas, which may have serious implications in the mobility of sediment-bound contaminants.

The Tinto River estuary (SW Spain), which is projected to be partially flooded by seawater in 2050 due to the rising sea level, have historically received significant amounts of potentially toxic elements originating from former metal mines, transported to the estuary by the Tinto River.

To estimate the potential release of metal(loid)s associated with seawater flooding, surface sediments were sampled to determine metal concentrations, total carbon content, pH, and particle size distribution. In addition, the contamination factor, geoaccumulation index, and pollution load index were calculated to evaluate metal(loid) pollution. To estimate metal(loid) mobilization upon sea level rise a delimited area of the Tinto River estuary was defined (according to sea level rise projections), and elements mobilization was calculated using values obtained from inundation experiments (Kerl et al., 2023) and sequential extraction methods.

Sediments from the study site turn out to be highly polluted with calculated pollution load indices over 1 and surpassing Spanish guidelines and international sediment quality guidelines , especially for As (300 – 1300 mg/kg), Cu (300 – 3500 mg/kg) and to a lesser extent Zn (100 – 1400 mg/kg) and Cd (0.2 – 5.8 mg/kg). Results show that significant amounts of Fe, Cu, Zn and As (36800, 11200, 1390, 3.22 kg, respectively) can be mobilized under short-term inundations (65 days) related to climate change scenarios predicted for 2050. Under 2100 projections, the mobilization of those metal(loid)s is expected to be further enhanced by the additonal release of large amounts of Fe, as a result of the reductive dissolution of Fe- or Mn-oxyhydroxides, which is mainly attributed to the promotion of reduced conditions in currently oxic sediment layers. These results provide a first estimation of the potential mobilization of potentially toxic elements upon climate change, which is of paramount importance for risk assessment in metal(loid) polluted estuaries worldwide.

How to cite: Basallote, M. D., Miranda, R. G., Frank, M., Olías, M., and Cánovas, C. R.: Potential metal(loid)s mobilization from acid mine drainage-affected sediments under sea level rise projections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5364, https://doi.org/10.5194/egusphere-egu24-5364, 2024.

EGU24-5631 | ECS | Orals | BG1.13

High enrichment of U, Cr, As and V in fish scales from the Namibian shelf of the Benguela Upwelling System. 

Frederik Gäng, Lena Göller, Volker Brüchert, Niko Lahajnar, Katharina Pahnke, and Philipp Böning

Enrichment patterns of redox- and biosensitive trace elements (TEs) are powerful tools to reconstruct depositional conditions during sedimentation in continental marine sediments. For several TEs (e.g., U, Cr, As and V), the mechanisms that lead to their accumulation in the sediment are not fully understood yet. To complement the discussion, we analyzed several major elements and TEs (P, Ca, Sr, U, V, As and Cr) in fish scales from two short cores (30 cm sediment depth) from the central and southern shelf of the Namibian anoxic-euxinic continental margin (from 67 and 100 m water depth). We found both fresh, young scales in the upper sediments and clearly altered scales, in deeper sections of the cores. The P, Ca and Sr values appear to be good indicators of the changing condition of the respective fish scales, as Ca, Sr and P decrease with the sediment depth from which the fish scales were taken. The lower the Ca, Sr and P values, the more altered the fish scales and the higher the TE enrichment. These more altered fish scales have high values of U (up to 88 ppm), Cr (up to 97 ppm) and V (up to 130 ppm), raising the importance of fish scales as a sink for these elements in shelf sediments, leading to extreme enrichments that are not primarily related to redox conditions. In contrast to the high TE values in altered scales, high values of As (up to 140 ppm) were found in fresh fish scales in core top sections and a decrease with sediment depth. Previous studies showed that high bulk U content in central Namibian shelf sediments is due to high anthropogenic U input by mining activities (in addition to U enrichment during authigenic apatite formation in the sediments). This U-mining activity in the central Namibian hinterland is further reflected in higher U values in the core from the central shelf compared to the core from the southern shelf. The increase of all TEs in scales with increasing sediment depth indicates authigenic enrichment over time within the sediment. Therefore, we suggest that fish scales are an important authigenic sink of several TEs which may be substantial for the element budget calculations in continental margins.

How to cite: Gäng, F., Göller, L., Brüchert, V., Lahajnar, N., Pahnke, K., and Böning, P.: High enrichment of U, Cr, As and V in fish scales from the Namibian shelf of the Benguela Upwelling System., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5631, https://doi.org/10.5194/egusphere-egu24-5631, 2024.

Extreme climate change can lead to a drastic deterioration in water quality. However, researchers often struggle to find long-term water quality monitoring data, especially at a daily scale, which hinders the understanding of the response relationship between extreme climate, hydrology, and water quality. This study proposes an integrated machine learning framework with physical constraints from various environmental domains such as meteorology and water quantity that can effectively impute a high percentage of missing data and downscale time series data of water quality, producing satisfactory results. Over 78% of the physical water quality variables exhibit NSE (Nash-Sutcliffe efficiency coefficient) values greater than 0.45, and more than 66% of the chemical water quality variables achieve NSE values greater than 0.35. The results of this work demonstrate the effectiveness of the proposed framework as a data augmentation and temporal interpolation tool to enhance the adequacy of water quality monitoring and explore the mechanisms underlying the impact of extreme climate on water quality.

How to cite: Li, L. and Yang, D.: Enhancing Water Quality Monitoring: An Integrated Machine Learning Framework with Physical Constraints for Imputation and Time Series Downscaling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5988, https://doi.org/10.5194/egusphere-egu24-5988, 2024.

EGU24-6168 | Posters on site | BG1.13

Sedimentary mercury cycling in recent upwelling systems 

Philipp Böning, Frederik Gäng, Katharina Pahnke, and Olaf Dellwig

The sedimentary database of mercury (Hg) in modern upwelling sediments from the Humboldt and Benguela current systems is sparse, yet this element is a prime indicator of anthropogenic perturbations of the marine realm. Mercury has various natural and anthropogenic sources, occurs in different species, and internal recycling processes before final burial renders the interpretation of the Hg accumulation process challenging. Here, we present data of total Hg (along with Al, P, Zr, organic carbon and Pb, another anthropogenic indicator) for 210Pb-dated continental margin sediments from Peru, Chile and Namibia from within and below their respective oxygen minimum zones (OMZs). All sediments exhibit upcore authigenic enrichments of Hg in the upper 20 - 30 cm, which suggests that Hg has an anthropogenic source, similar to Pb. Moreover, the Hg enrichments are highest off Peru with up to 800 ppb authigenic Hg in the early ‘80s, followed by those off Chile (~ 150 ppb Hg) and Namibia (~ 80 ppb Hg). This is likely due to a high number of industrial and pre-industrial mining sites in Peru, which is less important in Chile and essentially missing in Namibia. The data further suggest that Hg is trapped by organic particles, which settle quickly through O2-deficient waters. In contrast to Pb, which is rapidly removed from the water column at OMZ sites, Hg is also exported to the deep sea environment (> 1000 m water depth below OMZs). This is likely due to recycling processes before final Hg burial. Authigenic Hg enrichments in Peruvian sediments that have negligible authigenic Pb contents suggests the presence of Hg inputs since pre-industrial times (before ~ 1900 AD), which is in line with previous findings from Peruvian lakes and the Galapagos Islands. By contrast, anthropogenic Hg is only visible in near coastal Namibian sediments since the last ~ 70 years. Overall, our data indicate that upwelling sediments are valuable archives for the preservation of anthropogenic signals given the favorable boundary conditions (high productivity, high oxygen deficiency and high sedimentation rates).

How to cite: Böning, P., Gäng, F., Pahnke, K., and Dellwig, O.: Sedimentary mercury cycling in recent upwelling systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6168, https://doi.org/10.5194/egusphere-egu24-6168, 2024.

EGU24-7953 | ECS | Orals | BG1.13

Tracing the behavior of metallic oxyanions in an acid mine drainage polluted estuary (Tinto River estuary, SW Spain) 

Laura Sánchez-López, Jonatan Romero-Matos, Rafael León, Ricardo Millán-Becerro, Rémi Freydier, Francisco Macías, and Rafael Pérez-López

Estuaries are dynamic systems that play a crucial role in the transfer of trace elements from continent to ocean. The Ría de Huelva estuary is formed by the confluence of the Tinto and Odiel rivers, which are severely contaminated by acid mine drainage (AMD), transporting high pollutant loads of sulfates and metal(loid)s to the estuary and ultimately to the Atlantic Ocean. Despite extensive research on this estuary, the behavior of oxyanions has not yet been adequately addressed. This work assesses the variations of the concentration of oxyanion-forming elements such as As, Sb, V, and Mo within the fluvial domain of the Tinto River estuary. Two sampling campaigns were conducted under low river flow, one with a low tidal coefficient (26-30) and the other with a high tidal coefficient (99-102). Dissolved and particulate (>0.45 µm) As, Sb, V, and Mo concentrations were measured in samples of surface water collected by an autosampler Teledyne ISCO with high temporal resolution (hourly) for 24 hours. Additionally, physicochemical parameters were measured for each sample. During both sampling periods, several complete tidal cycles were recorded. The pH and EC values ranged from 4.0 to 6.3 and from 43.2 to 51.9 mS cm-1, respectively, with low tidal coefficient. With high tidal coefficient, the pH and EC values ranged from 4.4 to 7.6 and from 43.7 to 53.0 mS cm-1, respectively. Highest values were recorded during high tide conditions due to greater influence of seawater. Particulate oxyanions proportion displayed a general increase along with increasing pH, being retained by Fe-oxyhydroxisulfate precipitates like schwertmannite as demonstrated in previous research [1]. Data obtained suggest that during high tide with low tidal coefficient, oxyanions remain mainly in the particulate phase (55-100%). Nevertheless, at high tidal coefficient, a significant decrease in the particulate phase proportion is observed when pH is above 6.43 with total concentrations found in the dissolved phase (reaching 100%). This increase in the dissolved phase is probably associated with desorption processes related to the zero-point charge of schwertmannite in circumneutral water environments. During the seawater neutralization of the Tinto River’s acidic waters, when pH values are above 6, the schwertmannite surface becomes negatively charged, and since oxyanions are negatively charged, their desorption is expected [1]. Special attention should be paid to As, Sb, V, and Mo, as they return to solution when precipitates reach pH values above 6.43, contributing to the total amount discharged by the Tinto River, which later reaches the ocean.

Acknowledgments

This work is part of the I + D + i TRAMPA project (PID2020-119196RB-C21), funded by MCIN/AEI/10.13039/501100011033.

[1] Pérez-López, R., Millán-Becerro, R., Basallote, M. D., Carrero, S., Parviainen, A., Freydier, R., Macías, F., Cánovas, C. R. (2023). Effects of estuarine water mixing on the mobility of trace elements in acid mine drainage leachates. Marine Pollution Bulletin, 187, 114491.

How to cite: Sánchez-López, L., Romero-Matos, J., León, R., Millán-Becerro, R., Freydier, R., Macías, F., and Pérez-López, R.: Tracing the behavior of metallic oxyanions in an acid mine drainage polluted estuary (Tinto River estuary, SW Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7953, https://doi.org/10.5194/egusphere-egu24-7953, 2024.

EGU24-8029 | ECS | Orals | BG1.13

Hydrogeochemical modeling as a tool for the environmental management of mine water polluted river catchments: An application to the Odiel River network (Huelva, Spain) 

Jonatan Romero-Matos, Francisco Macías, José Miguel Nieto, Laura Sánchez-López, Rafael León, Ricardo Millán-Becerro, and Rafael Pérez-López

The impact of mine waters is currently one of the most severe environmental problems in the water environment. The Odiel River catchment is a clear worldwide example of a river network intensely affected by acid mine drainage, transporting large pollutant loads towards the Ría de Huelva estuary, and ultimately the Atlantic Ocean [1]. The release of acidity and metals, and the longevity of the process, represent a major source of pollution which treatment or possible solutions have been the subject of research in recent years. Prior to the adoption of restoration measures in the region, involving a large economic investment, it was proposed to build a hydrogeochemical model that represents the current situation of the pollution, and serves as a management tool for the Odiel River network. In this sense, its design allows to simulate remediation actions and evaluate their impact on the water quality. The model is based on a set of mixtures modeled with PHREEQC code [2] as analogs to the numerous river confluences. The "MIX" command was used, which enables the mixing two or more aqueous solutions at different mixing ratios. Each ratio theoretically assumes how much each member contributes to the final mixture. Each member is defined as a’ solution with the command "SOLUTION_SPREAD" including the physicochemical parameters and element concentrations, obtained experimentally and in the field. Coupling the "EQUILIBRIUM_PHASES" command includes the equilibrium reactions with Fe and Al mineral phases and the atmosphere. Consequently, each modeled and equilibrated mixture will be mixed again downstream in new confluences until a global modeling of the catchment is achieved. In this way, the model makes it possible to estimate changes in the physicochemical parameters, the evolution of metal concentrations, and variations in the saturation rates of the mineral phases (precipitation, dissolution or equilibrium). This kind of model is a useful tool for simulating reductions in the pollutant loads of sources predicting how real restoration actions will affect the water quality conditions along the Odiel River catchment. The proposed approach could be applied to other real case scenarios where mine waters originate from various sources, mainly different mines, within a complex river network, stablishing itself as an environmental tool for the management of mine water-polluted catchments.

Acknowledgements

This work is part of the I + D + i TRAMPA project (PID2020-119196RB-C21), funded by MCIN/AEI/10.13039/501100011033/. Jonatan Romero-Matos is financed by a FPU program of the Spanish Ministry of Education of Vocational Training (FPU20/04441).

[1] Nieto, J. M., Sarmiento, A. M., Canovas, C. R., Olias, M., & Ayora, C. (2013). Acid mine drainage in the Iberian Pyrite Belt: 1. Hydrochemical characteristics and pollutant load of the Tinto and Odiel rivers. Environmental Science and Pollution Research, 20, 7509-7519.

[2] Parkhurst, D. L., & Appelo, C. A. J. (2013). Description of input and examples for PHREEQC version 3—a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. US geological survey techniques and methods, 6(A43), 497.

How to cite: Romero-Matos, J., Macías, F., Nieto, J. M., Sánchez-López, L., León, R., Millán-Becerro, R., and Pérez-López, R.: Hydrogeochemical modeling as a tool for the environmental management of mine water polluted river catchments: An application to the Odiel River network (Huelva, Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8029, https://doi.org/10.5194/egusphere-egu24-8029, 2024.

EGU24-8769 | ECS | Orals | BG1.13 | Highlight

Microplastic occurrence in coastal waters and aquatic faunas of the Western Black Sea  

Iulian Pojar, Teodora Baboș, Oana Dobre, and Constantin Dobre

The Danube River, an important pathway connecting the western, central, and eastern Europe, serves as a route for various pollutants that ultimately accumulate in the Danube Delta and the broader Black Sea basin. These historically pristine regions now face escalating pressures from extensive tourism, intense fishing activities, regional conflicts, and inadequate waste disposal across the whole Danube basin. The imbalance in sediment flow, mainly caused by numerous upstream hydropower plants, aside the abovementioned anthropogenic factors, poses a severe threat to the deltaic and coastal ecosystems.

Among the emerging pollutants, litter stands out prominently, with anthropic macro-objects pervading natural environments. Microplastics (MPs) constitute a category of the litter, characterized by solid, petroleum-based items sized between 1 µm and 5 mm. These particles are either preformed within these dimensions or result from the fragmentation of larger plastic debris due to natural weathering. Known for their fast spreading across diverse environments, MPs possess a porous texture that might absorb substantial amounts of various pollutants, significantly impacting the entire food chain, particularly aquatic species.

Given the limited data on MPs pollution in Black Sea coastal areas, the precise impact on the natural environment remains largely uncertain. Furthermore, the correlation between MPs pollution in aquatic environments and the concentration of MPs within mussels and fish has yet to be established. To address these knowledge gaps, our study investigated the abundance of MPs in the water surface layer (average concentration of 0.63 MPs/m³) and in two distinct species: (i) the mackerel - Alosa immaculata – a pelagic fish captured at the Saint Geoge branch mouth of the Danube Delta during inland migration for reproduction, with an average concentration of 11.8 MPs/individual, and (ii) Mytilus galloprovincialis – a filter feeder mollusc collected near the Constanța harbour – with an average concentration of 6.05 MPs/individual.

Our findings indicate that fibers represent the predominant morphology of MPs found in both species, while fragments dominate the surface water layer. Notably, before the tourist season, the distribution of MPs types differs, suggesting potential influences from coastal natural factors such as wind, waves, and currents on the variety of MPs encountered. This research underscores the urgency of further investigations to comprehend the intricate dynamics of MPs pollution in these vital ecosystems and the cascading effects on marine life.

How to cite: Pojar, I., Baboș, T., Dobre, O., and Dobre, C.: Microplastic occurrence in coastal waters and aquatic faunas of the Western Black Sea , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8769, https://doi.org/10.5194/egusphere-egu24-8769, 2024.

EGU24-8827 | ECS | Posters on site | BG1.13

Alkalization of seawater enhances calcification of large benthic foraminifers. 

Shunichi Kinoshita, Yuri Hashimoto, Azumi Kuroyanagi, and Atsushi Suzuki

There is concern that the increasing pCO2 following the Industrial Revolution Period might lead to ocean acidification, which could affect calcifying organisms in the oceans. Recently, negative emission technology has been attracting attention as an effective countermeasure for greenhouse gas emissions. In the ocean, ocean alkalinization technology is proposed to neutralize acidified oceans and enhance the absorption capacity of CO2 in the oceans. The potential effectiveness of ocean alkalinization technology is also suggested by the history of the Earth. During the Cretaceous period, when pCO2 is interpreted >1,000 ppm, calcifying organisms thrived in the Cretaceous oceans. It is hypothesized that it was due to the total alkalinity (TA) of the seawater being maintained higher, thereby kept the calcium carbonate saturation state at necessary. In this study, we examined this hypothesis as well as attempted to predict the effects of the application of current alkalinization techniques in the ocean on calcifying organisms.

Clonal populations of large benthic foraminifers were cultured in highly alkalinized seawater under high pCO2 conditions, and amounts of calcification (weight and volume) were measured (Group 1: high TA and high pCO2). Specimens taken from same clonal population were kept in modern surface seawater (Group 2: low TA and low pCO2) as a control treatment. The same experiments were also conducted as Group 3 (low TA and high pCO2) to simulate future ocean acidification conditions, and as Group 4 (high TA and low pCO2) to simulate alkalinized ocean under a low pCO2 environment. It was showed significant differences in the amount of calcification in each of the Groups after three months cultivation. The amount of calcification in Group 1 was almost the same as that in the control treatment, confirming the possibility of maintaining the growth of calcifying organisms by alkalinization. Calcification amount in Group 3 was the smallest among all groups, indicating that future ocean acidification may inhibit calcification of large benthic foraminifers. In addition, the calcification rate was the greatest in Group 4, it is indicated that ocean alkalinization may enhance the calcification of the organisms. Finally, these results suggest that the calcium carbonate saturation state of seawater is an important parameter for calcification.

How to cite: Kinoshita, S., Hashimoto, Y., Kuroyanagi, A., and Suzuki, A.: Alkalization of seawater enhances calcification of large benthic foraminifers., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8827, https://doi.org/10.5194/egusphere-egu24-8827, 2024.

EGU24-8888 | Orals | BG1.13

The impact of land use on the adsorption of fluoroquinolone antibiotics: a study on bulk soils and organic matter pools 

Anna Vancsik, Lili Szabó, László Bauer, Csilla Király, Zsolt Pirger, Attila Csaba Kondor, Gergely Jakab, and Zoltán Szalai

Fluoroquinolone antibiotics are widely used in animal husbandry and human medicine and are therefore released into environmental systems in significant quantities. Because of its targeted antibacterial action, it directly disrupts the soil microbial ecosystem and alters soil carbon fixation. In order to maintain soil microbial communities and prevent groundwater pollution, it is essential to know what physicochemical properties a soil must have to be safe for sewage sludge application and irrigation with treated wastewater. To understand the effects of land use on the adsorption properties of Luvisols, three different land use areas (arable land, grassland, and forest) and two organic matter (OM) pools (fast and slow) were investigated. The soils were separated to a > 53 µm fraction related to the fast OM pool and a < 53 µm fraction containing the slow OM pool, to investigate the physicochemical properties that affect adsorption capacity. Ciprofloxacin, norfloxacin, and ofloxacin were chosen for adsorption experiments because they are widely detected in environmental systems. The effect of land use on adsorption was only observed in the slow pool in the ascending order of arable land, grassland, and forest. Principal component analysis showed that OM content and composition influenced adsorption in the slow pool. However, the adsorption of bulk soils and fast pools is primarily controlled by the physical soil properties rather than by soil OM. These findings indicate that the OM composition of the < 53 µm fraction with the slow pool can determine the adsorption of bulk soils. However, in the present study, this did not affect the adsorption of bulk soils because either 1) the ratio of the slow pool was small, but its adsorption capacity was high, as in the forest, or 2) the ratio of the slow pool was large but its adsorption capacity was low due to its OM composition, as in arable land and grassland. Therefore, irrigation with treated wastewater and sludge discharged on agricultural lands is more likely to leach pollutants into groundwater. Consideration should be given to the disposal of sludge in an area with a high aliphatic soil OM content, where the slow pool rate is high.

This research was supported by the National Research, Development, and Innovation Office (NKFIH), Hungary (project identification number: 2020–1.1.2-PIACI-KFI-2021-00309; 2021–1.2.4-TÉT-2021-00029, and K-142865). Project no. KDP-1015196 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2020 funding scheme. This study has also been supported by the Doctoral Excellence Program (DKOP-23) of the Ministry for Culture and Innovation, Hungary, from the source of the National Research, Development and Innovation Fund.

How to cite: Vancsik, A., Szabó, L., Bauer, L., Király, C., Pirger, Z., Kondor, A. C., Jakab, G., and Szalai, Z.: The impact of land use on the adsorption of fluoroquinolone antibiotics: a study on bulk soils and organic matter pools, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8888, https://doi.org/10.5194/egusphere-egu24-8888, 2024.

EGU24-8943 | ECS | Orals | BG1.13

Effects of root-derived organic acids on sorption of pharmaceuticals in cultivated sandy soil 

Lili Szabó, Anna Vancsik, László Bauer, Attila Csaba Kondor, Gergely Jakab, and Zoltán Szalai

Pharmaceutically active compounds (PhACs) in cultivated areas have become an important issue and have received significant public attention because of their availability to plants during nutrient uptake. This study highlights the effects of low-molecular-weight organic acids (LWMOAs) generated in the root environment on the sorption processes of PhACs in cultivated sandy soil. Sorption experiments are conducted using three PhACs characterised by different physicochemical properties: carbamazepine (CBZ), 17α-ethynylestradiol (EE2), and diclofenac-sodium (DFC). The results suggest that the adsorption of EE2 is more intense than the other two PhACs, whereas DFC and CBZ are primarily dominated by desorption. Additionally, LMWOAs mainly provide additional low-energy adsorption sites for the PhACs, and slight pH changes do no significantly affect the sorption mechanism. During competitive adsorption, the high-energy sites of the adsorbents are initially occupied by EE2 owing to its high adsorption energy. In addition, during multicomponent adsorption, new low-energy binding sites enhance the adsorption of DFC and CBZ. Our results show that LMWOAs promoted the adsorption of PhACs into the root environment, thus rendering PhACs available to plants.

This research was supported by the National Research, Development, and Innovation Office (NKFIH), Hungary (project identification number: 2020–1.1.2-PIACI-KFI-2021-00309; 2021–1.2.4-TÉT-2021-00029, and K-142865). Project no. KDP-1015196 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2020 funding scheme. This study has also been supported by the Doctoral Excellence Program (DKOP-23) of the Ministry for Culture and Innovation, Hungary, from the source of the National Research, Development and Innovation Fund.

How to cite: Szabó, L., Vancsik, A., Bauer, L., Kondor, A. C., Jakab, G., and Szalai, Z.: Effects of root-derived organic acids on sorption of pharmaceuticals in cultivated sandy soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8943, https://doi.org/10.5194/egusphere-egu24-8943, 2024.

EGU24-9035 | ECS | Posters on site | BG1.13

Remediation of rare earth elements (REE)-rich waters by precipitation of newly-formed phases. 

Ricardo Millan-Becerro, Encarnación Ruiz-Agudo, María P. Asta, Sarah Bonilla-Correa, Miguel Burgos Ruiz, and Francesco Santoro

The “Ría de Huelva” estuary (SW Spain) is highly affected by acid mine drainage and phosphate fertilizer industry effluents, which contain high concentrations of dissolved metal(loid)s, some of them of high economic interest such as Rare Earth Elements (REE). These elements are essential for the energy transition as they are used in various applications necessary for the production, transport, and accumulation of electrical energy from renewable sources. However, high dissolved concentrations of REE could have a significant environmental impact on aquatic organisms [1]. This research work focuses on the remediation of REE-laden solutions with different concentrations of these metals, using a sorption strategy with mineral phases such as gypsum (CaSO4·2(H2O)) and brushite (CaHPO4·2(H2O)), where these elements of high economic interest may be concentrated for its potential recovery. The main objectives of this research were to determine: (1) the removal processes of dissolved REEs, as well as (2) the preferential incorporation in the minerals studied. For this purpose, precipitation experiments of REE-rich sulfate and phosphate phases were carried out in the laboratory. The liquid and solid samples resulting from the precipitation experiments were analyzed by atomic emission spectroscopy with inductively coupled plasma (ICP-AES), mass spectrometry with inductively coupled plasma (MS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission Fourier transform infrared (FTIR), which allowed us to determine the capacity for REE incorporation by the tested minerals, as well as possible changes in the characteristics of the newly-formed phases. The concentrations of REE in the sulfate and phosphate phases increased progressively as solutions with higher concentrations of these metals were used in the laboratory experiments. However, the removal percentages of REE by gypsum precipitation were noticeably lower than those by brushite precipitation. This could be because brushite has a greater adsorption capacity than gypsum, as both mineral phases have similar crystalline structures and therefore the co-precipitation processes of REE with both minerals should be similar. These results show that the removal of REE from solutions during the precipitation of newly-formed phases could be a viable strategy for the concentration of these valuable elements and the remediation of contaminated waters.

Acknowledgements

This work is part of the I+D+i TRAMPA project (PID2020-119196RB-C21), funded by MCIN/AEI/10.13039/501100011033/.

 

[1] Oral, R., Bustamante, P., Warnau, M., D'Ambra, A., Guida, M., Pagano, G., 2010. Cytogenetic and developmental toxicity of cerium and lanthanum to sea urchin embryos. Chemosphere 81:194–198.

How to cite: Millan-Becerro, R., Ruiz-Agudo, E., Asta, M. P., Bonilla-Correa, S., Burgos Ruiz, M., and Santoro, F.: Remediation of rare earth elements (REE)-rich waters by precipitation of newly-formed phases., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9035, https://doi.org/10.5194/egusphere-egu24-9035, 2024.

EGU24-9323 | ECS | Orals | BG1.13

Fixed-bed thermodynamical analysis of the sorption mechanisms of Pharmaceutically Active Compounds (PhACs) in sandy soil 

László Bauer, Lili Szabó, Anna Vancsik, Attila Kondor, Gergely Jakab, and Zoltán Szalai

In the last couple of decades, the utilization of different Pharmaceutically Active Compounds (PhACs) significantly has increased. The applications of the treated wastewater (discharge into surface waterbodies, sewage sludge disposal), have resulted that those PhACs world-wildly can be detected in the environment. Due to the negative effects of these PhACs on ecosystems, it is indispensable to analyze their behavior in the soil environment. In the soil solution systems (SSS) the sorption mechanisms of the PhACs are significantly being influenced by various environmental factors like pH, and temperature. In our research, PhACs with different physicochemical properties have been studied such as 17α-ethynylestradiol (EE2), diclofenac-sodium (DFC), and lidocaine (LID). Owing to these facts, the main questions of our research were: (a) How to estimate the Van’t Hoff equation’ parameters in fixed-bed SSS? (b) How does the temperature change affect the intermolecular reactions of the PhACs on the solid/liquid interface in the single and multi-component systems? Single and multicomponent fixed-bed sorption experiments were carried out. All of the sorption experiments have been investigated at 5 different temperatures. The fixed-bed sorption experiments have been performed at the ploughed layer of calcareous, humic sandy soil. The adsorbate-adsorbate and adsorbent-adsorbate interactions have been evaluated by different empirical formulas. To conduct the results of our study, different statistical analyses (2-way ANOVA, Principal Component analysis, regression analysis, and Pearson correlation have been performed. In the scientific literature, the thermodynamical parameters had been carried out in batch experiments. Nevertheless, this way of sorption analysis in an environmental system often overestimates the equilibrium constant (Kc) in the Van’t Hoff equation. Due to this fact, we hypothesized that if the experiment is implemented in a fixed-bed SSS, the real Kc value can be calculated from the real empirical qe value, which could provide the optimal results of the thermodynamical parameters. Our results show that in single-component systems EE2, LID, and DFC have got spontaneous endotherm sorption reactions. While in a multicomponent SSS system, the LID and EE2 had an exothermic enthalpy-driven reaction. Furthermore, in all cases, the Gibbs free energy has been decreased when the temperature was increased.

This research was supported by the National Research, Development, and Innovation Office (NKFIH), Hungary (project identification number: 2020–1.1.2-PIACI-KFI-2021-00309; 2021–1.2.4-TÉT-2021-00029, and K-142865). Project no. KDP-1015196 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2020 funding scheme. This study has also been supported by the Doctoral Excellence Program (DKOP-23) of the Ministry for Culture and Innovation, Hungary, from the source of the National Research, Development and Innovation Fund. And The Hungarian National Research, Development and Innovation Fund OTKA-142865

How to cite: Bauer, L., Szabó, L., Vancsik, A., Kondor, A., Jakab, G., and Szalai, Z.: Fixed-bed thermodynamical analysis of the sorption mechanisms of Pharmaceutically Active Compounds (PhACs) in sandy soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9323, https://doi.org/10.5194/egusphere-egu24-9323, 2024.

EGU24-11594 | ECS | Posters on site | BG1.13 | Highlight

The influence of industrial metal pollution on Foraminifera in the Gulf of Naples (Bagnoli) 

Leon Plakolm, Sergio Balzano, Matthias Nagy, Petra Heinz, Daniela Gruber, Katy Schmidt, Martin Stockhausen, Thilo Hofmann, and Michael Lintner

Chemical pollutants, such as heavy metals, are a major threat to marine ecology and biodiversity in the Mediterranean Sea. The Gulf of Naples plays a crucial role in risk assessment and mitigation of waste contamination in the area, as severe anthropogenic pressure originates from local urban and industrial areas and intense maritime traffic. The now defunct ILVA steel plant in Bagnoli, constructed between 1905 and 1910, was a leading contributor of metal pollution in the Gulf of Naples until its shutdown in 1990. In order to evaluate the potentially long-lasting impact of this industrial activity on local foraminiferal communities, as well as the response of individual benthic foraminifera, multiple geochemical and sedimentological analytical techniques were employed and the results compared to a non-impacted reference area; inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES) revealed exceptionally high levels of metals in the sediment samples taken in close proximity to the former steel plant. Faunal analysis via stereo microscopy and scanning electron microscopy (SEM) concluded slightly lower biodiversity indices and a lower abundance of living foraminifera in the polluted sample, and the near absence of the otherwise ubiquitous genus Ammonia in the reference area. Energy-dispersive X-ray spectroscopy (EDX) was utilized to determine concentrations of iron within foraminiferal tests and established that all analyzed specimens from the polluted sampling site had elevated quantities of iron in their tests, compared to individuals from the reference sampling site. Based on the findings of this investigation, the metal pollution emitted by the former steel mill is still impacting foraminiferal assemblages and individuals to this day. However, the complex interactions of anthropogenic toxins, benthic microorganisms and the environment are not fully unraveled yet and require further analysis.

How to cite: Plakolm, L., Balzano, S., Nagy, M., Heinz, P., Gruber, D., Schmidt, K., Stockhausen, M., Hofmann, T., and Lintner, M.: The influence of industrial metal pollution on Foraminifera in the Gulf of Naples (Bagnoli), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11594, https://doi.org/10.5194/egusphere-egu24-11594, 2024.

EGU24-14211 | ECS | Posters on site | BG1.13

Release and turn-over of carbon, nitrogen and metals under oxic and suboxic conditions in long-term incubations of Skagerrak sediments  

Anna Siems, Tina Sanders, Tristan Zimmermann, Michael E. Wieser, and Daniel Pröfrock

Suspended particulate matter and associated pollutants from the entire North Sea are deposited in the Skagerrak, located between Norway and Denmark. Consequently, the sediments of the Skagerrak play a key role for long-term carbon storage within the North Sea. Due to its location and bathymetry, the bottom sediment redox conditions within the Skagerrak are heterogeneous and cover a wide range from oxic to suboxic conditions. We investigated nitrogen sequestration processes and the mobility of pollutants in these sediments during incubation experiments that simulated oxic and suboxic conditions. Analysis of isotopic fractionation was used as a tool to better understand the nitrogen sequestration pathways (δ15NO3-) and redox conditions (δ98/95Mo).

Typically, incubation experiments last days to weeks but do not cover long-term effects. In contrast, we incubated different zones of three sediment cores with North Sea water for up to twelve months. The sediments originated from locations with (a) mainly iron reduction, (b) mainly manganese reduction and (c) both iron and manganese reduction. After one, three, six and twelve months, we sampled water and sediments from the incubations for various parameters (e.g., trace elements, carbon and nitrogen content, nutrients, δ15NO3-, δ98/95Mo). Under aerobic conditions, the sediments with high organic carbon content (2.78 ± 0.05 %) released up to 33 ± 6 µmol g‑1 NO3- during remineralization, while in anaerobic incubations, these sediments released only up to 4.8 ± 0.8 µmol g-1 NH4+. However, sediments with lower organic carbon contents (1.89 ± 0.05 %) released only 4.8 ± 1.2 µmol g‑1 NO3- and 1.18 ± 0.19 µmol g-1 NH4+, respectively. In combination with trace element concentrations, δ98/95Mo ratios allowed to distinct between different organic matter oxidation pathways. The aerobic incubations released mainly copper, lead and nickel while under  anaerobic conditions, also  cobalt but significantly less copper has been released. Hence, the prevailing oxygen conditions also have a strong impact on the remobilization of e.g., legacy pollutants stored in the sediments. The results of our long-term incubations reveal important biogeochemical processes and indicate that some processes are only traceable at larger timescales applied in this study, but not by incubation durations that are usually applied for biogeochemical studies.

How to cite: Siems, A., Sanders, T., Zimmermann, T., Wieser, M. E., and Pröfrock, D.: Release and turn-over of carbon, nitrogen and metals under oxic and suboxic conditions in long-term incubations of Skagerrak sediments , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14211, https://doi.org/10.5194/egusphere-egu24-14211, 2024.

EGU24-14425 | Orals | BG1.13 | Highlight

Hadal trenches are experimental fields for geological and biological systems 

Hiroshi Kitazato

Hadal trench shows integration of landscapes of plate tectonics, geological evolutions of trenches, surface and deep-water circulations, biogeochemical cycles and others.  On these environmental components, we can understand historical backgrounds of benthic organisms. I have long been worked on the deep sea benthic foraminiferal communities at the Western Pacific.  We analyzed localities of the western Pacific deep-sea, from bathyal to abyssal depths, in particular to hadal depths. Hadal foraminiferal community consists of monothalamous soft-shelled forms, agglutinated forms, porcelaneous forms, hyaline forms and large xenophyophores.  In contrast to the bathyal to abyssal depths, the hadal depths are much challenging.   Because, a lot of accidental events take place naturally, such as collisions, subductions, separations or fusion of trenches.  Trenches are fascinating natural laboratories for thinking about evolution of benthic organisms in connection to trenches.

Here, I try to discuss what kind of changes should take place when trench fuse respectively.  Case studies will be given from the late Cenozoic marine strata of the Central Kwanto regions at the central Japan (Kitazato, 1997).

How to cite: Kitazato, H.: Hadal trenches are experimental fields for geological and biological systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14425, https://doi.org/10.5194/egusphere-egu24-14425, 2024.

EGU24-14624 | Posters on site | BG1.13

Calcification Strategies in Sorites orbiculus: Insights from Ultrafine Structure Observations and pH Variations 

Takashi Toyofuku, Yukiko Nagai, Remi Tsubaki, and Kazuhiko Fujita

Biomineralization processes are remarkably varied across the biosphere, yet the foraminifera stands out for their intricate construction of calcium carbonate shells—a phenomenon critical for interpreting paleoceanographic applications. In our research, we delve into the latest observations on the calcification strategy employed by the porcelain-shelled foraminifera Sorites orbiculus (Forsskål in Niebuhr, 1775), offering a reevaluation of the prevailing models of chamber formation. Utilizing focused ion beam scanning electron microscopy (FIB-SEM), we meticulously documented the ultrastructural development of the shell in calcification. Our findings may challenge the traditional vesicle-mediated crystal formation hypothesis, revealing a unique and complex cotton candy-like structure at the calcification site instead.

Simultaneously, pH imaging conducted during chamber formation has disclosed a fascinating pattern of pH elevation that transcends the newly formed chambers, extending to the final stages of calcification. This suggests a more intricate and systemic approach to biomineralization than previously understood. The localized increases in pH not only coincide with the morphological intricacies of the shell but also suggest a remarkable environmental plasticity inherent to S. orbiculus. Our nuanced comprehension of calcification, grounded in precise pH measurements and detailed microstructural observations, illuminates new facets of this species' biomineralization strategy. The insights gleaned here hold profound implications for redefining elemental partitioning and isotopic fractionation in foraminiferal shells and may herald a paradigm shift in our understanding of biomineralization within porcelain foraminifera.

 

How to cite: Toyofuku, T., Nagai, Y., Tsubaki, R., and Fujita, K.: Calcification Strategies in Sorites orbiculus: Insights from Ultrafine Structure Observations and pH Variations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14624, https://doi.org/10.5194/egusphere-egu24-14624, 2024.

EGU24-15333 | Orals | BG1.13

Boron isotope signals of benthic foraminifera during the Santonian 

Erik Wolfgring, Giulia Amaglio, and Maria Rose Petrizzo

We investigated the δ11Bisotope profiles in Cretaceous benthic foraminifera, focusing on the epibenthic species Notoplanulina rakauroana and Nuttallinella coronula. This study aims at understanding the implications of changes in δ11B isotope signatures for pH, associated with paleoenvironmental factors during the beginning of the Late Cretaceous cooling in the Santonian in the southern high latitudes.

We examine 10 levels through the Santonian of International Ocean Discovery Program (IODP) Site U1513 in the Mentelle Basin, some kilometres offshore Western Australia. Following a biostratigraphic framework relying on planktonic foraminifera and calcareous nannofossils, foraminiferal samples of Notoplanulina and Nuttallinella, representing significant elements of bottom water fauna through this period of significant cooling in surface and bottom waters, have been processed.

The geochemical signals preserved in the tests of epibenthic foraminiferal species are supposedly less prone to representing vital effects as some stability in the paleohabitat in bottom waters is implicit (see Rae et al. 2011). The analysis of well-preserved foraminiferal tests by Inductively Coupled Plasma Mass Spectrometry (ICPMS) is imperative of a cleaning protocol that involves several steps of ultrasonic baths in clear water and alcohol (see Henehan et al. 2019).

The results of benthic foraminiferal δ11B add information to our understanding of the relationbetween climate shifts and changes in the geochemical composition visible in foraminiferal tests. Results help to reconstruct prevailing pH of bottom waters during the documented reorganization of oceanic pathways in the southern high latitudes and offer a further perspective on the extent of paleoenvironmental change in the bottom waters.

References:
Rae, JWB, Foster, GL, Schmidt, DN, Elliott, T, 2011. Boron isotopes and B/Ca in benthic foraminifera: Proxies for the deep ocean carbonate system, Earth and Planetary Science Letters, 302, 3–4.
Henehan, MJ, Ridgwell, A, Thomas, E, et al., 2019. Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact. PNAS, 116, 45, 22500-22504.



How to cite: Wolfgring, E., Amaglio, G., and Petrizzo, M. R.: Boron isotope signals of benthic foraminifera during the Santonian, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15333, https://doi.org/10.5194/egusphere-egu24-15333, 2024.

EGU24-16323 | Orals | BG1.13

Temperature Influence on Proton Pumping and Mg-Incorporation in Foraminifera 

Daniel Francois Do Nascimento Silva, Lennart de Nooijer, and Gert-Jan Reichart

The Mg/Ca ratio in foraminiferal shells is commonly used as a proxy for reconstructing sea surface and bottom water temperatures. However, its incorporation results from complex interactions between seawater conditions and biologically regulated factors. While the former effects are well-constrained, poorly understood biological factors contribute to interspecies variations in Mg/Ca-temperature calibrations and a notable difference in Mg sensitivity compared to inorganically precipitated calcium carbonates. Here we show that temperature significantly influences cellular ion modulation in low-Mg species, leading to elevated enzymatic reaction rates that enhance H+ removal (J = 0.67 to 5.00 nmol-s) during calcification, and boost the precipitation rate. On high-Mg species, on the other hand, a similar fivefold increase in H+ local flux was observed (J = 0.08 to 0.40 nmol-s), but its impact on the calcification rate was mild. In both cases, H+ pumping rates align with Mg uptake, indicating a potential (indirect) link between temperature-sensitive behavior of transporters and Mg partitioning.

How to cite: Do Nascimento Silva, D. F., de Nooijer, L., and Reichart, G.-J.: Temperature Influence on Proton Pumping and Mg-Incorporation in Foraminifera, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16323, https://doi.org/10.5194/egusphere-egu24-16323, 2024.

EGU24-17428 | ECS | Orals | BG1.13

Mercury(Hg) Speciation in different environmental compartments of the India: A Thermo-desorption-Driven Approach 

Prasad Padalkar, Parthasarathi Chakraborty, Arup Dey, and Malay Bhattacharya

India has a rich environmental ecosystem, stretching from high-rise mountains to coastal areas. The surge in industrialization and economic growth in the country has imposed a considerable burden on the environment, hindering progress toward sustainable development goals. One critical concern in this context is mercury (Hg) pollution, where special attention is needed. On June 18th 2018, India ratified the Minamata Convention to address Hg pollution. However, a significant data gap exists regarding comprehensive baseline information from different environmental compartments in India, which is crucial for assessing the convention's effects. To bridge this research gap, an effort was made to access Hg distribution and speciation in various environments. For this study, soil and sediments samples were collected from diverse regions: the metropolitan city (Kochi, Kerala, India), agricultural lands (Dhapa, Kolkata), hilly areas (Tea Garden, Darjeeling), and the coastal sediments (collected from continental shelf/slope of the west coast of India). The total soil Hg concentration in metropolitan soil, agricultural soil, and tea garden soil ranged from 16 ± 0.84 µg/kg to 2674 ± 133 µg/kg, 726 ± 36 µg/kg to 2318 ± 115 µg/kg, and 158 ± 7 µg/kg to 9441 ± 472 µg/kg, respectively. Meanwhile, the total Hg concentration in the studied continental shelf sediment samples varied from 8 ± 0.14 µg/kg to 50 ± 2 µg/kg. This result shows that a significantly higher total concentration of Hg in the tea garden soil, whereas lowest Hg concentration were observed in the coastal sediment. Chemical speciation of Hg was carried out using thermo-desorption technique. It was found that the major part of the total Hg was predominantly associated with organic matter in the soil as well as in the coastal sediments. This indicates that organic matter was key host for Hg in soil as well as in coastal sediments. Interestingly, the second-highest fraction in the all types of soil was Hg0, indicating more reduction of Hg in the soil. The elevated Hg0 levels in the soils raises concerns due to its high volatility at ambient temperatures. The evasion of Hg0 from the soil can serve as a significant non-point source of Hg, posing potential risks to individuals living in these areas. Prolonged exposure to this toxic metal could lead to adverse health effects for the local population. Further in the sediments, Hg associated with sulphide was the second dominant Hg fraction, playing crucial role in Hg stability. Overall, these findings not only help to stakeholders and policy makers in addressing Hg pollution, but also contributes to progress towards achieving Sustainable Development Goals.

How to cite: Padalkar, P., Chakraborty, P., Dey, A., and Bhattacharya, M.: Mercury(Hg) Speciation in different environmental compartments of the India: A Thermo-desorption-Driven Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17428, https://doi.org/10.5194/egusphere-egu24-17428, 2024.

EGU24-17814 | ECS | Orals | BG1.13

Hydrothermal Vents in Panarea, Italy: Investigating Mercury inputs and evaluating Biota Oxidative Stress Status with a focus on Phorcus turbinatus as a Bioindicator of Mediterranean Sea Health 

Andreia C. M. Rodrigues, Mariia V. Petrova, Natalia Torres-Rodriguez, Aurelie Dufour, Claudia Cosio, Deny Malengros, Christian Marschal, Gianluca Lazzaro, Manfredi Longo, and Lars-Eric Heimbürger-Boavida

Panarea, an island in the Tyrrhenian Sea, Mediterranean Sea, is distinguished for its hydrothermal vent ecosystems that substantially influence the local biodiversity. While hydrothermal vents are recognised for their mineral-rich composition, the potential release of mercury (Hg), a non-essential metal, into the surrounding environment raises environmental concerns. This study investigates the oxidative stress status and cellular energy allocation of the autochthonous marine gastropod Phorcus turbinatus (Born, 1778), collected from rocky shores at two distinct hydrothermal vents, Bottaro and La Calcara, characterized by different hydrothermal vent activities. Our results show a higher THg input at La Calcara vent (864 pM) when compared to Bottaro (45.9 pM), suggesting exposure by diet. Accordingly, significantly higher levels of oxidative damage, measured as lipid peroxidation (LPO), were observed in gastropods from La Calcara compared to their counterparts from Bottaro. This observation aligns with lower catalase (CAT) activity and total glutathione levels (tGSH) in these gastropods, indicating compromised antioxidant defenses against reactive oxygen species (ROS). No significant differences were observed in energy metabolism when comparing cellular energy allocation (CEA) between snails from the two locations. Nevertheless, gastropods from La Calcara exhibited significantly reduced levels of available sugars, suggesting potential energetic costs of dealing with higher levels of oxidative stress due to increased Hg exposure. Understanding the complex relationships among hydrothermal vent activity, Hg inputs, Hg transfer in food webs, and biota responses provides valuable insights for conservation and management efforts in these unique and fragile ecosystems. Future research should focus on elucidating the long-term effects of Hg exposure at several hydrothermal vent locations, their biodiversity, and ecosystem dynamics, contributing to the broader understanding of metal contamination in marine environments.

How to cite: Rodrigues, A. C. M., Petrova, M. V., Torres-Rodriguez, N., Dufour, A., Cosio, C., Malengros, D., Marschal, C., Lazzaro, G., Longo, M., and Heimbürger-Boavida, L.-E.: Hydrothermal Vents in Panarea, Italy: Investigating Mercury inputs and evaluating Biota Oxidative Stress Status with a focus on Phorcus turbinatus as a Bioindicator of Mediterranean Sea Health, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17814, https://doi.org/10.5194/egusphere-egu24-17814, 2024.

EGU24-18686 | ECS | Orals | BG1.13

Partitioning of multiple elements as a function of seawater [Ca2+]: results from foraminiferal culture experiments.  

Laura Pacho, Lennart de Nooijer, and Gert-Jan Reichart

Climate reconstructions are important for validating climate models and hence constrain climate change predictions. Such reconstructions are based on indirect tools (proxies) in which a fossil or chemical remnant corresponds to an environmental parameter. When employing foraminifera as proxies, elemental concentrations in their shells have been shown to correlate with environmental parameters including temperature (that determines the calcite’s Mg/Ca), seawater [HCO3-] (Sr/Ca and B/Ca) and [CO32-] (S/Ca). When reconstructing theses parameters on longer geological timescales (i.e. millions of years), the seawater’s major ion concentrations may affect these proxy relationships. Especially the concentration of calcium will affect all of these calcitic elemental ratios and therefore, we varied [Ca2+] in controlled growth experiments to test its effect on incorporation of Mg, Sr, B and S in the benthic foraminifer Amphistegina lessonii. For the divalent cations we find a decrease in the partition coefficient (D) for Mg (DMg) with a changing [Ca2+] (and hence seawater Mg/Ca) while DSr does not vary significantly with [Ca2+]. For SO42- and B(OH)4- against S/Casw and B/Casw respectively, we observe a significant decrease in the partition coefficients with decreasing [Ca2+]. These results gives new information for SO42- and B(OH)4- incorporation and represents a step forward towards comprehending the impact of [Ca2+]sw alterations on foraminiferal calcite chemistry and hence their application as paleoproxies in deep time. 

How to cite: Pacho, L., de Nooijer, L., and Reichart, G.-J.: Partitioning of multiple elements as a function of seawater [Ca2+]: results from foraminiferal culture experiments. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18686, https://doi.org/10.5194/egusphere-egu24-18686, 2024.

EGU24-18922 | Orals | BG1.13

Aquatic eddy covariance pH and O2 fluxes, a technique for observing calcification in benthic ecosystems 

Dirk Koopmans, Allison Schaap, Volker Meyer, Paul Färber, Lauren Queiss, Luis M. Montilla, Socratis Loucaides, Soeren Ahmerkamp, and Ulisse Cardini

Calcifying organisms, including scleractinian corals and coralline algae, play a pivotal role in supporting benthic habitats and their associated ecosystem functions. However, many of them are threatened by ocean warming and acidification caused by anthropogenic CO2 emissions. Our understanding of their capacity to adapt to changes in their natural environment remains limited. To address this knowledge gap, we introduce a non-invasive method to quantify calcification from the simultaneous measurement of H+ ion and O2 fluxes utilizing the aquatic eddy covariance technique. Because calcification is a net source of H+ ions, it can be quantified as a source of H+ ions in excess of those generated by organic carbon metabolism. To examine the effect of ocean acidification on calcification by coralline algae epiphytes, we measured H+ and O2 fluxes at a seagrass meadow at a CO2 vent and at a control meadow, 670 m away. At both meadows we found that opposing flows were enriched in vent CO2. Additionally, vent CO2 diffused upwards through sediments at both sites. Because of this, we were unable to completely separate the calcification signal (non-metabolic H+ ion production) from the persistent background signal of vent CO2. However, we use these data as a demonstration of how H+ and O2 eddy covariance can reveal a subtle time-varying signal consistent with calcification in a benthic ecosystem. Based on the results of this study, H+ and O2 eddy covariance can quantify changes in benthic calcification over time, and therefore it can support better-informed management of scleratinian corals, coralline algae, and other benthic calcifiers. 

How to cite: Koopmans, D., Schaap, A., Meyer, V., Färber, P., Queiss, L., Montilla, L. M., Loucaides, S., Ahmerkamp, S., and Cardini, U.: Aquatic eddy covariance pH and O2 fluxes, a technique for observing calcification in benthic ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18922, https://doi.org/10.5194/egusphere-egu24-18922, 2024.

EGU24-19630 | ECS | Orals | BG1.13

Developing trace element proxy calibrations for reconstructing polar surface ocean hydrography based on laboratory-grown planktonic foraminifera Neogloboquadrina pachyderma 

Adele Westgård, Julie Meilland, Freya E. Sykes, Thomas B. Chalk, Gavin L. Foster, Melissa Chierici, and Mohamed M. Ezat

Proxy based records of past changes in the polar surface ocean-cryosphere-climate interactions can provide invaluable constraints on ongoing and future climate change. However, studying polar ocean palaeoceanography remains challenging largely due to a lack of robust proxy calibrations. For example, the commonly used foraminiferal Mg/Ca paleothermometer does not have a reliable calibration at polar conditions and there are currently limited trace element proxies for other environmental variables such as salinity or carbonate chemistry. In addition, Neogloboquadrina pachyderma, the dominant foraminifera species in polar regions, sometimes grows a thick calcite crust outside its main growth phase calcite with different geochemical composition. This poses a challenge to the Mg/Ca paleothermometer as the crusts have lower Mg/Ca than the ontogenetic calcite.

To address this, we cultivated >1500 individual specimens of N. pachyderma over a wide range of temperatures (2 to 9°C), salinities (~30 to 36.5), pHs (~7.7 to 8.4 total scale), carbonate ion concentrations (~100-250 µmol/mol at stable and variable pH), and Ba concentrations (2-4 times natural). The experimental water was spiked with 135Ba to label laboratory-grown calcite. Elemental ratios in the specimens have been analysed using laser ablation mass spectrometry (LA-ICP-MS), providing high resolution elemental profiles of intra-shell variability.

Our microscopic observations and element ratios results suggest the growth and addition of crust in all treatments, allowing, for the first time, laboratory-based proxy calibrations for N. pachyderma’s crust. A preliminary data analysis show variability in trace element ratios in relation to variable temperature, salinity, barium concentration and carbonate chemistry. Our results also indicate significant distinction in trace element ratios between crust and ontogenetic calcite components of the N. pachyderma tests when both are grown in culture. We are in the process of developing separate laboratory-based proxy calibrations for the crust and ontogenetic calcite which will significantly improve the applicability of the proxy calibrations as well as our understanding of crust formation in this species. We aim to present Mg/Ca-temperature calibrations for the crust and ontogenetic parts separately as well as detailing the respective effects of salinity and carbonate chemistry on Mg/Ca ratios.  

How to cite: Westgård, A., Meilland, J., Sykes, F. E., Chalk, T. B., Foster, G. L., Chierici, M., and Ezat, M. M.: Developing trace element proxy calibrations for reconstructing polar surface ocean hydrography based on laboratory-grown planktonic foraminifera Neogloboquadrina pachyderma, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19630, https://doi.org/10.5194/egusphere-egu24-19630, 2024.

Carlos Ruiz Cánovas1, Manuel Olías1, Francisco Macías1, María Dolores Basallote2, Eduardo Navarrete3 and Juan Mantero4

1Department of Earth Sciences & Research Center on Natural Resources, Health and the Environment. University of Huelva, Campus El Carmen, E-21071, Huelva, Spain manuel.olias@dgyp.uhu.es; carlos.ruiz@dgeo.uhu.es, manuel.olias@dgyp.uhu.es, carlos.ruiz@dgeo.uhu.es, francisco.macias@dgeo.uhu.es

2Department of Ecology and Coastal Management, Institute of Marine Sciences of Andalusia, CSIC, E-11510, Puerto Real, Cádiz, Spain mdolores.basallote@csic.es

3Andalusian Environmental and Water Agency, C/ Johan G. Gutenberg, 1 - Isla de la Cartuja, 41092 Seville, Spain  eduardo.navarrete@juntadeandalucia.es

4Department of Applied Physics II, ETSA, University of Seville, Av Reina Mercedes 2, 41012 Seville, Spain, manter@us.es

 

This work studies the behavior of Uranium (U) and Thorium (Th) in the Tinto River during the hydrological year 2017/2018. The dissolution of surrounding rocks due to extreme acidity conditions, generated during the oxidation of sulfides, induces the release of high concentrations of U and Th into the water. Maximum dissolved concentrations of 57 μg/L of U and 61 μg/L of Th were determined in this study, coinciding with the first precipitation events of the hydrological year due to the washout of evaporitic salts covering the riverbed and mining areas during the dry period, as well as the transport of sulfide oxidation products. Subsequently, a progressive decrease in concentrations was observed, reaching values close to 5 μg/L by February 2018, which are much higher than those found in freshwaters.

With the arrival of intense rains in March and April 2018, a significant decrease in concentrations (<1 μg/L) occurred, primarily due to dilution. Both elements exhibit quasi-conservative behavior due to the low pH values in the river (2.1-4.2), preventing the precipitation of Al mineral phases and the incorporation of U and Th into them. Although the precipitation of Fe mineral phases at these pH values is intense, the adsorption/coprecipitation processes of U and Th onto these phases seem to be limited by the formation of sulfate complexes (Th(SO4)2), ThSO42+, UO2SO4). The transport of U and Th by particulate matter is very limited, although there appears to be a correlation with Al. An increase in concentration of U and Th is observed during the mixing of these acidic waters with ocean waters due mainly to the formation of carbonate complexes which enhances the mobility of U and Th in the estuarine domain.

How to cite: Ruiz Cánovas, C.: Transport of U and Th from a river affected by acid mine drainage (AMD) to the Atlantic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20607, https://doi.org/10.5194/egusphere-egu24-20607, 2024.

EGU24-20817 | ECS | Posters on site | BG1.13

Assessment of pollutant load in Tharsis mine (Huelva, Spain): A study of evaporitic salts using UAS-Based Hyperspectral 

Raul Moreno Gonzalez, Luis Barbero, Andrea Celeste Curcio, Rafael León, and Jonatan Romero

One of the major environmental problems caused by mining operations is water pollution. In sulfide mining, pyrite is exposed to atmospheric conditions causing oxidize and release acidity and metals. The water transports these contaminants, producing a leachate known as Acid Mine Drainage (AMD). The Iberian Pyritic Belt (IBP), which belongs the province of Huelva, is very rich in massive sulfide deposits that are mainly composed of pyrite. Mining activity has left numerous abandoned mines with enormous amounts of waste rich in sulfides, including Tharsis mines. Numerous acid leachates emerge from the waste from the Tharsis mines, which have not been active since 2001, and drain to rivers of the area. In the dry season, pollutants precipitate in the form of soluble evaporitic salts that are redissolved with the first important rains of autumn. This redissolution of salts generates a pH decrease and the release of high amounts of contaminants such as Fe, Al, Zn, Mn, As, SO4, Cu, Ni, etc. Remote sensors provide a cost-effective, consistent and accurate approach to monitoring mining pollution. Multispectral and hyperspectral sensors have been widely used due to the distinctive spectral absorption characteristics of minerals. The emerging use of unmanned aerial systems (UAS), such as multicopters coupled with hyperspectral sensors, has become a tool for collecting data at a higher spatial resolution than most aircraft and satellites, resulting in greater accuracy.

To obtain the aerial images, a DJI Matrice 600 Pro octacopter UAS was used with a Headwall Hyperspectral (HS) Coaligned VNIR-SWIR sensor with visible and near infrared range (VNIR; 400-1000 nm) and shortwave infrared range (SWIR; 900-2500 nm) and equipped with a LiDAR to quickly obtain an DSM for georeferencing of the hypercubes. The data obtained have been preprocessed to obtain an orthomosaic with the VNIR and SWIR spectra. The data are processed with ENVI v 5.3.6 and QGIS v 3.26.3 software. Wavelengths from 2001 nm to 2450 nm are selected to identify the minerals that are present in the study area, resulting in an orthomosaic with 76 exploitable bands. MNF and PPI techniques are applied to this orthomosaic to obtain the spectral signatures of the study area. These spectral signatures are compared to the USGS mineral library to identify the minerals present. In this way, 8 minerals are identified: hematite, goethite, jarosite, epsomite, copiapite, illite, clinochlore and chlorite + muscovite. Afterwards, the pixels in the study area are classified and the location of the minerals is obtained. Jarosite, epsomite and copiapite are the most abundant minerals and mainly present in the surroundings of waste leachates. The first rains after summer, evaporitic salts and Fe oxides, hydroxides and hydrosulfates are redissolve and cause a considerable polluting load increase. The surface area occupied by these minerals is 3,861 m2, which represents a high load of pollutants that reach the rivers in the area.

How to cite: Moreno Gonzalez, R., Barbero, L., Curcio, A. C., León, R., and Romero, J.: Assessment of pollutant load in Tharsis mine (Huelva, Spain): A study of evaporitic salts using UAS-Based Hyperspectral, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20817, https://doi.org/10.5194/egusphere-egu24-20817, 2024.

EGU24-21639 | ECS | Posters on site | BG1.13

Investigating the influence of temperature on respiration rates of the benthic foraminifer Nonionella sp. T1 

Tina Palme, Petra Heinz, Irina Polovodova Asteman, and Matthias Nagy

With the warmest year on record and heating of oceans all over the world, it is of increasing interest how marine organisms adapt to these changing conditions. Benthic foraminifera are important components of marine ecosystems, contributing to biogeochemical cycling and serving as indicators of environmental change. Gaining knowledge of their role in energy and nutrient flows leads to a better understanding of ecosystem functioning. In this study we investigated oxygen respiration rates of the potentially invasive benthic foraminifer Nonionella sp. T1 originating from sediments within the Gullmar Fjord and cultivated in artificial sea water (ASW) in the laboratory at the University of Vienna. Nonionella sp. T1 was incubated at two different temperatures: 12 °C closely resembling natural fjord conditions and 20 °C simulating thermal stress to the foraminifers. Additionally, the influence of light on this species’ oxygen consumption was tested because it is known to harbour kleptoplasts (= functioning chloroplasts from algal food source), but little information exists about kleptoplast potential photosynthetic activity. Prior to the experiment, foraminifers were fed with the living diatom Phaeodactylum tricornutum, which is also used as food source for the culture. A non-invasive method was used to analyze oxygen respiration rates. The method involved placing an Oxygen Sensor Spot in a small, 2.5 ml airtight glass vial filled with ASW alongside the foraminifera. Oxygen concentrations under dark and light conditions and at 12 °C and 20 °C, respectively, were documented using an Oxygen Microsensor. We used a large number (n = 100, triplicates) of cleaned, living specimens. Respiration rates are given in µmol O2/h calculated for biovolume (µm³) which was assessed for each individual using photo microscopy. The measured oxygen respiration rates under dark conditions at 12 °C fall within the upper range of previously observed foraminiferal respiration rates. Lower respiration rates during light exposure indicate oxygen production which is likely related to the activity of kleptoplasts. The pending results of the experiment at 20 °C will show if respiratory activity of Nonionella sp. T1 will increase with temperature and if the efficiency of oxygen production of their kleptoplasts is temperature-dependent.

How to cite: Palme, T., Heinz, P., Polovodova Asteman, I., and Nagy, M.: Investigating the influence of temperature on respiration rates of the benthic foraminifer Nonionella sp. T1, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21639, https://doi.org/10.5194/egusphere-egu24-21639, 2024.

EGU24-93 | ECS | PICO | AS3.9

Late Pleistocene East Asian monsoon intensity variations and driving mechanisms: Evidence from a multi-proxy analysis of loess deposits on an East China Sea island 

Zhigang Wang, Laurent Marquer, Yuanyu Cheng, Xiuxiu Ren, Hao Long, Shaofang Ren, Peng Qian, and Xiangmin Zheng

Shengshan Island (SSD), located in East China Sea, contains loess deposits that serve as an excellent carrier for recording environmental changes in the eastern subtropical region of China. Different from the continental Loess Plateau, SSD loess possesses distinctive characteristics due to its coastal location. Here we conducted the first pollen analysis to reconstruct vegetation dynamics in the SSD region during the middle to late Late Pleistocene period (75-40 ka). Biological indicators (i.e., total organic concentration and δ13Corg), along with geochemical proxies (i.e., quartz grain size, magnetic susceptibility, iron oxide ratios, clay minerals, and trace elements), were employed to reconstruct climatic dynamics in the SSD area. The study identified two stages in the evolution of the East Asian Monsoon. In Stage I (75-60 ka), various indicators (i.e., pollen concentration, Pinus concentration, magnetic susceptibility, C4 abundance, K/(I+Ch), Illite crystallinity, CII, Hm/Gt, quartz median grain size, Zr/Rb) increased, suggesting a strengthening of both winter and summer monsoons. In Stage II (60-40 ka), some indicators (i.e., pollen concentration, Pinus concentration, quartz median grain size, Zr/Rb) continued to increase while others (i.e., magnetic susceptibility, C4 abundance, K/(I+Ch), Illite crystallinity, CII, Hm/Gt) decreased, indicating a continued intensification of the winter monsoon but a weakening of the summer monsoon. Further, we explored the driving forces behind variations in monsoon intensity, analyzing changes in various δ18O proxies and sea-level fluctuations. The findings suggest that different mechanisms influence the winter and summer monsoons. Summer monsoon intensity is linked to changes in summer solar radiation at mid-latitudes in the Northern Hemisphere, while winter monsoon dynamic is affected by changes in ice volume and ice sheets. These insights contribute to our understanding of environmental changes related to the East Asian Monsoon, offering valuable perspectives on how these mechanisms could respond to future climate changes.

How to cite: Wang, Z., Marquer, L., Cheng, Y., Ren, X., Long, H., Ren, S., Qian, P., and Zheng, X.: Late Pleistocene East Asian monsoon intensity variations and driving mechanisms: Evidence from a multi-proxy analysis of loess deposits on an East China Sea island, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-93, https://doi.org/10.5194/egusphere-egu24-93, 2024.

EGU24-430 | ECS | PICO | AS3.9

West African dust load modeling and its impact on solar radiation forecast during the dry season 

Léo Clauzel, Sandrine Anquetin, Christophe Lavaysse, Guillaume Siour, Gilles Bergametti, Béatrice Marticorena, Christel Bouet, Rémy Lapere, and Jennie Thomas

The expected growth of solar photovoltaic (PV) production in West Africa over the coming decades poses challenges to the electrical network requiring accurate solar forecasts for both energy producers and power grid managers. Furthermore, solar radiation is affected by dust aerosols which play a significant role in West African meteorology, due to the proximity of this region to the Sahara desert, which is the world's largest source of mineral dust aerosols emissions.

In this general context, our research aims at identifying the impact of mineral dust on solar energy production. Thus, this study focuses on evaluating the influence of dust aerosols on solar radiation forecasts for the Zagtouli solar plant in Burkina Faso. 

Employing a coupled approach between a meteorological model (WRF) and a chemical transport model (CHIMERE), two dust events that are representative of the dry season are simulated in line with West African climatology. While one event is linked to dust emissions from the Bodélé plateau (Chad), the other is related to dust sources located within the South Atlas area.

The model undergoes rigorous assessment in regards to dust life cycle parameters (Aerosol Optical Depth (AOD), PM10, size distribution) and variables essential for solar energy production (Global Horizontal Irradiance (GHI), temperature) using in-situ measurements from long-term observatories (AERONET, INDAAF, AMMA-CATCH) and from the solar farm (GHI), satellite observations (AQUA/TERRA-MODIS, CALIPSO-CALIOP), and reanalysis data (CAMS). This evaluation shows a robust performance of the model.

In addition, sensitivity studies are implemented to evaluate the respective impacts of direct and indirect effects of dust aerosols on the amount of solar radiation available at the surface.

Overall, this study provides strong support for a modeling approach that couples meteorological processes with the dust life cycle to refine solar forecasts in the West African region.

How to cite: Clauzel, L., Anquetin, S., Lavaysse, C., Siour, G., Bergametti, G., Marticorena, B., Bouet, C., Lapere, R., and Thomas, J.: West African dust load modeling and its impact on solar radiation forecast during the dry season, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-430, https://doi.org/10.5194/egusphere-egu24-430, 2024.

EGU24-989 | ECS | PICO | AS3.9 | Highlight

Atmospheric radioisotopes in cryoconite from the Flade Isblink ice cap, NE Greenland 

Dylan Beard, Giovanni Baccolo, Caroline Clason, Geoffrey Millward, Edyta Łokas, Sally Rangecroft, Dariusz Sala, Przemysław Wachniew, and William Blake

Under climatic warming and increased melting, glaciers and ice caps are becoming secondary sources of contaminants deposited decades ago. Cryoconite, an organic-rich material found on the surface of many glaciers, is particularly efficient at accumulating airborne contaminants due to biogeochemical exchanges with the organic matter within cryoconite. Atmospherically derived radioactive isotopes, commonly referred to as fallout radionuclides, have now been found to accumulate in cryoconite globally. However, data from the polar regions, especially ice sheets and ice caps, is scarce. This study helps to address this regional gap in understanding fallout radionuclide accumulation in glacial settings. We present the first radioactivity dataset from cryoconite on a Greenlandic ice cap and assess the role of cryoconite in the distribution of radioactive species in the High Arctic. Forty-six cryoconite samples were collected from the Flade Isblink ice cap (NE Greenland) in August 2022. These samples were analysed via alpha and gamma spectrometry for atmospheric radionuclides, including 137Cs, 241Am, 210Pbexc., 207Bi, 7Be, and several plutonium isotopes. The results of this study confirm cryoconite's exceptional ability to accumulate fallout radionuclides, even in remote and relatively pristine regions such as Northern Greenland. The activities of radionuclides in cryoconite from Flade Isblink are among the highest reported across the High Arctic and the highest ever reported from Greenland. Flade Isblink's radioactivity source is compatible with the stratospheric reservoir established during atmospheric nuclear tests and with weapon-grade fissile fuel, likely originating from Novaya Zemlya. Our findings emphasise the necessity for continued research efforts on the release of legacy contaminants from glaciers, particularly given accelerated global warming and consequent glacier retreat.

How to cite: Beard, D., Baccolo, G., Clason, C., Millward, G., Łokas, E., Rangecroft, S., Sala, D., Wachniew, P., and Blake, W.: Atmospheric radioisotopes in cryoconite from the Flade Isblink ice cap, NE Greenland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-989, https://doi.org/10.5194/egusphere-egu24-989, 2024.

EGU24-1776 | PICO | AS3.9 | Highlight

Assessment of the Impact of Coarse and Fine Dust on Solar Devices in the Middle East 

Suleiman Mostamandi, Georgiy Stenchikov, Ahmed Balawi, Illia Shevchenko, Dania Kabakebji, and Thomas Altmann

Dust in the Middle East (ME) significantly impacts regional climates and negatively affects the operation of solar farms in the ME region. Suspended dust particles attenuate downward short wave (SW) radiation, while dust deposited on the solar devices decreases effectiveness. This study theoretically assesses dust's attenuation and soiling effects on solar panels within the ME, employing a Weather Research Forecasting Model coupled with the aerosol-chemistry module, WRF-Chem, constrained by observed dust depositions. By analyzing the size distribution of dust deposition samples, we found that a major part of the deposited mass resulted from the deposition of dust particles with radii > 10 um. However, the models usually consider only particles with radii < 10 um.

We corrected this deficiency and conducted a year-long simulation using WRF-Chem. We found that the dust (primarily fine particles with radii < 3 m) reduces the downward SW radiation near the surface by 5-10%. Meanwhile, dust deposition (mostly coarse dust particles with radii > 6 m) imposes soiling losses of 12 to 36 % in different parts of the ME, assuming a weekly cleaning cycle.

Our findings unveil a complex interplay between dust size and its multifaceted impact on solar energy production. This novel insight could lead to optimized maintenance strategies and novel mitigation approaches tailored to the unique dust burden of the Middle East. Ultimately, this study aims to advance solar energy resource assessment and pave the way for enhanced photovoltaic efficiency in dust-prone regions.

How to cite: Mostamandi, S., Stenchikov, G., Balawi, A., Shevchenko, I., Kabakebji, D., and Altmann, T.: Assessment of the Impact of Coarse and Fine Dust on Solar Devices in the Middle East, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1776, https://doi.org/10.5194/egusphere-egu24-1776, 2024.

EGU24-1827 | PICO | AS3.9

Investigation of the mineralogical composition of desert dust particles during a transboundary pollution episode in the UK and implications for health effects  

Stavros Solomos, Christina Mitsakou, Samuel Thompson, Helen Macintyre, Karen Exley, Stuart Aldridge, Christos Zerefos, Nikolaos S. Bartsotas, Christina Kalogeri, and Christos Spyrou

Toxicological and epidemiological studies have supported links between desert dust particles and health impacts, such as worsened asthma, hospitalization for respiratory infections, and seasonal allergic rhinitis. Airborne desert dust particles could serve as a medium for interacting with chemicals on their surfaces, potentially enhancing the bioreactivity of fine particles during episodes of dust storms. The role of the different mineralogical composition (e.g. quarz, iron, feldspars) on the biological effects of mineral dust remains to be determined. In this work we analyze the severe dust event that affected the UK on 15 and 16 March 2022 in terms of the synoptic situation leading to this event, the spatiotemporal distribution of the dust plumes over UK and the chemical/mineralogical composition of the particles. We employ the METAL-WRF model to investigate the atmospheric properties and the quantification of particle concentrations in ambient air but also in dry and wet depositions of dust. The METAL-WRF model includes prognostic fields for ten (10) minerals: illite, kaolinite, smectite, calcite, quartz, feldspar, hematite, gypsum, phosphorus and iron. We also investigate the health impacts linked to the desert dust transport on the population in UK regions. Our results are discussed across similar findings at more frequently dust-affected regions such as the Mediterranean.  

Acknowledgment This study is partially supported by the Hellenic Foundation for Research and Innovation project Mineralogy of Dust Emissions and Impacts on Environment and Health (MegDeth - HFRI no. 703) and the project Bioclimatic urban design for the sustainability and resilience of the urban environment in the context of climate change (BIOASTY)

How to cite: Solomos, S., Mitsakou, C., Thompson, S., Macintyre, H., Exley, K., Aldridge, S., Zerefos, C., Bartsotas, N. S., Kalogeri, C., and Spyrou, C.: Investigation of the mineralogical composition of desert dust particles during a transboundary pollution episode in the UK and implications for health effects , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1827, https://doi.org/10.5194/egusphere-egu24-1827, 2024.

EGU24-2280 | ECS | PICO | AS3.9

Different orbital rhythms in loess grain-size records across the Chinese Loess Plateau 

Deai Zhao, Guoqiao Xiao, Qingzhen Hao, Shaohua Tian, Zhipeng Wu, Hao Lu, Gaowen Dai, Shuzhen Peng, Chunjv Huang, and Qiuzhen Yin

The thick loess-paleosol sequences on the Chinese Loess Plateau (CLP) are among the best terrestrial archives for the understanding of the global paleoenvironment and East Asian monsoon changes. In particular, orbital-scale variations characterized by major periodicities of ~100 kyr, ~40 kyr and ~20 kyr are recorded by various proxies in the loess, which is often suggested to reflect the orbital control on East Asian climate. However, whether these climate periods could be affected by the signals from the dust source areas remains unknown. Here we present the spectrum results of grain size records from the Baoji loess section spanning the past 400 ka in the southeastern part of the CLP, and compare with the previous results in the western CLP (to the west of the Liupanshan Mts.), including Gulang, Menyuan, Lanzhou, Linxia, Jingyuan loess sections, and loess sections in the eastern CLP (to the east of the Liupanshan Mts.), including Luochuan, Xifeng, Lantian, and Weinan sections. The results show that the dominant periods in different sections are spatially different, and the ~20-kyr precession cycle from the western CLP is significantly stronger than that in eastern CLP. Albeit dust accumulation rates in the Jingbian loess section from the eastern CLP are very high, the lack of precession signal suggests that high sedimentation rate is not the main factor for occurrence of precession cycle in grain size records. The results also suggest that the dust source areas for the eastern and western CLP are different, specifically, the loess deposits in western CLP were mainly sourced from the NE Tibetan Plateau, while the loess deposits in eastern CLP were significantly fed by the deserts to the north CLP (including deserts in Northern China and Southern Mongolia). As the dust production and transportation in NE Tibetan Plateau and the deserts to the north CLP were significantly driven by the ~20-kyr local summer insolation and the ~100-kyr ice age cycle, respectively, we argue that the climate cycle in loess grain size of the CLP indeed reflects the climate signals of their source areas, rather than the deposition areas. Our results suggest that caution should be taken when explaining the meaning of the loess grain size records.

How to cite: Zhao, D., Xiao, G., Hao, Q., Tian, S., Wu, Z., Lu, H., Dai, G., Peng, S., Huang, C., and Yin, Q.: Different orbital rhythms in loess grain-size records across the Chinese Loess Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2280, https://doi.org/10.5194/egusphere-egu24-2280, 2024.

EGU24-3106 | PICO | AS3.9 | Highlight

African dust transport and deposition modelling verified through a successful citizen science campaign in Finland   

Outi Meinander, Rostislav Kouznetsov, Andreas Uppstu, Mikhail Sofiev, Anu Kaakinen, Johanna Salminen, Laura Rontu, Andre Welti, Diana Francis, Ana A. Piedehierro, Pasi Heikkilä, Enna Heikkinen, and Ari Laaksonen

On 21–23 February 2021, dust from a sand and dust storm (SDS) in northern Africa was transported to Finland, north of 60°N. The episode was predicted 5 days in advance by the Finnish Meteorological Institute (FMI) global operational SILAM forecast (silam.fmi.fi), and its key features (e.g., spatial distribution of wet and dry deposition amounts and particle sizes) were confirmed and detailed by a retrospective analysis. SILAM is among the dust forecast models included in the Word Meteorological Organization Sand and Dust Storm Warning Advisory and Assessment System WMO SDS-WAS.  

Dust deposition was observed on 23 February over a large area in the Southern and Central Finland from 60°N to >63.8°N. The ground was covered with snow making dust more easily detectable. The coloured snow caused people to contact FMI asking what is happening. FMI launched a citizen science campaign on Saharan dust with the help of social media, and people were asked to report their observations and to collect dust-containing snow and to extract the dust according to the guidelines. The campaign gained wide national interest in television, radio, newspapers and social media, and resulted in success in receiving citizen samples from 525 locations, with one to over ten samples in each.

The amounts of deposition calculated from the citizen samples were found to be up to 1.1 g/m2 and such maximum amounts per unit area agree with the SILAM calculations. The SILAM model and particle magnetic properties confirmed that dust came from a wide Sahara and Sahel area, from 5000 km away. The median diameters of the dust particles were in the modes of <10 µm and >20 µm. The mineral composition was dominated by quartz, feldspars, and soft phyllosilicates such as micas and clay minerals.

To extract dust from snow, Meinander et al. (2023) protocol recommends: 1. Collect snow samples within one week of the deposition event to minimize post-deposition changes. 2. Evaporate snow under 75oC to preserve the magnectic properties (particles should not be subjected to temperatures higher than 90oC). 3. Keep the remaining particles in the container in which the evaporation took place (e.g., a sheet of aluminium folio on a large oven tray and evaporating the snow in the oven) to best preserve all the particle sizes. 

Reference: Meinander, O., Kouznetsov, R., Uppstu, A. et al. African dust transport and deposition modelling verified through a citizen science campaign in Finland. Sci Rep 13, 21379 (2023). https://doi.org/10.1038/s41598-023-46321-7. 

 

 

How to cite: Meinander, O., Kouznetsov, R., Uppstu, A., Sofiev, M., Kaakinen, A., Salminen, J., Rontu, L., Welti, A., Francis, D., A. Piedehierro, A., Heikkilä, P., Heikkinen, E., and Laaksonen, A.: African dust transport and deposition modelling verified through a successful citizen science campaign in Finland  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3106, https://doi.org/10.5194/egusphere-egu24-3106, 2024.

Dust storms are severe and disastrous weather events that typically occur in arid and semi-arid desertification areas. The frequent occurrences of spring dust storms in East Asia in recent years have drawn widespread attention in the context of the significant achievements in ecological management and sand prevention. Identifying the source and transport of dust storms in East Asia is key to comprehending the ecological environment and climate. In this study, the MODIS annual product MCD12C1 is used as labels to classify the land cover of Landsat 8/9 images using the Random Forest method in order to obtain the dynamic distribution of dust source areas. The land cover results are processed to the WRF model to provide the meteorological field, after which a Lagrangian transport model FLEXPART-WRF is used to simulate the horizontal and vertical transport of particles from five dust source regions in East Asia during the March 22, 2023 dust storm event. The source apportionments for regions on the transmission path of different dust sources are revealed by an online tracer-tagged of air quality model NAQPMS. The results show that the total area of the East Asian dust source regions in March 2023 is 1.5×106 km2. Cold high pressure from Siberia and the Mongolian cyclone are key synoptic situations for dust emission and transport from dust source areas. The Taklimakan Desert and the Tarim Basin mainly affect northwestern China. The Badain Jaran Desert and Horqin Sandy Land have a greater impact on northern China, with longer transmission distances, and can even affect southeast and Northeast China. The Gobi Desert affects northern China by influencing the dust source areas in Inner Mongolia. The vertical transport height is up to 500m from the ground. The PM2.5 source apportionments show that the Badain Jaran Desert contribution of Beijing-Tianjin-Hebei and its surrounding areas accounted for 45.5 %, while the Gobi Desert accounted for 1.4 %.

How to cite: Li, Y. and Wu, Q.: How dust sources affect downstream regions in East Asia during a dust storm event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3981, https://doi.org/10.5194/egusphere-egu24-3981, 2024.

EGU24-4003 | ECS | PICO | AS3.9

New insights into the atmospheric dust dynamics in the Carpathian and Wallachian Basin during MIS 1-MIS 2 

Zoran Perić, Helena Alexanderson, Slobodan Marković, Milica Radaković, Petar Krsmanović, and Cathal Ryan

Fine-grained windblown deposits, known as loess, in which fossil soils (palaeosols) are preserved, serve as excellent records of past climate. However, paleoclimate reconstruction studies on loess-palaeosol sequences (LPS) in Southeastern Europe have primarily focused on climate changes during the last one or two glacial-interglacial cycles. Surprisingly, little attention has been given to the climate of the current interglacial, the Holocene. This oversight may be attributed to the prevailing notion that, based on ice core and marine isotope records, the Holocene is considered a climatically stable period. Additionally, the scarcity of LPS with well-preserved Holocene loess has contributed to this lack of attention until now. Three recently discovered loess-palaeosol sequences in the Eastern Carpathian and the Wallachian Basins present fully preserved loess covering MIS 1-MIS 2 offering the potential to unveil new and detailed information about Holocene climate. In this study, we present initial results from two of these LPS: Kisiljevo (44°44′0'' N and 21°25′0'' E) in the Carpathian Basin, and Velika Vrbica (44°35’1.70’’N, 22°43’15.97’’E) in the Wallachian Basin. For both sequences, detailed optically stimulated luminescence (OSL) chronologies using 63-90 µm quartz have been constructed. Age models based on the OSL ages were constructed using the r.bacon software (Blaauw & Christen, 2011), following which dust accumulation rates (MAR) for the last approximately 30,000 years were calculated. The initial results from Kisiljevo reveal a significant loess accumulation during the Holocene, amounting to approximately 120 cm. The highest MARs were observed between 10 and 12 ka (10,000-8,000 BC) with a mean value of 148 g m2 a-1. A similar trend is evident at the Velika Vrbica LPS, where the average calculated MARs during the early Holocene (8 – 11.7 ka) were 189 g m2 a-1, showing a decreasing trend toward the later part of this period (3.1 – 8 ka) with average values reaching 132.1 m2 a-1. Interestingly, at this site, the mean MARs during Marine Isotope Stage 1 (MIS) were higher than during the cold, stadial MIS 2, where the recorded values averaged 177 g m2 a-1. These initial results suggest that the Holocene dust dynamics in this region was more variable than what generally accepted models suggest.

References: Blaauw & Christen (2011). Flexible paleoclimate age-depth models using an autoregressive gamma process. Bayesian Analysis, 6(3), 457–474.

How to cite: Perić, Z., Alexanderson, H., Marković, S., Radaković, M., Krsmanović, P., and Ryan, C.: New insights into the atmospheric dust dynamics in the Carpathian and Wallachian Basin during MIS 1-MIS 2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4003, https://doi.org/10.5194/egusphere-egu24-4003, 2024.

Colour is a fundamental morphological feature commonly documented during the description of loess layers and soils developed on loesses – both contemporary and fossil. These colours are typically identified directly in the field, matching specific hues from the Munsell Soil Colour Chart. However, this method is highly subjective, with accuracy hinging on the observer's expertise and weather conditions. Introducing digital spectrometers for colour analysis, conducted in the lab on powdered samples, enhances objectivity. This approach was applied to samples from the Middle-Upper Pleistocene loess-palaeosol sequences (L2-S1-L1-S0) in Ukraine's Dnieper basin.

The laboratory work aimed to pinpoint chromatic parameters that typify each loess layer, considering their distinct features and stratigraphic positions, as well as various soil horizons, each with unique degrees of pedogenic alteration. Key colour metrics included lightness (L*), redness (a*), yellowness (b*), chroma (c*), and the R-index. The resultant database of spectrophotometric data helps identify colour patterns characteristic of different sequence components.

Our analysis revealed considerable variation across all measured parameters, yet maintained the distinct coloration typical of loess and soils. We also created a digital colour record corresponding with the analogue Munsell scale, lending further objectivity to colour descriptions. Notably, digital colour identification often markedly differs from traditional, "analogue" methods. Applying RGB tuning, we devised models that realistically replicate colours observed in the field.

The documented chromatic parameters enable geological profile analysis in both vertical and spatial dimensions – following the Dnieper valley's sub-meridian and sub-latitudinal orientations across the river basin. These colour profiles mirror the diverse litho-, pedo-, and diagenetic processes across different genetic stages. Crucially, we identified diagnostic colour characteristics unique to primary loesses (L2 vs. L1), various soil types, their development stages (full-profile vs. reduced), and preservation forms (modern vs. ancient).

Thanks to the high resolution and sensitivity of our spectrophotometric analysis, we detected nuanced chromatic shifts, often abrupt. This revealed otherwise invisible erosional surfaces and concealed boundaries, shedding light on changes in loess lithology or the progression of pedogenic processes. The documented colour shifts illustrate the dynamic evolution of the natural environment, from loess accumulation (cold phases) to soil formation (warm periods).

It should be noted that primary loesses of varying ages, collected from different geological sites, which are primarily described as light yellow, show significant differences in the L*, a*, b*, c* parameters in light of spectrophotometric analyses. This variability aligns well with the findings of geochemical analyses.

Research carried out as part of the grant of National Science Centre, Poland as the project no. 2018/31/B/ST10/01507 entitled “Global, regional and local factors determining the palaeoclimatic and palaeoenvironmental record in the Ukrainian loess-soil sequences along the Dnieper River Valley - from the proximal areas to the distal periglacial zone”.

How to cite: Mroczek, P., Łanczont, M., and Komar, M.: Loess chromaticity as an environmental change recorder: spectrophotometric study of aeolian dust and its role in paleoclimate studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4619, https://doi.org/10.5194/egusphere-egu24-4619, 2024.

EGU24-4749 | PICO | AS3.9 | Highlight

Recent developments in dust electrification research  

Keri Nicoll and R. Giles Harrison

Electrification of dust in the atmosphere is abundant, observed by helicopter blades glowing from corona discharge in dusty environments, and sparks from barbed wire fences during the US Dust Bowl.  Electrification of particles in blowing sand, dust devils and dust storms can result from contact charging/triboelectrification during dust generation or through its atmospheric transport, causing particles to accumulate large amounts of charge on their surface.  Strong electrostatic forces can affect the lofting of dust particles from the ground, as well as the transport of dust particles, however the details of such effects are still largely unexplored.  The charging of dust particles, and separation of the charge by mechanical processes yields large electric fields (E-fields, up to tens of kV m1).  Satellite remote sensing of dust is based on measurements of electromagnetic wave propagation, which can be attenuated by large electric fields, thereby the accuracy of dust measurements can be affected by electric fields arising from charge separation in dusty environments. Such E-fields are also expected to alter the orientation of dust particles, changing the effective optical depth of dust layers, existing calculations for which assume randomly oriented particles.

Although the existence of dust electrification has been known about for over a century, the details of the electrification mechanisms, and impact of dust electrification on particle behaviour are not yet fully understood.  This is partly due to a lack of observations of coincident space charge, E-field and particle measurements in dusty regions, particularly at altitudes above the surface.  This presentation will discuss recent research in understanding dust electrification processes, including surface observations of dust electrification in the United Arab Emirates (UAE), and measurements of charge in high altitude dust layers above the surface.

How to cite: Nicoll, K. and Harrison, R. G.: Recent developments in dust electrification research , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4749, https://doi.org/10.5194/egusphere-egu24-4749, 2024.

EGU24-4799 | ECS | PICO | AS3.9

Modeling the Mercury Cycle in the Sea Ice Environment: A Buffer between the Polar Atmosphere and Ocean 

Shaojian Huang, Feiyue Wang, Tengfei Yuan, Zhengcheng Song, Peipei Wu, and Yanxu Zhang

Sea ice (including overlying snow) is a dynamic interface between the atmosphere and the ocean, influencing the mercury (Hg) cycling in polar oceans. However, a large-scale and process-based model for the Hg cycle in the sea ice environment is lacking, hampering our understanding of regional Hg budget and critical processes. Here, we develop a comprehensive model for the Hg cycle at the ocean–sea ice–atmosphere interface with constraints from observational polar cryospheric data. We find that seasonal patterns of average total Hg (THg) in snow are governed by snow thermodynamics and deposition, peaking in springtime (Arctic: 5.9 ng/L; Antarctic: 5.3 ng/L) and minimizing during ice formation (Arctic: 1.0 ng/L, Antarctic: 0.5 ng/L). Arctic and Antarctic sea ice exhibited THg concentration peaks in summer (0.25 ng/L) and spring (0.28 ng/L), respectively, governed by different snow Hg transmission pathways. Antarctic snow-ice formation facilitates Hg transfer to sea ice during spring, while in the Arctic, snow Hg is primarily moved through snowmelt. Overall, first-year sea ice acts as a buffer, receiving atmospheric Hg during ice growth and releasing it to the ocean in summer, influencing polar atmospheric and seawater Hg concentrations. Our model can assess climate change effects on polar Hg cycles and evaluate the Minamata Convention’s effectiveness for Arctic populations.

How to cite: Huang, S., Wang, F., Yuan, T., Song, Z., Wu, P., and Zhang, Y.: Modeling the Mercury Cycle in the Sea Ice Environment: A Buffer between the Polar Atmosphere and Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4799, https://doi.org/10.5194/egusphere-egu24-4799, 2024.

EGU24-5430 | PICO | AS3.9

A near-global multiyear climate data record of the fine-mode and coarse-mode components of atmospheric pure-dust 

Emmanouil Proestakis, Antonis Gkikas, Thanasis Georgiou, Anna Kampouri, Eleni Drakaki, Claire L. Ryder, Franco Marenco, Eleni Marinou, and Vassilis Amiridis

Dust aerosols play a key role in the Earth’s radiation budget, in climate system, environmental conditions, and human health. However, the complex role of dust depends not only on the physical and chemical properties, but in addition to the particle size distribution, spanning from less than 0.1 μm to more than 100 μm in diameter. Larger mineral dust particles are more efficiently removed through dry deposition close to the source regions and act more efficiently as CCN and/or IN than fine-mode dust particles, whereas fine dust particles are more prominent to long-range transport, resulting to degradation of air-quality and induced negative disorders on human health.
Here, a new four-dimensional, multiyear, and near-global climate data record of the submicrometer and supermicrometer (in terms of diameter) components of atmospheric pure-dust, is presented. The separation of the two modes of dust is based on a combination of (1) the total pure-dust product provided by the ESA-LIVAS database and (2) the supermicrometer-mode component of pure-dust provided by the first-step of the two-step POLIPHON technique, developed in the framework of EARLINET. The submicrometer-mode component of pure-dust is extracted as the residual between the LIVAS total pure-dust and the supermicrometer-mode component of pure-dust. The decoupling scheme is applied to CALIPSO observations at 532nm. The final products consist of the submicrometer-mode and supermicrometer-mode of atmospheric pure-dust, of quality-assured profiles of backscatter coefficient at 532nm, extinction coefficient at 532nm, and mass concentration. The datasets are established primarily with the original L2 horizontal (5 km) and vertical (60 m) resolution of CALIOP along the CALIPSO orbit-path, and secondly in averaged profiles of seasonal-temporal resolution, 1o×1o spatial resolution, and with the original vertical resolution of CALIPSO, between 70oS and 70oN and covering more than 15-years of Earth Observation (06/2006-12/2021).
The climate data record is unique with respect to a wide range of potential applications, including climatological, time-series, and trend analysis over extensive geographical domains and temporal periods, validation of atmospheric dust models and reanalysis datasets, assimilation activities, and investigation of the role of airborne dust on radiation and air quality.

How to cite: Proestakis, E., Gkikas, A., Georgiou, T., Kampouri, A., Drakaki, E., Ryder, C. L., Marenco, F., Marinou, E., and Amiridis, V.: A near-global multiyear climate data record of the fine-mode and coarse-mode components of atmospheric pure-dust, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5430, https://doi.org/10.5194/egusphere-egu24-5430, 2024.

EGU24-5573 | ECS | PICO | AS3.9

Stronger early-spring dust outbreaks across the Northern Hemispheric mid-latitudes in a warmer climate 

Yiting Wang, Yan Yu, Ji Nie, and Paul Ginoux

This research focuses on changes in early-spring dust emissions from Northern Hemispheric mid-latitudes, in the context of global warming. Our study was motivated by the abnormally early and strong dust storms across East Asia in March 2021 and March 2023. These two recent dust extremes opposed the decadal decline of East Asian dust activities. Past studies have attributed this dustiness decline to expanded vegetation cover and resultant weaker near-surface winds in April and May; while in March, dust source regions in the Northern Hemispheric mid-latitudes have been mainly covered by snow or frozen soil instead of vegetation. Inspired by the abnormally warm and snow-free conditions associated with both the 2021 and 2023 early-spring dust extremes, our study examines an alternative hypothesis on dust regimes over the Northern Hemispheric mid-latitudes: in a warmer climate, earlier snow melt may cause stronger early-spring dust outbreaks. Here, using multiple observational datasets and model simulations, we show a 10-35% increase in March dust emission across the East Asian, Central Asian and North American drylands, from the 1980s towards the end of the 21st century, bringing ~20% extra PM10 to Beijing and Denver. This hemispherical enhancement in early-spring dust emission is primarily caused by reduced snow cover in response to warming, and further promoted by dynamical coupling between snow, wind, and soil moisture changes. The increased amount of dust, a light absorbing aerosol, may in turn accelerate larger-scale snow melt when it deposits, thereby triggering positive feedbacks between snow melting, dust emission, and warming. Our findings call for adaptation to the anticipated stronger early-spring dust storms across the North Hemispheric mid-latitudes in the upcoming decades.

How to cite: Wang, Y., Yu, Y., Nie, J., and Ginoux, P.: Stronger early-spring dust outbreaks across the Northern Hemispheric mid-latitudes in a warmer climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5573, https://doi.org/10.5194/egusphere-egu24-5573, 2024.

EGU24-6384 | PICO | AS3.9

Trade-offs of simplified versus comprehensive representation of mineralogy when studying dust impacts on Earth’s climate systems 

Paul Ginoux, Qianqian Song, María Gonçalves Ageitos, Ron L. Miller, Vincenzo Obiso, and Carlos Pérez García-Pando

The intensity and direction of dust impacts on Earth’s climate systems depend on mineral composition. For example, the presence or absence of a few percent of iron oxides in dust will determine if dust is warming or cooling the atmosphere. Similarly, feldspar will enhance ice cloud formation, while acid gases in the atmosphere will react on the surface of dust calcite limiting acid rain. Still, most climate models use a simplified representation of dust mineralogy. They assume a fixed composition at emission which stays invariant during transport and removal. Such simplification assumes spatially and temporally constant physical and chemical properties of dust, and appears to provide satisfactory results when comparing some properties with observations. The trade-off is their lack of spatial gradients, which will fail to induce circulation, cloud and precipitation changes. The two reasons to omit mineral variations are the uncertainty of current atlases of soil mineral composition in arid regions, and, more practically, an improved runtime efficiency. The former reason is losing ground with the recent launch (July 2022) of a dedicated mission (NASA/JPL EMIT) to retrieve global soil mineralogy of dust sources at high spatial resolution.

While the EMIT science team is finalizing a satisfactory global map of mineral composition of dust sources, we analyzed the interaction of dust mineralogy on radiation and its impact on the fast temperature response using different representations of mineral composition from detailed and spatially varying to simplified and globally uniform, assuming different hematite contents and methods to calculate optical properties.  

Our results show that resolving dust mineralogy reduces dust absorption, and results in improved agreement with observation-based single scattering albedo (SSA), radiative fluxes from CERES (the Clouds and the Earth’s Radiant Energy System), and land surface temperature from CRU (Climatic Research Unit), compared to the baseline bulk dust model version. It also results in distinct radiative impacts on Earth’s climate over North Africa. From our 19-year simulation, we will show that it leads to a reduction of over 50% in net downward radiation at top of atmosphere (TOA) across the Sahara and an approximately 20% reduction over the Sahel. We will explain how the surface temperature response affects the monsoon flow from the Gulf of Guinea.

Interestingly, we find similar results by simply fixing the hematite content of dust to a globally uniform value of 0.9% by volume. We will discuss the underlying reasons for such results and show that they may be unrelated to the distribution of soil mineralogy. Still, an accurate representation of soil mineralogy is necessary to better understand dust impacts on the Earth’s climate systems.

How to cite: Ginoux, P., Song, Q., Gonçalves Ageitos, M., Miller, R. L., Obiso, V., and Pérez García-Pando, C.: Trade-offs of simplified versus comprehensive representation of mineralogy when studying dust impacts on Earth’s climate systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6384, https://doi.org/10.5194/egusphere-egu24-6384, 2024.

EGU24-7235 | ECS | PICO | AS3.9

Quantifying dust emission following wildfires on the global scale 

Xianglei Meng, Yan Yu, and Paul Ginoux

Wildfires can reduce vegetation cover and soil adhesivity, thus expanding bare grounds susceptible to wind erosion. Although in situ observations have confirmed dust emission following wildfires, a quantitative and mechanistic understanding of post-fire dust emissions is limited. Here, on the basis of satellite observations of active fires, aerosol abundance, vegetation cover and soil moisture from 2003 to 2020, we found that 91% and 54% of large wildfires are followed by reduced vegetation cover and enhanced dust emission, leaving intensive dust loadings for 1-25 days over normally dust-free regions. Furthermore, small wildfires, which naturally occur more widespread and frequently than large wildfires, lead to more considerable post-fire dust emissions, mostly global semi-arid regions. The occurrence and intensity of post-fire dust emission are regulated primarily by the extent of precedent wildfires and resultant vegetation anomalies, and modulated secondarily by pre-fire drought conditions. Despite the episodic nature of post-fire dust events, the amount of post-fire dust emission has shown an upward trend over the past two decades, especially over the Northern Hemispheric mid-latitudes, where droughts and wildfires are intensifying. These post-fire dust events impose greater socioeconomic and health impacts than dryland dust, due to the closer location of the former to populated areas. With an ongoing enhancement of extreme wildfires and concurrent droughts under global warming, our results emphasize the emerging importance of post-fire dust emissions on global and regional scales.

How to cite: Meng, X., Yu, Y., and Ginoux, P.: Quantifying dust emission following wildfires on the global scale, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7235, https://doi.org/10.5194/egusphere-egu24-7235, 2024.

EGU24-7871 | ECS | PICO | AS3.9

Wind erosion in Western Sahel : Quantifying the impact of land use and land management 

Paul-Alain Raynal, Caroline Pierre, Béatrice Marticorena, Jean-Louis Rajot, Abdourahmane Tall, Issa Faye, Diouma Cor Fall, Bineta Amar, Antoine Couedel, Gatien Falconnier, Jean-Alain Civil, Olivier Roupsard, and Sidy Sow

It is currently estimated that around 15% of the global mineral dust load comes from the Sahel. In this area, rainfed agriculture and livestock grazing play a crucial role in the livelihood of its rapidly growing population. Cropland is likely to be a main source of anthropogenic dust emissions in this region, as this land use type can favor wind erosion if land management deprives the soil of vegetation cover.

Yet, in situ measurements of wind erosion fluxes are scarce in the Sahel, and usually monitor only one type of land use and an associated land management (eg. whether or not to harvest crop residues, intercropping, etc.). Thus, there is room to improve the assessment of the Sahelian anthropogenic contribution to the global dust load, especially through a regional modelling approach relying on field measurements.

In this study, we combined in situ measurements from Sahelian Senegal with a modelling approach to estimate the effect of the main Sahelian land uses on wind erosion. Furthermore, we monitored contrasting land management per land use, representative of the last decades (1960-2020). Here we present the results for one groundnut field over two years (2020-2021), four different fallowed fields over one year (2022/2023), four millet fields over one year (2023/2024). All 1ha-plots were located near the town of Bambey in central Senegal (Groundnut Basin). The observations included sand-traps monitoring (for each 1ha-plot, 5 masts of 5 « Modified Wilson And Cooke » or MWAC sand traps each; collected every 2 weeks), meteorological data (e.g., wind and temperature profiles, and rainfall; at 5-minutes resolution) and vegetation monitoring (aboveground biomass, surface cover, height; weekly to monthly).

For each land use and land management, we estimated the aerodynamic surface roughness length and the wind friction velocity to simulate the horizontal flux of aeolian sediments using a dedicated model (the Dust Production Model – DPM). We then combined the wind erosion model (DPM) with vegetation models (STEP for fallows and STICS for crops) to simulate the vegetation growth and the associated horizontal flux of aeolian sediment. These simulations are compared to the in situ monitoring from the sand traps. Finally, we used ERA5 meteorological time series from the ECMWF to simulate the horizontal flux for the 1960–2020 period over a typical plot from the study area, for different realistic scenarios of land uses and land management.

Our study revealed the variability of wind erosion horizontal flux for the main Sahelian land use types (400 kg/m/yr for bare soil, 200 kg/m/yr for cropland, less than 10kg/m/yr for fallows), as well as slighter differences related to land management for a same land use. These results help to understand the link between wind erosion and agropastoral practices in Sahelian conditions over multi-decadal periods of time.

How to cite: Raynal, P.-A., Pierre, C., Marticorena, B., Rajot, J.-L., Tall, A., Faye, I., Fall, D. C., Amar, B., Couedel, A., Falconnier, G., Civil, J.-A., Roupsard, O., and Sow, S.: Wind erosion in Western Sahel : Quantifying the impact of land use and land management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7871, https://doi.org/10.5194/egusphere-egu24-7871, 2024.

EGU24-8628 | PICO | AS3.9 | Highlight

Impact of Saharan mineral dust layers on cloud formation and cloud properties 

Silke Gross, Martin Wirth, and Florian Ewald

Mineral dust contributes strongly to the global aerosol load. The largest source region of mineral dust is the Sahara. But mineral dust cannot be treated as a regional phenomenon. Once lifted in the air, it can be transported thousands of kilometers over several days. The main transport pathway spans over the Atlantic Ocean from Africa towards the Caribbean; with its peak season during the summer months. But transatlantic dust transport can also happen during wintertime, however with less frequency. In addition, the dust particles can be transported northward over the Mediterranean and Europe. In rare events, it can even reach the Arctic region. All the way during transport the dust layer has an impact on the Earth’s radiation budget, by direct interaction with the incoming and outgoing radiation by scattering and absorption, and by indirect interaction as dust can impact cloud formation and cloud properties.

To study long-range transported Saharan dust as well as the dust’s impact on cloud formation and properties, airborne lidar measurements with the WALES lidar system onboard the German research aircraft HALO have been performed over the western sub-tropical North-Atlantic Ocean during NARVAL-II in August 2016 and EUREC4A in January/February 2020. We observed dust transport during the summertime in the clearly separated and well-defined Saharan Air Layer (SAL) as well as during wintertime, when dust transport happens at lower altitudes and the SAL is less separated. In addition, we were also able to capture an event of dust long-range transport into the Arctic during the HALO-(AC)3 campaign in spring 2022. From our measurements we could show, that small amount of water vapor embedded in the SAL has a strong impact on the atmospheric stability and thus also impacts the formation and properties of clouds during long-range transport. Additionally, dust particles are known to act as ice nuclei and with that lead to ice formation at different environmental conditions, changing the ice cloud’s microphysical properties.

In our presentation we will give an overview of the performed WALES measurements. We use these measurements to study dust long-range transport and its impact on the atmospheric stability, cloud formation and cloud properties.

How to cite: Gross, S., Wirth, M., and Ewald, F.: Impact of Saharan mineral dust layers on cloud formation and cloud properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8628, https://doi.org/10.5194/egusphere-egu24-8628, 2024.

EGU24-8749 | ECS | PICO | AS3.9

Influence of aerosol deposition on snowpack evolution in simulations with the ORCHIDEE land surface model  

Sujith Krishnakumar, Samuel Albani, Martin Ménégoz, Catherine Ottlé, and Yves Balkanski

Simulating seasonal snow with state-of-the-art global general circulation models (GCMs) is still challenging. Snow provides fresh water to billions of people and plays an important role in the energy budget of the earth through albedo, which affects not only local but also remote and global climate/hydrological patterns. Therefore, changes in snow amount and length of the season are crucial when investigating climate variability.  One key aspect often overlooked in GCMs is the inclusion of Light Absorbing Particles (LAPs) in snow simulations. LAPs dramatically reduce snow albedo, particularly for visible solar radiation, leading to considerable implications for climate modeling. The intention is to lay the foundations for addressing the issues across different climate conditions through simulations, by adding the snow darkening effect to a multilayered intermediate complexity scheme within ORCHIDEE, the land surface model embedded in the IPSL Earth System Model.

LAPs are commonly deposited on the surface of fresh snow and progressively become embedded into deeper layers of the snowpack.  The LAP species taken into account include four log-normal modes of dust, soot, and organic carbons. These tracers allow for the movement of LAPs through different layers of the snowpack, adjusting with snow accumulation or melting. In order to simulate the movement of LAPs, ORCHIDEE has been enhanced with a tracer flow mechanism that carry LAPs from the top snow layer following deposition and move through various layers as snow thickens or flushes with meltwater flow. Our approach to snow albedo deviates from the default method in ORCHIDEE as a function of snow aging through an exponential decay function with dependence on the degree of water saturation and the occurrence of fresh snow deposition. Instead, it integrates the Warren and Wiscombe snow radiative transfer scheme with Kokhanovsky's single scatter properties of snow crystals and the optical properties of LAPs to compute the albedo of impure snow. This study conducted site-level offline ORCHIDEE simulations using observed atmospheric conditions and MERRA2 aerosol deposition data. The integration of LAPs and related processes has led to improved simulations of seasonal snow, achieving more realistic representations of snow albedo compared to pure snow. Our results also show that LAPs play an important role in determining the local snow season length.

How to cite: Krishnakumar, S., Albani, S., Ménégoz, M., Ottlé, C., and Balkanski, Y.: Influence of aerosol deposition on snowpack evolution in simulations with the ORCHIDEE land surface model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8749, https://doi.org/10.5194/egusphere-egu24-8749, 2024.

EGU24-8796 | PICO | AS3.9 | Highlight

Potential environmental impacts of natural and mining related dust in Greenland and Svalbard 

Jens Søndergaard, Christian Frigaard Rasmussen, Hanne Hvidtfeldt Christiansen, and Christian Juncher Jørgensen

Dispersion and deposition of mineral dust from natural or anthropogenic sources such as proglacial rivers, mines and haul roads can have both positive and negative effects on the environment, depending on the geochemical and mineralogical composition of the dust. Some elements in dust may act as nutrients for, for example, plants, lichens and soil communities, while other elements may act as pollutants with negative impacts on growth or reproduction or cause diseases in animals and plants.

To support the sustainable development of environmentally safe mining in sensitive Arctic land areas and reduce airborne environmental pollution, an improved understanding of processes leading to the dispersion of mineral dust in a changing Arctic is needed. This involves improved methods for monitoring dust emissions and dust deposition in a cold environment as well as analytical tools and methods to source trace and differentiate between natural and mining related dust. Accurate identification of individual dust sources subsequently makes it possible to mitigate emissions and target the regulation of mining activities towards these sources.

In this study, we present preliminary results from two new arctic dust monitoring stations in West Greenland and Svalbard. In Kangerlussuaq, West Greenland, mineral dust has been collected using a wide array of passive and active dust samplers, including a continuously operated high volume dust sampler at a weekly sampling frequency over 2022/2023. In Svalbard, mineral dust has been collected in Adventdalen using passive dust collectors in a transect along the haul road to the active coal mines. Samples have been collected on a weekly sampling frequency in the period September to November 2023 to investigate the temporal and spatial variations in dust deposition rates, as well as the impact of haul road traffic relative to the natural dust emissions and depositions.

How to cite: Søndergaard, J., Frigaard Rasmussen, C., Hvidtfeldt Christiansen, H., and Juncher Jørgensen, C.: Potential environmental impacts of natural and mining related dust in Greenland and Svalbard, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8796, https://doi.org/10.5194/egusphere-egu24-8796, 2024.

EGU24-9570 | ECS | PICO | AS3.9

On the importance of Mongolian cyclones to East Asian dust storm activities 

Feifei Mu and Stephanie Fiedler

Desert-dust aerosols affect the climate, human health, and socio-ecomomic activities. In East Asia, the passage of Mongolian cyclones induce dust-emitting winds in the Gobi Desert. While cyclones are known as driver of dust outbreaks, the relative contribution of Mongolian cyclones to the total East Asian dust emission amount and the dust aerosol optical depth has not been quantified from a climatological perspective. To address this gap in knowledge, the present study systematically assesses the co-occurrence of Mongolian cyclones and dust aerosols in East Asia for 2001 to 2022. This study pairs output of the automated detection algorithm for extra-tropical cyclones in ERA5 re-analysis from the ETH Zürich with data for dust aerosols from multiple sources. Through the use of multiple dust data sets, we account for the substantial data uncertainty for dust aerosols in term of the spatial pattern and the absolute emission magnitudes, which can differ by an order of magnitude. The climatological analysis shows a high frequency and intensity for the occurrence of Mongolian cyclones in the lee of the Altai-Sayan Mountains (100Eo–125Eo and 37No–53No), favouring the seasonal dust activity in the Gobi Desert. The results highlight a tight constraint on the mean Mongolian cyclone contribution to the total dust emission amount of 39-47% in the spatial mean for spring based on data from MERRA-2 and Wu et. al. (2022), despite substantial differences in the absolute emission magnitudes. The dust-laden air from the Gobi Desert during such events typically moves southeastwards over China in the wake of the cyclones affecting the aerosol optical depth. For southern Mongolia and Northeastern China (105Eo–130Eo and 37No–52No), we estimate 34% (MERRA-2) to 43% (CAMS) of the dust aerosol optical depth (DOD) being associated with Mongolian cyclones. A decrease in dust emission fluxes and dust storm frequencies have been reported for Northern China in the past two decades and is thought to be connected to decreasing near-surface winds. Our results point to a negative trend in the dust emission flux and DOD associated with the occurrence of Mongolian cyclones. However, our results also point to the co-occurrence of particularly intense Mongolian cyclones, measured by the 99th percentile of the wind speed, with exceptionally strong dust storms in recent years, e.g., in March 2021, despite a mean negative trend in dust activity. Given the connection of Mongolian cyclone to high-impact dust storms in East Asia, the potential future development of such events should be addressed in future research.

How to cite: Mu, F. and Fiedler, S.: On the importance of Mongolian cyclones to East Asian dust storm activities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9570, https://doi.org/10.5194/egusphere-egu24-9570, 2024.

Water-soluble organic carbon (WSOC) and its brown carbon (BrC) components in the cryosphere have significant impact on the biogeochemistry cycling and snow/ice surface energy balance. In this study, snow samples were collected across regional area of northern Xinjiang, China to investigate the chemical composition, optical properties, and radiative forcing (RF) of WSOC. Based on the geographic differences and proximity of emission sources, the sampling sites were grouped as urban (U), remote (R), and soil-influenced (S) sites, for which WSOC concentrations were measured as 1968±953 ng g-1 (U), 885±328 ng g-1 (R), and 2082±1438 ng g-1 (S), respectively. The S sites showed the higher mass absorption coefficients at 365 nm (MAC365) of 0.94±0.31 m2 g-1 compared to those of U and R sites (0.39±0.11 m2 g-1 and 0.38±0.12 m2 g-1, respectively). Molecular-level characterization of WSOC using high-resolution mass spectrometry (HRMS) provided further insights into chemical differences among samples. Specifically, much more reduced S-containing species with high degree of unsaturation and aromaticity were identified in U samples, suggesting an anthropogenic source. Aliphatic/proteins-like species showed highest contribution in R samples, indicating their biogenic origin. The WSOC components from S samples showed high oxygenation and saturation levels. The WSOC-induced RF were estimated as 0.04 to 0.59 W m-2, which contribute up to 16% of that caused by BC, demonstrating the important influences of WSOC on the snow energy budget. Furthermore, the molecular composition and light-absorbing properties of BrC chromophores were unraveled by application of a high-performance liquid chromatography (HPLC) coupled to photodiode array (PDA) detector and HRMS. The chromophores were classified into five major types, i.e., (1) phenolic/lignin-derived compounds, (2) flavonoids, (3) nitroaromatics, (4) oxygenated aromatics, and (5) other chromophores. Identified chromophores account for ~23% – 64% of the total light absorption measured by the PDA detector in the wavelengths of 300 – 370 nm. In the representative U and R samples, oxygenated aromatics and nitroaromatics dominate the total absorbance. Phenolic/lignin-derived compounds are the most light-absorbing species in the S sample. Chromophores in two remote samples exhibit ultraviolet-visible features distinct from other samples, which are attributed to flavonoids. Identification of individual chromophores and quantitative analysis of their optical properties are helpful for elucidating the roles of BrC in snow radiative balance and photochemistry.

How to cite: Zhou, Y., Wang, X., and Laskin, A.: Molecular composition, optical properties, and radiative forcing of water-soluble brown carbon in seasonal snow samples from northern Xinjiang, China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9995, https://doi.org/10.5194/egusphere-egu24-9995, 2024.

EGU24-10547 | ECS | PICO | AS3.9

Development of a dusty cirrus calendar based on satellite data 

Samaneh Moradikian, Sanaz Moghim, and Gholam Ali Hoshyaripour

Mineral dust particles have the potential to serve as natural nuclei for cirrus cloud formation in the upper troposphere. Several studies demonstrate that dust aerosol plays a pivotal role in initiating cirrus clouds and forming extended optically thick cirrocumulus decks known as “dusty cirrus”. Despite this, our ability to accurately identify and predict these climatically significant clouds is still limited. In this work, we propose an algorithm to identify dusty cirrus clouds based on satellite data over the Aral Sea region between 2006 and 2021. The algorithm uses the CALIOP Vertical Feature Mask (VFM) to verify the coexistence of dust particles and cirrus clouds and determine the occurrence of dusty-cirrus. To enhance the accuracy of the algorithm, temperature obtained from an external source (the GEOS-5 data product supplied to CALIPSO) is also incorporated as a constraint for cirrus cloud identification. A random selection of identified dusty cirrus events (5% of the data, 90 events) is cross-validated against other data sources including cloud top temperature (MODIS), cloud top height (MODIS), and AOD (MODIS and VIIRS). The cross-validation confirms approximately 97% of the events to be associated with dusty-cirrus. This confirms that the developed algorithm can be used for developing a dusty cirrus calendar using available CALIOP data. This calendar reveals different facts about the dusty-cirrus occurrence in the study area. Out of the 4407 available samples, 2709 cirrus cloud events are identified, with approximately 65% (1790 events) of them being associated with dusty cirrus. The average values obtained for summer, fall, winter, and spring are 54%, 63%, 66% and 75%, respectively. Annual and seasonal trend analysis reveals different increasing rates for this region. Despite the important uncertainties, our analysis and results suggest that the proposed algorithm can be used for first-order identification and statistical analysis of dusty cirrus.

How to cite: Moradikian, S., Moghim, S., and Hoshyaripour, G. A.: Development of a dusty cirrus calendar based on satellite data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10547, https://doi.org/10.5194/egusphere-egu24-10547, 2024.

EGU24-11462 | ECS | PICO | AS3.9

Seasonal effects of wind-blown dust emissions on size-resolved aerosol acidity over the U.S 

Stylianos Kakavas, Evangelia Siouti, Athanasios Nenes, and Spyros Pandis

Wind-blown dust emitted by the Earth’s surface is one of the major sources of dust emissions especially in non-vegetated areas like deserts and can affect both climate and human health. Acidity is an important property of atmospheric aerosols impacting a series of related processes and can be affected by these emissions of alkaline dust. In this work, we use a wind-blown dust emissions model to quantify the wind-blown dust emissions over the continental United States during February and July 2017. The modeling domain covers a region of 4752 × 2952 km2 including northern Mexico and southern Canada with a horizontal grid resolution of 36 × 36 km. Then, the hybrid version of aerosol dynamics in PMCAMx (Particulate Matter Comprehensive Air-quality Model with Extensions) chemical transport model is used to simulate size-resolved aerosol acidity. In this version of PMCAMx for fine (PM1) particles, bulk equilibrium is assumed, while for larger particles a dynamic model is used to simulate the mass transfer to each size section. Two cases of simulations are performed. The first is the base case simulation and includes the wind-blown dust emissions for both months. The second one neglects these emissions in order to study their effects on aerosol acidity during a wintertime and a summertime period as a function of particle size and altitude.

How to cite: Kakavas, S., Siouti, E., Nenes, A., and Pandis, S.: Seasonal effects of wind-blown dust emissions on size-resolved aerosol acidity over the U.S, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11462, https://doi.org/10.5194/egusphere-egu24-11462, 2024.

EGU24-11544 | ECS | PICO | AS3.9

Abundance of giant mineral dust particles: Insights from measured emitted dust size distributions during the J-WADI campaign 

Hannah Meyer, Andres Alastuey, Sylvain Dupont, Vicken Etyemezian, Jessica Girdwood, Cristina González-Flórez, Adolfo González-Romero, Tareq Hussein, Mark Irvine, Konrad Kandler, Peter Knippertz, Ottmar Möhler, George Nikolich, Xavier Querol, Chris Stopford, Franziska Vogel, Frederik Weis, Andreas Wieser, Carlos Pérez García-Pando, and Martina Klose

Gaining a precise understanding of the particle size distribution (PSD) of mineral dust at emission is critical to assess its climate impacts. Despite its importance, comprehensive measurements at dust sources remain scarce and usually neglect part of the super-coarse (particle diameter d between 10 and 62.5 μm) and the entire giant (d > 62.5 μm) particle size ranges. Measurements in those size ranges are particularly challenging due to expected relatively low number concentrations and low sampling efficiencies of instrument inlets.

This study aims to better constrain the abundance of super-coarse and giant dust at emission as part of the Jordan Wind erosion And Dust Investigation (J-WADI, https://www.imk-tro.kit.edu/11800.php) field campaign conducted north of Wadi Rum in Jordan in September 2022. The goal of J-WADI is to improve our fundamental understanding of the emission of desert dust, in particular its full-range size distribution and mineralogical composition.

To capture the dust PSD across the entire size spectrum, we deployed multiple aerosol spectrometers, including active, passive, and open-path devices, such that in combination, a size range from approximately 0.4 to 200 μm was covered. Here we investigate the variability of the PSD in the super-coarse and giant ranges from observed dust events, address instrumental uncertainties and the impact of different inlets on the resulting PSDs. Our preliminary results reveal a mass concentration peak at around 30 μm, potentially limited toward larger sizes by substantially reduced inlet efficiencies. Giant dust particles were generally detected during active dust emission starting from friction velocities larger than around 0.2 m s-1.

Based on our results, we will investigate the mechanisms facilitating super-coarse and giant dust particle emission and transport. Quantifying the conditions for and the amount of super-coarse and giant dust at emission will lay the foundation to incorporate its impacts in weather and climate models.

How to cite: Meyer, H., Alastuey, A., Dupont, S., Etyemezian, V., Girdwood, J., González-Flórez, C., González-Romero, A., Hussein, T., Irvine, M., Kandler, K., Knippertz, P., Möhler, O., Nikolich, G., Querol, X., Stopford, C., Vogel, F., Weis, F., Wieser, A., Pérez García-Pando, C., and Klose, M.: Abundance of giant mineral dust particles: Insights from measured emitted dust size distributions during the J-WADI campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11544, https://doi.org/10.5194/egusphere-egu24-11544, 2024.

EGU24-12203 | ECS | PICO | AS3.9

Black Carbon and Dust in the snow of Chilean Central Andes: From albedo reductions to radiative forcing 

Maria Florencia Ruggeri, Ximena Fadic, Gonzalo Barcaza, and Francisco Cereceda-Balic

The cryosphere, a vital component of the Earth's climate system, holds substantial importance in both the hydrological cycle and the energy balance. Current apprehension turns around alterations in the cryosphere linked to the reduction in Surface Snow Albedo (SSA).

The decrease in SSA is primarily attributed to the presence of light-absorbing particles (LAPs) and the growth of snow grain size (SGS). The quantitative assessment of these SSA reductions' climatic impact is reflected through their Radiative Forcing (RF), indicating the change they induce in the net radiative flux at the tropopause or the top of the atmosphere. LAPs, mainly composed of Black Carbon (BC) and Mineral Dust (MD), contribute to albedo reduction at visible wavelengths. BC originates from the incomplete combustion of fossil fuels and biomass, while MD primarily emanates from arid and semi-arid regions with low vegetation cover. Precise RF calculations resulting from SSA reductions gain significance, particularly in regions where snow cover governs freshwater availability. Chile exemplifies such a concern, possessing the largest portion of the Andean cryosphere, highly responsive to climate change. This has significant implications for water resources, impacting freshwater availability for Chile's residents and key economic activities.

To quantify the Radiative Forcing RF generated by LAPs in the Chilean Central Andes, snow samples were collected at Portillo, from 2017 to 2022. NUNATAK-1 is a portable, flexible, collaborative scientific platform belonging to the Centre for Environmental Technologies (CETAM-UTFSM), specially designed for research campaigns under extreme conditions, equipped with different automatic and real-time monitoring instruments to measure meteorology, net albedo, solar radiation, gases and aerosols, among others. The samples underwent analysis to determine BC and MD concentrations, following the methodologies outlined in Cereceda-Balic et al. (2022). Snow albedo was modeled using the SNow, ICe, and Aerosol Radiation (SNICAR). Evaluating the singular and combined effects of LAPs, snow albedo was simulated for four scenarios: clean snow (without LAPs), BC only, dust only, and BC + dust. RF represents the variance in absorption between LAP-influenced scenarios and clean snow. For RF calculation, measured solar irradiance specific to each sampling date at the designated site was used. BC concentrations ranged from 2.6 to 717.2 ng g-1, while MD concentrations varied between 1.6 and 181.3 mg kg-1, leading to SSA reductions of up to 21% relative to clean snow. Notably, it was observed that the absorption produced by BC and MD could be comparable, underscoring the significant role of MD in this semiarid location. Moreover, even with relatively moderate or low LAP concentrations in the snow, substantial RF values are generated, emphasizing the heightened climatic influence of LAPs in the region.

Acknowledgments: ANID-Fondecyt Projects 11220525 and 1221526, ANID ANILLO ACT210021, FOVI 230167.

How to cite: Ruggeri, M. F., Fadic, X., Barcaza, G., and Cereceda-Balic, F.: Black Carbon and Dust in the snow of Chilean Central Andes: From albedo reductions to radiative forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12203, https://doi.org/10.5194/egusphere-egu24-12203, 2024.

EGU24-12289 | ECS | PICO | AS3.9

Image-based nowcasting of dust storms by predicting SEVIRI desert dust RGB composites 

Kilian Hermes, John Marsham, Martina Klose, Franco Marenco, Melissa Brooks, and Massimo Bollasina

Dust storms are frequent high-impact weather phenomena that directly impact human life, e.g., by disrupting land and air traffic, posing health threats, and affecting energy delivery from solar-energy systems. Timely and precise prediction of these phenomena is crucial to mitigate negative impacts.

Currently operational numerical weather prediction (NWP) models struggle to reliably reproduce or resolve dynamics which lead to the formation of convective dust storms, making short-term forecasts based on observations (“nowcasts”) particularly valuable. Nowcasting can provide greater skill than NWP on short time-scales, can be frequently updated, and has the potential to predict phenomena that currently operational NWP models do not reproduce.  However, despite routine high frequency and high resolution observations from satellites, as of January 2024, no nowcast of dust storms is available.

In this study, we present an image-based nowcasting approach for dust storms using the SEVIRI desert dust RGB composite. We create nowcasts of this RGB composite for a large domain over North Africa by adapting established optical-flow-based methods as well as a machine learning approach based on a U-net. We show that our nowcasts can predict phenomena such as convectively generated dust storms (“haboobs”) which currently operational NWP may not reliably reproduce. Furthermore, we show that a machine learning model offers crucial advantages over optical-flow-based nowcasting tools for the application of predicting complete RGB images.

Our approach therefore provides a valuable tool that could be used in operational forecasting to improve the prediction of dust storms, and indeed other weather events. Due to the technical similarity of RGB composite imagery from geostationary satellites, this approach could also be adapted to nowcast other RGB composites, such as those for ash, or convective storms.

How to cite: Hermes, K., Marsham, J., Klose, M., Marenco, F., Brooks, M., and Bollasina, M.: Image-based nowcasting of dust storms by predicting SEVIRI desert dust RGB composites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12289, https://doi.org/10.5194/egusphere-egu24-12289, 2024.

Two billion tons of dust are annually transported in our atmosphere all around the world. High latitudes include active desert regions with at least 5 % production of the global atmospheric dust. Active High Latitude Dust (HLD) sources cover > 1,600,000 km2 and are located in both the Northern (Iceland, Alaska, Canada, Greenland, Svalbard, North Eurasia, and Scandinavia) and Southern (Antarctica, Patagonia, New Zealand) Hemispheres. Recent studies have shown that HLD travels several thousands of km inside the Arctic and > 3,500 km towards Europe. In Polar Regions, HLD was recognized as an important climate driver in the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate in 2019. In situ HLD measurements are sparse, but there is increasing number of research groups investigating HLD and its impacts on climate in terms of effects on cryosphere, cloud properties and marine environment.

Long-term dust in situ measurements conducted in Arctic deserts of Iceland and Antarctic deserts of Eastern Antarctic Peninsula in 2018-2023 revealed some of the most severe dust storms in terms of particulate matter (PM) concentrations. While one-minute PM10 concentrations is Iceland exceeded 50,000 ugm-3, hourly PM10 means in James Ross Island, Antarctica exceeded 300 ugm-3 in 2021-22. The largest HLD field campaign was organized in Iceland in 2021 where 11 international institutions with > 70 instruments and 12 m tower conducted dust measurements (Barcelona Supercomputing Centre, Darmstadt, Berlin and Karlsruhe Universities, NASA, Czech University of Life sciences, Agricultural University of Iceland etc.). Additionally, examples of aerosol measurements from Svalbard and Greenland will be shown. There are newly two online models (DREAM, SILAM) providing daily operational dust forecasts of HLD. DREAM is first operational dust forecast for Icelandic dust available at the World Meteorological Organization Sand/Dust Storm Warning Advisory and Assessment System (WMO SDS-WAS). SILAM from the Finnish Meteorological Institute provides HLD forecast for both circumpolar regions. 

Icelandic dust has impacts on atmosphere, cryosphere, marine and terrestrial environments. It decreases albedo of both glacial ice/snow similarly as Black Carbon,  as well as albedo of mixed phase clouds via reduction in supercooled water content. There is also an evidence that volcanic dust particles scavenge efficiently SO2 and NO2 to form sulphites/sulfates and nitrous acid. High concentrations of volcanic dust and Eyjafjallajokull ash were associated with up to 20% decline in ozone concentrations in 2010. In marine environment, Icelandic dust with high total Fe content (10-13 wt%) and the initial Fe solubility of 0.08-0.6%, can impact primary productivity and nitrogen fixation in the N Atlantic Ocean, leading to additional carbon uptake.

Sand and dust storms, including HLD, were identified as a hazard that affects 11 of the 17 Sustainable Development Goals. HLD research community is growing and Icelandic Aerosol and Dust Association (IceDust) has > 110 members from 57 institutions in 22 countries (https://icedustblog.wordpress.com, including references to this abstract). IceDust became new member aerosol association of the European Aerosol Assembly in 2022. New UArctic Thematic Network on HLD was established in 2023.   

How to cite: Dagsson Waldhauserova, P., Meinander, O., and members, I.: High Latitude Dust (HLD) measurements in Iceland, Antarctica, Svalbard, and Greenland, including HLD impacts on climate and HLD networking, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13103, https://doi.org/10.5194/egusphere-egu24-13103, 2024.

EGU24-13462 | ECS | PICO | AS3.9

Local anthropogenic factors contributing to constrasting glacier response in two mountain glaciers, located in Central Andes, Chile 

Felipe McCracken, María Florencia Ruggeri, Gonzalo Barcaza, Ximena Fadic, and Francisco Cereceda-Balic

Contrasting behaviour of neighbouring mountain glaciers, sharing similar mass balance gradients, have been observed, suggesting the influence of local anthropogenic factors altering the surface energy balance and then explaining larger down-wasting trends in glacier response. It is in this context that for this work the comparison of two contrasting glaciers was used to analyze these differences: considering the Paloma Norte Glacier (PNG), exposed to anthropogenic emissions from local mining activities, and the Yeso Glacier (YG), isolated of these sources. The objective of this research is to combine the remote analysis of light-absorbing particles, such as Black Carbon (BC), Organic Carbon (OC), as well as the estimation of area and albedo, together with the analysis of local climatic trends of each glacier according gridded data, in order to evaluate their differences and the influence of each of these parameters on the surface variation of each glacier.

We determined glacier shrinkage, interannual albedo reduction and black carbon estimates using satellite images over the last 22 years for the Paloma Norte and Yeso glaciers. The results show that in the range 2000-2022, the GPN experienced a 27.11% greater surface loss than the GY, 83.49% higher albedo change rates, and almost 23 times higher BC+OC concentrations compared to the GY. Furthermore, the multivariate regression analysis identified that the most influential parameters was BC-OC, which is consistent with the disparities in glacial retreat observed in this period.

These results are part of an ongoing research, where, in addition, it is intended to contrast these values with measured data at ground stations, where we will use the data from NUNATAK-1 (-32,844, -70,129) and 2 (- 33,665, -70,086) refuge laboratories in the Central Andes. NUNATAK-1 is a portable, flexible, collaborative scientific platform belonging to CETAM, specially designed for research campaigns under extreme conditions equipped with different automatic and real-time monitoring instruments to measure meteorology, net albedo, solar radiation, gases and aerosols, among others. Which are parameters that will also be used to compare with glacial ablation and radiative transfer models, to evaluate the scenarios of albedo change under a pristine environment and another under the scenario of aerosol deposition on the surfaces of the glaciers of interest. All the above mentioned is being carried out to determine to whether these differences are purely due to the orientation of each glacier or the local anthropogenic influence to which they are exposed, and thus decouple the natural effect of climate change from the local anthropogenic effect.

In summary, the results of this work will aim to guide decision-makers, to guarantee greater protection and awareness of the effects that local emissions may (or may not) have on the conservation of these important reservoirs of drinking water, which will allow for a decoupling of the influence and/or impact of local anthropogenic activity from the natural effect of climate change.

Acknowledgments: This research has been carried out with the financial support of CETAM-UTFSM, and the ANID projects: Fondecyt Initiation 11220525, Fondecyt Regular N° 1221526, ANID Anillo ACONCAGUA Project N°ACT210021 and FOVI230167.

How to cite: McCracken, F., Ruggeri, M. F., Barcaza, G., Fadic, X., and Cereceda-Balic, F.: Local anthropogenic factors contributing to constrasting glacier response in two mountain glaciers, located in Central Andes, Chile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13462, https://doi.org/10.5194/egusphere-egu24-13462, 2024.

EGU24-14539 | ECS | PICO | AS3.9

Exploring the effects of mineral dust acidification on oxidative potential and limiting nutrient solubility 

Andrea Baccarini, Carolina Molina, Christos Kaltsonoudis, Katerina Seitanide, Maria Georgopoulou, Ali Waseem, Georgia Argyropoulou, Adolfo Gonzalez-Romero, Xavier Querol, Carlos Pérez García-Pando, Dimitrios Papoulis, Satoshi Takahama, Kalliopi Violaki, Spyros N. Pandis, and Athanasios Nenes

Mineral dust aerosol particles are ubiquitous in the atmosphere; they contribute to more than half of the total atmospheric aerosol burden and have far-reaching impacts on biogeochemical cycles, air quality and Earth’s radiative budget. Much of the impact of dust is linked to its mild alkalinity and metal content, which directly influence atmospheric reactivity. However, metals and other trace nutrients (TN), such as phosphorous, are largely insoluble in freshly emitted dust and exhibit limited bioavailability for ecosystems upon deposition. The same metals can induce considerable oxidative stress upon inhalation, but mostly if in soluble form. Previous studies have found that atmospheric processing and, in particular, acidification of dust (caused by reactions with sulfuric, nitric, hydrochloric and organic acids) can promote TN solubility and increase the adverse health effects of population exposure to dust. Atmospheric processing also influences dust hygroscopicity and cloud-forming ability, directly affecting Earth’s radiative budget and deposition patterns.

Previous experiments investigating the effect of atmospheric processing on mineral dust properties were mainly conducted in bulk materials and samples. The dissolution kinetics of metals and TN remains poorly constrained under real atmospheric conditions. To address this issue, we have developed an atmospheric simulation chamber facility where mineral dust particles from a wide range of soils can be generated and aged by any mechanisms relevant to the atmosphere (e.g., acidification through photooxidation and/or nocturnal chemistry).

This study provides a detailed characterization of the chamber facility and explores how acidification alters the properties of mineral dust. In particular, we examine the effect of nitrate and sulfate aging on the solubility of TN and the oxidative potential (measured with a DTT assay) of the dust, under atmospherically relevant conditions. We conclude by relating these findings to field observations and discussing the implications for biogeochemical cycles and air quality.

How to cite: Baccarini, A., Molina, C., Kaltsonoudis, C., Seitanide, K., Georgopoulou, M., Waseem, A., Argyropoulou, G., Gonzalez-Romero, A., Querol, X., Pérez García-Pando, C., Papoulis, D., Takahama, S., Violaki, K., N. Pandis, S., and Nenes, A.: Exploring the effects of mineral dust acidification on oxidative potential and limiting nutrient solubility, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14539, https://doi.org/10.5194/egusphere-egu24-14539, 2024.

EGU24-16299 | PICO | AS3.9 | Highlight

Diverse and high pollution of microplastics in seasonal snow across Northeastern China 

Xin Wang and Hanxuan Wen

Snow scavenging is recognized as one of the major sinks for atmospheric microplastics (MPs). However, little is known about the properties of MPs in large-scale surface snow. Using Nile Red staining and micro-Fourier transform infrared spectroscopy, we identified the shapes, sizes, and polymer components of MPs in seasonal snow across northeastern (NE) China, a major industrial area. The average concentration of MPs was (4.52 ± 3.05) × 104 MPs L−1 , and the highest contamination (6.65 ± 3.89) × 104 MPs L−1 was observed in Changbai Mountains, which was the highest concentration observed in surface snow to the extent of literature. The majority of snow MPs were smaller than 50 μm and composed primarily of fragments. Ethylene vinyl acetate and polyethylene were the dominant contributors to their chemical components. Investigation with positive matrix factorization revealed that the MPs were primarily generated by debris from packaging materials, followed by industrial and construction activities. In addition, the winter atmospheric circulation over the northwestern Siberian and Mongolian plateaus likely dominated the wide-range dispersion and deposition of the MPs across NE China. These results provide a first comprehensive perspective of MPs from sources to removal associated with snow in a large geographic region.

How to cite: Wang, X. and Wen, H.: Diverse and high pollution of microplastics in seasonal snow across Northeastern China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16299, https://doi.org/10.5194/egusphere-egu24-16299, 2024.

EGU24-16833 | ECS | PICO | AS3.9

Cumulative and relative impact of aerosol species on snowmelt runoff from the Hindu Kush Himalayan glaciers 

Sauvik Santra, Shubha Verma, and Shubham Patel

Himalayan glaciers are a significant contributor to the global supply of snowmelt water and serve as the primary source for major rivers in South Asia. In this study, we have evaluated the effect of aerosol species on glaciers in the Hindu Kush Himalayan (HKH) region and identified the glaciers most affected, as well as the relative and cumulative impact of different aerosol species, including black carbon (BC). We estimate the surface concentration of organic carbon (OC), sulfate (Sul), and dust aerosols in the HKH region. We also measured the concentration of these aerosol species in the snow of nine glaciers and investigated their influence on annual glacier runoff. Furthermore, we identified the source regions and sectors that are responsible for aerosol loading in the region. In this study, we combined free-running (freesimu) and constrained (constrsimu) aerosol simulations with an atmospheric general circulation model, an aerosol-snow radiative interaction model, and a novel hypsometric glacier energy mass balance model. The freesimu estimates of aerosol species concentrations were more accurate at high-altitude (HA) stations than at low-altitude (LA) stations. However, the constrsimu estimates performed significantly better at LA stations. A hotspot location of high concentration of aerosol species was identified near Manora Peak, located almost at a central location in the HKH region. Although the concentration of other aerosol species was 2 to 5 times higher than BC (< 70 μg kg-1), they caused significantly less reduction in snow albedo than BC over the HKH glaciers. The cumulative snow albedo reduction (SAR) due to all aerosol species, including BC, was estimated to be as much as 7 to 8% over the Gangotri and Chorabari glaciers, with Gangotri being one of the most important glaciers responsible for the formation of the Ganges River. The Pindari glacier was found to have the highest annual runoff increase (ARI) of all glaciers studied despite having a lower aerosol-induced SAR than the Gangotri and Chorabari glaciers. Five of the nine glaciers (Pindari, Sankalpa, Milam, Gangotri, and Chorabari) had ARI higher than 300 mm w.e. y-1 due to aerosol-induced SAR. Glaciers located in the HKH region were found to be two to three times more sensitive to SAR than cold Tibetan glaciers. This, combined with the recent increase in temperature due to global warming, paints a worrying picture for the future. Analysis of the fractional contribution of aerosol species revealed that BC aerosols, although having a less than 15% contribution to the total aerosol loading, contribute 55 to 70% of total aerosol-induced ARI, followed by dust (20 to 30\%), Sul and OC aerosols respectively. Analysis of region- and source-tagged simulation data revealed that the main sources of OC and Sul aerosols south of 30°N were biomass burning and open burning (for OC), and fossil fuel burning (for Sul) from the nearby Indo-Gangetic plain. For regions located north of 30°N and for dust aerosols, the main contributor was identified as long-range intercontinental transport from far-off regions of Africa and West Asia.

How to cite: Santra, S., Verma, S., and Patel, S.: Cumulative and relative impact of aerosol species on snowmelt runoff from the Hindu Kush Himalayan glaciers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16833, https://doi.org/10.5194/egusphere-egu24-16833, 2024.

EGU24-16834 | ECS | PICO | AS3.9

Characterisation of algal blooms on seasonal snowfields through a combination of field spectrometry, drone imagery and radiative transfer modeling at Hardangerjøkulen (Hardanger glacier), Southern Norway 

Lou-Anne Chevrollier, Adrien Wehrlé, Joseph M. Cook, Alexandre M. Anesio, Liane G. Benning, and Martyn Tranter

Pigmented microalgae bloom on glaciers and snowfields worldwide, contributing to carbon storage and enhanced surface melt through surface darkening. The darkening impact of snow algal blooms is being increasingly studied on terrestrial glaciers and ice sheets but less attention has been given to seasonal snowfields, despite their ecological and climatic relevance. Algal blooms are typically widespread but heterogeneously distributed and therefore high resolution airborne observations provide important insights to better understand the spatial patterns and impact of the blooms. Here, we present 130 field spectra colocated with low-cost and light-weight drone imagery acquired over 6 different snowfields in July and August 2023 around Hardangerjøkulen (Hardanger glacier), Southern Norway. We combine these high-resolution measurements with radiative transfer modeling to provide estimates of abundance, carbon storage and albedo impact of snow algal blooms on seasonal snowfields.

How to cite: Chevrollier, L.-A., Wehrlé, A., M. Cook, J., M. Anesio, A., G. Benning, L., and Tranter, M.: Characterisation of algal blooms on seasonal snowfields through a combination of field spectrometry, drone imagery and radiative transfer modeling at Hardangerjøkulen (Hardanger glacier), Southern Norway, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16834, https://doi.org/10.5194/egusphere-egu24-16834, 2024.

EGU24-17044 | PICO | AS3.9

Inaugural dust and climate model simulations with the new EMIT global mineral abundance maps 

María Gonçalves Ageitos and the EMIT team

Minerals in dust shape the interaction of this ubiquitous aerosol with relevant components of the Earth system. Iron oxides absorb short-wave radiation, while quartz or k-feldspars act as efficient ice nuclei, contributing to the formation of mixed-phase clouds. In addition, iron and phosphorus containing minerals transport nutrients to terrestrial and marine ecosystems. Other minerals, like calcite, affect aerosols’ pH and intervene in atmospheric chemistry processes. Incorporating these complex effects into Earth System Models (ESM) has proven challenging due to our limited knowledge about the mineralogy of dust sources and its particle size distribution at emission.

The ongoing NASA Earth Surface Mineral Dust Source investigation (EMIT) project has produced a first version of a global mineral abundance map at an unprecedented resolution based on spaceborne imaging spectroscopy observations from the International Space Station. Using this new product, we have conducted multi-annual simulations with several ESMs that explicitly represent dust mineralogy. Our study characterizes the relevance of the new map in the ESM results by comparison with our previous baseline simulations. We conduct a thorough evaluation against a global mineral fraction compilation derived from concentration and deposition measurements. Our results are also compared against single scattering albedo (SSA) retrievals from dusty AERONET sites. Our focus is primarily iron oxides, hematite and goethite, which, together with particle size, control the dust SSA in the short-wave.

By providing a first set of simulations with the new EMIT mineral abundance maps and their evaluation, our work contributes to advancing the representation of this key aerosol within ESMs and to further assessing its significance within the global climate system.

How to cite: Gonçalves Ageitos, M. and the EMIT team: Inaugural dust and climate model simulations with the new EMIT global mineral abundance maps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17044, https://doi.org/10.5194/egusphere-egu24-17044, 2024.

EGU24-17082 | PICO | AS3.9

Underestimation of desert dust ingested by aircraft from the CAMS reanalysis compared to CALIOP retrievals 

Claire Ryder, Clement Bezier, Helen Dacre, Rory Clarkson, Vassilis Amiridis, Eleni Marinou, Emmanouil Proestakis, Zak Kipling, Angela Benedetti, Mark Parrington, Samuel Remy, and Mark Vaughan

Atmospheric mineral dust aerosol constitutes a threat to aircraft engines from deterioration of internal components. Here we fulfil an outstanding need to quantify engine dust ingestion at worldwide airports.  The vertical distribution of dust is of key importance since ascent/descent rates and engine power both vary with altitude and affect dust ingestion. We use representative jet engine power profile information combined with vertically and seasonally varying dust concentrations to calculate the ‘dust dose’ ingested by an engine over a single ascent or descent. Using the Copernicus Atmosphere Monitoring Service (CAMS) model reanalysis, we calculate climatological and seasonal dust dose at 10 airports for 2003-2019. Dust doses are mostly largest in summer for descent, with the largest at Delhi (6.6 g). Beijing’s largest dose occurs in spring (2.9 g). Holding patterns at altitudes coincident with peak dust concentrations can lead to substantial quantities of dust ingestion, resulting in a larger dose than the take-off, climb and taxi phases. We compare dust dose calculated from CAMS to spaceborne lidar observations from two dust datasets derived from the Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP). In general, seasonal and spatial patterns are similar between CAMS and CALIOP though large variations in dose magnitude are found, with CAMS producing lower doses by a mean factor of 2.4±0.5, particularly when peak dust concentration is very close to the surface. We show that mitigating action to reduce engine dust damage could be achieved, firstly by moving arrivals and departures to after sunset and secondly by altering the altitude of the holding pattern away from that of the local dust peak altitude, reducing dust dose by up to 44% or 41% respectively.

How to cite: Ryder, C., Bezier, C., Dacre, H., Clarkson, R., Amiridis, V., Marinou, E., Proestakis, E., Kipling, Z., Benedetti, A., Parrington, M., Remy, S., and Vaughan, M.: Underestimation of desert dust ingested by aircraft from the CAMS reanalysis compared to CALIOP retrievals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17082, https://doi.org/10.5194/egusphere-egu24-17082, 2024.

EGU24-17880 | PICO | AS3.9

Unveiling the provenance of dust in the EPICA Dronning Maud Land Ice Core (Antarctica) throughout the Last Deglaciation (7–27 kyr BP): A Quantitative Record Using a Novel Rare Earth Element Mixing Model 

Steeve Bonneville, Aubry Vanderstraeten, Laruelle Goulven, Sibylle Boxho, Bory Aloys, Gabrielli Paolo, Gili Stefania, and Nadine Mattielli

Antarctic ice cores have provided valuable insights into the intricate interplay between dust and climate dynamics in the Southern Hemisphere. However, until now, a continuous and quantitative record detailing the origin of dust during the last deglaciation is lacking. In this study, we utilized a novel database comprising 207 Rare Earth Element (REE) patterns obtained from dust and fine sediment/soil fractions collected from well-known potential source areas (PSA) in the Southern Hemisphere. By combining this comprehensive dataset of REE patterns, we developed a robust statistical model to best match the REE patterns measured in the Epica Dronning Maud Land (EDML) ice core in East Antarctica. Among the 398 samples analyzed in the EDML core, 386 have been un-mixed with statistical significance. When coupled with data on total atmospheric deposition, our findings enable the first quantification of the dust flux from the various PSA reaching the EDML region between 7,000 and 27,000 years before present (kyr BP). Our results unveil that, despite a substantial decrease in atmospheric deposition at the onset of deglaciation around 18,000 years ago, the dust composition remained relatively uniform throughout the Last Glacial Maximum (LGM, 18-27 kyr BP) and Heinrich Stadial 1 (HS1, between 14.7-18 kyr BP). During this period, approximately 68% of the total dust deposition was coming from Patagonian sources, with the remaining contributions originating from Australia (14-15%), Southern Africa (~9%), New Zealand (~3-4%), and Puna-Altiplano (~2-3%). A significant shift in dust provenance occurred around 14.5 kyr BP, marked by a drop in Patagonian contribution to below 50%, while low-latitude PSAs increased their contributions, accounting for 21-23% from Southern Africa, 13-21% from Australia, and ~4-10% from Puna-Altiplano. We propose that this shift is linked to enduring alterations in the hydrology of Patagonian rivers, including Atlantic-Pacific drainage reversals and the decline of braided planform, along with the sudden submersion of the Patagonian shelf. Indeed, between 15 and 14.0 kyr BP, the PAT shelf surface area was halved and by ∼13 kyr BP, it had shrunk by 70% from to its former maximum glacial expansion, with most of the PAT shelf south of 40°S submerged. The drastic reduction of the area subjected to aeolian deflation coupled with the reduction of fine sediment supply of eastern plains in PAT induced an overall decline in dust emission from Patagonian sources. Our finding emphasizes an important feedback between dust composition in Southern Hemisphere and eustatic sea level during the Last Glacial-Interglacial Transition. The early Holocene dust composition reveals heightened variability, with a prevalent contribution from Patagonia at ~50%. Post 11.5 kyr BP, as Puna-Altiplano experienced persistent aridity, our records demonstrate a noticeable increase in dust contribution. Leveraging a comprehensive coverage of both local and distal PSA, our statistical model, based on REE patterns, provides a straightforward and cost-effective method for tracing dust sources in ice cores.

How to cite: Bonneville, S., Vanderstraeten, A., Goulven, L., Boxho, S., Aloys, B., Paolo, G., Stefania, G., and Mattielli, N.: Unveiling the provenance of dust in the EPICA Dronning Maud Land Ice Core (Antarctica) throughout the Last Deglaciation (7–27 kyr BP): A Quantitative Record Using a Novel Rare Earth Element Mixing Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17880, https://doi.org/10.5194/egusphere-egu24-17880, 2024.

EGU24-17990 | ECS | PICO | AS3.9

Impactor-Based Size Fractionation of Aerosol Particles over the Tropical Atlantic Ocean: Source Identification using Nd, Sr, and Pb Isotopes  

Oriol Teruel-Cabello, Leo Pena, Ester Garcia-Solsona, Eduardo Paredes, Isabel Cacho, Antoni Rosell-Melé, and Joan Villanueva

Airborne mineral dust is a significant constituent of the Earth's climate system that warrants detailed investigation to comprehend its impact on climate processes. This work presents a comprehensive multiproxy approach, utilizing Sr-Nd-Pb isotopes, to discern mineral dust source areas from North Africa, a region contributing approximately 55% of the global annual dust load. Our research not only focuses on identifying provenance but also explores the relationship between climate processes in source areas and aerosol properties at remote locations. We collected samples during three oceanographic campaigns in the tropical Atlantic Ocean conducted in 2020, 2021, and 2022, spanning late winter and entire spring periods. The interannual aspect allows us to capture variations, enhancing our understanding of dust emission and transport dynamics. The implementation of a sampling device that separates aerosol particles of different sizes allows for the detailed isotopic characterization of particles in each size range. Our results indicate the existence of diverse origin and transport patterns depending on the particle size. Differentiation based on particle size uncovers compelling insights into the dynamics of dust dispersion, revealing size-dependent variations in dust behavior. Notably, we observe distinctive pathways for the mass of elements at each size, elucidating the complex interplay between Nd, Sr, and Pb. 

How to cite: Teruel-Cabello, O., Pena, L., Garcia-Solsona, E., Paredes, E., Cacho, I., Rosell-Melé, A., and Villanueva, J.: Impactor-Based Size Fractionation of Aerosol Particles over the Tropical Atlantic Ocean: Source Identification using Nd, Sr, and Pb Isotopes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17990, https://doi.org/10.5194/egusphere-egu24-17990, 2024.

Vegetation fires represent a major, mostly anthropogenically-driven, component of the Earth system that are affecting different landscapes in multiple regions of the globe and are supposed to increase further in number and severity with the ongoing climate change. Measurements and conceptional model studies have already shown that the fire-induced disturbance of the near-surface wind patterns allow for the mobilization of soil dust particles and their injection into the atmosphere through the pyro-convective updrafts related to the fires. However, the dust emission schemes of the current generation of aerosol-climate models do not consider this fire-related emission pathway and focus on wind-driven dust emissions of mostly unvegetated landscapes such as deserts only. This can result in an underrepresentation of dust particles in the fire-affected regions with consequences regarding a correct representation of aerosol-atmosphere interactions such as the radiation budget.

Therefore, the present study aims to provide more insights concerning the importance of fire-driven dust emissions in the climate system. In order to achieve this, the process was implemented as a new emission pathway into the aerosol module HAM (Hamburg Aerosol Module) of the newly coupled aerosol-climate model ICON-HAM. Information about the behavior of the fire-affected wind fields and their potential to overcome typical emission thresholds have been used to set the dust emission fluxes in relation to data of the global fire activity, expressed by the fire radiative power (FRP), and to land-surface characteristics such as soil type and surface roughness.

Multi-year global simulations of ICON-HAM were analyzed to quantify the impacts of the additional dust emissions caused by the fire activity and their injection parameterization on a seasonal and continental scale. It was found that the strength of the fire-related dust emissions strongly depends on the region where the fire occurs, which is determined by the local soil-surface conditions and not only by the fire strength. However, the vegetation fires can lead to an increase of the atmospheric dust load even in regions far away from those commonly known as dust source areas, highlighting that fire-driven dust emissions can substantially contribute to the total aerosol load and in particular its composition within fire-prone regions or also within a fire-prone climate.

How to cite: Wagner, R. and Schepanski, K.: Fire-driven dust emissions – applying a newly developed parameterization scheme in a global aerosol-model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18339, https://doi.org/10.5194/egusphere-egu24-18339, 2024.

EGU24-18556 | PICO | AS3.9

EMIT Global Dust Source and Emission Mineral Abundance Maps for Dust and Climate Modeling 

Carlos Pérez García-Pando and the EMIT Team

Soil dust aerosols, comprised of diverse minerals with varying relative abundances, particle size distribution (PSD), shape, surface topography, and mixing state, exert a significant influence on climate. Despite this complexity, conventional Earth System Models tend to assume a globally uniform dust aerosol composition, overlooking well-documented regional variations in the mineralogy of their sources. Existing models addressing dust mineralogical variations often rely on mineral abundance maps extrapolated from an insufficient and non-uniform set of soil sample analyses, especially scarce in arid and semiarid regions.

This study introduces the first version of a series of global dust source and emission mineral abundance maps for dust and climate modelling built upon data from the Earth Surface Mineral Dust Source Investigation (EMIT) imaging spectrometer that is currently operational on the International Space Station (ISS). EMIT measures the spectral range from 0.38 to 2.50 microns through 285 contiguous spectral channels at a high spatial resolution of approximately 60 meters per pixel and ~77 km swath width. The EMIT ground system, utilizing Tetracorder, enables material identification and mapping on mineral spectra. EMIT provides quantitative maps for 10 critical minerals over dust sources pivotal for understanding interactions with the Earth System, with a specific emphasis on mapping iron oxides (hematite and goethite) to constrain the dust direct radiative effect.

Our study offers a comprehensive overview of the diverse methods explored, challenges faced, and key assumptions made to provide quantitative dust source mineralogy. Notably, addressing the absence of information on quartz and feldspar, whose absorption features extend beyond the measured spectral range, poses a significant challenge. Methodologies range from a model that linearly relates mineral abundance to absorption-feature band depth, to more advanced models solving the non-linear multiple scattering radiative transfer problem, providing abundances across a broader range of conditions.

Furthermore, the study provides insights into key assumptions guiding the derivation of mineral abundance maps for both clay and silt fractions of the soil. It also details methods rooted in brittle fragmentation theory, essential for estimating emitted size-resolved mineralogy, which is the critical input for Earth System Models.

This research contributes to advancing our understanding of soil dust aerosols, laying the foundation for improved climate models that account for nuanced regional variations in mineralogical composition.

How to cite: Pérez García-Pando, C. and the EMIT Team: EMIT Global Dust Source and Emission Mineral Abundance Maps for Dust and Climate Modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18556, https://doi.org/10.5194/egusphere-egu24-18556, 2024.

EGU24-18893 | ECS | PICO | AS3.9

Size segregation process along the soil-saltation-dust continuum: observations in southern Tunisia  

Rizewana Marécar, Béatrice Marticorena, Gilles Bergametti, Jean Louis Rajot, Christel Bouet, Servanne Chevaillier, Anais Féron, Bouthaina Khalfallah, Stéphane Alfaro, Mohamed Taieb Labiadh, Thierry Henry des Tureaux, Saad Sekrafi, and Mohsen Lifti

The particle size segregation processes occurring between the soil, the saltation layer and the dust layer close to the surface are not well described while they are key steps for a precise assessment of dust emission. Improving our understanding and quantifying the role of the processes acting in these three compartments should significantly enhance the consistency of dust emission models.

Data obtained during the WIND-O-V (WIND erOsion in presence of sparse Vegetation) field campaign that took place in spring 2017 in southern Tunisia have been analyzed. Eight saltation events of durations from 1 to 4 hours were sampled and corresponded to a range of wind friction velocities between 0.28 and 0.46 m s-1. The dispersed and non-dispersed size distributions of the soil and of the saltation fluxes were characterized and the micrometeorological conditions were also analyzed. Simultaneous measurements of size resolved saltation fluxes and size-resolved vertical dust fluxes were carried out. The combined analysis of size distributions of the parent-soil and of the horizontal and vertical fluxes reveals an enrichment of fine particles that increases with height. A consistent behavior is observed when comparing the particle size distribution of the saltation and of the vertical dust fluxes. Moreover, we observe changes in the size distributions from one event to another that are similar for the saltation and the dust fluxes. This strongly suggests that the processes controlling the saltation significantly affect the dust size distribution. The roles of the vertical transfer and of the micrometeorological conditions on the size distributions are also discussed.

How to cite: Marécar, R., Marticorena, B., Bergametti, G., Rajot, J. L., Bouet, C., Chevaillier, S., Féron, A., Khalfallah, B., Alfaro, S., Labiadh, M. T., Henry des Tureaux, T., Sekrafi, S., and Lifti, M.: Size segregation process along the soil-saltation-dust continuum: observations in southern Tunisia , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18893, https://doi.org/10.5194/egusphere-egu24-18893, 2024.

EGU24-19326 | PICO | AS3.9

Why does it rain in the desert? The dust record in Tunisia. 

Anna Bird, Ian Millar, Doris Wagner, Kaja Fenn, Rachel Smedley, Barbara Mauz, Moez Mansoura, Michael Rogerson, Marc Luetscher, Mahjoor Lone, and Noureddine Elmejdoub

North Africa is one of the regions identified by UNESCO as experiencing severe water stress, and further drying could be devastating for region that is also insecure. Tropical semi-arid regions, such as North Africa are highly sensitive to climate change, and climate predictions for this area suggest that this region will experience drying in the next decades and centuries. This contrasts with findings from palaeo-studies which show that, during the Pleistocene, global warming often correlates to humid phases. This project uses speleotherm records with palaoedust (loess) archives to assess the climate record over humid and dry periods to improve our understanding of past climate change in the sensitive but under-represented central northern Africa region. This presentation will focus on findings from the most important loess deposit in northern Africa, at Matmata in Tunisia.

The loess sections within the Matmata Plateau have loess and soil horizons relating to a series of humid and arid phases during the Quaternary, a sequence that provides valuable insight into the origins and dynamics of desert deposits and the interplay between continental and maritime weather systems. Previous work, in the 1990s, on the Matmata loess has shown onset of loess deposition to be during a humid phase (~70 ka) with loess deposition continuing as the climate becomes more arid into the Upper Holocene. It is currently assumed that the source of this material is the Grand Erg Orient, based on a relatively old study (1987). However, new OSL data presented here shows that the onset of loess deposition was much older than previously thought (~300 ka), with the top of the sections dated at ~24 ka. It appears that deposition was not continuous with a large gap in the record from 143 – 45 ka. Gaps in sedimentation for the section older than ~140 ka are difficult to determine due to limited reliability of older OSL ages.

Provenance analysis has been undertaken on many of the dated samples to establish past transport directions. Detrital zircon U-Pb data suggest that there is dominant Algeria-type source with some input from the north. The amount of this input varies over time with samples older than 200 ka showing a larger input from the north. 87Sr/86Sr and 143Nd/144Nd isotopes from different grainsize fractions tell a similar story, with a dominant west African source.

How to cite: Bird, A., Millar, I., Wagner, D., Fenn, K., Smedley, R., Mauz, B., Mansoura, M., Rogerson, M., Luetscher, M., Lone, M., and Elmejdoub, N.: Why does it rain in the desert? The dust record in Tunisia., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19326, https://doi.org/10.5194/egusphere-egu24-19326, 2024.

EGU24-20434 | ECS | PICO | AS3.9

Forcing factors behind primary productivity variabilities in Western Arabian Sea  since the Last Glacial Maximum: an important role of mineral dust supplies 

Alice Karsenti, Charlotte Skonieczny, Stéphanie Duchamp-Alphonse, Xinquan Zhou, Kara Labidi, Nicolas Musial, Ana Alves, Maxime Leblanc, Julius Nouet, Amélie Plautre, Sébastien Bertrand, Eva Moreno, Annachiara Bartolini, Catherine Kissel, and Franck Bassinot

Located in the Northwestern part of the Indian Ocean, the Arabian Sea (AS) is surrounded by vast arid regions (e.g. Arabian Peninsula, Pakistan, Iran), regularly swept by regional winds, that supply important amounts of mineral dust to the sea. This oceanic area is also under the influence of Indian monsoon surface winds that create a coastal upwelling off Somalia and Oman during summer and a convective mixing north of 15°N during winter. Consequently, mineral dust, coastal upwelling and convective mixing bring important amounts of nutrients to the euphotic zone, making the AS one of the most productive oceanic regions in the world. Although older studies usually highlight the coastal upwelling as a major factor behind primary productivity (PP) patterns in the AS, more recent studies have demonstrated that mineral dust inputs and convective mixing could have a significant influence on PP as well, at least since the Last Glacial Maximum (LGM). This time interval encompasses a glacial-interglacial transition with rapid fluctuations of ice sheet volume and atmospheric CO2 concentration, and represents therefore, a perfect case study to explore the impact of key Earth’s climate forcing mechanisms on the PP for both, past and future climate conditions. Yet, mineral dust component is still poorly documented by proxy data in the AS and direct reconstruction of PP are rare, which limit our understanding of how fertilization of the euphotic zone either by dust, coastal upwelling and/or convective mixing, impacts PP in the past. In this study, we combine high resolution bulk geochemical composition, detrital fraction grain-size distribution and clay mineralogy composition, together with coccoliths counting and carbon organic analyses from sediment cores MD00-2354 and MD00-2355, both retrieved on the Owen ridge. The aim is to reconstruct high-resolution mineral dust and PP patterns over the western part of the AS since the LGM. Both sites are located under the direct influence of dust plumes and among the seasonal latitudinal shift of monsoonal winds. They are therefore willing to register nutrient inputs from mineral dusts, winter convective mixing and/or summer coastal upwelling. Combined with previous paleoclimate records from the area, they will provide for the first time, an unprecedented overview of the forcing factors behind PP distribution in the past. Preliminary results show decreasing PP at both sites through the last 20 ka, suggesting a regional pattern of nutrient distribution in the western AS. Particularly, a strong correlation between PP and mineral dust signals reinforces the hypothesis of a key role of mineral dust on PP in the area. 

How to cite: Karsenti, A., Skonieczny, C., Duchamp-Alphonse, S., Zhou, X., Labidi, K., Musial, N., Alves, A., Leblanc, M., Nouet, J., Plautre, A., Bertrand, S., Moreno, E., Bartolini, A., Kissel, C., and Bassinot, F.: Forcing factors behind primary productivity variabilities in Western Arabian Sea  since the Last Glacial Maximum: an important role of mineral dust supplies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20434, https://doi.org/10.5194/egusphere-egu24-20434, 2024.

EGU24-20949 | PICO | AS3.9

Radiative Forcing Assessment of Black Carbon in Snow from the Antarctic Peninsula  

Francisco Cereceda-Balic, María Florencia Ruggeri, Gonzalo Barcaza, Ximena Fadic, and Hans Moosmüller

The pristine Antarctic environment, despite its remoteness, is not immune to the influence of anthropogenic
pollutants. This study focuses on quantifying the Radiative Forcing (RF) resulting from Black Carbon (BC)
concentrations in snow samples collected from various points on the Antarctic Peninsula during the austral summer
of 2023, aiming to assess the impact of BC on the snowpack albedo and, consequently, on the regional climate. To the
best of our knowledge, in most of the locations studied, BC concentrations in snow have never been measured before.
Snow samples were meticulously collected from different locations on the Antarctic Peninsula, covering a diverse
range of environments, including base surroundings, remote locations, and icebergs. This effort was undertaken as
part of the ECA59 campaign, funded by the Chilean Antarctic Institute (INACH). The sampling constituted the initial
phase of a project involving three distinct sampling periods. Specifically, the collection sites were situated in the
eastern sector of the peninsula, known for its minimal human presence and limited prior research, making it a
relatively unexplored region. BC concentrations in our snow samples were measured following the method described
in Cereceda-Balic et al. (2022, https://doi.org/10.1016/j.envres.2022.113756). To understand the BC RF, the SNICAR
(SNow, ICe, and Aerosol Radiation) model was employed to simulate snow albedo for measured BC concentrations.
This methodology allowed for an assessment of the potential BC-induced changes in albedo and the resulting RF. The
analysis revealed a significant range of BC concentrations in Antarctic snow samples, spanning from 2.4 to 1157 ng g-1. Simulating snow albedo using the SNICAR model indicated BC-induced albedo reductions of up to 20% relative to clean snow. The calculated BC-induced RF reached up to 38 W m-2, indicating a substantial climatic impact of BC in the Antarctic Peninsula region.

Our findings underscore the influence of BC on the radiative properties of snow in the Antarctic Peninsula. The diverse
BC concentrations observed here suggest varying sources and highlight the need for continued monitoring. The results
reveal the vulnerability of the Antarctic Peninsula to the impacts of anthropogenic pollutants, even in its seemingly
pristine surroundings. Acknowledging and addressing these influences is essential for assessing the broader
implications of climate change in polar regions. Continued research at these little-explored sites is crucial for refining
climate models and informing mitigation strategies to preserve the integrity of the Antarctic environment.


Acknowledgments: INACH Project RT_34-21, and ANID Project: Fondecyt Projects N°1221526 andN°11220525, ANILLO ACONCAGUA N°ACT210021, and FOVI230167

How to cite: Cereceda-Balic, F., Ruggeri, M. F., Barcaza, G., Fadic, X., and Moosmüller, H.: Radiative Forcing Assessment of Black Carbon in Snow from the Antarctic Peninsula , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20949, https://doi.org/10.5194/egusphere-egu24-20949, 2024.

EGU24-22132 | ECS | PICO | AS3.9

Reading dust provenance record in Epica Dome C Ice Core (EDC) of Antarctica reveals a shift from Patagonian to African sources through the last deglaciation (2.9 – 33.7 kyr) 

Sibylle Boxho, Nadine Mattielli, Aubry Vanderstraeten, Goulven G. Laruelle, Aloys Bory, Paolo Gabrielli, Stefania Gili, and Steeve Bonneville

Epica Dome C (EDC) ice core is invaluable and highly-resolved record of Earth’s climate. Within the database of climate proxies in deep ice core, quantifying the contribution of the various sources of dust has been very challenging and, so far, no continuous record of dust provenance has been established. Here, we developed an algorithm that combines the REE patterns from a large database (from 207 sediments/soils in well-known Potential Source Areas - PSA - in the Southern Hemisphere) to fit the REE patterns measure in EDC data[1]. Complemented by Monte Carlo simulations to account for analytical uncertainties and by evaluation of goodness-of-fit, our model quantifies the respective contribution of the dust sources (regrouped by large PSA like Patagonia, Africa, S-E Australia, New Zealand and Puna-Altiplano) deposited in EDC ice core between 2.9 and 33.7 kyr at a centennial resolution.

Our provenance record reveals that a major shift in dust provenance occurred at ~14.5-kyr BP during which the contribution of Patagonia (PAT – the main supplier of dust of the Last Glacial Maximum -LGM) declined from   ̴55% to 35% (% of total dust deposition) while African dust (SAF) became more prevalent from   ̴20% during LGM to   ̴40% after 14.5 kyr BP. As a matter of fact, the main supplier of dust in EDC during the Holocene is Southern Africa. We ascribe this abrupt shift to (i) long-lasting changes in the hydrology and of Patagonian rivers and (ii) to a sudden acceleration of sea-level rise between 14 and 15 kyr BP that submerged vast swathes of Patagonian continental shelf, triggering a decline in PAT dust supply to Antarctica. In turn, this induced a steep increase – in relative term - of SAF dust contribution in EDC.

Importantly,our record for EDC is very much consistent with our previous results for Epica Dronning Maud Land (EDML)[2] ice core showing the exact same shift (PAT for SAF dust) between 14 and 15 kyr BP. Yet, compared to EDML, EDC record shows generally larger contribution for SAF and lower PAT dust which seems logical considering the respective localization of EDML and EDC. Our results for EDC thus confirms the relationship between dust composition and eustatic sea level and also highlight the importance of African dust deposition in the Southern Indian ocean and in the adjacent sector of the Southern Ocean since 14 kyr. Our tracing method using REE patterns offers a new, high-resolution tool for the reconstruction of atmospheric paleo-circulation and paleoclimate in the Southern Hemisphere.

[1]Gabrielli et al., (2010), Quaternary Science Review 29, 1-2.

[2]Vanderstraeten et al., (2023), Science of the Total Environment 881, 163450

How to cite: Boxho, S., Mattielli, N., Vanderstraeten, A., Laruelle, G. G., Bory, A., Gabrielli, P., Gili, S., and Bonneville, S.: Reading dust provenance record in Epica Dome C Ice Core (EDC) of Antarctica reveals a shift from Patagonian to African sources through the last deglaciation (2.9 – 33.7 kyr), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22132, https://doi.org/10.5194/egusphere-egu24-22132, 2024.

EGU24-1283 | Orals | ITS1.6/BG1.18

Present and future importance of protected areas as carbon sinks and storages in Finland 

Martin Forsius, Virpi Junttila, Heini Kujala, Mikko Savolahti, and Torsti Schulz

The EU aims at reaching carbon neutrality by 2050 and Finland by 2035. Net negative greenhouse gas emissions are needed to comply with the targets of the Paris climate agreement. We integrated results of three spatially distributed model systems (FRES, PREBAS, Zonation) to evaluate the potential to reach this goal at both national and regional scale in Finland, by simultaneously considering protection targets of the EU biodiversity strategy. Modelling of both anthropogenic emissions and forestry measures were carried out, and forested areas important for biodiversity protection were identified based on spatial prioritization. We used scenarios until 2050 based on mitigation measures of the national climate and energy strategy, forestry policies and predicted climate change, and evaluated how implementation of these scenarios would affect greenhouse gas fluxes, carbon storages, and the possibility to reach the carbon neutrality target. Potential new forested areas for biodiversity protection according to the EU 10% strict protection target provided a significant carbon storage (426-452 TgC) and sequestration potential (-12 to -17.5 TgCO2eq a-1) by 2050, indicating complementarity of emission mitigation and conservation measures. Assuming a price of ca. 80 € ton-1 CO2eq according to the current level of the EU emission trading system (EU ETS), the economic value of the carbon sequestration of the current protected areas in Finland would be about 500 million € per year. These areas thus provide ecosystem services of significant economic value. The results of our study can be utilized for integrating climate and biodiversity policies, accounting of ecosystem services for climate regulation, and delimitation of areas for conservation.

How to cite: Forsius, M., Junttila, V., Kujala, H., Savolahti, M., and Schulz, T.: Present and future importance of protected areas as carbon sinks and storages in Finland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1283, https://doi.org/10.5194/egusphere-egu24-1283, 2024.

EGU24-3894 | ECS | Orals | ITS1.6/BG1.18 | Highlight

Impact of clouds on the forest albedo measured at the Leipzig Canopy Crane - A pilot study 

Kevin Wolf, Michael Schäfer, Sudhanshu Shekhar Jha, Alexandra Weigelt, Ronny Richter, Tom Kühne, André Ehrlich, Evelyn Jäkel, and Manfred Wendisch

Albedo, defined as the ratio between reflected radiation and total incoming radiation, is a key variable in the Earth radiative budget. In a fast changing climate with more frequent extreme events, such as droughts and excessive heat, vegetation is under constant stress. Such stress factors might modify the tree physiology, the reflectivity of individual leaves, and, eventually, the forest albedo as an entity. This might alter the local radiative budget and contribute to changes in the local climate, e.g., intensifying drought - a potential feedback loop. The understating of those effects might be further complicated by the occurrence of clouds. Therefore, this study presents spectral solar measurements of upward and downward irradiance that are used to determine the spectral albedo over a forest canopy. Since June 2021, ongoing measurements are performed on top of the Leipzig Canopy Crane located in the Leipzig floodplain forest. The measurements are separated for illumination geometries, i.e., the solar zenith angle, as well as for different cloud conditions. The interpretation of the measurements is aided and validated by coupled radiative transfer simulations using the library for radiative transfer model (libRadtran) and the Soil Canopy Observation of Photosynthesis and Energy fluxes (SCOPE2.0) model. Both models allow for simulations in the visible, near- and far-infrared wavelength range. By that, the impact of clouds on the spectral and broad band albedo, as well as the net radiative budget can be investigated. First simulations revealed that the presence of clouds enhance the spectral forest albedo. The magnitude of the effect is controlled by the cloud optical thickness, i.e., the ratio of direct and diffuse radiation. The enhancement is more pronounced for small solar zenith angles. However, the effect from clouds appears to be smaller than influences of variations in the surface properties. The presentation aims to outline the measurement set-up and strategy, and to discuss preliminary results. Furthermore, the new, iterative coupling of the atmosphere and soil-vegetation model is presented, which aims to improve the understating of cloud-vegetation radiation interactions.

How to cite: Wolf, K., Schäfer, M., Shekhar Jha, S., Weigelt, A., Richter, R., Kühne, T., Ehrlich, A., Jäkel, E., and Wendisch, M.: Impact of clouds on the forest albedo measured at the Leipzig Canopy Crane - A pilot study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3894, https://doi.org/10.5194/egusphere-egu24-3894, 2024.

EGU24-3958 | Posters on site | ITS1.6/BG1.18

Modelling the effects of forest use change on brownification of Finnish rivers under pressures of acidification and climate change 

Katri Rankinen, José Enrique Cano Bernal, Maria Holmberg, Magnus Nordling, Torsti Schulz, Annikki Mäkelä, Ninni Mikkonen, Heini Kujala, Leah Jackson-Blake, Heleen De Wit, and Martin Forsius

Browning of surface waters due to increased terrestrial loading of dissolved organic matter is observed across the Northern Hemisphere. Brownification directly influences freshwater productivity and ecosystem services like water purification. Brownification often is explained by changes in large-scale anthropogenic pressures and ecosystem functioning, including acidification and climate change. Land use or cover changes and forestry measures have recently been observed to be one reason for the increase in brownification. Climate change influences brownification by increasing temperatures and thus stimulating the decay of dissolved organic carbon in soils, and by changing the timing and intensity of precipitation and snowmelt. A decrease in sulphur deposition is assumed to increase soil organic matter solubility. In Finland, productive forests cover about 66% of the land area. This study aimed to examine the effect of forest use changes on water browning in Finland under pressure of acidification and climate change. EU land use policies (Biodiversity Strategy, LULUCF Policy) influence land use but also forestry practices. Finland is committed to the EU's goal of protecting 30% of land and sea areas, and 10% of them strictly. The LULUCF regulation agrees how carbon sinks and greenhouse gas emissions from the land use sector are considered in the EU's climate goals until 2030. Finland aims to keep forests as carbon sinks. When studying the environmental effects of land use/cover changes due to these policies, environmental influence on biodiversity, and ecosystem services (sustainability of forestry, and water quality) should be simultaneously considered. We modelled organic carbon loading from river basins under changes in global pressures (climate and deposition) by mathematical models. We combined the watershed scale model (Simply-C) with scenarios of climate change, atmospheric deposition, and forest use change (1985-2060). We used daily data from five global climate models (CMIP5) under representative concentration pathway (RCP) scenarios RCP4.5 and RCP8.5. For atmospheric sulphur deposition, we used the chemical transport model results that are based on the EMEP MSC-W model (v4.4) and the MATCH model results. We explored two forest use scenarios that focus on potential changes taking place in the forested areas in Finland: 1) forest management, and 2) forest protection. The forest management scenario was based on simulations of clear-cut following Finnish national recommendations with the PREBAS forest growth and carbon balance model. Forest protection scenarios were based on spatial data of forests with high conservation value, optimized by Zonation programme. Modelling results indicated that global influence (atmospheric deposition, climate change) seemed to weaken in southern Finland after 2016. That gave more space for the effect of local forest use change due to different EU land use policies. Forest use change was more influential in river basins dominated by organic soils than in mineral soils. In northern Finland brownification seemed to continue, mainly driven by climate change.

How to cite: Rankinen, K., Cano Bernal, J. E., Holmberg, M., Nordling, M., Schulz, T., Mäkelä, A., Mikkonen, N., Kujala, H., Jackson-Blake, L., De Wit, H., and Forsius, M.: Modelling the effects of forest use change on brownification of Finnish rivers under pressures of acidification and climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3958, https://doi.org/10.5194/egusphere-egu24-3958, 2024.

The loss of biodiversity from human activities on land is a widely-recognized, worldwide problem. Since the advent of the industrial revolution the loss of plant and animal species has increased dramatically, with 25% of species now at risk of extinction. Conventions and targets to protect biodiversity have been implemented, but with limited success. The Aichi targets for 2020, for example, were almost all missed, with worsening trends for 12 out of the 20 targets. One reason for this failure is the ineffective application of broad-scale measures that are not tailored to the underlying causes of biodiversity loss. Knowledge on the spatial and temporal distribution of anthropogenic drivers of biodiversity loss would therefore enable targeted interventions that address location-specific stressors and thus would be better-adapted measures to protect biodiversity.

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) has identified five main drivers of anthropogenic origin as the causes of biodiversity loss: land use, natural resource extraction, climate change, pollution, and invasive alien species. However, when seeking to quantify impacts on biodiversity, these drivers are still usually treated separately. We develop a Biodiversity Pressure Index (BPI) by quantifying and mapping data for nine indicators of the five drivers into a single, annually changing index with a spatial resolution of 0.1° at global scale covering the period 1990-2020.

We find that large areas (approximately 86%, including Antarctica, Greenland) are under major human pressure and that almost all areas have experienced an increase (about 96% of land) in pressure over the past thirty years. Industrialised regions had high pressure levels already in 1990 and continue to do so in 2020, whereas regions with rapid economic growth setting in after 2000 where low in pressure in 1990, but show high pressure levels today. Whilst areas impacted by human activities are increasing, areas of wilderness are decreasing to a point that in 2020, only 0.02% of the terrestrial land are entirely free from human influence. (Sub-) tropical wetlands and temperate grasslands are the biomes with the highest pressures today. And whilst land use is still one of the main factors, climate change - especially increasing temperature - is one of the major recent and future threats to biodiversity.

How to cite: Ramm, K., Brown, C., Arneth, A., and Rounsevell, M.: Human pressure on global land ecosystems and biodiversity increases notably from 1990-2020 - Development of a spatially explicit Biodiversity Pressure Index (BPI), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5708, https://doi.org/10.5194/egusphere-egu24-5708, 2024.

EGU24-7473 | ECS | Posters on site | ITS1.6/BG1.18

Developing Restoration Strategies for Dynamic Population Changes of Plant-Pollinator Networks in a Warming Climate 

Adrija Datta, Sarth Dubey, and Udit Bhatia

Ensuring robust pollination service is vital for sustainable food production, as three-quarters of crops require insect pollinators to reproduce, but many insect populations are rapidly declining.  Yet, it is widely reported that insect pollinators face increased extinction risk due to habitat loss and warming climate. The biological impact of global mean temperature projections on individual terrestrial ectotherms is often predicted to increase with the rate of warming. However, it also depends on the interdependence of the plant-pollinator network and the physiological sensitivity of ectotherms to temperature change over time. Here, we have used sampled plant-pollinator network data from different climatic zones and the Earth system model projected temperature data of different future projection scenarios. In this study, we present a mathematical framework for modeling species population dynamics using the Lotka-Volterra model, where parameters are integrated from empirical fitness curves of terrestrial insects at different latitudes. This approach also investigates how species abundance evolves in the twenty-first century with and without species management, focusing on maintaining a constant abundance of generalist species to avert sudden ecosystem collapses over declining environmental health. The results show that tropical networks are more sensitive in abundance and extinction to future temperature increase as they live very close to their optimal temperature. In contrast, species of temperate regions have broader thermal tolerance, so the warming may increase their abundance. This study offers insights into how different future temperature projections influence species management, thereby restoring the functional integrity of the entire ecosystem. Also, this study provides region-specific restoration guidelines, offers insights for agro-advisory services, informs sustainable cropping patterns, and optimizes resource allocation. 

How to cite: Datta, A., Dubey, S., and Bhatia, U.: Developing Restoration Strategies for Dynamic Population Changes of Plant-Pollinator Networks in a Warming Climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7473, https://doi.org/10.5194/egusphere-egu24-7473, 2024.

EGU24-10432 | Orals | ITS1.6/BG1.18 | Highlight

Plant diversity-climate interactions from a modeling perspective 

Pin-hsin Hu, Christian H. Reick, Axel Kleidon, and Martin Claussen

Mounting evidence from field observations has shown that high functional diversity is associated with strong ecosystem resilience and stability. However, plant ecology studies have focused on the passive response of global ecosystems to climatic changes while the impacts of plant-functional diversity on climate including its feedback are seldom addressed. Moreover, state-of-the-art climate models are insufficient to address such topics. Their land component models cover only a restricted range of present-day plant features, so that adaptation at the sub-grid scale is ignored. Based on a process-based plant functional trade-off scheme developed by Kleidon and Mooney (2000), we have set up a new vegetation model JeDi-BACH into the land component of the ICON-Earth System Model (ICON-ESM). The advantage of this new model is that the representation of global vegetation is an emergent outcome of environmental filtering following several well-known fundamental functional trade-offs that link plant functions to abiotic and biotic attributes. In such a way, plants dynamically adjust to the changing environment and meanwhile modify climate. With this new model, we present a series of sensitivity studies investigating the effect of plant trait diversity on the coupled vegetation-climate system in a coupled land-atmosphere setup. We found that high plant diversity ecosystems tend to stabilize terrestrial climate in a high water-turnover state, leading to a wet and cool climate. The enhancement in evapotranspiration with increasing diversity found in our study is consistent with the BEF (Biodiversity-Ecosystem Functioning) relationship derived from the field studies. Our modeling results demonstrate the importance of the "biodiversity-climate feedback" and highlight the role of plant functional diversity in shaping a robust climate.

Kleidon, A. and Mooney, H. A.: A global distribution of biodiversity inferred from climatic constraints: Results from a process-based modelling study, Glob. Chang. Biol., 6(5), 507–523, doi:10.1046/j.1365-2486.2000.00332.x, 2000.

 

How to cite: Hu, P., Reick, C. H., Kleidon, A., and Claussen, M.: Plant diversity-climate interactions from a modeling perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10432, https://doi.org/10.5194/egusphere-egu24-10432, 2024.

EGU24-10869 | Orals | ITS1.6/BG1.18

A vertical RothC model for simulating the Soil Organic Carbon  dynamics in coastal wetland environments 

Carmela Marangi, Vsevolod Bohaienko, Fasma Diele, Angela Martiradonna, and Antonello Provenzale

The significance of considering vertical layers in studying soil organic carbon (SOC) dynamics within wetlands arises from the interplay of hydrological and ecological factors across various soil depths, where anaerobic conditions prevail in the deeper layers. This anaerobic environment significantly influences microbial processes, leading to methane production rather than carbon dioxide. Factors such as the accumulation of organic material, temperature gradients, and fluctuations in the water table contribute to diverse SOC dynamics across different vertical strata. Understanding these variations in vertical layers is crucial for accurate assessments of carbon stocks, greenhouse gas emissions, and the overall role of wetlands in the global carbon cycle. Such understanding is essential for devising effective conservation and management strategies, particularly in the face of climate change and land-use modifications impacting wetlands.  To model these dynamics, a vertical extension of the Rothamsted Carbon (RothC) model can be successfully employed in conjunction with the Richardson equation. This combined approach simulates the influence of soil moisture flux on the transport of carbon throughout the soil column. The specific scenario examined is focused on the growth of rice in the Ebro Delta lands and on the carbon flux emissions in the Ria de Aveiro Coastal lagoon, both sites being part of the Long-Term Ecological Research (LTER) network and the eLTER RI community.  This work contributes to the research activities carried out by the authors within the projects H2020 eLTER PLUS, HE RESTORE4Cs, and PNRR - “National Biodiversity Future Centre”, funded by the European Union – NextGenerationEU.

 

References

D.S. Jenkinson, P.B.S. Hart, J.H. Rayner and L.C. Parry, "Modelling the turnover of organic matter in long-term experiments at Rothamsted". INTECOL Bulletin 15 (1987): 1–8

F. Diele, C. Marangi, A. Martiradonna, "Non-Standard Discrete RothC Models for Soil Carbon Dynamics." Axioms 10.2 (2021): 56.  

F. Diele, I. Luiso, C. Marangi, A. Martiradonna, E. Wozniakk, "Evaluating the impact of increasing temperatures on changes in soil organic carbon stocks: sensitivity analysis and non-standard discrete approximation", Computational Geosciences 26 (2022) 1345–1366.

 J. Smith, P. Gottschalk, J. Bellarby, M. Richards, D. Nayak, K. Coleman, J. Hillier, H. Flynn, M. Wattenbach, M. Aitkenhead, et al., "Model to estimate carbon in organic soils–sequestration and emissions (ecosse)", Carbon 44 (2010) 1–73.

Y. Zhang, C. Li, C. C. Trettin, H. Li, G. Sun, "An integrated model of soil, hydrology, and vegetation for carbon dynamics in wetland ecosystems", Global biogeochemical cycles 16 (2002) 9–1.

 

How to cite: Marangi, C., Bohaienko, V., Diele, F., Martiradonna, A., and Provenzale, A.: A vertical RothC model for simulating the Soil Organic Carbon  dynamics in coastal wetland environments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10869, https://doi.org/10.5194/egusphere-egu24-10869, 2024.

EGU24-12455 | ECS | Orals | ITS1.6/BG1.18

Identification of socio-economic variables to implement advanced artificial intelligence models to manage climate change risk 

David Jesús Felibert Álvarez, Manuel Enrique Guineme Baracaldo, Jhon Alexander Triana Forero, Johanna Karina Solano Meza, and Javier Rodrigo-Ilarri

To develop climate change mitigation strategies, it is necessary to identify variables that facilitate the modeling of prospective scenarios. There are a large number of variables that must be analyzed in an integrated manner in order for scenarios to be proposed that include the particularities of a given area, measuring the possible effects of this phenomenon in terms of productivity. Identifying and analyzing variables and their variations over time enables fundamental predictions to understand the potential environmental impacts on ecosystems and human activity. Understanding these variables is important to support decision-making, policy development and implementing actions that help reduce greenhouse gas emissions and guarantee food security. This research study not only seeks to determine the technical variables, which are fundamental in predictive models, but also sets out to emphasize the importance of integrating social and economic aspects that can become decisive factors.

Rural areas in Colombia, with the department of Cundinamarca used as a case study, have been affected in various ways by climate change [1]. This scenario represents a challenge that needs to be addressed in a prioritized manner to ensure food security and independence, economic development, sustainability, livestock and human health, among other aspects that precisely relate to the development of a region. To propose solutions, artificial intelligence (AI) is emerging as an innovative alternative that makes it possible to process large amounts of data and find patterns, correlations and trends that can provide an understanding of the variables’ behavior, as well as develop systems to adapt to climate change. Therefore, identifying variables to apply advanced AI models to forecast the effects of climate change in a given region is a fundamental step towards generating an efficient and accurate tool to establish mitigation actions in a region that, together with the implementation of policies and actions that promote sustainability, will strengthen communities’ current capacity for action.

The variables identified include economic structure, access to technological resources, governance models, education levels, access to public services, poverty rate, demographics and crop price references. Through AI models and an in-depth analysis of available information, these types of models will become more precise for the implementation of early warning systems (EWS) and sustainable practices, as well as strengthen infrastructure. Historically in Colombia, rural areas are the most vulnerable to climate change given that they have fewer economic and technological resources that enable them to adapt to its impacts, with the most frequent phenomena being torrential rainfall, extreme flooding and forest fires; events associated with climate change.

  • Peña Q, Andrés J, Arce B, Blanca A, Boshell V, J. Francisco, Paternina Q, María J, Ayarza M, Miguel A, & Rojas B, Edwin O. (2011). Trend analysis to determine hazards related to climate change in the Andean agricultural areas of Cundinamarca and Boyacá. Agronomía Colombiana, 29(2), 467-478. Retrieved January 09, 2024, from http://www.scielo.org.co/scielo.php?script=sci_arttext&pid=S0120-99652011000200014&lng=en&tlng=en.

How to cite: Felibert Álvarez, D. J., Guineme Baracaldo, M. E., Triana Forero, J. A., Solano Meza, J. K., and Rodrigo-Ilarri, J.: Identification of socio-economic variables to implement advanced artificial intelligence models to manage climate change risk, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12455, https://doi.org/10.5194/egusphere-egu24-12455, 2024.

In the temperate region, inter-annual variation of air temperature affects leaf phenology, i.e., timings of leaf emergence and growth in spring and defoliation in autumn. These changes have significant impacts not only on the canopy of dominant trees of forest ecosystems, but also on the seasonal light environment within the forest understory which further influences the growth and survival of tree seedlings, shrubs, and herbaceous species. Consequently, global warming is expected to influence biodiversity by altering species-specific growth responses to the environmental shifts, affecting primary production and hence the progress of vegetation succession. Therefore, in order to comprehensively monitor and assess the state and changes in forest ecosystems across wide geographical and decadal scales, it is important to observe leaf phenology at both the species and ecosystem scales, which is considered one of Essential Biodiversity Variables (EBVs).

The objective of this study is to investigate the decadal-scale change of the leaf phenology in deciduous forest in Japan. We examined 20-year changes of the dates of leaf emergence, leaf area index (LAI) reached its maximum, and defoliation by using in-situ and satellite data. The in-situ remote sensing has been conducted by a spectroradiometer and automated digital cameras on a canopy tower since 2003 at a deciduous forest in Takayama site, located in the cool-temperate region in the central Japan. The system is part of the Phenological Eyes Network (PEN). We estimated the dates of leaf emergence, maximum LAI, and defoliation based on the seasonal pattern on the Green-Red Vegetation Index (GRVI). These dates exhibit notable inter-annual variations, and notably, the date of maximum LAI occurrence tended to shift earlier over the 20-years period from 2004 to 2023. Those inter-annual variations in the leaf phenology were strongly related to the air temperature. Based on the knowledge gained at the Takayama site, we then examined the spatial distribution and annual changes of phenology of the deciduous forests in Honshu Island with satellite-GRVI. We will discuss the spatial and temporal changes in phenology along the environmental gradient and rising air temperature due to global warming, and evaluate the sensitivity or tolerance of these forests by focusing on species composition and geographical characteristics.

The authors thank PEN for sharing the data of spectral reflectance and canopy images.

How to cite: Noda, H., Takeuchi, Y., and Muraoka, H.: Assessing the 20-Year Changes in Leaf Phenology of Temperate Deciduous Forests in Japan Using in-situ and Satellite-GRVI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15339, https://doi.org/10.5194/egusphere-egu24-15339, 2024.

Forest carbon sequestration is a key part of the European transition to carbon neutrality. Quantification of forest carbon sequestration rates relies on relies on successful integration of high volumes of remote sensing and in-situ data arriving at ever increasing velocities with a bewildering variety of “long tail” and legacy data. Research Infrastructures (RIs) can add value to these data by supporting their harmonised, cross-site collection, curation and publication and by providing a platform for assessing data veracity. Integration of RI networks through site co-location and standardised observation methods has been proposed as one way of dealing with the Big Data needed to quantify societally relevant environmental processes including those related to the carbon cycle. However, the full potential of RI network integration as a tool to improve environmental understanding has yet to be realised.

Here, we review current successes, identify challenges to better integration, and suggest ways forward. We provide recommendations for scientists, site managers and policy makers that will support the transition to a Big Data approach to quantifying and communicating forest carbon sequestration using the Swedish situation as an example.

How to cite: Futter, M., Högbom, L., Moldan, F., Peacock, M., and Villwock, H.: Challenges and Opportunities for Research Infrastructure Co-location to Improve Understanding of Terrestrial Carbon Cycling in Northern European Forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15707, https://doi.org/10.5194/egusphere-egu24-15707, 2024.

EGU24-16679 | ECS | Posters on site | ITS1.6/BG1.18

Biodiversity changes atmospheric chemistry through plant volatiles and particles 

Anvar Sanaei, Hartmut Herrmann, Loreen Alshaabi, Jan Beck, Olga Ferlian, Khanneh Wadinga Fomba, Sylvia Haferkorn, Manuela van Pinxteren, Johannes Quaas, Julius Quosh, René Rabe, Christian Wirth, Nico Eisenhauer, and Alexandra Weigelt

Given the significant human-induced changes in biodiversity and climate, the link between atmospheric and biological measurements is crucial to improve our understanding of atmosphere-biosphere feedbacks. Changes in climate and biodiversity influence the emission of biogenic volatile organic compounds (BVOCs) from plants, leading to the formation of biogenic secondary organic aerosols (BSOA). These BSOA can have diverse effects, including influencing Earth's radiative balance and impacting cloud and precipitation formation. However, at present, it is unclear how changing biodiversity will lead to changes in BVOC emissions, BSOA and their corresponding effects. We present a conceptual framework of the relationships between biodiversity and BVOC emissions based on our current mechanistic understanding and combining knowledge from the fields of biology and atmospheric chemistry. In this framework, first, we hypothesized that mixed forests enable resource partitioning, often leading to higher stand productivity and leaf area index, thus emitting higher amounts of BVOC. Second, given the significant difference in biotic and abiotic stress in monoculture and mixture plots, we hypothesized that increasing tree diversity would decrease BVOC emissions. We tested the effect of tree diversity on BVOC emission and BSOA formation in this framework by varying tree species richness, including monocultures, two- and four-species mixtures at the MyDiv experimental site in Germany. We quantified nine different BVOCs from the investigated plots, i.e., α-pinene, camphene, β-pinene, 3-carene, p-cymene, limonene, α-terpinene, isophorone, and acetophenone. The relative differences in tree monocultures and mixtures show that the overall concentration of BVOC decreases with increasing biodiversity. For BSOA, a total of fifteen BSOA compounds have been quantified, including diaterpenylic acid acetate [DTAA], 3-methyl-1,2,3-butanetricarboxylic acid [MBTCA], norpinonic acid, pinonic acid, terebic acid, terpenylic acid, pinic acid, adipic acid, pimelic acid, azelaic acid, suberic acid, succinic acid, glutaric acid, salicylic acid, and sebacic acid. The relative differences in tree monocultures and mixtures for BSOA showed mixed and overall non-significant results. A deeper understanding of how changing biodiversity influences biogenic organic compound emissions and biogenic secondary organic aerosol formation requires in-depth investigations of microclimate conditions, accurate monitoring of above- and below-ground biotic and abiotic stress, and manipulating stress conditions across long-term biodiversity experiments. Our findings highlight the need for multidisciplinary work at the interface between the biosphere and the atmosphere to better understand the reciprocal effects of biodiversity and climate change.

How to cite: Sanaei, A., Herrmann, H., Alshaabi, L., Beck, J., Ferlian, O., Fomba, K. W., Haferkorn, S., van Pinxteren, M., Quaas, J., Quosh, J., Rabe, R., Wirth, C., Eisenhauer, N., and Weigelt, A.: Biodiversity changes atmospheric chemistry through plant volatiles and particles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16679, https://doi.org/10.5194/egusphere-egu24-16679, 2024.

EGU24-16765 | Orals | ITS1.6/BG1.18

A comprehensive tool for prioritising ecologically sensitive locations and driving nature-positive actions 

Thea Piovano, Rhosanna Jenkins, Lorna Burnell, Claire Burke, and Beccy Wilebore

There exists an urgent need to address the ongoing nature crisis, and businesses must play a pivotal role in fostering positive change. As a result, there has been a significant increase in corporate attention on biodiversity. In response to this attention, several frameworks for companies to report their impacts on nature have emerged, including the EU’s Corporate Sustainability Reporting Directive (CSRD) and the Taskforce on Nature-related Financial Disclosures (TNFD). These frameworks set out steps for companies wanting to make a positive impact and include nature in business, particularly through determining their proximity to ecologically sensitive locations.

Our advanced prioritisation tool enables screening of any site in the world (both terrestrial and marine assets) for its proximity to ecologically sensitive locations. This tool incorporates metrics including Ecological Integrity, Decline in Ecological Integrity, Areas of High Physical Water Stress, Areas of High Potential Ecosystem Services and Biodiversity Sensitive Areas. Our tool aligns with best practices and with reporting guidance and standards (TNFD and CSRD).

By leveraging our screening tool, businesses can turn data-driven insights into responsible nature-positive actions.

How to cite: Piovano, T., Jenkins, R., Burnell, L., Burke, C., and Wilebore, B.: A comprehensive tool for prioritising ecologically sensitive locations and driving nature-positive actions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16765, https://doi.org/10.5194/egusphere-egu24-16765, 2024.

EGU24-18370 | ECS | Orals | ITS1.6/BG1.18 | Highlight

Drone4Tree: A cloud-based geospatial platform for large-scale UAV data processing and tree canopy detection 

Sharad Kumar Gupta, Franz Schulze, Ralf Gründling, and Ulf Mallast

Forests cover approximately 31% of the global land area and are home to 80% of the Earth's terrestrial biodiversity. Humans depend on forests for countless ecosystem services, but these ecosystems are highly vulnerable to human-induced climate change. As our climate undergoes dynamic changes, it is imperative to implement automated monitoring systems to quantify canopy growth and assess changes occurring within forest structures, especially at the level of individual trees, to determine the response of forests to climate anomalies. In this context, tree canopy detection can be considered one of the most important applications using Unmanned Aerial Vehicles (UAVs) as it can be used to obtain information on numerous essential ecosystem variables (EEVs) such as gross primary productivity, leaf area index, etc. for individual trees or shed light on essential biodiversity variables (EBVs) such as ecosystem structure and function. However, due to the plethora of information available, users may find it challenging to apply UAVs and algorithms to their specific projects. Hence, an integrated, seamless platform that can process UAV-acquired images to generate ortho-mosaics, detect individual trees, and monitor specific traits (including ecosystem structure and function) is the need of the hour.

In this study, a platform, Drone4Tree, has been developed using Streamlit and Flask to provide an end-to-end solution for generating orthomosaics and delineating individual tree crowns from UAV images. Users simply upload raw UAV survey data and receive the final results. The complete processing chain is carried out on our high-end servers, which is an advantage for users with limited computing resources. The developed web application uses open-source algorithms, models, and frameworks for easy implementation of components such as orthomosaic (structure from motion in OpenDroneMap), tree canopy detection (DeepForest and U-Net segmentation), and downloading of results. The platform offers two processing modes: standard and advanced. The standard mode comes with default parameters for orthomosaic generation and tree canopy detection, benefiting users with no experience in UAV image processing. The advanced mode allows users to customize the processes, such as the scale of the generated canopy boundary or patch size for large images. It also extends its functionality towards analysis-ready drone image time series (incl. a co-registration of orthomosaics to a reference image using the AROSICS method and reprojection using the geospatial data abstraction library (GDAL)). Finally, the processing outcomes can be easily downloaded using the generated links. 

The web app was used to generate a time series of individual tree canopies, which provided a deeper understanding of changes in EEVs during a phenological cycle. The canopy boundaries can also be used to generate spectral libraries for tree species from high spatial resolution hyperspectral images, which has several applications in species detection and mapping. This platform can guide other users wishing to efficiently produce individual tree canopy boundaries for large areas without investing substantial time tailoring imagery acquisition and processing parameters. The resulting tree canopy boundaries can provide opportunities to characterize individual trees' species, size, condition, and location and are critical resources for advancing ecological theory and informing forest management.

How to cite: Gupta, S. K., Schulze, F., Gründling, R., and Mallast, U.: Drone4Tree: A cloud-based geospatial platform for large-scale UAV data processing and tree canopy detection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18370, https://doi.org/10.5194/egusphere-egu24-18370, 2024.

EGU24-19043 | ECS | Orals | ITS1.6/BG1.18 | Highlight

Exploring climate-biodiversity interactions in observational data and models 

Petra Sieber, Jonas Schwaab, Dirk Karger, and Sonia Seneviratne and the FeedBaCks consortium

Climate change and biodiversity loss are increasingly considered jointly, particularly to find optimal solutions for both crises and to avoid negative side-effects and feedbacks. Much research has been devoted to predicting the effects of climatic changes on the distribution of species, but the consequences of biodiversity changes for the climate system are less understood. For instance, what are the main aspects (species richness, functional diversity, land cover patchiness) and mechanisms through which biodiversity interacts with the climate? Do landscapes with different levels of diversity contribute differently to climate regulation or feedbacks? How do human choices such as nature conservation or natural resources production affect the climate? To address these questions, we combine observational and modelling approaches in a collaborative effort of ecologists and climate scientists.

First, we present how ecosystem diversity affects forests’ climate response (indicated by interannual variability in summer NDVI) and climate effect (indicated by interannual variability in summer LST), using 20 years (2003-2022) of remote sensing data at 1 km resolution over Europe. We consider different diversity levels (taxonomic, functional, structural) together with various ecosystem, topography, soil, and climate predictors in a multiple linear regression with Ridge regularisation. This approach allows isolating the effects of specific biodiversity aspects (e.g. tree species richness, forest edge density), functional properties (e.g. leaf type, leaf traits), and structure (e.g. canopy height, tree cover density), and determining the sign and magnitude of their contribution. We show which aspects and scales of biodiversity are relevant for ecosystem stability and climate regulation, respectively, and classify forests into response and effect types that could be considered in coupled biosphere-atmosphere models.

Second, we discuss how biodiversity aspects can be integrated into the coupled biosphere-atmosphere regional climate model COSMO-CLM2 to quantify their effects on land-atmosphere interactions and feedbacks over Europe. We demonstrate one approach, utilising future land cover scenarios derived from the Nature Futures Framework that represent different value perspectives on nature (intrinsic, instrumental, and relational), habitat types from EUNIS (European Nature Information System), and species abundances from EVA (European Vegetation Archive). Our results show temperature differences of up to several degrees locally, with enhanced temperature sensitivities under hot and dry conditions. Such findings can help identify synergies between biodiversity conservation, climate change mitigation, and adaptation, and support the development of effective policy solutions.

Finally, this presentation will provide perspectives for research at the interface of biodiversity and climate change.

How to cite: Sieber, P., Schwaab, J., Karger, D., and Seneviratne, S. and the FeedBaCks consortium: Exploring climate-biodiversity interactions in observational data and models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19043, https://doi.org/10.5194/egusphere-egu24-19043, 2024.

EGU24-19803 | ECS | Posters on site | ITS1.6/BG1.18

Exploring the carbon dynamics and epiphytic lichen diversity of boreal old-growth forests  

Anu Akujärvi, Aleksi Nirhamo, Risto K. Heikkinen, Juha Pykälä, Otto Saikkonen, Timothy Green, Mikko Peltoniemi, and Annikki Mäkelä

The loss of pristine old-growth boreal forest landscapes due to the intensive management for timber production has caused both a severe decline of forest biodiversity in Northern Europe as well as significantly altered their carbon stocks and dynamics. Understanding of the dynamics of old-growth forests is needed to evaluate the consequences of different forest management and conservation strategies on climate change mitigation and biodiversity conservation. It is increasingly suggested that integrated forest management and conservation planning is required to secure both biodiversity and carbon storage values. However, it is insufficiently known how closely these values coincide at the local level, i.e., whether the same structural and quality features in old-growth forests support both high biodiversity and carbon stock.

The objectives of this study were, first, to explore the dynamics of stand growth and carbon sequestration in boreal old-growth forests and second, to investigate whether the occurrence of red-listed epiphytic forest lichens coincides with high carbon stock and structural features related to it. The study was based on an extensive repeated forest inventory dataset collected between 1990 and 2019 in southern Finland and a lichen inventory conducted during 2020 – 2021 at the same sites.

The estimated volume of standing trees and deadwood were higher in the studied forest stands than in managed forests on average. Estimates of net primary production showed varying trends of carbon sequestration among the study plots. Stand gross growth increased by 50% during the study period. The standing volume remained stable because a large proportion of the biomass increment was allocated to deadwood. The study sites showed a high occurrence of red-listed epiphytic lichens. No relationship was found between the species richness of red-listed lichens and the aboveground carbon stock. However, a significant negative relationship was found between the number of red-listed lichen occurrences and carbon stock.  The species richness of red-listed lichens showed a strong unimodal response to the aboveground carbon stock change: the highest species richness was associated with intermediate carbon sinks.

Our results highlight the major role of tree mortality driving the carbon dynamics of old-growth forests, with simultaneous benefits for deadwood-associated species. However, more research is needed on the stability of carbon stocks of forests in the face of shifting disturbance regimes due to climate change. While the species richness of red-listed epiphytic lichens had a neutral relationship with the aboveground carbon stock size, we observed fewer occurrences in carbon-rich forests, and lower species richness and occurrences in plots with large carbon sinks. Therefore, if climate benefits are sought with methods that increase stand density, negative impacts may be expected on lichen species that fare poorly in dense stands with low light. Additionally, high carbon sequestration in fast-growing stands may come at the expense of reduced biodiversity.

In summary, this study supports the idea that old-growth forests provide considerable benefits regarding both climate change mitigation and biodiversity. Therefore, increasing the area of old-growth forests would simultaneously support these key goals.

How to cite: Akujärvi, A., Nirhamo, A., Heikkinen, R. K., Pykälä, J., Saikkonen, O., Green, T., Peltoniemi, M., and Mäkelä, A.: Exploring the carbon dynamics and epiphytic lichen diversity of boreal old-growth forests , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19803, https://doi.org/10.5194/egusphere-egu24-19803, 2024.

EGU24-20282 | ECS | Posters on site | ITS1.6/BG1.18 | Highlight

The Leipzig Canopy Crane experiment: DNA metabarcoding of air samples to monitor seasonal variations in airborne fungal and plant communities composition 

Ettore Fedele, Birgit Gemeinholzer, Ronny Richter, Christian Wirth, and Beatriz Sánchez-Parra

Rapid and accurate assessments of ecological responses to environmental changes are key to the development of effective measures aimed at the mitigation of detrimental effects on the integrity of ecosystems and the provision of services that support the livelihoods of billions of people worldwide. Traditionally, however, the study of ecological communities has relied on laborious and complex taxonomic work, that undermines the feasibility and practicality of urgent monitoring programmes.

In the last two decades, the emerging field of environmental DNA analysis has opened to the possibility to study complex systems at a fraction of the original time and financial costs, hence producing vast amounts of vital information. Here, we utilised DNA metabarcoding analysis of bioaerosol samples collected during 2019 at the Leipzig Canopy Crane to study seasonal variations in airborne fungal and plant species composition, in relation to changes in humidity, wind, and temperature. Preliminary results show significant differences in both plant and fungal communities. Specifically, climatic differences between the coldest and warmest months significantly affect the taxa Ascomycota and Basidiomycota, whereas the period between March and April reportedly displayed an increase in the abundance of anemophilous plants and members of the genus Salix. Lastly, with this study we intend to showcase the importance of long-term monitoring programmes of environmental DNA for investigating the implications of climate change.

How to cite: Fedele, E., Gemeinholzer, B., Richter, R., Wirth, C., and Sánchez-Parra, B.: The Leipzig Canopy Crane experiment: DNA metabarcoding of air samples to monitor seasonal variations in airborne fungal and plant communities composition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20282, https://doi.org/10.5194/egusphere-egu24-20282, 2024.

EGU24-1118 | ECS | PICO | ITS3.5/BG1.19

From electrical cable bacteria acidification to eelgrass colonisation: seasonal monitoring of foraminiferal ecology and shell preservation on estuarine mudflats. 

Maxime Daviray, Emmanuelle Geslin, Eric Beneteau, Sophie Quichard, Matéo Tougne, and Edouard Metzger

This study presents the seasonal monitoring of sediment acidification in two intertidal mudflat stations in the Auray river estuary (Atlantic coast, France). Sediment geochemistry and living benthic foraminifera and the preservation of their shells were investigated from April 2022 to July 2023. The development of eelgrass meadows was observed in both mudflats during Summer, something that had not happened for over ten years. Before these sprouts, the mudflats were bare, with seasonal algal deposits, and colonised by cable bacteria. Cable bacteria activity is characterised by electrogenic sulphide oxidation (e-SOx) measured by O2, H2S and pH microprofilings. e-SOx redesigns diagenetic processes generating strong pH gradients within the first few centimetres of sediment. The upstream mudflat showed seasonal dynamics of e-SOx. Cable bacteria appeared to be inactive in Winter (∆pH = 0.4) and led to intense pore water acidification during Fall (∆pH = 1.9) under meadow senescence. In the downstream mudflat, e-SOx remained continuous through the year with ∆pH from 0.9 in Winter to 2.3 in Fall. At both stations, the Ωcalc decreased from supersaturated to values well below 1 in the first few millimetres of sediment, excepted in Winter when Ωcalc was undersaturated due to freshwater flow. All year long, calcareous specimens, mostly dominated by Ammonia morphocomplex tepida and Haynesina germanica, showed test dissolution below the sedimentary oxic layer. During Fall, at both stations, calcareous specimens dwindled and tests were extremely corroded. In the meantime, the agglutinated species Ammobaculites balkwilli dominated the assemblage. During Spring, the upstream station was the setting for a H. germanica bloom after the cable bacteria seemed no longer active in Winter. During Summer, the upstream station showed a well-developed eelgrass meadow together with e-SOx (ΔpH = 1.3). Agglutinated species dominated the foraminiferal assemblage with A. balkwilli in the upper 5-mm and Eggerelloides scaber deeper down. The eelgrass colonisation has seemed to be beneficial to the foraminiferal community and stimulates its dynamism by encouraging a new species equilibrium in the assemblage. The most impacted species seemed to be A. morphocomplex tepida as between Summer 2022 and 2023 their density and relative abundance felt sharply in favour of Elphidium spp., Quiqueloculina spp. and A. balkwilli. These summery observations were quite different from those at the downstream station where cable bacteria were active all year long. Surprisingly, agglutinated species remained in minor proportions and A. morphocomplex tepida more or less constant. Moreover, dead assemblages showed important losses of calcareous tests where cable bacteria were active conducting to an organic lining enrichment with depth. To summarize, our study shows that foraminiferal ecology responds quickly to environmental changes in coastal sediments making them suitable for biomonitoring while the loss of their tests in acidic environments weakens their applicability for reconstructing temporal environmental chronicles.

How to cite: Daviray, M., Geslin, E., Beneteau, E., Quichard, S., Tougne, M., and Metzger, E.: From electrical cable bacteria acidification to eelgrass colonisation: seasonal monitoring of foraminiferal ecology and shell preservation on estuarine mudflats., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1118, https://doi.org/10.5194/egusphere-egu24-1118, 2024.

EGU24-1401 | ECS | PICO | ITS3.5/BG1.19 | Highlight

The distribution pattern of vascular plant alpha diversity in the Qinghai-Tibet Plateau 

Yajie Zhang and Tao Zhou

Biodiversity plays a vital role in maintaining ecosystem functioning. Quantifying the impact of biotic and abiotic factors on plant diversity and creating a prediction map of biodiversity on the Qinghai-Tibet Plateau (QTP) can provide data and mechanism support for biodiversity conservation and restoration. Species richness (SR) serves as one of the indicators of biodiversity. In this study, we developed a SR estimation model based on the random forest algorithm, using 275 SR observation data, soil attribute data, meteorological data, topographical data, and human activity data. We assessed the pattern of SR on the QTP from 2000 to 2020, analyzed its spatiotemporal variation, and further evaluated significant environmental factors influencing vegetation alpha diversity. Our results showed that (1) Climate factor is the main influencing factor of SR spatial variation on the QTP, followed by terrain conditions. (2) Machine learning can account for 56% of SR and unveil distribution patterns showing a decrease in species richness from southeast to northwest on the QTP. (3) Over the past 20 years, there has been an increase in SR, particularly in the southeastern region.

How to cite: Zhang, Y. and Zhou, T.: The distribution pattern of vascular plant alpha diversity in the Qinghai-Tibet Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1401, https://doi.org/10.5194/egusphere-egu24-1401, 2024.

EGU24-1572 | ECS | PICO | ITS3.5/BG1.19

Simulating and analysing seabird flyways: An approach combining least-cost path modelling and machine learning 

Nomikos Skyllas, Mo Verhoeven, Maarten Loonen, and Richard Bintanja

Seabird migration is driven by general wind circulation and productive ocean regions. As a result, bird migration takes place along distinct corridors or "flyways” that have evolved by earth’s large-scale atmospheric circulation patterns. These flyways form a link between climate and bird migration, and by simulating their pattern we might better understand the present corridor and predict the potential future impacts of climate change. However, few studies have focused on modelling flyways (especially for multiple bird strategies, populations, seasons, species and oceans), with most of them simulating trajectories of individual birds.

We use climatic data in combination with a least-cost-path modelling approach to simulate and describe multiple seabird flyways. By combining bird tracking data and machine learning, we are able to infer whether the flyways used by the birds optimise time and/or energy. We focussed on five seabird flyways of arctic terns and sooty shearwaters, both spring and autumn migration either over the Atlantic or the Pacific Ocean. We will show that a bird's effort is influenced by tailwinds, crosswinds and food availability, and we use this to calculate how close to the theoretical optimal migration (time- or energy-minimising) these birds actually fly. Our findings show that it is possible to recreate observed flyways using environmental data and that these simulations can generate predictions about the effect of future climate change.

How to cite: Skyllas, N., Verhoeven, M., Loonen, M., and Bintanja, R.: Simulating and analysing seabird flyways: An approach combining least-cost path modelling and machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1572, https://doi.org/10.5194/egusphere-egu24-1572, 2024.

EGU24-2306 | PICO | ITS3.5/BG1.19

Global Potential Riparian Zones Estimation 

Ibrahim Mohammed, Kashif Shaad, John Bolten, and Maira Bezerra

The recently announced Freshwater Challenge (FWC) initiative (https://www.freshwaterchallenge.org/) at the United Nations Water conference, sets an ambitious goal of restoring 300,000 kilometers of degraded rivers and 350 million hectares of degraded wetlands across the globe by 2030. Central to moving towards this goal will be including tangible actions for freshwater and linked ecosystems into supporting country’s Nationally Determined Contributions (NDCs) and National Biodiversity Strategies and Action Plans (NBSAPs). This in turn relies on the availability and fidelity of geospatial information that can be the basis for planning. The currently available geospatial data that captures accurate delineation of riparian zones, i.e., the transitional semiterrestrial/semiaquatic areas regularly influenced by fresh water, usually extending from the edges of water bodies to the edges of upland communities, must be improved to address the needs highlighted in the Freshwater Challenge. This presentation gives a methodology for deriving a global potential riparian zones layer obtained by processing wetlands, riparian buffers, headwater catchments, layers, assets, and information. We process near real-time land cover dataset from dynamic World (https://dynamicworld.app/), global wetland maps (Tootchi et al., 2019), and High‐Resolution Global Hydrography Maps (Yamazaki et al., 2019; Amatulli et al., 2022) for our analysis. We further explore how this analysis will inform governments around the world on assessing the current state of Riparian Zones as well as estimating benefits from restoration effort, allowing movement towards the goals set by the Freshwater Challenge.

How to cite: Mohammed, I., Shaad, K., Bolten, J., and Bezerra, M.: Global Potential Riparian Zones Estimation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2306, https://doi.org/10.5194/egusphere-egu24-2306, 2024.

EGU24-2513 | PICO | ITS3.5/BG1.19 | Highlight

Overwintering and migration of sea turtles in Jeju Island of Korea: lessons from “SEAturtle” PICES special research project (2019-2023)  

Taewon Kim, Soojin Jang, Mi-Yeon Kim, Byung-Yeob Kim, Kyungsik Jo, Sookjin Jang, Jibin Im, George Balazs, Hideaki Nishizawa, Connie Ka Kan NG, George Shillinger, and Michelle María Early Capistrán

PICES special research project “SEAturtle” launched in 2019 to understand the ecology of sea turtles around Jeju Island in relation to environmental stressors. Though COVID 19 had interrupted the project, we had quite a successful outcome over the last 5 years. Until now (June 15, 2023), a total of 16 iridium transmitters were deployed on sea turtles (14 on green sea turtles and 2 on loggerhead sea turtles). Among them, we received the signals successfully from 15 sea turtles. We found that quite a proportion of green sea turtles released in Jeju Island (N = 4 out of 12, approx. 40%) overwintered nearby even in the cold sea where the temperature dropped to 15 °C. The diving duration increased to approx. 6 hrs with decreasing temperature. Most of migrating green sea turtles (N = 4) traveled toward southern Japan which suggests a strong link to the population in Japan. Our population genetics result on green sea turtles stranded suggests that a subunit of Jeju population also have an affinity to Japan population. On the other hand, one of our loggerhead sea turtles moved westward but the other moved southward from Jeju Island, suggesting that they may also have connectivity to both Japan and China. Our populations genetics and stable isotope analysis on the commensal barnacles support this. We also have actively worked on the threat of plastics on Jeju populations and found that derelict recreational fishing gears might cause more serious problems than commercial derelict fishing gears. Microplastics are other threats to them too. To conserve the population of sea turtles in Jeju Island, we need further extensive research and should keep up international cooperation.

How to cite: Kim, T., Jang, S., Kim, M.-Y., Kim, B.-Y., Jo, K., Jang, S., Im, J., Balazs, G., Nishizawa, H., Ka Kan NG, C., Shillinger, G., and María Early Capistrán, M.: Overwintering and migration of sea turtles in Jeju Island of Korea: lessons from “SEAturtle” PICES special research project (2019-2023) , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2513, https://doi.org/10.5194/egusphere-egu24-2513, 2024.

EGU24-6353 | ECS | PICO | ITS3.5/BG1.19

Biodiversity Data Cubes for Cross-Cutting Science and Policy 

Lina M. Estupinan Suarez, Laura Abraham, Tim Adriaens, Lissa Breugelmans, David A. Clarke, Peter Desmet, Shawn Dove, Katelyn T. Faulkner, Miguel Fernandez, Louise A. Hendrickx, Cang Hui, Alexis Joly, Sabrina Kumschick, Ward Langeraert, Matilde Martini, Joe Miller, Damiano Oldoni, Henrique Pereira, Cristina Preda, and Quentin Groom and the Biodiversity Building Blocks for Policy Project

Biodiversity and the Earth climate system are coupled through multiple biotic and abiotic feedbacks. Although there are clear links between the two systems, there is a lack of integrative research to evaluate them. One reason is that both systems operate on different scales, impacting integration efforts. In addition, the state of the art for each has evolved at different rates over recent decades. The growing number of satellite missions has made it possible to measure Earth system variables on a global scale and with great frequency. This enormous amount of data, captured even on an hourly basis, in tandem with a network of gauging stations, and open-access policies have boosted Earth system modeling and projections, and thus increased our understanding of one of the Earth's components (i.e. climate). Biodiversity data has also increased, albeit at a slower rate. Citizen science, along with the application of different technologies such as camera traps, phenocams, bioacoustics and, more recently, eDNA, are enabling scientists to obtain data more efficiently. However, there are still large gaps in geographic and taxonomic coverage.This is partially related to abrupt biodiversity gradients and insufficient  explanatory variables that hinder modeling  biodiversity as smooth gradients in climate systems. Another reason is the difference between data formats and approaches among fields; for example, biodiversity data are often recorded as spatial points, in contrast to gridded satellite data. All these pose numerous challenges for a more coordinated and cross-cutting research. As a starting point, it is our task to reach other scientific communities and offer harmonized solutions for data integration and analysis. Specifically, in the Biodiversity Building Blocks for Policy project (B-Cubed) we are developing informatics workflows to facilitate the analysis of species occurrence information in a data cube format. We are using, though are not limited to, the world’s largest biodiversity database, the Global Biodiversity Information Facility (GBIF), to provide species occurrence information in a more interoperable format. Furthermore, we are also leveraging the concept of data cubes to standardise access to biodiversity data using the Essential Biodiversity Variables framework. Currently, the implementation of species occurrence cubes is aimed at analyzing invasive species, improving species distribution modeling techniques, and developing effective indicators for informing policy. We strongly believe that data cubes will facilitate both data sharing and processing, and the co-development of tools and approaches between biodiversity and Earth sciences, which will undoubtedly benefit cross-cutting research. Synergies between biodiversity and Earth system sciences are urgently needed for better informing decision makers about feedbacks in both systems that can respond to adopted and upcoming policies.

How to cite: Estupinan Suarez, L. M., Abraham, L., Adriaens, T., Breugelmans, L., Clarke, D. A., Desmet, P., Dove, S., Faulkner, K. T., Fernandez, M., Hendrickx, L. A., Hui, C., Joly, A., Kumschick, S., Langeraert, W., Martini, M., Miller, J., Oldoni, D., Pereira, H., Preda, C., and Groom, Q. and the Biodiversity Building Blocks for Policy Project: Biodiversity Data Cubes for Cross-Cutting Science and Policy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6353, https://doi.org/10.5194/egusphere-egu24-6353, 2024.

River corridors, i.e. channel and adjacent floodplains, are hotspots of biodiversity and provide manifold ecosystem services. Their functioning and thus their ability to maintain biodiversity and to provide ecosystem services is controlled by a complex interplay of hydrologic, geomorphic and ecologic processes. These processes both affect and depend on hydrologic, geomorphic and ecologic connectivity within the river system. Today, process regimes of most (large) rivers are affected by human activities such as the construction of dams and reservoirs, flood protection measures or the withdrawal of water for agricultural irrigation. Dams modify longitudinal connectivity and thus the natural flow and sediment regime, while flood protection dikes disconnect channel and floodplain. There is a growing body of research on how hydrology-geomorphology-ecology-interactions shape river corridors and how these interactions are disturbed by humans. However, these insights tend to arise from studies at either the small river system or the reach scale. Truly understanding the impact of human interventions on rivers requires a dynamic, system scale perspective on process regimes. In our contribution, we take the river network in the Aral Sea Basin in Central Asia as an example and demonstrate the use of satellite time series to make a functional assessment of the process regimes controlling riparian ecosystem development. This river network has a total length of 75.000 km draining a catchment of 1.2 million km². We start the assessment with the delineation of the river network and the riparian zone from digital elevation models. Then, we use a novel unsupervised approach to create a map of landcover and general habitat types within the river corridors. In a second step, we create a dam and reservoir database in order to assess river fragmentation. In a third step, we use time series of Landsat and MODIS satellite imagery to assess hydrologic and geomorphic dynamics as well as vegetation development. These time series are the basis to analyze the relationship of e.g. floodplain inundation dynamics and vegetation trends or the impact of flood pulses on morphological change triggering vegetation change. The results show that the Aral Sea Basin is highly fragmented and that this fragmentation influences downstream process regimes and initiates modifications in the riparian ecosystems. Our satellite time series approach is able to capture relevant process dynamics and their impact on ecosystem development (i) in data-scarce regions, (ii) at large spatial scales (large river basins) and (iii) at high temporal frequency as enabled by short revisit times of current satellite constellations and cloud computing. Thus, it is a promising way to generate system-scale knowledge on the interaction of hydrologic, geomorphic and ecologic processes being the basis for biodiversity maintenance and ecosystem service provision in river corridors.

How to cite: Betz, F., Lauermann, M., Schmitt, R., and Heckmann, T.: Towards system scale understanding of the complex interaction of hydrologic, geomorphic and ecologic processes controlling ecosystem functioning in river corridors: Using satellite time series to assess the river network in the Aral Sea Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11602, https://doi.org/10.5194/egusphere-egu24-11602, 2024.

EGU24-13341 | ECS | PICO | ITS3.5/BG1.19 | Highlight

Terrestrial land cover shapes fish diversity in major subtropical rivers 

Heng Zhang, Rosetta Blackman, Reinhard Furrer, Maslin Osathanunkul, Jeanine Brantschen, Cristina Di Muri, Lynsey Harper, Bernd Hänfling, Pascal Niklaus, Loïc Pellissier, Michael Schaepman, Shuo Zong, and Florian Altermatt

Freshwater biodiversity is critically affected by human modifications of terrestrial land use and land cover (LULC). Yet, knowledge of the spatial extent and magnitude of LULC-aquatic biodiversity linkages is still surprisingly limited, impeding the implementation of optimal management strategies. Here, we compiled fish diversity data across a 160,000-km2 subtropical river catchment in Thailand characterized by exceptional biodiversity yet intense anthropogenic alterations, and attributed fish species richness and community composition to contemporary terrestrial LULC across the catchment. We created a spatially explicit model and estimated a spatial range of LULC effects extending up to about 20 km upstream from sampling sites. The model explained nearly 60 % of the variance in the observed species richness, associated with major LULC categories including croplands, forest, and urban areas. We find that integrating both spatial range and magnitudes of LULC effects is needed to accurately predict fish species richness. Further, projected LULC changes showcase future gains and losses of fish species richness across the river network and offer a scalable basis for riverine biodiversity conservation and land management, allowing for potential mitigation of biodiversity loss in highly diverse yet data-deficient tropical to sub-tropical riverine habitats.

How to cite: Zhang, H., Blackman, R., Furrer, R., Osathanunkul, M., Brantschen, J., Di Muri, C., Harper, L., Hänfling, B., Niklaus, P., Pellissier, L., Schaepman, M., Zong, S., and Altermatt, F.: Terrestrial land cover shapes fish diversity in major subtropical rivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13341, https://doi.org/10.5194/egusphere-egu24-13341, 2024.

EGU24-15186 | PICO | ITS3.5/BG1.19

Development of a Web-Responsive Analysis Tool for Tracking Sea Turtle Behavior and Habitat 

Kim Taehoon, Kim Bo ram, Hong Sang Hee, and Lee Chol young

  The environmental issues caused by marine debris and the problem of habitat pollution for marine organisms are pervasive worldwide. Both floating debris and sunken debris contaminate various habitats, including coastlines, coral reefs, and seaweed beds. Various marine organisms exposed to such marine debris ultimately suffer from entanglement and ingestion, with sea turtles, in particular, accounting for 66% of reported cases of harm among all marine mammals. In Korea, various cases of mortality due to entanglement and ingestion in sea turtles have been widely reported. To comprehend the correlation between the behavior, habitats, and marine debris associated with sea turtles, ecological research is being conducted through location tracking. it is essential to conduct habitat degradation research for sea turtles by analyzing their spatial behavior using location-based methods and understanding feeding patterns using various environmental information. To address these issues, it is crucial to accurately understand the movement routes and activity patterns of marine organisms. In the field of wildlife research, various studies are being conducted using geographic information systems to utilize diverse analytical methods.

  In this study, we aimed to develop a web-responsive analysis tool for continuous tracking of sea turtle behavior and habitat foraging. The analysis module comprises three parts: the preprocessing module, spatial analysis module, and exploratory analysis module. The preprocessing module functions to extract necessary data from Argos satellite-received location information and refine it into clean data. It extracts latitude, longitude, sea surface temperature, and depth information from multiple files, organizes them into a single table, and saves them in a analyzable file format. The analysis module includes functions for deriving sea turtle activity ranges and overlapping analyses of habitat within activity zones. The activity range analysis utilizes Kernel Density Estimation (KDE) based on sea turtle location point data. Bandwidth, defined automatically based on the distribution of accumulation and points, allows for efficient analysis. The habitat overlapping analysis integrates various biological occurrence information such as coral, algae, and jellyfish within the sea turtle's activity zone. This enables exploration of the sea turtle's habitat environment within dense areas. The exploratory analysis module offers visualization features for location information, received depth, and sea surface temperature derived from data received by Argos satellites. Depth and sea surface temperature details are presented alongside location information, utilizing color coding for enhanced comprehension.

  The analysis module and the platform it is implemented on were developed in the form of a responsive web application using the open-source R-shiny. The responsive web application allows researchers to input and analyze sea turtle location data directly from a web page in any internet-enabled environment. It is fast and efficient as the results can be promptly visualized on a map. The sea turtle behavioral analysis tool developed in this study enables researchers to obtain standardized information related to behavior and habitat using location-based sea turtle data received from various satellites. It establishes a systematic approach for researchers to easily utilize this information through the web.

How to cite: Taehoon, K., Bo ram, K., Sang Hee, H., and Chol young, L.: Development of a Web-Responsive Analysis Tool for Tracking Sea Turtle Behavior and Habitat, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15186, https://doi.org/10.5194/egusphere-egu24-15186, 2024.

EGU24-15721 | PICO | ITS3.5/BG1.19 | Highlight

Alternative migration strategies of fin whales in the Mediterranean sea : evidence of a lunar influence 

Clément Fontana, Hervé Glotin, and Carlo Brandini

Understanding migrational behavior of fin whales (Balaenoptera physalus) in the Mediterranean basin is of greatest importance in terms of research on cetaceans, but also in terms of conservation for a specie considered as ‘endangered’ based on the IUCN Red List criteria. We investigate in this study the migrational behavior of several individuals from this population. Several datasets (telemetry-tracking, satellite-estimated chlorophyll concentration and oceanic currents) are used to assess their long- and short-term behavioral adaptations to diverse biomes. We highlight the fact that meeting points with the North Atlantic population exist at strategical environmental locations. We prove that migrating fin whales show distinct swimming behaviors depending on the lunar phases by comparing their daily distances swam to the tortuosity of their paths. These distinct behaviors might be due to prey availability as well as acting as a temporal trigger to maximize chances of reproduction success. Indeed, this migration strategies of the Mediterranean population is also explained by reproductive constraints of an isolated population susceptible to inbreeding. We then focus the study on two fin whale paths in the Strait of Sicily showing that they are able to communicate between each others, adapt their foraging area to instantaneous moon-driven changes of oceanic conditions but also to follow cyclic seasonal variations of resources availability. We finally bring a new insight on an alternative pattern for migration strategies of fin whales in the Mediterranean sea.

How to cite: Fontana, C., Glotin, H., and Brandini, C.: Alternative migration strategies of fin whales in the Mediterranean sea : evidence of a lunar influence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15721, https://doi.org/10.5194/egusphere-egu24-15721, 2024.

EGU24-18071 | PICO | ITS3.5/BG1.19

Impact of Hermodice carunculata (Pallas, 1766) (Polychaeta: Amphinomidae) on artisanal fishery: A case study from the Mediterranean Sea 

Emanuele Mancini, Riccardo Martellucci, Sebastiano Marino, Bianca Maria Lombardo, Umberto Scacco, and Francesco Tiralongo

Invasive species can cause severe economic damages, ecosystem alterations, and can even threat human health. In the global warming scenario, which can act as a driving force for the expansion of thermophilic species, we investigated for the first time the economic damage caused by the invasive bearded fireworm, Hermodice carunculata, to artisanal longline fishery in the Mediterranean Sea. We focused on bottom longline fishery targeting the highly prized white seabream Diplodus sargus, investigating catch composition of the fishing gear and Catch Per Unit Effort (CPUE) of species caught, with particular emphasis on the economic damage caused by the bearded fireworm, H. carunculata, in relation to water temperature. Our results clearly indicated direct and indirect economic damage to fishing activities practiced in the southeastern coast of Sicily (Ionian Sea). Type and extent of the damage caused by the invasive worm (H. carunculata) were discussed in relation to temporal scale and overall yields obtained by this traditional artisanal fishery, and some solutions are proposed. However, the actual situation requires special attention because it is expected to worsen in the context of the global warming future scenarios, such that further studies are urgently needed.

 

How to cite: Mancini, E., Martellucci, R., Marino, S., Lombardo, B. M., Scacco, U., and Tiralongo, F.: Impact of Hermodice carunculata (Pallas, 1766) (Polychaeta: Amphinomidae) on artisanal fishery: A case study from the Mediterranean Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18071, https://doi.org/10.5194/egusphere-egu24-18071, 2024.

Opencast limestone mines, being oligotrophic environments characterized by harsh environmental conditions are considered as challenging habitat for colonization and growth of all life forms. These conditions include elevated temperatures, prolonged exposure to sunlight, and deficiencies in organic matter, moisture, and soil nutrients. In such environments, lithobionts may play an important role as the main sources of primary production and maintaining the ecosystem functioning. Unfortunately, our knowledge regarding the taxonomic diversity, potential functions, and ecology of limestone quarry/mines remains quite limited. Here, we explored the taxonomic composition and metabolic potential of lithobiontic microorganisms dwelling carbonate rocks of a limestone mine in Udaipur, Rajasthan, India by using high-throughput shotgun metagenomic sequencing. Community profile analysis revealed that the lithobiontic community was dominated by bacteria (98.94 %), with a minute fraction of the Eukaryota (0.77 %) and archaeal population (0.23 %). Microbes belonging to Phylum Cyanobacteria (39.74 %), Proteobacteria (35.21 %) and Actinobacteria (10.34 %) were predominant followed by a remarkable share of Chloroflexi (4.77 %) and Firmicutes (2.41 %). Metabolic potential analysis, based on six functional modules of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, revealed that functional genes involved in microbial metabolisms are highly represented in this community (59.68 %). Functional analysis of the carbonate microbiome indicated their capacity to influence carbon, nitrogen, and sulfur cycles. Results suggest that the oxygenic photosynthetic bacteria contribute significantly to primary productivity as well as carbonate precipitation in such arid and oligotrophic environments. Multi-omics level study on isolated cyanobacterial strains is underway to gain deeper insights into habitat adaptation and the functioning of lithobiontic niche of cyanobacteria in carbonate rocks.

How to cite: Singh, J. and Maharana, C.: Metagenomics of carbonate rocks from limestone mines, Udaipur, Rajasthan, India, reveal insight into lithobiontic microbial community and biogeochemical cycling., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18368, https://doi.org/10.5194/egusphere-egu24-18368, 2024.

Agricultural land area is increasing globally despite the loss of productive agricultural lands in some world regions. The knowledge about major agricultural land changes and the impacts on the quality of land in both cropland and grassland in Africa is still very limited. We conducted an African continent-wide assessment of the dynamics of agricultural landscapes (i.e., gains, losses, and net change). With pressure mounting to halt biodiversity loss and stem land degradation in agricultural areas across all world regions, promoting sustainable agriculture requires not only an understanding of agricultural land-use change but also the impacts of such changes on land quality.
We identify influencing factors and model the quality of land associated with agricultural land gains and losses between 2000 and 2018. Land quality in gained and displaced croplands and grasslands was established using spatially-explicit analysis of changes in Net Primary Productivity, soil organic carbon content, crop suitability and percent yield change for five major crops of global importance grown across Africa. These are maize, rice, soybean, wheat, and alfalfa.
Influencing factors in each agricultural land change area (i.e., areas of cropland and grassland gains and losses) were examined. In cropland loss and gain areas, settlement development,
proximity to perennial rivers/water bodies, and access to a major road were important. For example, most land areas transitioning to cropland in Africa were associated with large distances away from major roads. The preceding finding suggests the remoteness of newly gained croplands. However, distances to a major road, waterbody, settlement, and elevation were important for explaining grassland dynamics. Land quality was better in gained
croplands than in those lost, whereas gained grasslands were of lesser quality compared to areas of grassland loss.
Five typologies of African countries were developed based on net yield and amount of land cultivated per crop in cropland change areas. Type 1 typifies net yield increase and cultivated land decrease, while type 2 is characterized by yield increase consequent upon cropland expansion. Net yield and land remain unchanged in type 3, while in type 4, cultivated land increased, but yield decreased for maize in 40% of African countries, and in type 5, yield and land area decreased. This study thus provides evidence about the quality of land in gained and lost agricultural areas and generalizable insights on their dynamics across Africa.

How to cite: Akinyemi, F. O. and Speranza, C. I.: Changes to agricultural landscapes impact the quality of land: An African continent-wide assessment in gained and displaced agricultural lands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21129, https://doi.org/10.5194/egusphere-egu24-21129, 2024.

Reversing the declines in biodiversity trends is a widely adopted goal, reflected in both the Kunming-Montreal Global Biodiversity Framework, and the EU 2030 Biodiversity Strategy. In this presentation, we will show two examples of how models and scenarios can be mobilized to provide support to achieving these goals in the context of the broader sustainable agenda. In a first example, multiple economic and biodiversity models are used to assess long-term, global scale, pathways aiming to explore whether—and how—humanity can reverse the declines in terrestrial biodiversity caused by habitat conversion reverse global biodiversity losses (Leclere et al, 2020). The results show that i) immediate efforts of unprecedented ambition and coordination could enable reversing the global terrestrial biodiversity trends caused by habitat conversion, and ii) that an integrated approach, combining increased protection and restoration efforts with sustainable production and consumption measures, is essential to not only enable a bending of global biodiversity trends before 2050, but also limit trade-offs and harness synergies with other sustainable goals. In a second example, we will demonstrate how models and scenarios are also mobilized to support policy design at the EU scale, with an application focusing on assessing the land use, LULUCF emissions and biodiversity implications of EU climate (e.g., Fitfor55 package and LULUCF regulation) and biodiversity (e.g., Nature Restoration Law) and their interactions.

How to cite: Havlík, P., Leclere, D., and Visconti, P.: Modeling of in support of long-term pathways and EU policies for bending the curve of biodiversity loss, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22576, https://doi.org/10.5194/egusphere-egu24-22576, 2024.

EGU24-410 | ECS | Orals | EOS3.1 | Highlight

Family-Friendly Conferences in the Geosciences 

Elena Päffgen, Leonie Esters, and Lisa Schielicke

Participation in (inter-) national conferences, seminars, and workshops such as the EGU General Assembly is important for professional exchange and personal networking, especially for early career scientists. Enabling scientists with family obligations to take part in conferences will increase gender equity and diversity, as women remain to be the main caregivers in most families.

The questions of family planning and kickstarting a professional career arise simultaneously in almost any field. What makes this particularly challenging for young families in academia is that this line of work frequently requires for parents to move, making traditional forms of supportive caregiving by extended family members often unavailable. The vital role conference attendance plays for an academic career only aggravates that challenge. Therefore, a lack of opportunities to attend conferences and workshops clearly puts young parents at a disadvantage, especially young women in academia.

The Project for Family-Friendly Conferences has been initiated by Leonie Esters and Lisa Schielicke from the Department of Geosciences at the University of Bonn in April 2023. Elena Päffgen joined as a research assistant (WHK) later the same year. With an initial duration of one and a half years the project is funded by the Gleichstellungsbüro (office for equal opportunities) of the university. Our principal goal is to find out, how conference and workshop participation can be made more family-friendly.

The present work analyses an online survey with 245 participants who were interviewed on the topic of family-friendly conferences. The survey was addressed to all scientists with a focus on geosciences, 58% of all participants claimed to have children, while 42% were childless. 61 comments expressing wishes and needs of parents and guardians we received from the participants underscore the urgency of the matter. Key concerns of the participants were clear communication (e.g., whether children could be brought along to the events in question), awareness among event-organizers, and easy access to financial assistance (e.g. for babysitting). For instance, more hybrid events, on-site childcare and designated family-friendly activities at conferences were named as possible improvements. However, considering that families and their challenges are diverse, a wide array of offers and flexibility are required to address their needs.

Our project aims to educate the wider academic community on family-specific challenges. Based on the results of this survey, we will provide conference organizers with guidelines to improve family-friendliness of conferences and facilitate their exchange among each other. Additionally, we want to keep parents informed about the offers for families that are already in place at conferences in our field of study. Overall, we are convinced that outcomes of our project will be beneficial for conference and workshop organizers likewise as for researchers who are parents and will contribute to gender equity and diversity in academia.

Children, parents and guardians are particularly welcome to the poster presentation and discussion.

If you would like to participate in our survey: https://www.empirio.de/s/VxLGGLxWv2

 

 

How to cite: Päffgen, E., Esters, L., and Schielicke, L.: Family-Friendly Conferences in the Geosciences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-410, https://doi.org/10.5194/egusphere-egu24-410, 2024.

The European Geosciences Union (EGU) is the leading organisation supporting Earth, planetary and space science research in Europe, upholding and promoting the highest standards of scientific integrity, open science and open access research. EGU’s vision is to realise a sustainable and just future for humanity and the planet through advances in Earth, planetary and space sciences.

The EGU awards and medals programme acknowledges distinguished scientists every year for their exceptional research contribution to the Earth, planetary and space sciences. Furthermore, it recognises the awardees as role models for the following generation of early-career scientists, encouraging geoscience research. 

Except for EGU council and award committee members everyone (including non-EGU members) is eligible for receiving an EGU award. Nominations need to be submitted by EGU members online by 15 June every year. Each EGU medal or award is selected through a rigorous assessment of the candidates and their merits through the respective committee. The procedures for nomination, selection of candidates and the time schedule are described in detail on the EGU website. 

EGU is committed to recognizing scientific excellence providing equal opportunities. The processes and procedures that lead to the recognition of excellence must be transparent and free of biases. However, establishment of clear and transparent evaluation criteria and performance metrics to provide equal opportunities to researchers across gender, continents and ethnic groups can be challenging since the definition of scientific excellence is often elusive. 

The purpose of this presentation is to share the experiences and efforts of the European Geosciences Union to ensure equal opportunities. The presentation will showcase data and statistics to provide constructive directions towards the objective of offering equal opportunities to researchers from diverse demographic backgrounds.

How to cite: Blunier, T.: Equality of opportunities in EGU recognitions: The EGU Awards Committee experience, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1620, https://doi.org/10.5194/egusphere-egu24-1620, 2024.

EGU24-9435 | ECS | Orals | EOS3.1 | Highlight

Navigating parenthood as an early career scientist: insights and challenges from hydrological sciences 

Diana Spieler, Lina Stein, and Rodolfo Nóbrega

Combining an academic career with caretaking responsibilities is an often-overlooked challenge. Juggling the workload, conference attendance, or the potential requirement to move to a new job all become more demanding when children or other caretaking responsibilities are a part of your life. We, members of the Young Hydrology Society (YHS), wanted to hear some views from academic parents in hydrology. What are the challenges they face, what is their advice to other parents and what systematic changes would they like to see? This non-scientific initiative gathered responses from academics within the hydrology community from different parts of the world at different career stages, including PhD candidates, postdoctoral researchers, assistant professors, and group leaders. The survey revealed diverse challenges and strategies employed by academic parents to balance their professional and personal lives. We identified a complex interplay of personal, institutional, and cultural factors that influence these experiences in academia. A common theme across responses was the strategic timing of parenthood, often aligned with phases of planning security, such as after having won a longer-term grant. Despite the varying international backgrounds, many responses highlighted the supportive role of national policies, particularly in countries like Sweden, which offer substantial parental support and flexible work arrangements. However, challenges such as reduced research productivity, lack of support to attend conferences, and the need to relocate were frequently mentioned as limiting factors for career development and progression. Among the strategies employed to minimise these challenges, we highlight adjusting work schedules, reducing workloads, and relying on support from partners and extended family. Childcare distribution varied, with many striving for an equitable split between partners, though this was often influenced by career demands and cultural standards or expectations. The responses also contained suggestions for systemic improvement, including extended childcare facilities at conferences, more flexible job contracts, and institutional support for parents, particularly during fieldwork and conferences. While there are notable advancements in some areas, there remains a significant need for systemic changes to better support academic parents and ensure a more inclusive and equitable academic environment. It is fundamental to highlight, however, that the results of this initiative do not capture the entire spectrum of experiences faced by those with caretaking responsibilities, and that our survey is likely to be biased towards ECS who still were engaged and successful in their work. We aim to release these results as a series of blog posts on the YHS webpage (https://younghs.com/blog/) to disseminate this topic with the main aim of offering valuable reassurance to current and future parents in academia facing similar challenges.

How to cite: Spieler, D., Stein, L., and Nóbrega, R.: Navigating parenthood as an early career scientist: insights and challenges from hydrological sciences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9435, https://doi.org/10.5194/egusphere-egu24-9435, 2024.

EGU24-9557 | Orals | EOS3.1

Diversity at a Small Geoscience Conference 

Alice Lefebvre and Renée Bernhard

Conferences are places where intellectual and communication standards are shown. Ultimately, they can contribute to create a sense of belonging or inadequateness. However, several analyses of specific diversity measures have demonstrated that large conferences often lack diversity in terms of gender, geographic location or race. The present contribution presents an analysis of the gender, country of affiliation and student status of the participants and presenters during four instances of a small European geoscience conference, as well as the length of presentation and number and tone of questions of the latest instance of this conference. We found that women make up about one-third of participants, session chairs, invited keynote speakers, and presenters (oral and poster) on average, but percentages vary greatly from one year to the next. Students represent around 30% of participants, but over 40% of poster presenters and 28% of long presentations. In total, only half of the participants asked a question, and most of the questions were asked by senior men. Around 25% of the questions were asked with a friendly tone; the remainder were neutrally asked. Friendly questions were asked more frequently after keynote lectures and long presentations than following short talks. We suggest concrete actions that can be taken to promote the development of an inclusive and supportive environment at small conferences.

How to cite: Lefebvre, A. and Bernhard, R.: Diversity at a Small Geoscience Conference, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9557, https://doi.org/10.5194/egusphere-egu24-9557, 2024.

EGU24-10508 | ECS | Posters on site | EOS3.1 | Highlight

An Evaluation of the ADVANCEGeo Partnership Bystander Intervention Model 

Blair Schneider, Christine Bell, Stefanie Whitmire, Horinek Hannah, Meredith Hastings, Rebecca Barnes, Allison Mattheis, Billy Williams, and Erika Marin-Spiotta

The ADVANCEGeo Partnership program, funded by a National Science Foundation ADVANCE award in 2017, was designed to empower geoscientists to transform workplace climate, and has been recently adapted to other STEMM disciplines as well. To date, the ADVANCEGeo Partnership has led over 230 workshops to institutions across the USA and Europe, in both virtual and in-person formats. A main strategy of ADVANCEGeo for organizational climate change is to enact interventions at the individual and collective level through behavior change education informed by intersectionality and ethics of care frameworks. The program uses a community-based model for bystander intervention and workplace climate education designed to give members of the academic community the knowledge and tools to identify, prevent, and mitigate harm from exclusionary behaviors that directly affect the retention of historically excluded groups in STEMM. 

Evaluation data from 81 workshops held between 2018-2022 were analyzed using a transtheoretical framework of behavioral change. All of these workshops used a consistent structure and length of presentation (averaging 2.5 hours overall). Thirty six workshops were conducted in-person (44%) and forty five workshops were conducted virtually (56%) using the Zoom platform. The workshops were conducted for a variety of audiences, including institutional leadership, academic departments, professional societies, research groups, and student groups. Each workshop included the same core components, though some materials in the presentation portion were tailored to the needs of the audience as requested. Evaluation results show positive increases in participant knowledge, satisfaction, and intent to change behavior directly after the workshop. An additional follow up survey that was disseminated approximately 6 months after the workshop provides evidence of longitudinal behavior change. These results demonstrate that the ADVANCEGeo Bystander Intervention model design successfully shifts behaviors in workshop participants, with an aim to create more positive workplace climates for all seeking to be a part of STEMM.

How to cite: Schneider, B., Bell, C., Whitmire, S., Hannah, H., Hastings, M., Barnes, R., Mattheis, A., Williams, B., and Marin-Spiotta, E.: An Evaluation of the ADVANCEGeo Partnership Bystander Intervention Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10508, https://doi.org/10.5194/egusphere-egu24-10508, 2024.

EGU24-11929 | ECS | Orals | EOS3.1 | Highlight

Promoting and Supporting Equity, Diversity, Inclusion, and Accessibility: A Collaborative Approach in the Hydrogeological Community and Beyond 

Luka Vucinic, Viviana Re, Barbara Zambelli, Theresa Frommen, Fatima Ajia, and Shrikant Limaye

The International Association of Hydrogeologists (IAH) is a scientific and educational charitable organisation for scientists, engineers, water managers and other professionals working in the fields of groundwater resources planning, management and protection. Comprising various commissions and networks, IAH engages in activities such as contributing to groundwater science, outreach, education, and training. While IAH takes meaningful steps towards equity, diversity, inclusion, and accessibility, recognising the importance of putting these principles into practice, it is essential to acknowledge that there are still numerous challenges and barriers that need to be addressed. It is worth noting that IAH shares similar challenges with many other organisations and associations in navigating the path towards greater equity, diversity, and inclusion. Therefore, the establishment of a dedicated working group became imperative to address and overcome these challenges effectively.

The Socio-Hydrogeology Network (IAH-SHG), an official IAH network, aims to integrate social sciences into hydrogeological research, and has two active working groups: the Working Group on Groundwater and Gender, and the newly established Equity, Diversity, Inclusion, and Accessibility (EDIA) Working Group. This group is designed to further enhance the EDIA landscape within the IAH and beyond. It is the result of collaborative endeavours, extensive discussions, and productive meetings within the IAH and IAH-SHG, and it builds on the work and experience of the Working Group on Groundwater and Gender and the IAH-SHG in general. We will showcase the key insights gained from our IAH-SHG experiences and demonstrate how we applied these lessons to facilitate the establishment of the EDIA Working Group.

By harnessing the power of collective effort, the EDIA Working Group aims to foster a positive impact that resonates throughout the IAH and wider hydrogeological community. We will present our experience regarding the pivotal role of networks, such as IAH-SHG, in advancing equity, diversity, inclusion, and addressing barriers within the geosciences. We will also share our plans for collaboration with other IAH commissions, networks, IAH members, and other individuals (i.e. membership in the IAH is not a prerequisite for individuals interested in joining the IAH-SHG or any of its working groups), as well as ideas and recommendations for new and innovative strategies to identify and overcome barriers. Furthermore, we will share the EDIA Working Group's experience so far, providing insights that may be valuable for other associations, organisations, and groups facing similar challenges.

How to cite: Vucinic, L., Re, V., Zambelli, B., Frommen, T., Ajia, F., and Limaye, S.: Promoting and Supporting Equity, Diversity, Inclusion, and Accessibility: A Collaborative Approach in the Hydrogeological Community and Beyond, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11929, https://doi.org/10.5194/egusphere-egu24-11929, 2024.

EGU24-12182 | ECS | Orals | EOS3.1 | Highlight

Is my teaching gender-fair? A self-assessment questionnaire. 

Sílvia Poblador, Maria Anton-Pardo, Mireia Bartrons, Xavier Benito, Susana Bernal, Eliana Bohorquez Bedoya, Miguel Cañedo-Argüelles, Núria Catalán, Isabel Fernandes, Anna Freixa, Ana Genua-Olmedo, Elisabeth León-Palmero, Anna Lupon, Clara Mendoza-Lera, Ada Pastor, Pablo Rodríguez-Lozano, Aitziber Zufiaurre, and María del Mar Sánchez-Montoya

The study of inland waters - Limnology - is full of fascinating women who have vastly contributed to our understanding of these valuable ecosystems. Although women’s visibility was low during the early years of Limnology, it has increased over time. Nowadays, women represent half of the early-career limnologists in Europe. However, as in many other fields, their scientific contributions have been traditionally neglected from schools to universities (i.e., the Matilda effect). The project “Gender LimnoEdu”, developed by the Gender&Science AIL group and funded by EGU (2020), aims to increase the visibility of women in Limnology and related subjects - such as Ecology, Hydrology or other Geosciences - in academic courses and lectures. We have created a set of online ready-to-use resources: (1) a self-evaluation form to detect gender biases and raise self-awareness for teachers of Limnology and Geosciences courses (the form is applicable to a wide range of courses and disciplines), (2) teaching nutshells highlighting key female limnologists (and their history) to help lecturers to acknowledge the role of women in Limnology in their courses, and (3) a complete teaching unit about the past and present situation of women in the field of Limnology. All these resources are freely available (https://www.genderlimno.org). Here, we will present this toolbox of resources and guide you on how to use them for your teaching needs. Moreover, we will share the preliminary results of the self-evaluation form to showcase how gender-fair Limnology lessons in high-education courses are. We welcome everybody to take it! https://www.genderlimno.org/gender-fair-lessons.html

How to cite: Poblador, S., Anton-Pardo, M., Bartrons, M., Benito, X., Bernal, S., Bohorquez Bedoya, E., Cañedo-Argüelles, M., Catalán, N., Fernandes, I., Freixa, A., Genua-Olmedo, A., León-Palmero, E., Lupon, A., Mendoza-Lera, C., Pastor, A., Rodríguez-Lozano, P., Zufiaurre, A., and Sánchez-Montoya, M. M.: Is my teaching gender-fair? A self-assessment questionnaire., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12182, https://doi.org/10.5194/egusphere-egu24-12182, 2024.

Many universities openly pledge commitments to improving diversity, with science, technology, engineering, and math (STEM) fields receiving significant attention. Despite these efforts, geoscience remains one of the least diverse fields in STEM. This recognition has prompted an increase in studies stressing the systemic lack of representation across the field and the barriers that exist for those within. However, much of this work has been limited by the use of demographic datasets that have been either passively collected or derived from government sources. Constraints include country-specific data collection policies, failures to collect field-specific data, and the absence of additional information necessary for intersectional analysis. Advancing diversity, equity, and inclusion (DEI) in our field requires meaningful datasets that clearly identify social inequalities. Limited, incomplete, or anecdotal data are too easily dismissed by those in power, stalling constructive efforts.

In Canada, demographic data is not regularly collected at academic institutions and is seldom field-specific. This absence of data undermines efforts to identify the current state of diversity in the field and prioritise initiatives for improvement. Collecting comprehensive demographic data is a crucial step in determining whether progress is evident. It can also help to highlight areas of concern, especially in fields lacking in diversity, such as geoscience. To address this absence of data, we disseminated a 22-question demographic survey to 35 academic geoscience departments across Canada in late 2022.

We received 482 eligible responses to the survey, accounting for approximately 20% of the research population. Overall, men make up a slight majority across all respondents (53%), and the percentage of individuals who identify as white (73%) is greater than the national average (67%). Additionally, results shows that research students (MSc and PhD) are a diverse group, while salaried positions (postdoc, research staff and faculty) lack diversity in a wide range of categories including, gender, race, LGBTQ+, Indigeneity, and disability. Moreover, tenured positions are overwhelmingly occupied by white men, with racial inequalities prominent in the data.

These data highlight several areas of concern in the academic career path. The transition from research student to salaried research remains a clear area of concern, while the tenure process appears to continually favour white able-bodied cisgender men. Moreover, the representation of Indigenous persons and those with self-identified disabilities remains very low. Solutions require institutional changes to recruitment, tenure applications, postdoctoral hiring, field work design, and mentoring practices. Importantly, they also require changes to how we collect and analyse demographic datasets in geoscience, as a continued reliance on data that is passively collected or obtained from government sources will continue to limit our abilities to identify areas of concern and create effective strategies.

How to cite: Jess, S., Heer, E., and Schoenbohm, L.: Active demographic data collection in geoscience: results, implications, and recommendations from a survey of Canadian academia  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12643, https://doi.org/10.5194/egusphere-egu24-12643, 2024.

EGU24-13028 | Orals | EOS3.1

Embedding EDI in Geoscience Publications – Examples from the AGU  

Matthew Giampoala, Mia Ricci, and Paige Wooden

The American Geophysical Union understands an expansive and inclusive geoscience community is key to furthering knowledge about the Earth and the universe and finding solutions to current societal challenges. Though the geosciences have historically been dominated by a few homogenous groups, the collaborative and global nature of our science impels us to change our systems to include historically marginalized voices. Supported by AGU’s 2018 Diversity and Inclusion Strategic Plan, in 2023, AGU Publications signed the Joint Commitment for Action on Inclusion and Diversity in PublishingSignatories agree to collect self-reported gender and race/ethnicity data, develop baselines, and set minimum standards for inclusion. We provide a demographic overview of our authors, reviewers, and editors over time, detail how we collect data while following privacy laws, and discuss how data informs our DEIA strategies. We provide reports to our journal editors who set baselines and develop journal goals. We launched various initiatives to increase diversity and equity and decrease bias in peer review processes, and used the data to assess outcomes of these initiatives. In addition, we present examples of policy and structural changes we have implemented to weave DEIA in the scientific publishing environment, including our equitable approach to Open Access, our Community Science Exchange, and the recently launched Inclusion in Global Research policy to improve equity and transparency in research collaborations.

How to cite: Giampoala, M., Ricci, M., and Wooden, P.: Embedding EDI in Geoscience Publications – Examples from the AGU , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13028, https://doi.org/10.5194/egusphere-egu24-13028, 2024.

EGU24-14684 | Posters on site | EOS3.1

Nakkihomma: attitudes towards and distributions of academic household work 

Katja Anniina Lauri, Xuefei Li, Paulina Dukat, Nahid Atashi, Laura Karppinen, Katrianne Lehtipalo, Anna Lintunen, Dmitri Moisseev, Janne Mukkala, Tuomo Nieminen, Rosa Rantanen, Timo Vesala, Ilona Ylivinkka, and Hanna Vehkamäki

The equality and work well-being group at the Institute for Atmospheric and Earth System Research (INAR) at the University of Helsinki conducted a survey about academic household work (AHW) tasks among the institute’s staff in autumn 2023. The main aim of the survey was to find out how different AHW tasks are divided among the staff members and how the staff members consider these tasks.

Before the actual survey, we asked the staff to list tasks they consider AHW (nakkihomma in Finnish; direct translation: Frankfurter task). A few examples of AHW tasks we got: sending calendar invitations for meetings, making coffee for others, helping to organize social events at the institute, emotional service work (being involved in discussion with colleagues or students about their personal affairs or problems). For the survey, we grouped the proposed tasks in three categories (number of tasks in parentheses): research-related tasks (3), society-related tasks (4) and community-related tasks (29). The last category was further divided into four subcategories: tasks related to meetings (7), social events (6) and facilities (9), and miscellaneous (7). We asked which tasks the staff members consider as AHW, and how frequently they are committed to each task.

We received a total of 91 answers to the survey. This corresponds to 33% of our staff, but according to the background information we collected, the different groups in terms of gender, career stage, language status (Finnish/non-Finnish speaker) and staff group (research/technical/administrative) were represented well.

The general attitude towards AHW was surprisingly positive: 57% of respondents had a positive attitude while 35% had a neutral attitude. Senior research staff members use a considerable amount of time participating in different committee meetings while early-career researchers do not so much; however, they do a great deal of practical duties related to meetings. Furthermore, we found out that a lot of emotional service work is being done. Interestingly, early career researchers do not consider this generally as AHW while senior researchers do. Male staff members contribute more to technical writing and guiding tasks while female staff use more of their time in emotional service work and general collective AHW tasks. Finnish speakers contribute more to writing and guiding tasks while non-Finnish speakers are more frequently committed in “catering” AHW like making coffee. Technical and administrative personnel generally contribute more to AHW than research staff.

We hope that the results of this survey will help us developing a more equitable and inclusive atmosphere in our institute by enabling us to pay more attention in distributing AHW tasks in a more equal and just manner.

How to cite: Lauri, K. A., Li, X., Dukat, P., Atashi, N., Karppinen, L., Lehtipalo, K., Lintunen, A., Moisseev, D., Mukkala, J., Nieminen, T., Rantanen, R., Vesala, T., Ylivinkka, I., and Vehkamäki, H.: Nakkihomma: attitudes towards and distributions of academic household work, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14684, https://doi.org/10.5194/egusphere-egu24-14684, 2024.

EGU24-16168 | Posters on site | EOS3.1

Inclusive excellence at the ERC: latest actions and results of sustained measures 

Claudia Jesus-Rydin, Luis Fariña-Busto, and Eystein Jansen

The European Research Council (ERC), Europe’s premiere funding agency for frontier research, views equality of opportunities as an essential priority and a vital mission to ensure fairness in the review process. The ERC monitors various demographic data yearly on every call and has taken actions to tackle imbalances and potential implicit and explicit biases.

The presentation focuses on ERC general historical data for the three individual funding schemes: Starting Grant, Consolidator Grant and Advanced Grant. Demographic geosciences data of proposals and grants, disaggregated by gender and country, is presented. After more than 14 years of existence and various specific actions to tackle societal imbalances, ERC data provides an insight of the impact of various actions.

In the first framework programme (FP7, 2007-2013), 25% of applicants were women. In the last years (Horizon 2020, 2014-2020), this percentage increased by 4%, with 29% of women applying for ERC grants. In the same periods of time, the share of women as grantees has also increased from 20% to 29%. In the last years, men and women enjoy equal success rates (data for non-binary applicants is also presented).

The most recent actions taken by the ERC to address gender and diversity (including disabilities and neo-colonialism) in its operations and processes are also presented.

The ERC knows that work to ensure inclusive excellence and equality of opportunities is never-ending. This presentation analyses the institutional efforts critically and discusses possible steps to consolidate the accomplished results.

How to cite: Jesus-Rydin, C., Fariña-Busto, L., and Jansen, E.: Inclusive excellence at the ERC: latest actions and results of sustained measures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16168, https://doi.org/10.5194/egusphere-egu24-16168, 2024.

EGU24-17197 | ECS | Orals | EOS3.1

Science Sisters: Interviews with diverse role models on career paths and academic life 

Marina Cano, Iris van Zelst, and Hinna Shivkumar

Science Sisters is a YouTube interview series and podcast hosted by Dr. Iris van Zelst. Lighthearted in tone, it explores different career paths, academic life, and science communication in the planetary and geosciences. The majority of the guests on the episodes are female and/or non-white to show a diverse range of role models in STEM and celebrate women in science. Together with the guest, Iris goes into the highs and lows of being a researcher and discusses issues in academia, such as the lack of permanent jobs in science and sexism. So far, two seasons of Science Sisters have been produced with topics including ethical fieldwork, switching careers, science communication, postdoc life, leadership, women in science, job applications, postdoc hopping, outreach, publishing, feeling incompetent, astronaut training, toxic academia, and how to build a research group.

Here, we present the project and some of the choicest nuggets of wisdom from the guests about academic life and careers. We also discuss the production phase of the series, highlighting for instance the considerations that go into selecting topics and guests, and the postproduction phase of editing and uploading the videos.

In addition, we present how we use Science Sisters as a way to start conversations in our own institutes. We organise a parallel seminar series where we watch the premieres of the episodes live on YouTube and afterwards have a discussion on the episode topic with the episode guest attending online. This has resulted in a greater understanding of each other and more cohesion within the institute. Early career scientists in particular say that Science Sisters is extremely useful to learn about life as a researcher and they enjoy the chatty, entertaining quality of the interviews.

How to cite: Cano, M., van Zelst, I., and Shivkumar, H.: Science Sisters: Interviews with diverse role models on career paths and academic life, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17197, https://doi.org/10.5194/egusphere-egu24-17197, 2024.

EGU24-18544 | ECS | Orals | EOS3.1

Time’s up, bottom-up! A successful bottom-up approach for diversity and inclusions at Utrecht University 

Manon Verberne, Jana R. Cox, Frances E. Dunn, Merel Postma, and Tina Venema

Young Women of Geoscience (YWOG) is a group of young professionals (PhDs, postdocs, assistant professors and supporting staff) at Utrecht University with the aim to inspire, connect and support women and historically underrepresented groups in the field of geosciences, by creating an equal and inclusive working environment. We do this by opening up conversations and creating a safe and positive space for discussion. Now in our seventh year, the committee has established itself as a constant and stable presence within the faculty with regular events and initiatives that can easily be organized from our reputable base.

Our regular events consist of meet-and-greet sessions with senior staff members, that are well-attended by a variety of colleagues, which result in inspiring conversations. Additionally, book give-aways combined with book discussions are a recurring event, where books on diversity, inclusions and climate change are used to open conversations. These events often engage individuals who may not have initially identified with the committee's target audience, but afterwards their interest was sparked. In recent years we also organized successful events due to requests from staff members. Parenting during COVID was a successful online event with a panel discussion consisting of colleagues sharing tips and struggles. Additionally, this year we organized an event on pronouns, reaching a wide audience, from PhDs to supporting staff, professors and the faculty dean. It was also this session, with informative presentations and lively discussion, that led to immediate action from higher level staff on practical matters concerning pronouns in the workplace.

Our experience highlights the importance of a bottom-up approach in instigating meaningful change. The pronouns event is a prime example of this, opening the eyes of many attendees and making people feel the urgency for action. The event stemmed from a need within the faculty. However, to be able to organize such an event there must be a platform to do so. We have the opportunity to organize many events helped by funding through an Equality, Diversity and Inclusion (EDI) scheme and an internal award won by the committee. We aim to continue with the regular events like the meet-and-greets and book shares, and hope to organize more events that are based on the needs in the faculty to open conversations. YWOG's experience demonstrates the efficacy of a bottom-up approach, emphasizing the importance of diverse perspectives in fostering substantial changes toward a more inclusive working environment. The committee looks forward to sharing its experiences, connecting with other faculties and universities, and inspiring collective efforts to promote diversity and inclusion within geosciences.

How to cite: Verberne, M., Cox, J. R., Dunn, F. E., Postma, M., and Venema, T.: Time’s up, bottom-up! A successful bottom-up approach for diversity and inclusions at Utrecht University, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18544, https://doi.org/10.5194/egusphere-egu24-18544, 2024.

EGU24-20027 | Orals | EOS3.1

Planning virtual and hybrid events: steps to improve inclusion and accessibility 

Aileen Doran, Victoria Dutch, Bridget Warren, Robert A. Watson, Kevin Murphy, Angus Aldis, Isabelle Cooper, Charlotte Cockram, Dyess Harp, Morgane Desmau, and Lydia Keppler

Over the last decade, the way we communicate and engage with one another has changed on a global scale. It is now easier than ever to network and collaborate with colleagues worldwide. But, the COVID-19 pandemic led to a rapid and unplanned move to virtual platforms, resulting in several accessibility challenges and the inadvertent exclusion of several people during online events. While virtual/hybrid events have strong potential to facilitate new opportunities and networks for everyone, they are also greatly positioned to increase the inclusion of groups traditionally excluded from purely in-person conferences. However, early and careful planning is needed to achieve this, with inclusion and accessibility considered from the start. Including a virtual element in a conference does not automatically equal inclusion or accessibility. Without effective planning, virtual and hybrid events will replicate many biases and exclusions inherent to in-person events.

This presentation will share lessons learned from previous events’ successes and failures, based on the combined experiences of several groups and individuals who have planned and run such events. This presentation is based on an EGU Sphere article, of the same title, that aims to provide guidance on planning online/hybrid events from an accessibility viewpoint based on the authors experiences. The goal of this presentation is to initiate discussion on event accessibility and inclusion and to help generate new ideas and knowledge from people outside of the authors network. Every event is unique and will require its own accessibility design, but early consideration is crucial to ensure everyone feels welcome and included. Our suggested accessibility considerations have been broken down into three stages of event planning: 1) Pre-event planning, 2) on the day/during the event, and 3) after the event.

Ensuring accessibility and inclusivity in designing and running virtual/hybrid events can help everyone engage more meaningfully, resulting in more impactful discussions including groups with limited access to in-person events. However, while this article is intended to act as a starting place for inclusion and accessibility in online and hybrid event planning, it is not a fully comprehensive guide. As more events are run, it is expected that new insights and experiences will be gained, helping to continually update standards.

How to cite: Doran, A., Dutch, V., Warren, B., Watson, R. A., Murphy, K., Aldis, A., Cooper, I., Cockram, C., Harp, D., Desmau, M., and Keppler, L.: Planning virtual and hybrid events: steps to improve inclusion and accessibility, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20027, https://doi.org/10.5194/egusphere-egu24-20027, 2024.

EGU24-20337 | Posters on site | EOS3.1

The stagnation of low percentage of female scientists in Japan and JpGU's initiatives 

Rie Hori and Chiaki Oguchi

The percentage of female scientists in Japan is 17.5% in the 2021 survey. This percentage is the lowest among OECD countries. The percentages of female doctoral students in science and engineering graduate programs nationwide are 21.0% and 19.2%, indicating a gap between the percentage of female prospective researchers and the percentage of women actually employed. It is pointed out that this is due to gender bias at the time of recruitment. On the other hand, the percentage of female members of JpGU remains around 20%, which is higher than the average in Japan, but still low compared to the percentage of female geoscientists in EGU and AGU. One of the reasons for the low number of female scientists in Japan is the low percentage of female students entering science and engineering fields in Japan (27% in science and 16% in engineering). The Science Council of Japan's Subcommittee on Gender and Diversity in Science and Engineering analyzed this problem and pointed out that its cause lies in the environment of education system during elementary and junior high schools (Opinion of SCJ, 2023). In Japan, the following factors are considered to have contributed to the decline in the number of female students going on to study science and engineering, even though surveys such as PISA (2018) and TIMSS (2019) show that both male and female 15-year-olds have equal academic achievement and interested in science and mathematics in the early education stage. (1) The percentage of female science teachers in junior high school and above is significantly lower than in the OECD countries → Few role models. (2) Often exposed to obvious “implicit bias” that has no evidence to support it (for example, girls are not good at mathematics. Science and engineering professions are not suitable for girls).

JpGU and Japanese universities actively conduct outreach programs for female junior igh and high school students every year to foster future female scientists. However, only a small percentage of them in whole Japan participate in such events, and these initiatives does not give us a full solution.

How to cite: Hori, R. and Oguchi, C.: The stagnation of low percentage of female scientists in Japan and JpGU's initiatives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20337, https://doi.org/10.5194/egusphere-egu24-20337, 2024.

EGU24-22185 | Posters on site | EOS3.1

Signatures of Equality, Diversity and Inclusivity at EGU General Assemblies 

Johanna Stadmark, Alberto Montanari, and Caroline Slomp

The EGU recognises the importance of equality, diversity, and inclusion as a crucial foundation for scientific research to address fundamental scientific questions and societally relevant environmental challenges. The increasing diversity of our membership in all its facets fosters collaborative research and discovery that benefits humanity and our planet.

Since its founding, the EGU has worked to ensure equitable treatment for everyone in the community with the goal of increasing diversity. In autumn 2018, the EGU Council established a working group whose aim is to promote and support equality, diversity, and inclusion (EDI) in the Earth, planetary, and space sciences, with a focus on EGU activities. Less than three years later, the EDI group was upgraded into a committee and has delivered numerous actions.

The most recent achievements of EDI@EGU are the Champion(s) for Equality, Diversity and Inclusion Award that is bestowed to recognize excellent contributions to put into exemplary practice the principles of EDI. Furthermore, the EDI Committee is currently working on a new travel support scheme to promote diversity at the EGU General assemblies.

The above actions resulted in a more diverse attendance at EGU General Assemblies along the years. The total number of presenters has increased over the time period 2015-2023, and this increase was observed throughout all career stages. The proportion of women presenters has increased from 2015 to 2023. A similar trend was observed for the convenors, an increase in total numbers over the years and a higher proportion of women in 2023 than in 2015.

In the hybrid meeting in 2023 both early career scientists and more senior scientists to a higher extent participated physically in the meeting than online. While there were no differences in how women and men participated (online or physically), there are differences connected to the country affiliations. More than half of participants from countries in most of western Europe attended in Vienna, while participants from North America and Asia attended online.

Since EGU General Assembly is the largest geosciences conference in Europe understanding the demographic evolution and their participation to EGU activities, including the GA, of various groups is an important tool for EGU governing body to draw targeted actions to ensure that the current procedures are fair and that all in the community are being and feeling included. We therefore aim to analyse the changes in demographics with regards to gender, career stage as well as to geographical distribution of the presenters and convenors also in coming years to better understand the potential impacts of meetings organized online or physically, or as a combination of both these modes.

How to cite: Stadmark, J., Montanari, A., and Slomp, C.: Signatures of Equality, Diversity and Inclusivity at EGU General Assemblies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22185, https://doi.org/10.5194/egusphere-egu24-22185, 2024.

EGU24-149 | ECS | Orals | CR4.2

Quantifying permafrost organic carbon remineralization after redeposition on the ocean floor, using  δ13C and F14C. 

Manuel Ruben, Jens Hefter, Torben Gentz, Florence Schubotz, Bingbing Wei, Bo Liu, Michael Fritz, Anna Maria Irrgang, Anabel von Jackowski, Walter Geibert, and Gesine Mollenhauer

Arctic permafrost is a critical global tipping element in a warming climate. Annually, the erosion of coastal permafrost discharges an estimated 5 to 14 Tg of organic carbon (OC) into the Arctic Ocean. Although this previously stored OC has the potential to be reintroduced into the atmosphere, thus accelerating human-induced climate change, little is known about the benthic remineralization processes of permafrost OC after erosion and redeposition on the ocean floor. Our research quantified fluxes of dissolved inorganic carbon (DIC) and analyzed its isotopic composition of nearshore sediments in the Canadian Beaufort Sea, specifically off Herschel Island. Our findings showed a DIC release of 0.217 mmo/m²/d, with an average signature of δ13C = -22.44 ± 72 ‰ and F14C = 0.548 ± 0.007. Utilizing a model that combines two carbon isotopes, we estimate that approximately 38 ± 10% of the released DIC is a result of subsurface degradation of redeposited permafrost OC, with an additional 15 ± 12% originating from redeposited active layer OC. Additionally, isotopic endmember analysis was utilized on bacterial membrane lipids from live sedimentary bacteria to determine the relative utilization of OC sources in bacterial communities within shallow subsurface sediment (<25 cm). Our results indicate that, on average, these communities obtain 73 ± 10% of their OC from recent marine primary production, 11 ± 6% from permafrost OC, and 16 ± 11% from active layer OC. This study is the first direct quantitative assessment of the release of permafrost OC into the active carbon cycle after it has been redeposited on the ocean floor, as far as we know. The data suggest that the redeposited permafrost OC is easily accessible and utilized by subsurface bacteria. Considering the immense size and vulnerability of the eroding coastal permafrost OC pool, 27 to 53% of it contributing to benthic DIC fluxes could have a prolonged effect on the world's climate, worsening the climate emergency.

How to cite: Ruben, M., Hefter, J., Gentz, T., Schubotz, F., Wei, B., Liu, B., Fritz, M., Irrgang, A. M., von Jackowski, A., Geibert, W., and Mollenhauer, G.: Quantifying permafrost organic carbon remineralization after redeposition on the ocean floor, using  δ13C and F14C., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-149, https://doi.org/10.5194/egusphere-egu24-149, 2024.

EGU24-559 | ECS | Orals | CR4.2

Detecting lowland thermokarst development by UAV remote sensing in the Stordalen mire, Abisko, Sweden  

Maxime Thomas, Thomas Moenaert, Éléonore du Bois d’Aische, Maëlle Villani, Catherine Hirst, Erik Lundin, François Jonard, Sébastien Lambot, Kristof Van Oost, Veerle Vanacker, Reiner Giesler, Carl-Magnus Mörth, and Sophie Opfergelt

In situ field studies in thawing permafrost regions have shown that C emissions resulting from organic carbon (OC) decomposition depend among others on the variability in soil water content, which can be directly related to microtopography. A more precise assessment of the evolution of permafrost C emissions as a function of thermokarst development requires high-resolution quantification of thermokarst-affected areas, as lowland thermokarst development induces fine-scale spatial variability (~ 50 – 100 cm). Here, we investigate a gradient of lowland thermokarst development at Stordalen mire, Abisko, Sweden, from well-drained undisturbed palsas to inundated fens, which have undergone ground subsidence. We produced orthomosaics and digital elevation models from very-high resolution (10 cm) UAV photogrammetry as well as a spatially continuous map of soil electrical conductivity (EC) based on Electromagnetic Induction (EMI) measurements performed in September 2021. In conjunction, we measured in situ the soil water content from the different stages of thermokarst development at the same period. The soil EC values are contrasted along the gradient in line with contrasts observed in the landscape classification derived from the orthomosaics and digital elevation models: palsas are flat areas with low soil EC (drier), whereas fens are subsided areas with higher EC (water-saturated). Areas in the course of degradation (transition zones) are well identified based on their higher slope, and broad range of EC. Importantly, these transition zones are only detected using a very fine spatial scale (i.e., 10 cm) coupled to information on the microtopography. Compared to a set of previously collected orthomosaics and digital elevation models, our results show an acceleration of thermokarst development in this area with a rate of palsa decline 4 to 10 times greater in 2019-2021 than in 2000-2014.

How to cite: Thomas, M., Moenaert, T., du Bois d’Aische, É., Villani, M., Hirst, C., Lundin, E., Jonard, F., Lambot, S., Van Oost, K., Vanacker, V., Giesler, R., Mörth, C.-M., and Opfergelt, S.: Detecting lowland thermokarst development by UAV remote sensing in the Stordalen mire, Abisko, Sweden , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-559, https://doi.org/10.5194/egusphere-egu24-559, 2024.

EGU24-630 | ECS | Posters on site | CR4.2

Multitemporal UAV LiDAR detects seasonal heave and subsidence on palsas 

Cas Renette, Sofia Thorson, Mats Olvmo, Björn Holmer, and Heather Reese

In the context of the accelerating impacts of climate change on permafrost landscapes, this study employs UAV (Unmanned Aerial Vehicle) LiDAR technology to investigate seasonal terrain changes in palsas – mounds of frozen peat – since traditional remote sensing methods have struggled to capture the full dynamics of these landforms. We investigated two tall (4–5 m tall) palsas in Sweden's largest palsa mire complex, where we performed five field campaigns between September 2022 and September 2023 to track intra-annual frost heave and thaw subsidence. Our approach allowed us to create digital terrain models (DTMs) from high density point clouds (>1,000 points/m²) and analyze elevation changes over time. We found that both palsas heaved 0.15 m from September to April and subsided back to their height from the previous year, or slightly below, over the course of the following summer. At one of the palsas, we observed notable lateral degradation over the study period in a 300 m2 area, with 0.5–2.0 m height loss, likely initiated during the preceding warm and wet summer months. Part of this degradation occurred between September 2022 and April 2023, suggesting that the degradation of these palsas is not limited to the summer months. Our study shows the value of using UAV LiDAR for understanding how permafrost areas are changing. It helps in tracking the ongoing effects of climate change and highlights palsa dynamics that would not be captured by annual measurements only.

How to cite: Renette, C., Thorson, S., Olvmo, M., Holmer, B., and Reese, H.: Multitemporal UAV LiDAR detects seasonal heave and subsidence on palsas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-630, https://doi.org/10.5194/egusphere-egu24-630, 2024.

EGU24-2165 | ECS | Orals | CR4.2

Modern spatial distribution of diverse retrogressive thaw slumps in West Siberia 

Nina Nesterova, Ilya Tarasevich, Marina Leibman, Aleksander Kizyakov, Ingmar Nitze, and Guido Grosse

Regressive thaw slumps (RTSs) are permafrost landforms formed by the thawing of ice-rich permafrost or the melting of massive ground ice. The West Siberian Arctic (Yamal and Gydan peninsulas) is an area with widespread distribution of RTSs due to continuous permafrost and massive tabular ground ice close to the surface. The initiation of RTS in the region strongly affects the environment by altering vegetation and topography and releasing carbon. Roads and railways are also affected by RTS occurrence.  

There is still no complete understanding of the true RTS distribution and its environmental controls in the West Siberian Arctic because of the remote location of the region. A remote sensing technique can be used to enhance our understanding of the characteristics of RTS over a large area. However, automated mapping of RTSs has certain limitations, including the lack of ground truth data, the large number of false-positive detections, and the ambiguity in interpretation. Moreover, the polycyclic nature of RTS development leads to a very complex spatial aggradation with numerous overlapping or nested RTSs. This poses additional challenges for mapping.

Based on theoretical and field studies, we developed a classification to capture the main morphological and environmental parameters of RTS nature visible on satellite imagery. To minimize false-positive detections we performed in-detail manual mapping of the RTSs in West Siberia using multiple sources including the ESRI satellite base map, Google Earth satellite base map, and Yandex Maps satellite base map. Each point was classified by several parameters: morphology, spatial aggradation, concurrent cryogenic processes, terrain position, and attachment to the base level. Field experience and data at the key sites, as well as a helicopter-based inventory, helped to perform verification and estimate accuracy.

We identified more than 4000 RTSs. The spatial distribution of identified RTSs demonstrates clusters over the western Yamal Peninsula and central-northern Gydan Peninsula. This research aims at a comprehensive analysis of the spatial distribution of classified RTS concerning regional geological, climate, and other available environmental data. Our results are valuable for understanding the nature of this widespread phenomenon in the Arctic.

How to cite: Nesterova, N., Tarasevich, I., Leibman, M., Kizyakov, A., Nitze, I., and Grosse, G.: Modern spatial distribution of diverse retrogressive thaw slumps in West Siberia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2165, https://doi.org/10.5194/egusphere-egu24-2165, 2024.

EGU24-2291 | ECS | Orals | CR4.2

Expansion of wildfires and their impact on carbon emissions over pan-Arctic permafrost 

Xingru Zhu, Gensuo Jia, and Xiyan Xu

Wildfires over permafrost put perennially frozen carbon at risk. However, burned area and wildfire carbon emissions from biomass burning over the diverse range of permafrost regions have not been revealed. Here, we show that continuous permafrost was a major contribution to wildfire expansion and carbon emission in the pan-Arctic over the last two decades. Burned area and wildfire carbon emissions dramatically increased over continuous permafrost during the last two decades, but decreased in other permafrost regions. Accelerating wildfire emission from continuous permafrost region is the single largest contribution to the increased emissions in northern permafrost regions. The share of permafrost in global wildfire CO2 emissions grew from 2.42% in 1997 to 20.86% in 2021. Wildfire expansion is closely linked to an increased soil moisture deficit, considering wildfires there combust more than 90% of belowground fuel. Continuous permafrost experiences more severe fire-induced degradation. Active layer thickening following wildfires over continuous permafrost lasts more than three decades to reach a maximum of more than triple the pre-fire thickness. These findings highlight expansion of wildfires and acceleration of fire-induced carbon emission from continuous permafrost region, which disturbs organic carbon stock, accelerates the positive feedback between permafrost degradation and climate warming.

 

How to cite: Zhu, X., Jia, G., and Xu, X.: Expansion of wildfires and their impact on carbon emissions over pan-Arctic permafrost, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2291, https://doi.org/10.5194/egusphere-egu24-2291, 2024.

Thawing of permafrost due to climate change is known to release gases such as the climate drivers carbon dioxide and methane, as well as the carcinogen radon. Radon is a natural radioactive gas responsible for about 10% of lung cancer deaths globally, and substantially greater rates in sub-Arctic communities. Gas transport is significantly reduced in permafrost, but now that permafrost is thawing due to climate change, the effect on the release of CO2 and CH4, and on domestic radon exposure is unknown.

Measurement: Few experimental measurements have shown the gas permeability of permafrost to be very small (order of 10-16 m2). Here we present the initial measurements of the changes in porosity and gas permeability during the thawing of synthetic permafrost using a pyknopermeameter that we are developing. The results show increases in gas permeability by many orders of magnitude, that remain during freeze-thaw cycles providing the thawed water does not drain from the sample. Draining the thawed water leads to compaction which decreases the effects of subsequent thawing on the matrix gas permeability, but can cause fracturing which provide high permeability pathways for gas flow.

Modelling: Results from radon transport modelling through soil, permafrost, and model buildings either with basements or built on piles show that permafrost acts as an effective radon barrier, reducing radiation exposure to a tenth of the background level in dwellings while producing a ten-fold increase in the radon activity below the permafrost. When we model thawing of the permafrost barrier, we find no increase in radon to the background level for buildings on piles.  However, for buildings with basements, the level of radioactivity due to the radon increases to over one hundred times its initial value and can remain above the 200 Bq/m3 threshold for up to 7 years depending on the depth of the permafrost and the speed of thawing. When thawing speed is taken into account, radiations remain higher than the threshold for all scenarios where 40% thawing occurs within 15 years. This new information suggests that the sub-Arctic population could be exposed to dangerous radon levels as a result of climate change.

How to cite: Glover, P.: Modelling and Measurement of Radon and CO2 Release from Thawing Permafrost Caused by Climate Change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2682, https://doi.org/10.5194/egusphere-egu24-2682, 2024.

EGU24-2979 | Orals | CR4.2

Intensified warming effects on soil respiration upon thermokarst formation 

Yuanhe Yang, Guanqing Wang, and Yunfeng Peng

As global temperatures continue to rise, a key uncertainty of terrestrial carbon (C) climate feedback is the rates of C loss upon abrupt permafrost thaw. This type of thawing - termed thermokarst - may in turn accelerate or dampen the response of microbial degradation of soil organic matter and carbon dioxide (CO2) release to climate warming. However, such impacts have not yet been explored in experimental studies. Here, by experimentally warming three thermo-erosion gullies in an upland thermokarst site combined with incubating soils from another five thermokarst-impacted sites on the Tibetan Plateau, we investigate whether and how abrupt permafrost thaw would influence the responses of soil CO2 release to climate warming. Our results show that warming-induced increase in soil CO2 release is higher in thermokarst features than the adjacent non-thermokarst landforms. This larger warming response is mainly attributed to the lower substrate quality and higher abundance of microbial functional genes for recalcitrant C degradation in thermokarst-affected soils. Taken together, our study provides experimental evidence that abrupt permafrost thaw aggravates the warming-associated soil CO2 loss, which will exacerbate the positive soil C-climate feedback in permafrost-affected regions under future warming scenarios.

How to cite: Yang, Y., Wang, G., and Peng, Y.: Intensified warming effects on soil respiration upon thermokarst formation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2979, https://doi.org/10.5194/egusphere-egu24-2979, 2024.

EGU24-3674 | Posters on site | CR4.2

Rapidly forming submarine craters and massive ice outcrops along the Arctic shelf edge: by-products of subsea permafrost degradation 

Charles K. Paull, Jong Kuk Hong, David W. Caress, Roberto Gwiazda, Ji-Hoon Kim, Mathieu J. Duchesne, Eve Lundsten, Jennifer B. Paduan, Tae Siek Rhee, Young Keun Jin, Virginia Brake, Jeffrey Obelcz, and Maureen Walton

Substantial morphological changes are rapidly occurring along the Canadian Arctic shelf edge (Paull et al., 2022, PNAS). During a 2022 IBRV Araon cruise, autonomous underwater vehicle mapping surveys identified several new craters that formed between 2019 and 2022. Five multibeam bathymetric mapping surveys, each partially covering a 15 km2 study area between 120 and 200 mwd have now been conducted over a 12-year time period. These repeat surveys reveal 65 new depressions developed averaging 6.5 m deep and reaching up to 30 m deep. Remotely operated vehicle investigations also discovered outcrops of massive ice exposed on the flanks of the newest craters. This ice is not believed to be relic permafrost formed during Pleistocene sea-level low-stands because the host sediments were deposited in a submarine setting. The low porewater salinity and light isotopic compositions in the meltwater of ice samples from sediment cores indicate brackish waters reflecting a meteoric source are discharging and freezing in this area. The ascending brackish groundwater is likely derived from melting relict permafrost under the shelf. The ~ -1.4°C bottom water temperatures provide conditions appropriate for freezing brackish porewaters within the near seafloor sediments. Conditions appropriate for the melting of ice also exist nearby where ice is in contact with seawater or warmed by ascending groundwater. Small variations in either temperature or salinity, over time, can shift equilibrium conditions of ice formation and degradation, which leads to repetitive freezing and thawing of ascending brackish groundwater and the development of wide-spread ice layers in the near seafloor sediments. These conditions have produced a dramatic submarine thermokarst morphology riddled with multi-aged depressions captured in the repeat mapping surveys. These findings suggest that the distribution of submarine permafrost ice should be reassessed as it may include extensive areas where ice formed during the Holocene where groundwaters discharge at sub-zero temperatures, in addition to relict Pleistocene permafrost.

How to cite: Paull, C. K., Hong, J. K., Caress, D. W., Gwiazda, R., Kim, J.-H., Duchesne, M. J., Lundsten, E., Paduan, J. B., Rhee, T. S., Jin, Y. K., Brake, V., Obelcz, J., and Walton, M.: Rapidly forming submarine craters and massive ice outcrops along the Arctic shelf edge: by-products of subsea permafrost degradation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3674, https://doi.org/10.5194/egusphere-egu24-3674, 2024.

EGU24-4091 | ECS | Orals | CR4.2

Artificial light at night reveals hotspots and rapid development of industrial activity in the Arctic 

Cengiz Akandil, Elena Plekhanova, Nils Rietze, Jacqueline Oehri, Miguel O. Roman, Zhuosen Wang, Volker Radeloff, and Gabriela Schaepman-Strub

Climate warming enables easier access and operation in the Arctic, fostering industrial and urban development. However, there is no comprehensive pan-Arctic overview of industrial and urban development, which is crucial for the planning of sustainable development of the region. In this study, we utilize satellite derived artificial light at night (ALAN) data to quantify the hotspots and the development of human activity across the Arctic from 1992 – 2013. We find that out of 16.4 million km2 analyzed a total area of 839,710 km2 (5.14%) is lit by human activity with an annual increase of 4.8%. The European Arctic and the oil and gas extraction regions in Russia and Alaska are hotspots of ALAN with up to a third of the land area lit, while the Canadian Arctic remains dark to a large extent. On average, only 15% of lit area in the Arctic contains human settlement, indicating that artificial light is largely attributable to industrial human activity. With this study, we provide a new, standardized approach to spatially assess human industrial activity across the Arctic, independent from economic data. Our results provide a crucial baseline for sustainable development and conservation planning across the highly vulnerable Arctic region.

 

How to cite: Akandil, C., Plekhanova, E., Rietze, N., Oehri, J., Roman, M. O., Wang, Z., Radeloff, V., and Schaepman-Strub, G.: Artificial light at night reveals hotspots and rapid development of industrial activity in the Arctic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4091, https://doi.org/10.5194/egusphere-egu24-4091, 2024.

EGU24-4769 | ECS | Posters on site | CR4.2

Permafrost thermal response to improved soil hydro-thermodynamics in historical and scenario simulations with a modified version of the MPI-ESM  

Félix García-Pereira, Jesús Fidel González-Rouco, Nagore Meabe-Yanguas, Norman Julius Steinert, Johann Jungclaus, Philip de Vrese, and Stephan Lorenz

Soil warming is particularly sensitive in Arctic regions, underlain by permafrost. Permafrost degradation with warming enhances the release of substantial amounts of carbon into the atmosphere, which acts as a positive radiative feedback. However, the increasing temperature is not the only factor affecting permafrost degradation. Water availability changes affecting the Arctic, induced by changes in the atmospheric general circulation considerably affect the soil moisture and ice presence and subsequently thermal structure in permafrost regions. The interaction between soil hydrology and thermodynamics is still poorly represented by most of the CMIP6 land surface models (LSMs), mainly in terms of the soil depth, vertical resolution, and coupling between hydrology and thermodynamics.

This work explores the response of the Max Planck Institute Earth System Model (MPI-ESM) in historical and scenario simulations to changes in the hydrological and thermodynamic features of its LSM, JSBACH, in permafrost-affected regions. An ensemble of experiments was performed with varying soil depth and vertical resolution under two configurations of the hydro-thermodynamical coupling, which generate comparatively drier or wetter conditions over permafrost areas. Results show that deepening JSBACH reduces the intensity of near-surface warming, reducing the deep permafrost degradation area by ca. 2 million km2 and constraining the active layer thickness deepening by the end of the 21st century in high radiative forcing scenarios. Nevertheless, the largest impacts on permafrost extent and active layer thickness are produced by the dry and wet settings, which yield diverging soil moisture and warming conditions during the 21st century. These two configurations show differences in near-surface and deep permafrost extent of up to 5 million km2 by the end of the 21st century.

How to cite: García-Pereira, F., González-Rouco, J. F., Meabe-Yanguas, N., Steinert, N. J., Jungclaus, J., de Vrese, P., and Lorenz, S.: Permafrost thermal response to improved soil hydro-thermodynamics in historical and scenario simulations with a modified version of the MPI-ESM , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4769, https://doi.org/10.5194/egusphere-egu24-4769, 2024.

EGU24-5063 | Posters on site | CR4.2

Geological features of methane vents in the East Siberian Sea, the Arctic Ocean 

Jong Kuk Hong, Seung-Goo Kang, Yeonjin Choi, Tae Siek Rhee, Sookwan Kim, Younggyun Kim, and Young Keun Jin

The Eastern Siberian Sea is known for the presence of subsurface permafrost and for emitting significant amounts of methane close to the coastline. The thawing of permafrost accelerates the release of methane and carbon dioxide, contributing to increased greenhouse gas concentrations in the atmosphere. In 2021 and 2023, a multidisciplinary survey aboard the Korean icebreaker Araon was conducted on the continental shelf of the East Siberian Sea. The survey area lies more than 500 km away from the nearest coastline and falls within international waters. During the survey, areas with high methane concentration were identified on the shallow continental shelf, at depths ranging from 50 to 70 meters, utilizing underway CH4 measurements. These zones extend in a northwest-southeast direction. Multiple surveys were conducted to pinpoint gas seepage zones and delineate subsurface structures. The EK80 scientific echosounder proved instrumental in locating the gas vents, as it displayed methane gas eruptions clearly, resembling pillars in the imaging. The shallow sedimentrary structure of the lower part of the gas vent, observed  by the SBP survey, revealed high-amplitude reflections at a shallow depth (~5 m) below the seafloor. At the gas expulsion sites, seismic profiles show numerous vertical faults within the shallow sedimentary layers and scatterings in the water column caused by the methane emission from the seafloor. Backscattered images from the side-scan sonar clearly depict gases emitting from the vents and moving upward in the water column. These gas vents were found to have about 10 meters in diameter.

How to cite: Hong, J. K., Kang, S.-G., Choi, Y., Rhee, T. S., Kim, S., Kim, Y., and Jin, Y. K.: Geological features of methane vents in the East Siberian Sea, the Arctic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5063, https://doi.org/10.5194/egusphere-egu24-5063, 2024.

The stability and spatial distribution of subsea permafrost across the Arctic continental shelves play a pivotal role in our understanding of global warming. Serving as a significant carbon store, this permafrost has the potential to release greenhouse gases when it thaws, significantly influencing the global climate. This study is dedicated to a comprehensive investigation of the extent and state of submarine permafrost within the Arctic, with a particular focus on the comparative analysis of subsea permafrost development along the continental shelves of the Beaufort and East Siberian Seas. This research enhances our grasp of Arctic subsea permafrost's current variability and its role in global warming processes. To map the extent of subsea permafrost, we utilized multichannel seismic data from the Beaufort Sea (2014) and East Siberian Sea (2016, 2019), collected by the IBRV Araon. Employing a full waveform inversion approach, we precisely determined the seafloor permafrost's velocity structure, offering insights into its depth and state. The research reveals pronounced regional variations in the development of subsea permafrost on Arctic continental shelves. In particular, the continental shelf of the Beaufort Sea is characterized by a densely concentrated distribution of subsea permafrost extending to depths of up to 600 meters. In contrast, the continental shelf of the East Siberian Sea is dominated by permafrost that has thawed significantly, reaching depths of around 400 meters. These different regional patterns may be influenced by a number of factors, including the proximity of the shelf to the coast, the influence of ocean currents, the geological composition of the seabed and the prevailing thermal conditions. These findings suggest that the highly variable nature of submarine permafrost across the Arctic shelf is crucial to understanding warming induced changes in Arctic submarine permafrost and the potential for greenhouse gas release through permafrost dissociation.

How to cite: Jin, Y. K., Kang, S.-G., Choi, Y., Kim, S., and Hong, J. K.: Regional Variations of Subsea Permafrost Development on the Arctic Continental Shelves: A comparative analysis of the Beaufort and East Siberian Seas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5198, https://doi.org/10.5194/egusphere-egu24-5198, 2024.

EGU24-5562 | ECS | Posters on site | CR4.2

Dynamics of permafrost thaw in Western Siberia - a 200 years multi-proxy and high-resolution reconstruction from Khanymei peatlands 

Agnieszka Halaś, Mariusz Lamentowicz, Milena Obremska, Dominika Łuców, and Michał Słowiński

Western Siberian peatlands are one of the biggest peatland complexes in the world. Despite playing an essential role in regulating global climate, these ecosystems still remain understudied. A lack of long-term multi-proxy studies comprehensively examining the dynamics between permafrost thaw and peatland ecosystems in Siberia makes it difficult to determine how these areas will be affected by future climate change. Our research covers the history of the Khanymei peatlands (63°43’N, 75°57’E), located in the discontinuous permafrost zone in the last 200 years (from the end of the Little Ice Age to modern times). In this study, we applied multi-proxy analysis (testate amoebae, plant macrofossil, pollen, micro and macro charcoal, LOI and XRF) on two cores from a transect between a peat mound and a thermokarst lake. A newly developed by Halaś et al. (2023) testate amoebae calibration data set based on samples from the Khanymei peatlands complex was used to reconstruct past changes in peatland hydrology. In the last 200 years, we observed constant drying of studied peatlands with events of wetting caused by thawing permafrost. Reconstructed changes in peatland vegetation indicate that lichens (genus Cladonia) dominate during stable permafrost phases. We discovered that peatland drying in recent decades caused the expansion of shrubs onto Khanymei peatlands, which is also widely observed in other parts of Arctic tundra. The increase in peatland moisture after thawing is noted only in the initial period and in a limited area. Thawing led to high Sphagnum growth and change in the structure of testate amoebae communities, with an increase of mixotrophic species like Placocista spinosa. Species with organic and idiosomic tests started to dominate in the community replacing species with agglutinated shells. We discovered that permafrost thawing resulted in a short-term increase of peat accumulation and carbon sequestration, increased abundance of fungal communities, and promotion of oxic conditions. Initially, positive effects of thawing (like carbon accumulation) quickly weakened as favorable moisture conditions disappeared.
As permafrost continues to thaw, these processes will occur on an increasingly larger scale. According to climate change predictions, this region in Western Siberia may become unsuitable for the functioning of permafrost peatlands in their current form.

References:

Halaś, A., Lamentowicz, M., Łuców, D., & Słowiński, M. (2023). Developing a new testate amoeba hydrological transfer function for permafrost peatlands of NW Siberia. Quaternary Science Reviews, 308, 108067. https://doi.org/10.1016/j.quascirev.2023.108067

The study was supported by the National Science Center (Grant no. 2019/35/O/ST10/0290 and 2021/41/B/ST10/00060) and INTERACT No. 730938.

How to cite: Halaś, A., Lamentowicz, M., Obremska, M., Łuców, D., and Słowiński, M.: Dynamics of permafrost thaw in Western Siberia - a 200 years multi-proxy and high-resolution reconstruction from Khanymei peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5562, https://doi.org/10.5194/egusphere-egu24-5562, 2024.

EGU24-7215 | ECS | Posters on site | CR4.2

Abrupt increase in Arctic-Subarctic wildfires following permafrost thawing in a warmer climate 

In-Won Kim, Axel Timmermann, Ji-Eun Kim, Keith Rodgers, Sun-Seon Lee, Hanna Lee, and William Wieder

Greenhouse warming is accelerating permafrost thaw and the risk of wildfires in the northern high latitudes. However, the impact of permafrost thaw on Arctic-Subarctic wildfires and the associated release of greenhouse gases and aerosols is less well understood. Here we investigate the effect of future permafrost thaw on Arctic-Subarctic wildfires using the CESM2 large ensemble simulations forced by the SSP3-7.0 greenhouse gas emission scenario. We find that an increase in soil permeability induced by rapid permafrost thawing leads to an abrupt increase in sub-surface runoff and a decrease in soil moisture over the Arctic-Subarctic region. This sudden soil drying causes a significant increase in surface air temperature and a decrease in relative humidity during summer. The resulting soil drying and atmospheric dryness lead to a rapid intensification of wildfires in western Siberia and Canada in the mid-to-late 21st century.

How to cite: Kim, I.-W., Timmermann, A., Kim, J.-E., Rodgers, K., Lee, S.-S., Lee, H., and Wieder, W.: Abrupt increase in Arctic-Subarctic wildfires following permafrost thawing in a warmer climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7215, https://doi.org/10.5194/egusphere-egu24-7215, 2024.

EGU24-8248 | Posters on site | CR4.2

To tile or not to tile? 

Melanie A. Thurner, Xavier Rodriguez-Lloveras, and Christian Beer

Soils and landscapes vary within centimeters to decameters, which is not captured by state-of-the-art land-surface models that operate on kilometer scale. This leads to potential mismatches when simulating the exchange of energy, water and gasses between land and atmosphere, which are summarized under the term “aggregation error”, and is a major source of uncertainty. To overcome this issue and account for subgrid-scale heterogeneity so-called tiling approaches are used, which separate grid cells internally into different tiles that interact with each other. Although this is a valid approach, it remains unclear, if and to what extend tiling reduces the aggregation error and consequently, if tiling is sufficient to account for subgrid-scale heterogeneity.

Permafrost soils are especially heterogeneous and the aggregation error when simulating permafrost landscapes is especially problematic, because it can make the differences between frozen and unfrozen, as well as waterlogged and unsaturated areas. This affects the presence of permafrost itself, the build of soil ice and resulting frost heave, and determines pond locations as well as the duration and thickness of the seasonal snow cover, which all together influence vegetation and thus ecosystem dynamics.

To address the sufficiency of tiling at permafrost landscapes, we apply the two-dimensional pedon-scale soil model DynSoM at a non-sorted circle site. We run DynSoM with four different horizontal resolutions: (i) with an explicit resolution of 10cm, (ii) with three tiles, representing center, rim, and interface area, (iii) with two tiles, representing center and rim, and (iv) without tiling, representing a typical state-of-the-art land surface model. By comparing mean simulations, we assess the benefits, but also the shortcomings and limitations of the different tiling set-ups, and discuss implications for tiling within kilometer-scale land-surface models.

How to cite: Thurner, M. A., Rodriguez-Lloveras, X., and Beer, C.: To tile or not to tile?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8248, https://doi.org/10.5194/egusphere-egu24-8248, 2024.

EGU24-8527 | ECS | Orals | CR4.2

Geospatial modelling of soil organic carbon density in 3D across the northern circumpolar permafrost region 

Friedrich Röseler, Claire Treat, and Gerard Heuvelink

The northern circumpolar permafrost region contains up to half of the global soil carbon pool and twice as much carbon as currently is in the atmosphere. At the same time, the Arctic is rapidly warming due to climate change, causing the permafrost to thaw. There is a risk that substantial amounts of soil organic carbon (SOC) may be released into the atmosphere as greenhouse gases during this process. This makes permafrost carbon a potentially strong climate feedback that could further amplify global warming.

Currently, only a few studies attempted to quantify this permafrost carbon on a global scale. Despite the advances in estimating how much SOC is stored in the northern circumpolar permafrost region, there are still large uncertainties. Modelling permafrost carbon is particularly challenging due to the scarce availability of reference datasets on SOC content and great subsurface variability in the Arctic environment caused by cryoturbation. The high lateral (i.e. horizontal) and vertical (i.e. along the soil profile) variability results in several obstacles when mapping SOC in permafrost regions.

While previous studies on modelling permafrost carbon focused on quantifying its spatial heterogeneity, they lacked in capturing the complex (vertical) distribution of SOC as a function of depth. Furthermore, they often rely on discrete models to estimate the spatial variation. In this work, we focus on providing more accurate high-resolution, continuous global maps of permafrost SOC density using a 3D digital soil mapping approach. Digital soil mapping has shown to be a valuable tool in mapping SOC, as it can better capture the continuous variation of soil properties. Here, we used a random forest machine learning model to predict SOC based on a number of spatial variables representing soil forming factors (such as topographic attributes, climate, carbon age and land cover). The reference dataset that we used to train the model consists of soil profile observations from the permafrost region of the Northern Hemisphere, excluding alpine permafrost. We harmonised this dataset from existing databases and recent studies that provide information on carbon content from soil core measurements. Information on the bulk density was needed to calculate the SOC density and estimated for missing observations using pedotransfer functions. Results indicate that 3D modelling of permafrost carbon produces substantially different results than conventional 2D approaches. Furthermore, accounting for the vertical variation in SOC improves the prediction accuracy.

How to cite: Röseler, F., Treat, C., and Heuvelink, G.: Geospatial modelling of soil organic carbon density in 3D across the northern circumpolar permafrost region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8527, https://doi.org/10.5194/egusphere-egu24-8527, 2024.

The vulnerability of Arctic permafrost to climate change is evident, with anticipated widespread enhanced thawing under climate warming. This process may release substantial amounts of organic carbon. The positive feedback mechanism resulting from accelerated thaw and increased carbon emission is suspected to be a potential tipping element, possibly occurring within the 1.5 °C global warming range of the Paris Agreement. The consequences of Arctic permafrost thaw extend beyond carbon release, with the capability to drastically alter Earth's surface in Northern high latitudes.

This study employs high-resolution Large Eddy Simulations to investigate the impact of changing surfaces in the Arctic region on the neutrally stratified Atmospheric Boundary Layer. Utilizing a stochastic land cover model based on Gaussian Random Fields, representative permafrost landscapes are classified by distinct surface features. Experiments varying the areal fraction and surface correlation length of these surface features reveal significant insights into the sensitivity of the boundary layer to surface heterogeneity.

Key findings include a substantial impact of areal fraction of open water bodies on aggregated sensible heat flux at the blending height, suggesting a potential feedback mechanism: The smaller the areal fraction of open water bodies, the greater the sensible heat flux, the warmer the surface. Additionally, the blending height is significantly influenced by the correlation length of surface features. A longer surface correlation length leads to an increased blending height, highlighting the relevance of this metric for land surface models focused on Arctic permafrost.

How to cite: Schlutow, M. and Göckede, M.: Interaction of the Atmospheric Boundary Layer with degrading Arctic permafrost: A numerical study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9594, https://doi.org/10.5194/egusphere-egu24-9594, 2024.

EGU24-13717 | ECS | Posters on site | CR4.2

Evaluation of Standalone In-situ Simulations of Frozen Soil 

Zhicheng Luo, Bodo Ahrens, Danny Risto, and Mittal Parmar

The performance of a climate model to reproduce frozen soil depends on the modeled atmospheric forcing and the parameterizations in the land surface. Due to the complex land-air interactions caused by snow and soil freezing and thawing, biased simulations of climate models may be compensated or amplified by errors in land surface models. This may lead to a misjudgment of the simulation capabilities of the land surface model itself, especially when we are trying to improve the overall performance of the climate model without being able to balance the results in frozen soil. In order to separately investigate the simulation performance of the land surface model in the frozen soil region, we conduct simulations using the stand-alone land surface models CLM5, TERRA, and JSBACH at representative sites in Siberia, Alaska, and the Tibetan Plateau and explore the performance of the models from daily to interannual scales using the same atmospheric forcing and initial conditions.

The main evaluation objects will be the insulating effect of snow, soil energy balance, and soil moisture transportation to a depth of 3 meters below the ground surface. We look forward to the offline simulation experiments to evaluate the accuracy of different land surface model simulations, the optimal soil hydrothermal parameterization scheme, and important physical processes that may be neglected by the models’ prediction of frozen soil in daily and monthly time scales.

How to cite: Luo, Z., Ahrens, B., Risto, D., and Parmar, M.: Evaluation of Standalone In-situ Simulations of Frozen Soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13717, https://doi.org/10.5194/egusphere-egu24-13717, 2024.

EGU24-14659 | Orals | CR4.2

Q-Arctic: A synergetic approach to observe and model pan-Arctic interactions between hydrology and carbon 

Mathias Göckede, Victor Brovkin, Annett Bartsch, and Martin Heimann and the Q-Arctic Team

Arctic permafrost has been identified as a critical element in the global climate system, since it stores a vast amount of carbon that is at high risk of being released under climate change. The feedbacks between permafrost carbon and climate change are moderated by complex interactions between physical, hydrological, biogeochemical, and ecological processes. Many of these are not well understood to date, and therefore also only rudimentarily represented in current Earth System Models (ESMs). A particular problem in this context is a scaling gap between processes and model grid.

The Q-ARCTIC project funded by the European Research Council (ERC) follows a synergetic approach by combining remote sensing and local-scale observations with modeling on scales from a few meters to hundreds of kilometers. The primary objective of Q-ARCTIC is to close the gap between process scales and the much coarser grid resolution of Earth System Models (ESMs), with a particular focus on the net effect of disturbance processes and associated changes in hydrology on the pan-Arctic scale. To close this gap, we developed new ESM modules representing subgrid through stochastic parameterizations, trained and evaluated with high-resolution remote sensing data and site-level observations.

We will present novel results based on in-situ observations that characterize prominent Arctic disturbance features, and satellite remote sensing products investigating fine scale (few meters) patterns in Arctic landscapes that are undergoing modifications linked to climate change. Targets investigated include for example sinking surfaces, wetness gradients in heterogeneous landscapes, or drained lake basins. Assimilation of these new datasets supported the development of new ESM model components that successfully capture the statistics of small-scale features, e.g. depressions linked to sinking surfaces, or surface water bodies that form when soil ice melts. Our results demonstrate that the ability to project the response of the high-latitude water, energy and carbon cycles to rising global temperatures may strongly depend on the ability to adequately represent the soil hydrology in permafrost affected regions.

How to cite: Göckede, M., Brovkin, V., Bartsch, A., and Heimann, M. and the Q-Arctic Team: Q-Arctic: A synergetic approach to observe and model pan-Arctic interactions between hydrology and carbon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14659, https://doi.org/10.5194/egusphere-egu24-14659, 2024.

EGU24-15078 | ECS | Posters on site | CR4.2

Characterizing drained lake basins across the Arctic  

Helena Bergstedt, Annett Bartsch, Clemens von Baeckmann, Benjamin Jones, Amy Breen, Juliane Wolter, Louise Farquharson, Guido Grosse, and Mikhail Kanevskiy

Lakes and drained lake basins (DLB) are common landforms in permafrost lowland regions in the Arctic and widely cover 50% to 75% of the landscape in parts of Alaska, Siberia, and Canada. Lakes and DLBs create a heterogeneous and dynamic mosaic of terrain units, providing unique habitats for flora and fauna. Lakes and drained lake basins in permafrost regions play a crucial role in the regions landscape and ecosystem processes, influencing permafrost dynamics, biogeochemical processes, the hydrologic regime, as well as carbon cycling and greenhouse gas emissions. Depending on time passed since drainage of a given DLB, characteristics like surface roughness, vegetation, moisture, and abundance of ponds may vary between basins. Spatial heterogeneity within a single basin also varies between basins of different age. The mosaic of vegetative and geomorphic succession within DLBs and the distinct differences between DLBs and surrounding areas can be discriminated with remote sensing and used to derive a landscape-scale classification. In situ observations of these surface characteristics of DLBs are crucial for a better understanding of these features but can only describe a small percentage of existing DLBs.

In this study, we use a novel pan-Arctic assessment on DLB occurrence and the ESA Permafrost_cci circumpolar landcover unit data set based on Sentinel-1 and Sentinel-2 satellite imagery to assess the inter and intra-DLB spatial heterogeneity of surface characteristics. Building on existing research, we sort DLBs into distinct groups corresponding to previously published DLB age classification schemes (young, medium, old and ancient DLBs). DLB groupings show different landcover distribution within the basins, allowing for assumptions about the relative time passed since a drainage event occurred. To compliment and verify our remote sensing-based approach, a wide array of field data was collected at multiple sites across the Arctic, including on the Alaska North Slope. First results show distinct differences between DLBs within the study area, based on the landcover occurring within basins and other surface properties. Comprehensive mapping and characterizing of DLBs on a circumpolar scale will allow for improved parametrization of regional to pan-Arctic modeling efforts and improve our understanding of DLBs as a crucial landform in Arctic permafrost landscapes.  

How to cite: Bergstedt, H., Bartsch, A., von Baeckmann, C., Jones, B., Breen, A., Wolter, J., Farquharson, L., Grosse, G., and Kanevskiy, M.: Characterizing drained lake basins across the Arctic , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15078, https://doi.org/10.5194/egusphere-egu24-15078, 2024.

EGU24-15688 | Posters on site | CR4.2

Assessment of the Topographic Wetness Index in Permafrost landscapes  

Barbara Widhalm, Annett Bartsch, Helena Bergstedt, Clemens von Baeckmann, and Tazio Strozzi

Arctic permafrost regions are subject to rapid changes due to climate warming affecting hydrology, topography and ecology. Soil wetness is of great importance in these regions facilitating for example upscaling of carbon fluxes. In this study we therefore investigate the Topographic Wetness Index (TWI) as often used in land surface modelling, focusing on study regions in the Siberian and Canadian Arctic. We analyse the influence of the used Digital Elevation Model (DEM) by comparing results of the openly available ArcticDEM (2m resolution) and Copernicus DEM (30m resolution). Results are being validated against near-surface soil moisture in-situ measurements. Further comparisons are being made to other wetness indices such as the Tasselled Cap Wetness index or the Normalized Differential Moisture Index derived from Landsat 8. The relationship to InSAR derived surface displacements as an indicator of soil wetness is explored, as well as additional parameters such as the Topographic Position Index and correlations to other moisture indicators including land cover products.

How to cite: Widhalm, B., Bartsch, A., Bergstedt, H., von Baeckmann, C., and Strozzi, T.: Assessment of the Topographic Wetness Index in Permafrost landscapes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15688, https://doi.org/10.5194/egusphere-egu24-15688, 2024.

EGU24-15989 | ECS | Orals | CR4.2

Vulnerability assessment of Arctic coastal communities to the effects of coastal erosion and permafrost warming. 

Rodrigue Tanguy, Annett Bartsch, Ingmar Nitze, Anna Irrgang, Pia Petzold, Barbara Widhalm, Clemens von Baeckmann, Julia Boike, Julia Martin, Aleksandra Efimova, Gonçalo Vieira, Birgit Heim, Mareike Wieczorek, Guido Grosse, and Dorothee Ehrich

This study assesses the escalating vulnerability of Arctic coastal communities due to the combined impacts of coastal erosion and permafrost warming. With the Arctic experiencing heightened temperatures, coastal permafrost areas face increased instability, endangering vital infrastructures. The study focuses on a pan-Arctic evaluation of settlements and infrastructures at risk, enhancing the existing Arctic coastal infrastructure dataset (SACHI) to include road types, airstrips, and artificial water reservoirs.

By analyzing coastline change rates from 2000 to 2020, alongside permafrost ground temperature and active layer thickness trends from the ESA Permafrost Climate Change Initiative datasets, the research identifies settlements at risk for the years 2030, 2050, and 2100. The accuracy of the dataset is rigorously evaluated. Results indicate that by 2100, 23% of coastal settlements will face the impacts of coastal erosion. Projections based on linear trends suggest an 8°C increase in coastal permafrost ground temperature and a 0.9-meter growth in active layer thickness by the same year.

Crucially, the study reveals that 65% of all infrastructures and settlements will be affected by permafrost warming within the range of 5-15°C, with 35% experiencing active layer thickening between 1-5 meters. This research marks the first regional-scale identification of settlements at risk from coastal erosion along Arctic and permafrost-dominated coasts in the northern hemisphere. The findings emphasize the urgency of adapting to current and future environmental changes to mitigate the deterioration of living conditions in permafrost coastal settlements. Immediate action is imperative to counteract these challenges and ensure the resilience of these vulnerable communities.

How to cite: Tanguy, R., Bartsch, A., Nitze, I., Irrgang, A., Petzold, P., Widhalm, B., von Baeckmann, C., Boike, J., Martin, J., Efimova, A., Vieira, G., Heim, B., Wieczorek, M., Grosse, G., and Ehrich, D.: Vulnerability assessment of Arctic coastal communities to the effects of coastal erosion and permafrost warming., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15989, https://doi.org/10.5194/egusphere-egu24-15989, 2024.

EGU24-16738 | Posters on site | CR4.2

Modelling heterogeneity of land surface waters in the permafrost region 

Thomas Kleinen, Philipp de Vrese, Tobias Stacke, and Victor Brovkin

When considering high latitude regions, one of the striking characteristics is the abundance of surface water in comparison to lower latitudes. This difference is not just limited to the total area covered by surface water, but it also extends to the size distribution of water bodies: While surface water in lower latitudes most often occurs in the form of larger lakes or rivers, high latitude regions often display a wide variety of surface water features, ranging from small puddles to huge lakes. Considering the climatic and carbon cycle consequences of lower latitude large water bodies in land models is relatively straightforward – they can be considered static, be prescribed from observations, and described using dedicated submodels. However, considering surface water in the high latitudes comprehensively is substantially more challenging, as a much larger range of sizes needs to be considered, parts of which will not be available from observations. Furthermore, due to the dynamics of permafrost, these cannot be considered static any more and need to be treated dynamically.

To better represent high latitude regions in the ICON-Land land surface model, part of the ICON-ESM Earth System Modelling framework, we are developing a representation of multiple scales of water bodies, ranging from large lakes to small puddles, as well as areas of water-saturated soil. The smaller-scale features are of particular interest, as they do not just affect the exchange of water and energy between surface and atmosphere, but also have large impacts on the carbon cycle and methane emissions. To do this, we employ a statistical distribution function of water body sizes, allowing us to obtain energy, water, carbon and methane fluxes for water features of all sizes.

We will present our novel modelling framework and show first results covering selected Arctic locations.

How to cite: Kleinen, T., de Vrese, P., Stacke, T., and Brovkin, V.: Modelling heterogeneity of land surface waters in the permafrost region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16738, https://doi.org/10.5194/egusphere-egu24-16738, 2024.

EGU24-16785 | ECS | Posters on site | CR4.2

Status of the Circumpolar Landcover Unit database 

Rustam Khairullin, Clemens von Baeckmann, Annett Bartsch, Helena Bergstedt, Barbara Widhalm, Aleksandra Efimova, Xaver Muri, Ksenia Ermokhina, and Birgit Heim

The Circumpolar Landcover unit database provides landcover information in high detail, spatially (10m) and thematically (23 units). Such detail is needed for a wide range of applications targeting climate change impacts and ecological research questions. The landcover unit retrieval scheme used provides unprecedented detail. The landcover units have been derived by fusion of satellite data using Sentinel-1 (synthetic aperture radar) and Sentinel-2 (multispectral). The units reflect gradients of moisture as well as vegetation physiognomy.

 

The original database covered the Arctic north of the tree line. It has been extended towards south, providing additional detail within the tundra-taiga transition zone in permafrost regions. The available spatial detail provides the means to assess the complexity of this zone in addition to information on recent disturbance related to for example wildfire and thermokarst lake change.

 

Bartsch, A., Efimova, A., Widhalm, B., Muri, X., von Baeckmann, C., Bergstedt, H., Ermokhina, K., Hugelius, G., Heim, B., & Leibmann, M. (2023). Circumpolar Landcover Units (1.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.8399018

How to cite: Khairullin, R., von Baeckmann, C., Bartsch, A., Bergstedt, H., Widhalm, B., Efimova, A., Muri, X., Ermokhina, K., and Heim, B.: Status of the Circumpolar Landcover Unit database, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16785, https://doi.org/10.5194/egusphere-egu24-16785, 2024.

EGU24-17224 | ECS | Orals | CR4.2

Statistical Modelling of Permafrost Subsidence Based on High-resolution InSAR Data 

Zhijun Liu, Barbara Widhalm, Annett Bartsch, Thomas Kleinen, and Victor Brovkin

The northern high latitudes are warming much faster than the rest of the planet. While gradual thaw of permafrost is accounted for in the recent generation of the Earth System Models (ESMs), consequences of the abrupt thaw of permafrost and the subsequent greenhouse gas release are not yet taken into consideration. However, an abrupt thaw of very small fraction of the northern permafrost region can lead to significant carbon release and subsequent global warming (Turetsky et al. 2020).

An in-depth analysis of fine-scale permafrost subsidence processes is crucial for improved representation of abrupt thawing in simulations. Currently, permafrost subsidence is only taken into consideration in a few models, where subsidence is described in a deterministic process-based approach. This approach overlooks the high spatial heterogeneity in fine-scale permafrost processes.

Recent advancements in satellite technology allow the acquisition of Interferometric Synthetic Aperture Radar (InSAR) data on permafrost vertical displacement at meter-scale resolution. We conducted a case study on the Yamal Peninsula, Russia, where we compare permafrost subsidence data from Sentinel-1 with various potential driving factors, including climate forcing data from ERA5-Land and geomorphology data from MERIT Hydro. A statistical approach is taken to analyse the relationships between different factors and their contributions to permafrost subsidence. The results demonstrate the high heterogeneity of permafrost subsidence in the form of probability distribution functions at ESM-scale resolution. Eventually, our study aims to obtain a parameterization for pan-Arctic permafrost subsidence that can be implemented into the ICON-ESM in order to close the gap in permafrost modelling between process- and ESM-scale.

 

Reference: Turetsky, M.R., Abbott, B.W., Jones, M.C. et al. Carbon release through abrupt permafrost thaw. Nat. Geosci. 13, 138–143 (2020). https://doi.org/10.1038/s41561-019-0526-0

How to cite: Liu, Z., Widhalm, B., Bartsch, A., Kleinen, T., and Brovkin, V.: Statistical Modelling of Permafrost Subsidence Based on High-resolution InSAR Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17224, https://doi.org/10.5194/egusphere-egu24-17224, 2024.

EGU24-17398 | ECS | Orals | CR4.2

Cryogrid modelling of permafrost temperature in the Maritime Antarctic (Barton Peninsula, King George Island) 

Joana Baptista, Gonçalo Vieira, Sebastian Westermann, and Hyoungseok Lee

The temperature dynamics of permafrost is crucial for ecosystem processes in the ice-free areas of the Antarctic Peninsula, where a strong long-term warming trend with an increase of 3.4 ºC in the mean annual air temperature since 1950 has been recorded (Turner et al., 2020). The consequences of this warming on past and future permafrost degradation are still not fully understood, mainly due to the sparse spatial coverage and short time span of borehole data, only available after the mid to late 2000’s (Vieira et al., 2010; Bockheim et al., 2013). The Cryogrid Community Model is an adaptable toolbox for simulating the ground thermal regime and the ice/water balance for permafrost (Westermann et al., 2017, 2022). The modular structure allows combinations of classes that represent the snow conditions and the subsurface materials. Here, permafrost temperatures from the 13 m depth King Sejong Station borehole (KSS), from Barton Peninsula, King George Island were used to assess the performance of Cryogrid and the quality of ERA5 forcing. For evaluating model performance, the setup was firstly used in its basic version with the GROUND_freeW_ubtf class, which considers a temperature boundary condition, for which air temperatures from KSS were used. Modifications to the stratigraphy and parameters were performed to achieve the strongest correlations and lower Mean Absolute Errors (MAE) between the simulated and observed ground temperature at nine depth levels. This approach allowed for the definition of the stratigraphy and parameters later used with the GROUND_freeW_seb_snow class, in which the surface energy balance scheme is included. The results show that ERA5 air temperature underestimates the records from KSS, especially during the summer, impacting the representation of surface warming. This deviation was corrected using linear regression corrected temperatures. The Cryogrid modelling results indicate an overestimation of the ground temperature during the thawing season and an underestimation during the freezing season, being the difference more pronounced at the surface. A strong correlation was shown between the simulated and measured ground temperatures in KSS down to 6 m depth (r>0.9) with MAE ranging from 0.4 to 0.9 ºC. Below 6 m the correlation weakens to 0.45 (13 m depth) due to differences in heat propagation and lack of temperature oscillation on the records when compared with the simulation. However, MAE values are residual, ranging from 0.1 to 0.2 ºC. The active layer thickness was overestimated in about 1 m. This research was funded by the project THAWIMPACT (FCT2022.06628.PTDC) and by CEG/IGOT (UIDP/00295/2020). Joana Baptista is funded by the FCT with a doctoral grant (2021.05119.BD).

How to cite: Baptista, J., Vieira, G., Westermann, S., and Lee, H.: Cryogrid modelling of permafrost temperature in the Maritime Antarctic (Barton Peninsula, King George Island), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17398, https://doi.org/10.5194/egusphere-egu24-17398, 2024.

EGU24-17812 | ECS | Orals | CR4.2

Improving the simulation of permafrost extent by representing the multi-tiling energy budgets in ORCHIDEE-MICT model 

Yi Xi, Chunjing Qiu, Yuan Zhang, Dan Zhu, Shushi Peng, Gustaf Hugelius, Jinfeng Chang, Elodie Salmon, and Philippe Ciais

The surface energy budget plays a critical role in terrestrial hydrologic and biogeochemical cycles. Nevertheless, its highly spatial heterogeneity across different vegetation types is still missing in the land surface model, ORCHIDEE-MICT (ORganizing Carbon and Hydrology in Dynamic EcosystEms–aMeliorated Interactions between Carbon and Temperature). In this study, we describe the representation of a multi-tiling energy budget in ORCHIDEE-MICT and assess its short and long-term impacts on energy, hydrology, and carbon processes. We found that: 1) With the specific values of surface properties for each vegetation type, the new version presents warmer surface and soil temperatures, wetter soil moisture, and increased soil organic carbon storage across the Northern Hemisphere. 2) Despite reproducing the absolute values and spatial gradients of surface and soil temperatures from satellite and in-situ observations, the considerable uncertainties in simulated soil organic carbon and hydrologic processes prevent an obvious improvement of temperature bias existing in the original ORCHIDEE-MICT. 3) The simulated continuous permafrost area (15.2 Mkm2) and non-continuous permafrost area (3.1 Mkm2) are comparative to observation-based datasets from Brown et al. (2002) (10.8 Mkm2 for continuous and 4.6 Mkm2 for non-continuous) and Obu et al. (2019) (11.5 Mkm2 for continuous and 5.3 Mkm2 for non-continuous). Consequently, the new version will facilitate various model-based permafrost studies in the future. 

How to cite: Xi, Y., Qiu, C., Zhang, Y., Zhu, D., Peng, S., Hugelius, G., Chang, J., Salmon, E., and Ciais, P.: Improving the simulation of permafrost extent by representing the multi-tiling energy budgets in ORCHIDEE-MICT model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17812, https://doi.org/10.5194/egusphere-egu24-17812, 2024.

EGU24-19404 | ECS | Orals | CR4.2

Degradation and composition of organic carbon in the flocculation layer on the Laptev, East Siberian, and Kara seas 

Kirsi Keskitalo, Paul Mann, Tommaso Tesi, Bart van Dongen, Jannik Martens, Igor Semiletov, Oleg Dudarev, Örjan Gustafsson, and Jorien Vonk

Rapidly rising temperatures in the Arctic cause thaw of permafrost and increase coastal erosion that mobilizes permafrost-derived organic carbon (OC) into coastal waters. In the water column, permafrost-OC may either degrade and thus, enhance climate warming by adding greenhouse gases to the atmosphere or settle on the seabed and be buried in the sediments. In this study, we focused on the composition and degradation of particulate OC (POC) within the flocculation (nepheloid) layer - a turbulent layer close to seabed that holds a high amount of suspended sediments/particles and transports them across the vast Siberian Arctic shelves. More importantly, previous studies have shown that permafrost-OC, exported to the Arctic Ocean via coastal erosion, is largely carried in the POC fraction of the flocculation layer.

To study flocculation layer dynamics, sediment cores were collected using a multicorer device from the East Siberian Sea, Laptev Sea, and Kara Sea onboard R/V Akademik Mstistlav Keldysh in 2020. The overlying water of the sediment cores was stirred under controlled conditions to mimic sediment resuspension. The entrained suspended sediments were collected and incubated for two weeks (in the dark) to assess their susceptibility to degradation. During the incubation, dissolved O2, POC, dissolved OC (DOC), dissolved inorganic carbon and δ13C of each carbon pool were measured at set time points. Additionally, to better understand sediment entrainment and degradation, sediment physical properties, including grain size and mineral-specific surface area, and macromolecular composition were determined.

Our preliminary results show that stirring largely entrains the smallest sediment particles, while it seems not to influence sediment macromolecular composition suggesting that none of the compound classes such as polysaccharides or aromatic compounds are preferentially entrained. Our incubation data show losses in dissolved O2 suggesting microbial degradation, however, instead of decreases in the OC pools, especially POC shows increases combined with increases or decreases in DOC. These carbon dynamics likely result from interactions between different carbon pools such as adsorption of DOC to particles and/or leaching of POC to the DOC pool. With accelerated coastal erosion and increase in storminess in the Arctic Ocean due to sea ice loss, understanding dynamics of the flocculation layer and degradation of permafrost-OC on the Arctic sea shelves is becoming even more important to better constrain their potential climate impact.  

How to cite: Keskitalo, K., Mann, P., Tesi, T., van Dongen, B., Martens, J., Semiletov, I., Dudarev, O., Gustafsson, Ö., and Vonk, J.: Degradation and composition of organic carbon in the flocculation layer on the Laptev, East Siberian, and Kara seas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19404, https://doi.org/10.5194/egusphere-egu24-19404, 2024.

EGU24-19799 | ECS | Posters on site | CR4.2

Simulating Saline Permafrost and Cryopeg Evolution Using a Coupled Heat and Salt Diffusion Model 

Michael Angelopoulos, Pier Paul Overduin, Frederieke Miesner, Julia Boike, Michael Krautblatter, and Sebastian Westermann

Saline permafrost is primarily found in marine deposits beneath shallow shelf seas and can often extend several kilometres inland from present Arctic coastlines. On land, saline permafrost forms when previously submerged marine sediments are exposed to the atmosphere, either through a sea level regression or post-glacial rebound. Cryopegs are perennially cryotic layers or pockets within permafrost that remain unfrozen due to their high salt content. While heat and salt flow models have been applied to study subsea permafrost degradation, adapting these models to terrestrial saline permafrost remains a significant gap in model development. We utilize a version of the CryoGrid modelling suite that couples heat and salt diffusion. This enables us to simulate the formation of saline permafrost and the development of cryopegs during transitions from sub-aquatic to sub-aerial conditions. As the freezing front descends, ice forms in the sediment matrix, expulsing salts into the remaining unfrozen liquid water at sub-zero temperatures. The increased unfrozen porewater salt concentration gradient increases the rate at which salt diffuses downwards into the sediment column. Over time the thermal gradient weakens, potentially allowing a more effective salt build-up ahead of the freezing front.

How to cite: Angelopoulos, M., Overduin, P. P., Miesner, F., Boike, J., Krautblatter, M., and Westermann, S.: Simulating Saline Permafrost and Cryopeg Evolution Using a Coupled Heat and Salt Diffusion Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19799, https://doi.org/10.5194/egusphere-egu24-19799, 2024.

EGU24-20159 | Orals | CR4.2

MethaneCAMP project – overview of results 

Johanna Tamminen and the MethaneCAMP project team

The ESA funded MethaneCAMP project has focused on assessing, improving, and analysing satellite observations of methane (CH4) in the Arctic in support of the collaborative ESA-NASA Arctic Methane and Permafrost Challenge (AMPAC) initiative. 

Traditionally, the high latitude conditions have received minor attention when the satellite retrievals for methane have been optimised for global purposes as there has been known challenges caused by high solar zenith angles, low reflectivity over snow and ice, frequent cloudiness, varying polar vortex conditions and limited number of validation data sets. Now when the two-year MethaneCAMP project is finishing, we will demonstrate the recent improvements in the observation capacity over the polar regions by assessing and optimising methane SWIR and TIR retrievals at high northern latitudes. Moreover, the importance of AirCore reference observations of methane profiles in the varying polar vortex conditions will be highlighted.

We will analyse the long-term methane trends in the northern high latitudes and permafrost regions by using satellite observations and inverse modelling. We aim to demonstrate the potential of using satellite observations of methane together with modelling and surface observations in analysing spatial and temporal changes of the Arctic methane. Detection of methane hot spots will also be mentioned.

In MethaneCAMP project our focus has been on Sentinel 5P/TROPMI, GOSAT, GOSAT-2 and IASI XCH4 observations and GHGSat emission estimates. In this presentation we summarise the results of the project and discuss how the outcomes can be utilised in the AMPAC working group activities.

How to cite: Tamminen, J. and the MethaneCAMP project team: MethaneCAMP project – overview of results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20159, https://doi.org/10.5194/egusphere-egu24-20159, 2024.

EGU24-20267 | Posters on site | CR4.2

Projecting future permafrost thaw and subsidence driven infrastructure damage in the discontinuous permafrost zone 

Louise Farquharson, Dmitry Nicolsky, Monika Calif, Jennifer Schmidt, Vladimir Romanovsky, and Thomas Douglas

Permafrost thaw, ground-ice melt, and associated ground settlement pose significant hazards to northern communities and industry. Thaw of permafrost affected soils can decrease bearing capacity while settlement due to ground ice melt can cause ground collapse (thermokarst) and localized flooding. Here, explore ground ice distribution and potential for thaw induced settlement in the Fairbanks North Star Borough (FNSB), located in an area of discontinuous permafrost in Interior Alaska, USA. Pleistocene-Holocene sediment deposition, ice wedge development, and subsequent reworking due to thaw and hillslope processes have left a complex mosaic of cryolithological conditions that make thaw-related hazards a challenge to predict. The Borough is home to critical infrastructure including two military bases, a university, several gold mines, and the Trans Alaska Pipeline.

 

We created a permafrost hazard map by combining modelled ground ice distribution with projections of ground temperature through to 2090 using the GIPL 2.0 model for key ecotypes in the area. From this we were able to infer temperature dynamics, active layer deepening, talik development, and the potential for thermokarst degradation for IPCC Representative Concentration Pathway scenarios 4.5 and 8.5 through to 2090. We established ground ice distribution through a combination of existing geologic maps, numerical modeling, lidar derived thaw feature maps, and industry bore holes.  To extrapolate ground ice values from the representative sub-sample of ~ 2000km2 to the entire Borough we utilized a gradient-boosted decision tree aggregate model.

 

 Across the FNSB 23 % of the terrain is underlain by the high ground ice class, 10% medium, 4% low, 44% negligible, and 17% of the region is unaffected. High ground ice content underlines 23 % powerlines, 21% of roads and 4% of critical infrastructure (schools, hospitals, power plants etc.). Future projections of subsidence in areas of black spruce forest under RCP4.5 and 8.5 for areas respectively show that areas of high ice content could see subsidence of up to 5 and 10 meters respectively by 2090. Subsidence values for a range of topographic locations were calculated. Results from this study may help the FNSB, land managers, and homeowners best prepare and plan for the impacts of climate change in the Fairbanks region and potentially provide a hazard mitigation and climate change adaptation guides for other sub-Arctic communities.

How to cite: Farquharson, L., Nicolsky, D., Calif, M., Schmidt, J., Romanovsky, V., and Douglas, T.: Projecting future permafrost thaw and subsidence driven infrastructure damage in the discontinuous permafrost zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20267, https://doi.org/10.5194/egusphere-egu24-20267, 2024.

Estimates of the future methane (CH4) budget of northern permafrost landscapes remain highly uncertain with projections ranging from negligible to major CH4 releases to the atmosphere.

The German collaborative MOMENT project aims to address important gaps in process understanding of the high-latitude methane cycle using multi-scale methane flux observations in western Greenland linked to microbiological and biogeochemical laboratory studies. Through an innovative model-data integration framework, these novel datasets will be used to develop and evaluate land surface schemes of German Earth System Models (ESM) across terrestrial systems and multiple scales with the overarching goal to reduce uncertainties in future greenhouse gas projections.

We will introduce the overall project along with the innovations in experimental and observational techniques that facilitate observations at remote Arctic locations as well as in the lab. New remote sensing products allow for wall-to-wall mapping of structures on the finest scale across the Arctic, while novel computational infrastructure and modelling frameworks help with integration of all this information into next generation ESMs.

Selected preliminary results of the first field season and lab experiments will be highlighted.

How to cite: Sachs, T. and the the MOMENT project team: The MOMENT Project - Permafrost Research Towards Integrated Observation and Modelling of the Methane Budget of Ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21829, https://doi.org/10.5194/egusphere-egu24-21829, 2024.

Global warming could surpass the 1.5 oC temperature target within a decade and even inevitably exceed 2 oC in this century, if fossil fuel emissions are not abated sufficiently and artificial interventions are not implemented. Even a temporary overshoot beyond 2 oC potentially disrupts the global carbon cycle, with the risk of irreversible and devastating changes to current terrestrial carbon sinks, such as the tropical forests and the northern high-latitude permafrost. Large-scale geoengineering is proposed as an adjunct to the conventional mitigation to partially counteract anthropogenic warming, and avoid dramatic alterations in the Earth system and the hazardous consequences. However, carbon dioxide removal and solar radiation modification differ in their role in interacting with the terrestrial carbon cycle, through directly interfering with the carbon cycle and indirect perturbation by changing the energy balance. The varied regional responses also affect the capacity of global carbon uptake, which further impacts on the efficacy of geoengineering. It's prudent to investigate the responses of the global terrestrial carbon balance in such context, i.e., the delayed consideration of solar radiation modification or carbon dioxide removal on top of various possible overshoot scenarios, to bring the global temperature back to and maintain the long-term targets.

How to cite: Chen, Y. and Ji, D.: Terrestrial carbon cycle response to solar radiation modification and carbon dioxide removal under potential temperature overshoots , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-613, https://doi.org/10.5194/egusphere-egu24-613, 2024.

EGU24-918 | ECS | Orals | CL3.1.6

Potential Impact of Stratospheric Aerosol Injection on Horticulture Suitability in Africa? 

Temitope Samuel Egbebiyi, Chris Lennard, Kwesi Quagraine, Romaric C. Odoulami, Izidine Pinto, Babatunde J. Abiodun, Piotr Wolski, and Simone Tilmes

Global warming will be devastating for agriculture in Africa, with consequent impacts on horticultural crop suitability. Horticultural crops are the main source of vitamins and antioxidants into our body and provide nutritional security. Stratospheric Aerosol Injection (SAI), which involves the injection of sulfur into the stratosphere to reduce incoming solar radiation to the earth surface, has been proposed as a strategy to reduce global warming rate, however, how this may affect horticultural crops, mango, orange and tomato, in Africa is still unknown. Our study examines the impact of climate change (GHG) and SAI on crop suitability and planting season in Africa. We used datasets from the Stratospheric Aerosol Geoengineering Large Ensembles (GLENS) project for the periods 2011-2030 and 2070-2089 as inputs into Ecocrop model to investigate GHG and SAI impacts on horticultural crops suitability in Africa. Our findings show GHG may lead to an increase of 3-4oC in both minimum and mean temperature and a 5-10mm increase in total monthly rainfall in West, Central and East Africa but a decrease (10mm) in southern Africa. SAI intervention results in cooling over Africa of up to 3oC in both minimum and mean temperature and may also lead to a decrease, 10-20mm in total monthly rainfall over the region by the end of century. The intervention may lead to an increase (~0.2) in Suitability Index Value (SIV) of mango and tomato over West and central Africa. However, a projected decrease (~0.3) in SIV is expected for mango and orange from Angola extending to northern Mozambique in southern Africa. In addition, no change in SIV is expected for the three crops in North Africa. SAI intervention may lead to 2-5% increase in suitable area for mango and tomato but a decrease (2%) for orange. The study provides information for decision-makers about choice of adaptation strategies to enhance regional economies and promote healthy nutrition in Africa.

Plain Abstract

Africa's agriculture will suffer greatly from global warming and affect horticulture crops. Our bodies get the majority of their vitamins and antioxidants from horticultural crops, which also offer nutritional security. Although, the injection of sulphur into the stratosphere has been put forward as an option to reduce effect of global warming but how this might impact horticultural crops, tomatoes, oranges, and mangoes, grown in Africa is still unknown. To examine the effects of climate change (GHG) and SAI horticultural crops suitability in Africa, we utilised information from the Stratospheric Aerosol Geoengineering Large Ensembles (GLENS) project for the periods 2011–2030 and 2070–2089 as inputs into the Ecocrop model. Over West and Central Africa, the Suitability Index Value (SIV) of tomatoes and mangoes may rise (~0.2) because of the intervention while for mango and orange a decline (~0.3) in SIV is anticipated from Angola to northern Mozambique in southern Africa. Mango and tomato suitable areas may rise by 2-5% because of SAI intervention but decrease by 2% for orange. Decision-makers can use the study's insights to choose adaption methods that will boost African regional economies and encourage a healthy diet. 

How to cite: Egbebiyi, T. S., Lennard, C., Quagraine, K., Odoulami, R. C., Pinto, I., Abiodun, B. J., Wolski, P., and Tilmes, S.: Potential Impact of Stratospheric Aerosol Injection on Horticulture Suitability in Africa?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-918, https://doi.org/10.5194/egusphere-egu24-918, 2024.

The urgency to limit continued global mean temperature rise has prompted the emergence of methods of solar climate intervention (SCI) to cool the planet. Stratospheric aerosol injection (SAI) is a method of SCI that would cool the planet by injecting aerosols into the stratosphere to reflect a small amount of incoming solar radiation away from Earth. There is not yet a complete understanding of how the impacts and risks of SAI on human and natural systems compare to those of climate change alone. While there has been some work that has examined the potential impact of SAI on extreme weather events, none has thoroughly examined the potential impact of SAI on warm spells, defined as prolonged periods of anomalously warm temperature that may occur at any time of the year. Warm spells have detrimental impacts that are projected to worsen with continued climate warming including risks to human health, agriculture and ecosystems. Here, the impact of SAI on the frequency, magnitude, intensity, and duration of warm spells is investigated globally using the ARISE-SAI simulations. Specifically, future projections of warm spells under ARISE-SAI are compared to those under climate change alone following the moderate SSP2-4.5 emissions scenario.  The ARISE-SAI simulations indicate that increases in the frequency, magnitude, intensity and duration of warm spells could be limited if SAI were to be deployed, although there is significant regional variability. 

How to cite: Glade, I. and Hurrell, J.: Assessing the impact of stratospheric aerosol injection on warm spell characteristics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1689, https://doi.org/10.5194/egusphere-egu24-1689, 2024.

Model of stratospheric aerosol injection deployment scenarios have often assumed that a global sunscreen could be applied to the earth on relatively short notice, perhaps in response to a climate emergency.  This emergency response framing confuse the time scales associated with the commencement of such a program.  Once deployed, stratospheric aerosols could cool the earth quite quickly, but such a deployment would require aircraft and other infrastructure that does not currently exist.  Given the span required to develop and certify a novel aircraft program and thereafter to build a fleet numbering in the hundreds, scenario builders should assume a roughly two-decade interval between a funded launch decision and the attainment of a target level of cooling.

How to cite: Smith, W.: An assessment of the infrastructural and temporal barriers constraining a near-term implementation of a global stratospheric aerosol injection program, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2221, https://doi.org/10.5194/egusphere-egu24-2221, 2024.

EGU24-2611 | ECS | Posters on site | CL3.1.6

Modelling the Impact of Surfactants on Anthropogenic CO2 Transfer between the Ocean and Atmosphere 

Jianing Hu and Miguel Maqueda

During the industrial revolution, anthropogenic carbon dioxide (CO2) emissions have rapidly increased, raising worries about their impact on global climate change. The oceans are an important sink of anthropogenic CO2, taking in about 30% of emissions. Despite the important role of surfactants in reducing gas exchanges between the atmosphere and the ocean, their effect on oceanic intake of CO2 has received limited attention in ocean models. In this exploratory work, we examine the impact of a parameterization of surfactants on CO2 fluxes between the ocean and the atmosphere using the NEMO (Nucleus for European Modelling of the Ocean) ocean engine in the ORCA2-LIM-PISCES configuration. Understanding and quantifying the potential effect of surfactants on the ocean's absorption of anthropogenic CO2 is the main goal of our modelling. Using documented atmospheric CO2 concentrations from 1750 till present, we carried out three simulations of the intake of anthropogenic CO2 by the ocean, one in which the presence of surfactants was ignored and two in which different formulations of the impact of surfactants on air-sea gas exchange were used. According to the simulations, the impact of the presence of surfactant on net, basin-scale anthropogenic CO2 fluxes into the ocean is rather small, on the order of just a few percent. However, in regions where, in the model, the intake of anthropogenic CO2 is largest, such as the Southern Ocean and the Kuroshio and Gulf Stream region, the reduction in these fluxes can attain between 10% and 40%. On seasonal timescales, the global effect of surfactants is to slightly enhance the amplitude of the annual cycle of fluxes by between 10% and 15%. The presence of surfactants leads to a reduction in the total mass of anthropogenic dissolved inorganic carbon (DIC) in the global ocean by about 6% at the end of the integration. Regionally, the concentrations of anthropogenic DIC in the water column (mass of DIC per unit area) are up to 10% lower in the Southern Ocean and in the northern branch of the Kuroshio when surfactants are present.

How to cite: Hu, J. and Maqueda, M.: Modelling the Impact of Surfactants on Anthropogenic CO2 Transfer between the Ocean and Atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2611, https://doi.org/10.5194/egusphere-egu24-2611, 2024.

EGU24-4102 | ECS | Orals | CL3.1.6

Comparison of marine cloud brightening in large eddy simulations 

William McFarlane Smith

Modelling of marine cloud brightening (MCB), a form of solar radiation modification, has thus far proven challenging due to the incongruous nature of the scales required. The microphysics of the cloud droplets and aerosols can only be resolved at really small scales, but just as important are the large-scale impacts on circulation and radiation. Large eddy simulations (LES) seem best placed to deal with this problem; they can resolve circulation an turbulence, but also have small enough grid boxes that useful parametrisation of microphysics can be made. When coupled to parcel models their representation of microphysical processes can be improved even further, although at a computational cost. There have been multiple studies of MCB in LES so far, but with wide-ranging background conditions and experimental designs. This leads to varying results that are challenging to compare. The aim of this study is to directly compare the results of at least two LES models, MONC and DALES, for an MCB experiment. They will first be compared with a historic data set, before being configured to ran the MCB experiment. It is hoped that MONC can also be coupled to a parcel model to improve its representation of cloud microphysics.

How to cite: Smith, W. M.: Comparison of marine cloud brightening in large eddy simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4102, https://doi.org/10.5194/egusphere-egu24-4102, 2024.

EGU24-4114 | ECS | Posters on site | CL3.1.6

Sensitivities of Marine Cloud Brightening Studied with a Lagrangian Cloud Model 

Zachary Christopher Rowland, Fabian Hoffmann, Franziska Glassmeier, Isabelle Steinke, and Herman Russchenberg

Marine cloud brightening (MCB) is a proposed climate engineering technique in which shallow liquid clouds are deliberately seeded with aerosol particles to increase their albedo and lifetime. Development of accurate models is essential to assess the feasibility of MCB; however, this is complicated by the large number of interacting microphysical processes that occur during cloud formation and the many environmental parameters that influence them. To simulate these microphysical processes in the required detail, a Lagrangian cloud model has been coupled to a simple adiabatic parcel model for this study.

Using this modelling framework, a sensitivity analysis is performed to determine the susceptibility of MCB to the aerosol particle size distribution, meteorological conditions, and several cloud microphysical choices. Attention is paid to the effect of varying the number of giant cloud condensation nuclei (GCCN) in the aerosol distribution, as these are known to enhance precipitation, with potentially deleterious effects to MCB. The results of this analysis provide insight for understanding the susceptibility of cloud formation to environmental conditions and practical considerations for any possible future MCB implementation.

How to cite: Rowland, Z. C., Hoffmann, F., Glassmeier, F., Steinke, I., and Russchenberg, H.: Sensitivities of Marine Cloud Brightening Studied with a Lagrangian Cloud Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4114, https://doi.org/10.5194/egusphere-egu24-4114, 2024.

EGU24-4373 | Orals | CL3.1.6 | Highlight

Developing an African Climate Intervention Research Coalition 

Chris Lennard, Babatunde Abiodun, and Andy Parker

With the 1.5oC global warming target set to be breached in the next decade, and as the impacts of this warming across the world become more deleterious, Climate Intervention (CI) and in particular Solar Radiation Modification (SRM) will become the subject of global political discussion. While low latitude, developing countries have the most to gain or lose from CI and SRM, they are underrepresented in current discussions, however, decisions regarding development and implementation/rejection of SRM require that these countries be at the center of such conversations.

Preparing the African voice for this discussion is essential and requires a well-resourced and well-connected African research community that understands the regional impacts of global warming and how CI may mitigate or exacerbate these impacts. While there are many SRM research projects around Africa facilitated by the DEGREES Initiative, a coordinated CI research community does not yet exist.

Here we present results from a project that aims to transition the current loose research network into a well-structured CI and SRM research coalition, nurturing an expert SRM community in Africa over the next 5-10 years.

The main component of the project is a workshop that will bring together African CI and SRM researchers alongside representatives of the World Climate Research Programme, the Coordinated Regional Downscaling Experiment (CORDEX-Africa) and International African research institutions. The workshop will discuss how to build, grow, and sustain a coalition of African SRM researchers, considering its research and capacity-building activities, its initial composition, and its structure. The workshop will also develop an initial roadmap of activities for the coalition and consider potential funding sources to support it. Furthermore, we will explore using a research hub model as a vehicle through which the coalition, its activities and growth is supported.

The insights and outcomes from these discussions will be synthesized into a white paper outlining the goals and principles of the coalition, with concrete recommendations for next steps. Key messages of the white paper will be presented in this session.

The work is pioneering and entrepreneurial and we know of no other efforts like this. In fact, we believe this would be the first continental scale SRM research coalition in the world, let alone in the Global South.

How to cite: Lennard, C., Abiodun, B., and Parker, A.: Developing an African Climate Intervention Research Coalition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4373, https://doi.org/10.5194/egusphere-egu24-4373, 2024.

EGU24-6144 | Orals | CL3.1.6

Idealized modeling of uncooperative two-actor SRM deployment 

Olivier Boucher, Anni Määttänen, Thibaut Lurton, and François Ravetta

Potential SRM deployment scenarios are increasingly discussed in the literature and an effort to construct plausible scenarios is underway in the scientific community. Such deployment scenarios underpin the design of possible governance mechanisms of SRM. A wide range of possible scenarios can be envisaged, including unilateral deployment by one actor, uncooperative multi-actor deployment, global centralized deployment or a global moratorium. In order to inform the current dialogue on governance, we explore in this work the behavior of a system where two uncooperative actors deploy SRM. We rely on a simple four-box climate model that responds to stratospheric aerosol injection (SAI) in the northern and southern hemispheres, including the oceanic response. The stratospheric aerosol optical depth has been parameterized with impulse response functions fitted on IPSL-CM6A-LR runs with injections at different latitudes. We couple this model to a control module in order to investigate different controlled SRM deployment strategies, reflecting potential governance scenarios. The two actors inject varying amounts of aerosols in the stratosphere to reach their own climate target which is unknown by the other actor. The climate target can be a temperature target (change of the temperature with respect to the initial state) or a monsoon target (variability of the monsoon index). Depending on the objectives and the characteristics of the deployment strategies by the two actors, we construct several experiments that result in i) involuntary cooperation between the two actors, ii) conflicting behaviors, or ii) one actor taking advantage of the other (free riding). We have also constructed experiments mimicking political decision-making timescales and potential perceived failure of SRM, causing more or less random interruptions of the injections. Although the scenarios are highly idealized and do not represent a realistic implementation of SRM, they help to understand the potential, synergies, risks and challenges of a decentralized, uncooperative deployment of SRM. We will discuss how the analysis of this type of experiments can inform the discussion on potential SRM governance strategies. Our future plans include adding a parametrization of the sea level rise and of ocean acidification into the model to investigate the behavior of these parameters as a result of the different SRM deployment and governance strategies. The simple model could also be used for educational purposes, for example to inform and to train decision-makers on SRM climate intervention and its effects and consequences.

How to cite: Boucher, O., Määttänen, A., Lurton, T., and Ravetta, F.: Idealized modeling of uncooperative two-actor SRM deployment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6144, https://doi.org/10.5194/egusphere-egu24-6144, 2024.

EGU24-6419 | ECS | Orals | CL3.1.6

Africa's Climate Response to Marine Cloud Brightening 

Romaric C. Odoulami, Haruki Hirasawa, Kouakou Kouadio, Trisha D. Patel, Kwesi A. Quagraine, Izidine Pinto, Temitope S. Egbebiyi, Babatunde J. Abiodun, Christopher Lennard, and Mark G. New

Climate intervention through solar radiation modification is one proposed method for reducing climate risks from anthropogenic warming. Marine Cloud Brightening (MCB), one such approach, proposes to inject sea salt aerosol into a regional marine boundary layer to increase marine clouds' reflectivity. This study assessed the potential influence of four MCB experiments on the climate in Africa using simulations from the Community Earth System Model (CESM2) with the Community Atmospheric Model (CAM6). Four idealised MCB experiments were performed with the CESM2(CAM6) model under a medium-range background forcing scenario (SSP2-4.5) by setting cloud droplet number concentrations to 600 cm-3 over three subtropical ocean regions: (a) Northeast Pacific (MCBNEP); (b) Southeast Pacific (MCBSEP); (c) Southeast Atlantic (MCBSEA); and (d) the combination of these three regions (MCBALL). The CESM2(CAM6) model reproduces the observed spatial distribution and seasonal cycle of precipitation and minimum and maximum temperatures over Africa and its climatic zones well. The results suggest that MCBSEP would induce the strongest global cooling effect and thus could be the most effective in decreasing (increasing) temperatures (precipitation) and associated extremes across most parts of the continent, especially over West Africa, in the future (2035-2054) while other regions could remain warmer or dryer compared to the historical climate (1995-2014). While the projected changes under MCBALL are similar to those of MCBSEP, MCBNEP and MCBSEA could result in more warming and, in some regions of Africa, create a warmer future than under SSP2-4.5. Also, all MCB experiments are more effective in cooling maximum temperature and related extremes than minimum temperature and related extremes. These findings further suggest that the climate impacts of MCB in Africa are highly sensitive to the deployment region.

How to cite: Odoulami, R. C., Hirasawa, H., Kouadio, K., Patel, T. D., Quagraine, K. A., Pinto, I., Egbebiyi, T. S., Abiodun, B. J., Lennard, C., and New, M. G.: Africa's Climate Response to Marine Cloud Brightening, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6419, https://doi.org/10.5194/egusphere-egu24-6419, 2024.

EGU24-7071 | Orals | CL3.1.6

Multi-model simulation of solar geoengineering indicates avoidable destabilization of the West Antarctic ice sheet 

John Moore, Yangxin Chen, Chao Yue, Svetlana Jevrejeva, Dan Visioni, Petteri Uotilla, and Liyun Zhao

Heat transported in Circumpolar Deep Water is driving the break-up of ice shelves in the Amundsen Sea sector of Antarctica, that has been simulated to be unavoidable under all plausible greenhouse gas scenarios. However, climate intervention scenarios have not been considered. Solar geoengineering changes global thermal radiative balance, and atmospheric and oceanic transportation pathways. We simulate stratospheric aerosol injection (SAI) designed to reduce global mean temperatures from those under the unmitigated SSP5-8.5 scenario to those under the SSP2-4.5 scenario with six CMIP6-class Earth System Models. These consistently show intensified Antarctic polar vortex and sub-polar westerlies, which mitigates changes to easterly winds along the Amundsen Sea continental shelf compared with greenhouse gas scenarios. The models show significantly cooler Amundsen Sea waters and lower heat content at 300-600 m under SAI than with either solar dimming or the SSP5-8.5 unmitigated greenhouse gas scenarios. However, the heat content increases under all scenarios compared with present day suggesting that although vulnerable ice shelves would continue to thin, the rate would be lower for SAI even with SSP5-8.5 specified greenhouse gases, than for the moderate (SSP2-4.5) scenario. The simulations here use climate interventions designed for global temperature targets; interventions targeted at preserving the frozen high latitudes have also been proposed that might be expected to produce bigger local effects, but potentially deleterious impacts elsewhere. Considering the huge disruptions to society of ice sheet collapse, more research on avoiding them by intervention technology is a moral imperative. 

How to cite: Moore, J., Chen, Y., Yue, C., Jevrejeva, S., Visioni, D., Uotilla, P., and Zhao, L.: Multi-model simulation of solar geoengineering indicates avoidable destabilization of the West Antarctic ice sheet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7071, https://doi.org/10.5194/egusphere-egu24-7071, 2024.

EGU24-7258 | ECS | Orals | CL3.1.6

Exploring the impacts of changes in solar radiation on ecohydrological variables 

Yiran Wang, Naika Meili, and Simone Fatichi

Several geoengineering projects are designed to modify solar radiation to limit global warming. These changes in solar radiation can have impacts on ecohydrological systems which are poorly quantified. In this study, CMIP6 outputs were used to calculate sensitivities of global and local near-surface meteorological variables to solar radiation changes. These sensitivities were applied to the currently observed climate to perturb meteorological variables in response to changes in solar radiation. These new conditions were used as inputs to a mechanistic ecohydrological model (T&C) to analyze the partitioning and changes in energy and water fluxes and the response of vegetation productivity in different biomes and climates. Specifically, we run two simulation scenarios to understand the solar radiation impacts on ecohydrological systems. The first scenario focuses only on changes in solar radiation, while the second scenario considers the combined effects of solar radiation changes and its climate feedback. The results show that, in the absence of climate feedback, changes in solar radiation are mainly reflected in changes in sensible heat, with less impact on the hydrological cycle, and vegetation productivity is positively and linearly correlated with changes in solar radiation. When climate feedback is included, the effects on latent heat and hydrologic variables are more pronounced, and the response of vegetation productivity to negative and positive solar radiation changes tend to be asymmetric. These results provide a basis for how land-surface processes could respond to regional brightening and dimming and future solar geoengineering programs.

How to cite: Wang, Y., Meili, N., and Fatichi, S.: Exploring the impacts of changes in solar radiation on ecohydrological variables, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7258, https://doi.org/10.5194/egusphere-egu24-7258, 2024.

EGU24-8269 | ECS | Orals | CL3.1.6

 Evaluation of Some Atmospheric Transmittance Indices Over Nigeria 

Oluwatosin Obasi-oma, Israel Emmanuel, Olushola Ojo, and Babatunde Adeyemi

Atmospheric transmittance, encompassing parameters such as the clearness index, cloudiness index, and transmitting index, plays a pivotal role in the transfer of electromagnetic energy in the atmosphere. This research aimed to enhance our understanding of solar energy availability by investigating these transmittance indices across specific locations in Nigeria's diverse climatic zones. By analyzing satellite hourly data from MERRA-2 spanning ten years, the diurnal and spatial distribution patterns of solar radiation parameters and transmittance indices were examined. The research identified distinct patterns in the radiation parameters and transmittance indices. In the morning hours, radiation parameters exhibited an increasing trend from coastal to inland locations, while the afternoon period showed a reverse pattern for diffuse solar radiation. Clearness and transmitting coefficient demonstrated consistent increases from the coast inland during both morning and afternoon hours, whereas the cloudiness index displayed an opposite pattern. Moreover, the transmittance indices showed a gradual reduction from west to east during the evening. Coastal regions experienced average annual values of 100W/m2 for diffuse solar radiation, 1443W/m2 for direct solar radiation, and 500W/m2 for global solar radiation, while Sahelian regions recorded 104W/m2, 2081W/m2, and 678W/m2, respectively. The clearness index ranged from 0.35 to 0.54, the cloudiness index ranged from 0.15 to 0.46, and the transmitting coefficient ranged from 0.19 to 0.45 across the studied locations. The observed distribution patterns provide valuable insights into solar energy availability within Nigeria's climatic zones. The contrasting patterns between morning and afternoon periods suggest variations in atmospheric conditions. Importantly, the study emphasizes the significance of the transmitting coefficient in characterizing atmospheric transmittance and its role in defining radiation transfer variables. In conclusion, this research contributes to existing knowledge by evaluating atmospheric transmittance indices and their distribution patterns in specific locations across Nigeria. The findings underscore the importance of considering the transmitting coefficient alongside other parameters to accurately assess solar energy availability. Understanding these indices and their variations is essential for the effective utilization and management of solar energy resources.

How to cite: Obasi-oma, O., Emmanuel, I., Ojo, O., and Adeyemi, B.:  Evaluation of Some Atmospheric Transmittance Indices Over Nigeria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8269, https://doi.org/10.5194/egusphere-egu24-8269, 2024.

In this study, we present a series of systematic AIDA cloud chamber experiments investigating the cloud microphysics governing cirrus cloud thinning effectiveness (i.e., the competition between heterogeneous and homogeneous ice nucleation) at temperatures below 230 K. Parcel model simulations based on our experimental studies show that the total ice crystal concentrations are very sensitive to the complex interplay between background aerosol, seeding and updraft velocities. We find regimes of successful cirrus thinning, as well as regimes resulting in thicker cirrus (overseeding). In addition, we also find that updraft fluctuations potentially play a critical role in influencing cirrus cloud thinning effectiveness.

How to cite: Steinke, I., Schorr, T., and Leisner, T.: Using cloud chamber experiments and numerical simulations to investigate the complexities of cirrus cloud thinning effectiveness, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9732, https://doi.org/10.5194/egusphere-egu24-9732, 2024.

EGU24-10285 | ECS | Orals | CL3.1.6

Assessing GFDL-ESM4.1 Climate Responses to CESM2-WACCM6 Geoengineering Forcing for 2.0°C Warming Target 

Shipeng Zhang, Vaishali Naik, David Paynter, Simone Tilmes, and Jasmin John

In this work we apply GFDL Earth System Model (GFDL-ESM4.1) to explore the climate responses to a geoengineering scenario that aims to restrict global warming to 2.0°C above pre-industrial levels (1850–1900) under the CMIP6 overshoot scenario (SSP534-OS) . Simulations of this geoengineering scenario with the CESM Whole Atmosphere Community Climate Model (CESM2-WACCM6) showed nearly unchanged interhemispheric and pole-to-Equator surface temperature gradients relative to present-day conditions around 2020, and reduced global impacts, such as heatwaves, sea ice melting, and large shifts in precipitation patterns (Tilmes et al 2020). Here we implement the identical stratospheric forcing in the GFDL-ESM4.1 model and find excessive global surface cooling and reduced precipitation responses, compared to those projected in CESM2-WACCM. Notably, the Southern Hemisphere experiences more substantial cooling compared to the Northern Hemisphere, accompanied by a north-ward shift in the Intertropical Convergence Zone (ITCZ). These distinct climate responses between GFDL-ESM4.1 and CESM2-WACCM6 can be traced back to their different climate feedback parameters. Furthermore, our analysis reveals that spatially heterogeneous forcing within the geoengineering scenario results in diverse climate feedback parameters even just in one model, through varying surface warming and cooling patterns. This research highlights the importance of considering model structure uncertainties and spatial forcing patterns for a comprehensive evaluation of future scenarios and geoengineering strategies.

How to cite: Zhang, S., Naik, V., Paynter, D., Tilmes, S., and John, J.: Assessing GFDL-ESM4.1 Climate Responses to CESM2-WACCM6 Geoengineering Forcing for 2.0°C Warming Target, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10285, https://doi.org/10.5194/egusphere-egu24-10285, 2024.

EGU24-12943 | Orals | CL3.1.6

Links between boreal forest and clouds inferred from long-term atmospheric observations 

Ekaterina Ezhova, Aino Aarne, Antti Arola, Antti Liponen, Anna Lintunen, Taina Yli-Juuti, Jaana Bäck, Harri Kokkola, Veli-Matti Kerminen, Tuukka Petäjä, Annele Virtanen, and Markku Kulmala

Clouds play a vital role in the Earth's radiation budget, with low-level clouds having a net cooling effect. Evidence shows that forests alter low-level clouds' formation and physical properties (e.g., [1-3]). In their turn, clouds modify radiation transfer, influencing near-surface variables and forest carbon uptake. Shallow cumulus clouds can enhance photosynthesis due to the diffuse fertilization effect, and the relative increase in photosynthesis is most significant in boreal forests compared to other ecosystems [4]. All this evidence suggests a strong atmosphere-biosphere link for boreal forests. 

We use long-term observations at SMEAR II station in Finland and satellite data sets to study how air mass transformation over boreal forests changes the optical properties of low-level clouds. Further, we assess the dynamics of photosynthesis and net ecosystem exchange in response to changing cloud properties and near-surface variables under different low-level clouds. We show that stratus clouds dampen photosynthesis, and the effect is amplified with the time spent by an air mass over a forest. Oppositely, cumulus clouds enhance photosynthesis compared to the clear sky conditions. If an air mass is exposed to the boreal forest for several days, and cumulus clouds form during the daytime, photosynthesis is efficient, and clouds' transmittance somewhat decreases. Our results suggest that shallow cumulus clouds formed in an air mass interacting with boreal forest can become more reflective. At the same time, these clouds provide ideal conditions for enhanced boreal forest carbon uptake.

References

[1] Teuling, A. J., Taylor, C. M., Meirink, J. F., Melsen, L. A., Miralles, D. G., van Heerwaarden, C. C., Vautard, R., Stegehuis, A. I., Nabuurs, G.-J., and de Arellano, J. V.-G.: Observational evidence for cloud cover enhancement over western European forests, Nat. Commun., 8, 14065, 2017. 

[2] Yli-Juuti, T., Mielonen, T., Heikkinen, L., Arola, A., Ehn, M., Isokääntä, S., Keskinen, H.-M., Kulmala, M., Laakso, A., Lipponen, A., Luoma, K., Mikkonen, S., Nieminen, T., Paasonen, P., Petäjä, T., Romakkaniemi, S., Tonttila, J., Kokkola, H., and Virtanen, A.: Significance of the organic aerosol driven climate feedback in the boreal area, Nat. Commun., 12, 5637,  2021. 

[3] Petäjä, T., Tabakova, K., Manninen, A., Ezhova, E., O'Connor, E., Moisseev, D., Sinclair, V. A., Backman, J., Levula, J., Luoma, K., Virkkula, A., Paramonov, M., Räty, M., Äijälä, M., Heikkinen, L., Ehn, M., Sipilä, M., Yli-Juuti, T., Virtanen, A., Ritsche, M., Hickmon, N., Pulik, G., Rosenfeld, D., Worsnop, D. R., Bäck, J., Kulmala, M., and Kerminen, V.-M.: Influence of biogenic emissions from boreal forests on aerosol–cloud interactions, Nat. Geosci., 15, 42–47,  2022. 

[4] Zhou, H., Yue, X., Lei, Y., Zhang, T., Tian, C., Ma, Y., & Cao, Y.: Responses of gross primary productivity to diffuse radiation at global FLUXNET sites. Atmospheric Environment, 244, 117905, 2021.

How to cite: Ezhova, E., Aarne, A., Arola, A., Liponen, A., Lintunen, A., Yli-Juuti, T., Bäck, J., Kokkola, H., Kerminen, V.-M., Petäjä, T., Virtanen, A., and Kulmala, M.: Links between boreal forest and clouds inferred from long-term atmospheric observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12943, https://doi.org/10.5194/egusphere-egu24-12943, 2024.

EGU24-15670 | Posters on site | CL3.1.6

Hydro-meteorological and Agricultural drought assessment under Solar Radiation Modification over the Niger river basin in West Africa 

Amadou Coulibaly, Abdoulaye Ballo, Komlavi Akpoti, and Windmanagda Sawadogo and the Amadou Coulibaly1*

West African countries are vulnerable to the adverse impacts of climate extremes such as drought which are becoming more frequent and more intense over the past decades. However, drought characterization and its associated drivers are not well understood in the region. In this study, we will investigate the implication of Solar Radiation Modification (SRM) in Hydro-meteorological and Agricultural drought over the Niger River Basin, as well as their larger-scale atmospheric and ocean-atmosphere drivers. The impacts of SRM on these aspects of drought will be assessed using ARISE/GeoMIP Global Climate Model (GCM) data. The study will use three drought indices: Standardized Precipitation Evapotranspiration Index (SPEI) over each grid point for each dataset for 1 month, 3 months, 6 months and 12 months. Precipitation Concentration Index (PCI) employed as an indicator of rainfall concentration for annual and seasonal scales (wet and dry seasons). Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP) to measure the rainfall distribution and the peak rainfall date, based on the daily or monthly total precipitation. Standardized runoff index (SRI) and standardized soil moisture index (SSWI). The Soil and Water Assessment Tool (SWAT) will be used to assess the current and future water balance in the basin and to estimate the features of meteorological, hydrological and agricultural droughts. The model with be driven by a statistically downscaled of the SRM climate model data. In the Preliminary results, models reproduce the near normal drought for each type of drought over the basin. The ssp585 shows less dry condition in the far future over the basin. The model intervention reduces the gap and has serious implications for future management of droughts over the basins. This is an ongoing study. The results of this research will provide valuable insights to stakeholders in the region on the regional impacts of a global climate mitigation solution such as SRM on key socio-economic climate hazards. Details results from the study will be presented in oral at the workshop. The results will enable much better-informed contributions from African policymakers in the UNFCCC and other fora where the pros and cons of geoengineering of climate in general, and SRM in particular, are being debated.

How to cite: Coulibaly, A., Ballo, A., Akpoti, K., and Sawadogo, W. and the Amadou Coulibaly1*: Hydro-meteorological and Agricultural drought assessment under Solar Radiation Modification over the Niger river basin in West Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15670, https://doi.org/10.5194/egusphere-egu24-15670, 2024.

EGU24-15763 | ECS | Orals | CL3.1.6 | Highlight

Could planetary scale solar radiation management prevent a West Antarctic Ice Sheet collapse?  

Johannes Sutter, Thomas Frölicher, Anthony Jones, Christian Wirths, and Thomas Stocker

Solar radiation modification (SRM) is increasingly discussed as a tool to reduce or avert global warming and concomitantly the risk of ice-sheet collapse, as is considered possible for the West Antarctic Ice Sheet (WAIS). While there is a growing body of literature on the climate impacts of various hypothetical SRM employment schemes, the concomitant effects on ice sheet dynamics are much less studied let alone understood. We present the first study explicitly modelling the Antarctic Ice Sheet response to global SRM-interventions with a continental scale ice sheet model. Intuitively, the question whether a WAIS collapse can be prevented depends on a manifold of factors such as ice sheet sensitivity, timing and design of the SRM-intervention and underlying climate scenarios. Our study suggests that safeguarding the WAIS from long-term collapse would either require rapid decarbonization efforts or quasi-immediate SRM-interventions. Both cases are either politically unrealistic or imprudent considering the precautionary principle. We discuss the response of the Antarctic Ice Sheet under various climate and SRM scenarios and the associated uncertainties which need to be resolved to get a more conclusive understanding on the impact of SRM-geoengineering strategies on earth’s two remaining large ice sheets. 

How to cite: Sutter, J., Frölicher, T., Jones, A., Wirths, C., and Stocker, T.: Could planetary scale solar radiation management prevent a West Antarctic Ice Sheet collapse? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15763, https://doi.org/10.5194/egusphere-egu24-15763, 2024.

EGU24-15841 | ECS | Orals | CL3.1.6

Analysing the impact of solar radiation management on the terrestrial biosphere in CMIP6 models 

Isobel Parry, Paul Ritchie, and Peter Cox

Solar radiation management (SRM) has the potential to artificially cool the Earth by increasing the reflection of incoming sunlight. One commonly researched SRM strategy is stratospheric aerosol injection (SAI), which involves the injection of sulphate aerosols into the stratosphere that scatter incoming solar radiation, thus cooling the planet. There are large uncertainties in the potential impact that solar radiation management could have on the biosphere, and further work is required to improve our understanding of the risks associated with this form of climate intervention. This presentation examines the impact of SRM on vegetation carbon, net primary productivity, and land carbon. We take results from five 6th generation climate models (CMIP6) which ran experiments as part of the geoengineering model intercomparison project (GeoMIP) and compare them with a high emissions scenario (ssp585). The GeoMIP experiments aim to investigate the global effects of using stratospheric aerosol injections and directly decreasing solar irradiance to reduce global temperatures to a ‘middle of the road’ scenario (ssp245), but without reducing the high greenhouse gas concentrations. Compared to ssp585, we find that ssp585 plus SRM tends to increases global NPP and land carbon storage. The global patterns of change in vegetation carbon storage vary between the ESMs, but there is a widespread agreement that SRM would have a positive impact on carbon storage and NPP  in the Amazon rainforest.

How to cite: Parry, I., Ritchie, P., and Cox, P.: Analysing the impact of solar radiation management on the terrestrial biosphere in CMIP6 models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15841, https://doi.org/10.5194/egusphere-egu24-15841, 2024.

EGU24-18905 | Orals | CL3.1.6

Solid particle SAI with a fully coupled atmosphere-ocean-aerosol-chemistry-climate model SOCOLv4.0 

Timofei Sukhodolov, Sandro Vattioni, Fabrice Stefanetti, Iris Schuring, Jan Sedlacek, and Gabriel Chiodo

Solid particles, such as alumina, calcite, and diamond, have been proposed as an alternative material for the stratospheric aerosol injection (SAI) studies. The traditional SAI set-up based on sulphate aerosols was shown to have several limitations such as stratospheric heating, due to absorption of long wave radiation, or ozone depletion, due to chlorine activation at the particle surfaces. Solid particles are thought to potentially overcome these limitations by having better optical properties and/or larger chemical inertness. In our work, we use for the first time a fully coupled atmosphere-ocean-aerosol-chemistry-climate model SOCOLv4.0, which incorporates a solid particle emission scheme, to assess the SAI effects of the alumina, calcite, and diamond. For each solid particle type, we followed the GeoMIP protocols and performed G4 and G6 experiments, which are cooling efficiency calibration runs and the transient ensemble runs to bring decadal surface temperatures of the SSP5 scenario to the ones from the SSP2 scenario, respectively. For all considered SAI substances, we find that the resulting burden is close to the yearly emission quantity, suggesting an average lifetime of approximately one year. Diamond has the highest burden-per-emission ratio, suggesting a higher lifetime, which is explained by its small particle radius. Sulfur, alumina, and calcite provide very similar cooling per emission, while diamond has a cooling efficiency of about a factor of three higher. Diamond also has the lowest absorption in the long wave, which allows it to show the weakest heating of the lower stratosphere, no increase in the stratospheric water vapour, and smallest dynamical effects on ozone. In terms of surface climate artifacts, those species that show the weakest heating in the stratosphere (calcite and diamond) also show the least anomalies in atmospheric and oceanic circulation patterns compared to the SSP2 scenario. Information on the interaction between alumina, calcite and ozone-relevant chemical cycles is available, but has not been sufficient so far for implementing their ozone chemistry with high confidence in the results. Additional laboratory studies, thus, are required for further modelling research on this subject.

How to cite: Sukhodolov, T., Vattioni, S., Stefanetti, F., Schuring, I., Sedlacek, J., and Chiodo, G.: Solid particle SAI with a fully coupled atmosphere-ocean-aerosol-chemistry-climate model SOCOLv4.0, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18905, https://doi.org/10.5194/egusphere-egu24-18905, 2024.

A proposed method to aid in mitigating global climate change is stratospheric aerosol injection (SAI). Recent work on SAI has shown its ability to reverse some of the changes induced by global warming, if employed properly. Still, many uncertainties on the effects of SAI exist. It is unclear if we can reverse the same amount of change with delayed SAI at high resolution, to be defined as 0.25 degree atmosphere or finer. A method is introduced that produces the needed atmospheric forcing for the atmospheric model component, which has a lower model top than more generally used in SAI studies. This method is based on existing data from the Geoengineering Large Ensemble Project (GLENS), and allows us to run high-resolution experiments. In this study, we further investigate atmospheric circulation changes using the Community Earth System Model (CESM), with a focus on Antarctica.

How to cite: de Jong, J.: Atmospheric circulation changes due to delayed stratospheric aerosol injection in high-res CESM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19933, https://doi.org/10.5194/egusphere-egu24-19933, 2024.

EGU24-20697 | Orals | CL3.1.6

Diffuse radiation characterized gross primary production over the globe 

Mingjie Shi and Tirthankar Chakraborty

Diffuse radiation, which is modulated by cloud and aerosol conditions, can have varied impacts on gross primary production (GPP), with the specific impacts depending on vegetation density, environmental conditions, and the specific physiological characteristics of plants. To quantify the sensitivity of GPP variation to changes in diffuse radiation at the global scale, we use several reanalysis datasets and a satellite-derived products with distinct characterizations of the division between direct beam and diffuse radiation, to force the Energy Exascale Earth System Model Land Model (herein ELM). We find large variations in the range of GPP due to the change in ratio of diffuse radiation to the total downward shortwave radiation (or diffuse fraction). The research implies substantial control of diffuse radiation on atmosphere–biosphere interaction, and demonstrates the importance of thoroughly and systematically validating the simulated diffuse radiation by atmosphere modules, along with assessing the ecosystem responses to the diffuse radiation variations within global land models.

How to cite: Shi, M. and Chakraborty, T.: Diffuse radiation characterized gross primary production over the globe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20697, https://doi.org/10.5194/egusphere-egu24-20697, 2024.

EGU24-20960 | Orals | CL3.1.6

Tropical Cyclone-related Extreme Rainfall and Its Impact under Solar Radiation Management (SRM) in Eastern Indonesia Region  

Sorja Koesuma, Akhmad Faqih, Hendri Hendri, Jassica Listyarini, Adinda Madi Astiani, Delfina Azzahra Kusuma, and Rahmat Gernowo

The provinces of East Nusa Tenggara (NTT) and Papua are located in the eastern part of Indonesia. The occurrence of tropical cyclones and extreme weather events has recently increased in both regions. It is necessary to be aware of the impact, both direct and indirect, of tropical cyclones, which affect the weather, especially extreme rainfall. The study aims to investigate the impact of extreme rainfall and find potential solutions.

We use some of the following tropical cyclone data that happened in Indonesia. The tropical cyclone of Seroja on April 4, 2021, reached mainland NTT and had a significant impact, especially on Timor Island and Sumba Island. The tropical cyclone of Surigae was formed in the northern region of Papua on April 12-19, 2021. The peak of this cyclone was on 16 April 2021. The tropical cyclone of Ray formed around the Northwest/Western Pacific Ocean on December 13-20, 2021.

We analysed the atmospheric dynamics (rainfall) of the tropical cyclone events using the ERA5 model. We also use Bias correction from GeoMIP to analyse the rainfall and compare both results. The result shows that both data are well correlated and tend to decrease.

How to cite: Koesuma, S., Faqih, A., Hendri, H., Listyarini, J., Madi Astiani, A., Azzahra Kusuma, D., and Gernowo, R.: Tropical Cyclone-related Extreme Rainfall and Its Impact under Solar Radiation Management (SRM) in Eastern Indonesia Region , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20960, https://doi.org/10.5194/egusphere-egu24-20960, 2024.

BG2 – Methods in Biogeosciences

EGU24-305 | ECS | Posters on site | BG2.1

Using triple oxygen measurements of lacustrine carbonates to constrain the Miocene topography of the Dinaric Alps 

Gabriela Sanchez Ortiz, Marlene Löberbauer, Payal Banerjee, Nevena Tomašević, Oleg Mandic, Davor Pavelić, Vedad Demir, Zachary Sharp, Maud Meijers, and Jeremy Rugenstein

The Dinaric Alps formed as a result of the collision between the Adria microplate with Eurasia during ongoing closure of the Tethys Ocean. However, there remain a number of questions regarding the mechanisms that created and sustained the high topography (maximum modern elevation of ~2500 m) of this region. We take advantage of a series of lacustrine basins—known as the Dinaride Lake System (DLS)—that formed in the Early and Middle Miocene to constrain paleo-elevations of the Dinaric Alps using stable isotope paleoaltimetry. We collected authigenic lacustrine carbonate samples from six basins in Croatia and Bosnia and Herzegovina that span the range from sea-level to high-elevation (~1200 m) and measured these samples for δ18O. In addition, we also collected stream samples that span the range to constrain the modern change in δ18O across the Dinaric Alps. Stable-isotope paleoaltimetry is based on the concept that, as moist air parcels are forced upwards by orography, 18O is preferentially removed by the resulting precipitation, resulting in lower δ18O at higher-elevations and in the lee of ranges. Today, meteoric water δ18O is high (~ -6‰) at the coast and is ~5‰ lower at the crest of the range (~ -11‰). However, Middle Miocene lacustrine carbonate δ18O is high (~ -3‰) at the crest of the range and lower (~ -6‰) at the coast. Because lacustrine carbonate δ18O is frequently impacted by evaporation, we analyzed a subset of our samples for Δ17O, which is sensitive to the degree of evaporation. These carbonates have Δ17O values ranging from -68 to -150 per meg. Using our Δ17O data and a model of lake evaporation, we reconstruct the unevaporated meteoric water δ18O. Our preliminary results show a similar trend as in the modern, with higher δ18O values at the coast and lower δ18O at the crest of the range. Reconstructed unevaporated meteoric water δ18O at the crest is lower by 2-5‰ than modern water δ18O at the crest of the Dinaric Alps. That unevaporated meteoric water δ18O might have been lower than today at the crest of the range suggest that the Dinaric Alps were higher in the Middle Miocene that today, assuming that coastal meteoric water δ18O was similar to today. Thus, ongoing extension within the Dinaric Alps due to slab rollback may be responsible for lowering of topography.

How to cite: Sanchez Ortiz, G., Löberbauer, M., Banerjee, P., Tomašević, N., Mandic, O., Pavelić, D., Demir, V., Sharp, Z., Meijers, M., and Rugenstein, J.: Using triple oxygen measurements of lacustrine carbonates to constrain the Miocene topography of the Dinaric Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-305, https://doi.org/10.5194/egusphere-egu24-305, 2024.

EGU24-537 | ECS | Posters on site | BG2.1

Investigating the impact of diet on the stable isotope composition of human scalp hair and fingernails 

Gunjan Agrawal and Prasanta Sanyal

Diet-related diseases such as nutritional stress, malnutrition and eating disorders resulting from an unhealthy diet contribute to various health issues, which in some cases may be life-threatening. An accurate diet reconstruction is thus crucial for individuals at risk due to dietary concerns. The principle of diet reconstruction is rooted in the proverb ‘you are what you eat’, and an individual’s diet is the sole source of nitrogen and carbon in their body. The stable isotope composition of nitrogen (δ15N) and carbon (δ13C) can serve as a tool to recognise dietary patterns and identify health conditions. However, the variations in the values of δ15N and δ13C isotopes can imply either dietary changes or disorders associated with diet, making it challenging to ascertain the precise cause of such variations. This study aimed to establish the relationship between the isotopic composition of human tissues, specifically scalp hair and fingernails, and diet. Samples of human tissues were collected from 100 healthy participants within a 15-day period, with 74 of them providing comprehensive diet records. The participants resided in a controlled environment, a remote residential campus with limited food options and restricted access to external food sources. This controlled setting ensured that the isotopic composition of the collected samples solely reflected the impact of diet, eliminating the influence of environmental factors and dietary disorders on the isotopic composition. All the dietary sources and sixty-six food items available to the participants were considered and analysed, respectively, to determine the percentage of animal protein in their diet. This was correlated with the δ15N and δ13C values of human tissues to quantify the proportion of animal protein in diet using linear equations. The variations in the δ15N and δ13C values of human tissues resulting from dietary changes were calculated and distinguished from those caused by dietary disorders. The study results demonstrated that the amount and type of food consumed impact the δ15N and δ13C values of human tissues. An increase in animal protein intake was associated with an increase in the dual isotopic composition. Notably, the nitrogen isotope values of human tissues differed by 0.9‰ between lacto-vegetarians and omnivores. The study further revealed that a 5% dietary change resulted in fluctuation of 0.4 - 0.5‰ in both δ15N and δ13C isotope ratios. This was compared to changes caused by dietary disorders in δ15N and δ13C values of human scalp hair. These findings help in determining whether the variations in δ15N and δ13C values of human tissues result from increased animal protein intake or serve as indicators of dietary disorders.

How to cite: Agrawal, G. and Sanyal, P.: Investigating the impact of diet on the stable isotope composition of human scalp hair and fingernails, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-537, https://doi.org/10.5194/egusphere-egu24-537, 2024.

EGU24-1377 | ECS | Posters on site | BG2.1 | Highlight

Zinc Isotope Study of Baseline Occurrence Patterns and Potential Contamination of Sediments from the Great Lakes Basin 

Tassiane Junqueira, Daniel Ferreira-Araújo, and Bas Vriens

The Laurentian Great Lakes are a globally unique freshwater resource, playing a pivotal role in public water supply and agriculture, transportation, hydroelectric power, and ecosystem functioning. However, the Great Lakes also have a long history of metal contamination, especially in so-called Areas-of-Concern near urban areas and industrial sites. One major anthropogenic contaminant in the Great Lakes is Zn, derived from point-sources such as metal mining, smelting, and chemical industries, as well as diffuse sources such as fertilizer application or urban runoff, in addition to natural inputs from atmospheric deposition and natural weathering. Disentangling the importance of these geogenic versus anthropogenic sources and processes is critical to improving our understanding of the cycling and environmental fate of Zn in the Great Lakes region.

We examined spatiotemporal variations in Zn concentrations and isotopic compositions, as well as bulk physicochemical and mineralogical properties, of a total of 72 surface sediments and sediment core samples across nearshore-to-offshore gradients and depositional environments with distinct limnological conditions spanning >50 years.

Our results reveal spatial variations in both Zn concentrations (18 to 580 mg/kg) and isotopic compositions across oligotrophic (Lake Huron) to mesotrophic (Lake Erie) environments. Interestingly, the intra-lake heterogeneity is comparable to or higher than the variability observed at the inter-lake (basin-scale) level, with no upstream-to-downstream accumulation being evident. The isotopic signatures of surface sediment, measured as δ66Zn and ranging from -0.09‰ to +0.41‰, suggest a predominantly geogenic source for Zn. Furthermore, an examination of temporal trends in sediment cores from Lake Huron and Lake Erie indicates consistent metal concentrations and Zn isotopic signatures, implying minimal biogeochemical fractionation within the lakes themselves. Across all sediments and both lakes, metal concentrations and isotopes are positively but not very strongly (R2<0.49 overall) correlated to TOC, TN, and TP, but not to chlorophyll a.

In summary, our findings indicate that sedimentation plays a crucial role as a repository for metals in the Great Lakes, exerting significant influence on the distribution patterns of metals throughout the basin. Furthermore, the higher levels of metals at locations with historical contamination remain spatially constrained and do not seem to disrupt the interconnected system of the Great Lakes.

How to cite: Junqueira, T., Ferreira-Araújo, D., and Vriens, B.: Zinc Isotope Study of Baseline Occurrence Patterns and Potential Contamination of Sediments from the Great Lakes Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1377, https://doi.org/10.5194/egusphere-egu24-1377, 2024.

Formate is energetically equivalent to hydrogen and thus, is an important intermediate during the breakdown of organic matter in anoxic rice field soils and lake sediments. Formate is a common substrate for methanogenesis, homoacetogenesis and sulfate reduction. However, how much these processes contribute to formate degradation and fractionate carbon stable isotopes is largely unknown. Therefore, we measured the conversion of formate to acetate, CH4 and CO2 and the δ13C of these compounds in samples of paddy soils from Vercelli (Italy) and the International Rice Research Institute (IRRI, the Philippines) and of sediments from the NE and SW basins of Lake Fuchskuhle (Germany). The samples were suspended in phosphate buffer (pH 7.0) both in the absence and presence of sulfate (gypsum) and of methyl fluoride (CH3F), an inhibitor of aceticlastic methanogenesis. In the paddy soils, formate was found to be an excellent substrate for acetate formation, while CH4 was mainly produced from acetate. Acetate was also produced in the presence of sulfate. The produced acetate was strongly depleted in 13C relative to formate (about -50‰ to-25‰), but the consumption of formate itself displayed only a small isotope enrichment factor on the order of -8‰ to -6‰. Therefore, it is likely that formate was disproportionated to 13C-depleted acetate and 13C-enriched CO2. The δ13C of CO2 was indeed slightly higher than that of formate. Acetate was most likely produced by homoacetogenesis via the Wood-Ljungdahl pathway. Methane was only a minor product and was mainly produced from the acetate as its production was inhibited by CH3F. The homoactogenic bacteria in the paddy soils apparently competed well with both methanogenic and sulfate-reducing microorganisms, when formate was the substrate. In the lake sediments, the product spectrum was similar, but only under methanogenic conditions. In the presence of sulfate, however, acetate and CH4 were only minor products and no enrichment factor was detectable when formate was degraded to mainly CO2. Hence, homoacetogenesis was the major anaerobic degradation pathway of formate. Formate-dependent methanogenesis was negligible, and sulfate-dependent oxidation was only operative in the lake sediments but not in the paddy soils.

How to cite: Conrad, R. and Claus, P.: Formate consumption and stable carbon isotope fractionation in anoxic rice field soils and lake sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2895, https://doi.org/10.5194/egusphere-egu24-2895, 2024.

EGU24-3580 | ECS | Posters on site | BG2.1 | Highlight

Temporal and spatial investigations of the isotope biogeochemistry of a coastal peatland area under sporadic flooding  

Rhodelyn Saban, Anna-Kathrina Jenner, Catia Milene Ehlert von Ahn, Iris Schmiedinger, and Michael Böttcher

The interface between the terrestrial and marine environments regulates the interactions between the adjoining domains. Natural and anthropogenic alterations influence the processes and exchanges of materials. This study aims to determine the biogeochemical processes before and after anthropogenic changes in the coastal protection at the southern Baltic Sea coast proximal to a peatland (Hütelmoor, Rostock, Germany). Spatial and temporal investigations, with the use of stationary porewater lances, characterize the dynamics of biogeochemical transformation processes. Porewaters were measured for in-situ physico-chemical parameters and analyzed for dissolved organic and inorganic carbon (DOC and DIC), major ions, redox-sensitive elements and nutrients concentrations. Stable isotopes (ẟ13C-DIC and -DOC, ẟ2H- and ẟ18O-H2O, and ẟ34S- and ẟ18O-SO4, and ẟ34S-H2S) and non-stable isotopes (223Ra, 224Ra) were also measured. Results indicate high concentrations of DOC which may have originated from peat degradation and high concentrations of DIC, which may have been derived from organic matter mineralization, terrestrial and marine carbonate dissolution, and Baltic Sea-derived DIC. Minor contributions from CH4 oxidation cannot be ruled out. Diagenetic transformations are also reflected in the vertical profiles of redox-sensitive ions (such as Fe, Mn, SO4 and H2S). Sulfate, dominantly from Baltic Sea water and microbial reduction-oxidation, influences diagenesis. Water is a mixture of different brackish and freshwater sources.  Moreover, submarine groundwater discharge (SGD) was observed from 150 cmbsf and also evident in 224Ra activities. With the changes in the coastal protection status, internal transport processes of porewaters in the sediment are evidently influenced by the hydrogeodynamics along the coastline on a local to regional scale.

How to cite: Saban, R., Jenner, A.-K., Ehlert von Ahn, C. M., Schmiedinger, I., and Böttcher, M.: Temporal and spatial investigations of the isotope biogeochemistry of a coastal peatland area under sporadic flooding , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3580, https://doi.org/10.5194/egusphere-egu24-3580, 2024.

EGU24-3596 | Orals | BG2.1 | Highlight

Measuring δ17O and Δ′17O in precipitation across various spatial and temporal scales: spanning from global to local and from multi-year to sub-hourly resolutions 

Stefan Terzer-Wassmuth, Luis Araguas-Araguas, Leonard I. Wassenaar, Lucilena R. Monteiro, and Christine Stumpp

During the past decade, the rare O isotope 17O and the 17O-excess became attractive for potential new applications in hydrology, climatology, and broader oxygen isotope research. Although laser-based analysers are technologically capable of the needed Δ′17O assays, progress was hindered by the metrological challenges and the absence of fundamental spatiotemporal data on precipitation inputs. Uncertainties surrounding the input function of the water cycle complicate advancements of 17O as a tracer. This “emerging tracer dilemma” is a potential obstacle for further triple-O isotope research.

In this work, >3500 archived water samples from the Global Network of Precipitation (GNIP) sample archives (2015-2021) were re-analysed for  for δ17O and Δ′17O. For >60 GNIP stations, four or more years’ of samples were analysed, assessing the seasonality of Δ′17O, and constructing δ17O/ δ18O Local Meteoric Water Lines (LMWL). This global dataset allowed for a first-ever comprehensive assessment of the spatial patterns of δ17O/ δ18O LMWLs, and to devise a first-ever precipitation-weighted Global Meteoric Water Line (GMWL): δ′17O = 0.5280 ± 0.0002 δ′18O + 0.0153 ± 0.0013. This GMWL definition is similar to previous efforts albeit with a lower ordinate intercept.

We further analysed the Δ′17O of a 6-year daily/fortnightly precipitation sampling in Vienna as an example of seasonal isotopic variations at synoptic weather patterns’ resolution. Air moisture sources were determined by backwards trajectory analysis and corroborated with synoptic weather data from Austria’s meteorological service. The Δ′17O values correlated with δ18O seasonality. A comparison with the deuterium excess patterns (stemming from the Atlantic and Mediterranean domains) demonstrated that the “two excesses” carried different signals. While elevated d-excesses
mainly came from the central/eastern Mediterranean Sea or easterly continental sources during all seasons, we found elevated Δ′17O precipitation originated only from northerly or north-easterly sources, and predominantly during the winter season.

Finally, we present pilot Vienna precipitation events sampled at sub-hourly (to 5-minute) resolution, which included both cyclonic and convective rainfall events, which demonstrate the interplay of moisture sources using triple oxygen isotopes and deuterium excess. This work will help to shape our understanding of δ17O and Δ′17O in Earth’s precipitation, despite the ongoing metrological challenges faced, and promote discussion regarding the scientific value of routine measurements for triple-oxygen isotopes in precipitation.

How to cite: Terzer-Wassmuth, S., Araguas-Araguas, L., Wassenaar, L. I., Monteiro, L. R., and Stumpp, C.: Measuring δ17O and Δ′17O in precipitation across various spatial and temporal scales: spanning from global to local and from multi-year to sub-hourly resolutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3596, https://doi.org/10.5194/egusphere-egu24-3596, 2024.

EGU24-4590 | Orals | BG2.1

Triple sulfur isotope constraints on the sulfur cycling in Lake Sevan, Armenia 

Alexey Kamyshny, Khoren Avetisyan, Natella Mirzoyan, and Rayford Payne

Lake Sevan is a meso-eutrophic water body, which was severely impacted by anthropogenic level decrease, pollution and eutrophication during the last century. Starting in the 1970s, a decrease in the water level and an increase in dissolved inorganic nitrogen concentrations resulted in oxygen depletion in the hypolimnion of the lake during summer–autumn thermal stratification of the water column. Our work shows that in October 2019, the redox conditions in the hypolimnion progressed not only to full depletion of oxygen and nitrate, but to the formation of a hydrogen sulfide-rich deep-water layer, which covers 66% of lake’s bottom and accounts for 19% of its water volume. Concentrations of hydrogen sulfide in the hypolimnion of Major and Minor Sevan in October were as high as 9 and 39 μM, respectively.

Triple sulfur isotope composition of sulfate and hydrogen sulfide in the water column of the lake provides further constraints on the biogeochemical processes which result in the formation of hydrogen-sulfide hypolimnion. Values of δ34S for hypolimnetic sulfide are lower by only 7–12 ‰ compared to epilimnetic sulfate, while δ33S values of sulfide are similar to the δ33S values of sulfate. These isotopic fingerprints are not consistent either with microbial sulfate reduction in the water column or with its combination with re-oxidative sulfur cycle as the sources of hydrogen sulfide in the hypolimnion. We attribute the formation of a sulfidic deep-water layer to a combination of microbial sulfate reduction in the water column and diffusion of hydrogen sulfide from the sediments.

How to cite: Kamyshny, A., Avetisyan, K., Mirzoyan, N., and Payne, R.: Triple sulfur isotope constraints on the sulfur cycling in Lake Sevan, Armenia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4590, https://doi.org/10.5194/egusphere-egu24-4590, 2024.

EGU24-5453 | Orals | BG2.1 | Highlight

Response of two coastal peatlands to the duration of rewetting and the release of nutrients 

Maren Voss, Anne Breznikar, Iris Liskow, Daniel Poenisch, and Gregor Rehder

Along the German coastline of the Baltic Sea are numerous former coastal fens. The originally approx. 40,000 hectares of peatland that were regularly flooded are now mostly diked, drained and are mainly used for agriculture. In order to be prepared for rising sea levels in the future, attempts are being made to determine the consequences of renewed flooding for the development of the fen and the adjacent Baltic Sea. A first test area was a former peatland in Drammendorf on the island of Ruegen, Germany. It had been rewetted in a major campaign lead by the Baltic Sea Foundation. The other area, Karrendorf, had been flooded already 30 years ago. The two coastal fens had different periods of waterlogging and were studied comparatively over the course of a year. In addition to the typical seasonality, which is reflected in the same temperature and oxygen content at both sites and the adjacent bays, there are striking differences in nutrient concentrations and isotope signatures of organic matter and nitrate, some of which can be traced back to the history of the areas as agricultural land. Shortly after its rewetting in winter, for example, nitrate concentrations in Drammendorf were several times higher than in Karrendorf and nitrous oxide saturations were up to 4000 %.

We found that the longer the area was flooded and nutrients released to the overlying waters, the less nutrients are discharged into the adjacent Baltic Sea. This finding was not only reflected by lower nutrient concentrations in the surface water of Karrendorf, but also in much lower porewater nutrient concentrations. Moreover, we saw a close coupling of the microbial processes in the overlying water with the soils. Nitrification, which converts ammonium from decomposition processes into nitrate, was clearly recognizable in the nitrogen and oxygen isotopes of nitrate despite low rates. However, high δ18O values of nitrate indicate precipitation as another possible source of nutrients. In addition, the isotope values of the organic matter show that there is an intensive exchange between the Baltic Sea and the coastal fens, whereby Drammendorf is more strongly characterized by marine organic matter inflow than Karrendorf. Thus, the flooding of coastal peatlands initiates lateral transport across the terrestrial-marine interface, while the microbial processes play more of a role in the interaction between soil and water.

For future management, the soil composition and history should always be considered and the intensity of exchange with coastal waters taken into account so that these areas do not become hot spots of eutrophication due to their large nutrient reservoirs.

How to cite: Voss, M., Breznikar, A., Liskow, I., Poenisch, D., and Rehder, G.: Response of two coastal peatlands to the duration of rewetting and the release of nutrients, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5453, https://doi.org/10.5194/egusphere-egu24-5453, 2024.

EGU24-5836 | ECS | Orals | BG2.1

Contribution of triple oxygen isotopes measurement by Cavity Ring Down spectroscopy and Clumped isotopes to the understanding of kinetics effect in cold water corals. 

Marie Pesnin, Justin Chaillot, Thibault Clauzel, Claire Rollion-Bard, Sebastien Nomade, Samir Kassi, Franck Lartaud, and Mathieu Daëron

Kinetic isotopes effect (KIEs) describes a very common phenomenon related to change in chemical reaction rate due isotopic substitution. If in biological sciences, KIEs has received a lot of interest with the aim at understanding reaction mechanisms, their control on the isotopic composition of biogenic carbonate has long been overlooked. However, the initial assumption that isotopic fractionation primarily reflects a thermodynamic equilibrium process in the H2O-DIC-CaCO3 system is challenged by a growing number of observations. Not accounting for these disequilibrium effects leads to inaccurate estimates of carbonate growing temperature. In this scientific context, Triple oxygen isotopes systematic can help constraining kinetics isotopes fractionation associated with metabolic reactions implicated in biocarbonates formation. We thus took advantage from recent development in spectroscopic technique (VCOF-CRDS) to measured O17isotopic anomalies in CO2produced by carbonate acid reaction [1]. These samples were also analyzed for their δ13C, δ18O and Δ47 composition using a more classical mass spectroscopy technic. In this contribution we investigated cold-water corals (CWC) known to display strong isotopic disequilibria. For this 1st application, we selected four modern CWC species for which calcification conditions (T, S, pH, δ18Owater, Δ17Owater and δ13CDIC) are independently constrained. The measured isotopic signatures were compared to their respective expected values based on environmental constrains, assuming “pseudo-equilibrium” carbonate precipitation. In particular, corals Δ17O signatures were compared to the newly established equilibrium for O17 fractionation between calcite-water based on slow growing carbonates from Laghetto Basso and Devils Hole, measured using the same VCOF-CRDS technic [2]. We finally compared our experimental data with theoretical predictions for KIEs on DIC isotopic composition [3]. Interestingly, the correlation slope among Δ47 - Δ17O disequilibrium differ from the previous one derived from dual clumped (Δ47 - Δ48) isotopic measurements of the same species [4]. This founding suggesting that other biological parameter(s) should be taken into account to resolve CWC isotopic disequilibria.

[1] Chaillot. J., Daëron. M., Casado, M., Landais. A., Pesnin. M., Clauzel. T., Kassi. S. (in prep) Triple oxygen analyses of carbon dioxide, water and carbonates using VCOF-CRDS.

[2] Clauzel, T., Chaillot, J., Pesnin, M., Jautzy, J., Kessy, S., Daëron, M. (in prep) Advancing triple oxygen isotope analysis of carbonate and water using V-shaped Cavity Optical Feedback Cavity Ring-Down Spectroscopy (VCOF-CRDS): Calibration and implications for paleoclimate reconstruction.

[3] Guo. W. (2020). Kinetic clumped isotope fractionation in the DIC-H2O-CO2 system: Patterns, controls, and implications. Geochimica et Cosmochimica Acta, 268, 230-257.

[4] Davies. A. J., Guo. W., Bernecker. M., Tagliavento. M., Raddatz. J., Gischler. E., Floter. S., Fiebig. J. (2022). Dual clumped isotope thermometry of coral carbonate. Geochimica et Cosmochimica Acta, 338, 66-78.

How to cite: Pesnin, M., Chaillot, J., Clauzel, T., Rollion-Bard, C., Nomade, S., Kassi, S., Lartaud, F., and Daëron, M.: Contribution of triple oxygen isotopes measurement by Cavity Ring Down spectroscopy and Clumped isotopes to the understanding of kinetics effect in cold water corals., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5836, https://doi.org/10.5194/egusphere-egu24-5836, 2024.

EGU24-6261 | ECS | Posters on site | BG2.1

How hydroclimate variability drives triple oxygen isotope dynamics in permanent and temporal lakes in Southern Spain 

Claudia Voigt, Fernando Gázquez, Ana Isabel Sánchez-Villanueva, Lucía Martegani, Elvira Ruíz-Caballero, Jorge Cañada, and Miguel Rodríguez-Rodríguez

Triple oxygen isotopes of lacustrine gypsum and carbonate deposits are used to quantitatively assess past hydroclimate conditions. An accurate interpretation of these paleo-archives requires a fundamental understanding of processes driving the variability of 17O-excess in hydrologically different lake systems and their dynamics. Here, we present results of an ongoing monitoring study of triple oxygen and hydrogen isotopes and lake hydrology of two adjacent lakes in southern Spain, which differ in morphology, hydrogeological functioning, and water chemistry. Laguna Grande is a permanent, ∼8 m deep water body that receives groundwater discharge from the aquifer. In contrast, Laguna Chica is a temporal lake with a maximum depth of 1.5 m, which is only fed by precipitation and basin discharge and desiccates during exceptionally long periods of drought. The region is characterized by semi-arid climate and strong seasonality of precipitation. The dataset comprises three hydroperiods between 2020 and 2023. This period has been extremely dry in the South of Spain. We compare non-steady-state isotope and hydrological mass balance model results to monthly observations of lake levels and lake water isotope data to assess the mechanisms that control lake hydrology from daily to annual scale.

Laguna Grande showed significantly less isotope variability (δ18O ranged from 5.7 to 9.6‰, 17O-excess from -34 to -86 per meg, d-excess from -28 to -43‰) than Laguna Chica (δ18O ranged from -1.5 to 20.8‰, 17O-excess from -7 to -153 per meg, d-excess from -2 to -89‰). In general, 17O‑excess and d‑excess decreased with increasing δ18O, indicating the impact of evaporation. The highest δ18O and lowest 17O-excess and d-excess values occurred at the end of summer before the start of the next rainy season. Annual average δ18O of Laguna Grande increased by ∼0.7‰ per year, while 17O-excess (∼10 per meg per year) and d-excess (∼2 ‰ per year) decreased slightly. This indicates that evaporation exceeded water inflows, which is consistent with the 2 m water level drop observed over the study period. Laguna Chica showed high interannual isotope variability. In particular, the timing of desiccation determines its maximum evaporative isotope enrichment. The highest δ18O and lowest 17O-excess and d-excess were observed in October 2022, just before complete desiccation. The lake was refilled in the subsequent rainy season but dried up in May 2023 preventing it from reaching the high level of evaporation observed in the preceding hydroperiods. Changes in the length of the hydroperiod and the timing of desiccation need to be considered when interpreting isotope data of paleo-lake water obtained from lake sediment archives. The non-steady-state isotope-hydrological mass balance model agrees reasonably well with observations, showing that lake’s isotope variability can be predicted even in highly dynamic systems. However, uncertainty in the lake volume-to-surface area ratio at low water level stages challenge accurate prediction of the lake isotope composition. 

 

How to cite: Voigt, C., Gázquez, F., Sánchez-Villanueva, A. I., Martegani, L., Ruíz-Caballero, E., Cañada, J., and Rodríguez-Rodríguez, M.: How hydroclimate variability drives triple oxygen isotope dynamics in permanent and temporal lakes in Southern Spain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6261, https://doi.org/10.5194/egusphere-egu24-6261, 2024.

EGU24-6355 | ECS | Posters on site | BG2.1

Lead in particulate matter source apportioning by HR-MC-ICPMS stable isotope ratio measurements 

Giuseppe Caso, Maria Di Rosa, Salvatore Di Rosa, Mauro Rubino, and Fabio Marzaioli

During the last decades great attention was paid to Particulate Matter (PM) due to the correlation between fine PM exposure and adverse health effects.

  Among the airborne pollutants, Lead (Pb) is one of the most widespread and toxicologically important. Metallic Pb and inorganic Pb compounds are classified as possible carcinogenic for humans. Pb can bioaccumulate in the human body system, causing damage to human nervous system, cardiovascular diseases, reproductive impairments, and catalyzing cells oxidative stress.

  In Italy, Legislative Decree no. 155 of 13/08/2010 (implementation of European Directive 2008/50/EC) defines the atmospheric PM10, PM2.5 and airborne pollutants threshold concentration values. These threshold values are applied for anthropogenic particulates, so, the Pb source apportioning in PM can offer the key to manage the problem.

   Pb has four stable isotopes, i.e. 204Pb, 206Pb, 207Pb, and 208Pb. The isotopic ratios of Pb act as “fingerprint” that allows to identify the PM emission sources in the environment (crustal, vehicular traffic, municipal solid waste incinerator, etc …).

  The PM 2.5 and PM10 sampling will be carried out by ARPAC monitoring network, using high-volume samplers placed in Campania (Italy) environmental interest points (urban centers, busy roads…). The sampling flow is 2.36 m3/h, single sampling time is 24 hours and the use of quartz fiber filters Ø = 47mm is provided (according to the technical standard UNI EN 12341:2014).

  Precise and accurate measurement of Pb and relative isotope ratios requires a multi-step process for analysis of solid samples:

  • Microwave-assisted treatment of filters with strong acid to solubilize all the metallic species (EPA 3051 A 2007);
  • A First qualitative and quantitative measurement by Inducted Coupled Plasma Optical Emission Spectroscopy (ICP-OES) to estimate the total Pb concentration (moreover, the quali-quantitative determination of other metals is an important information for environmental purposes);
  • Lead Extraction and purification from matrix and interfering elements by ionic resins in ISO 4 clean room;
  • Mass spectrometry measurement for lead isotope analysis by High Resolution Multi-Collector Inducted Coupled Plasma Mass Spectrometry (HR-MC-ICPMS).
  • Improvement of data interpretation accuracy comparing experimental data to isotopic lead ratio values in research databases (i.e. IBERLID: lead isotope database and tool for metal provenance and ore deposits research).

  However, the identification of anthropogenic Pb sources enables to establish the origin of a portion of collected PM. So, when an overcoming of PM threshold concentration is observed, thanks to the isotopic analysis information, competent authorities can act in an efficient and successful way.

How to cite: Caso, G., Di Rosa, M., Di Rosa, S., Rubino, M., and Marzaioli, F.: Lead in particulate matter source apportioning by HR-MC-ICPMS stable isotope ratio measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6355, https://doi.org/10.5194/egusphere-egu24-6355, 2024.

EGU24-7124 | ECS | Posters on site | BG2.1

Development of a comprehensive and ultrasensitive isotope calibration method for soil amino acid profiles using Orbitrap mass spectrometry 

Tao Li, Yuhua Li, Ye Tian, Erika Salas, Xiaofei Liu, and Wolfgang Wanek

Bound amino acids constitute a significant portion of soil organic nitrogen, which represents an essential source of nitrogen for plant and microbial nutrition. The analysis of the content and isotope enrichment of bound amino acids still represents a significant challenge due to the degradation of certain amino acids following the conventional acid hydrolysis method, due to the low isotope enrichment levels reached under near-native soil conditions and due to the lack of isotopically labelled standards for some key amino acids. In this study, we used both a 13C-labeled and unlabeled 16 algal amino acid mixture to establish standard calibration curves for various amino acids, using the 6-Aminoquinolyl-N-hydroxysccinimidyl carbamate (AQC) derivatization method and the ultra-high-performance liquid chromatography with high-resolution Orbitrap mass spectrometry (UPLC-Orbitrap MS) platform. Molecular ions of AQC-derivatives for all amino acids were identified at the expected m/z values of the respective isotopologues, and the isotope calibration curves exhibited excellent linearity for those amino acids where we had isotope standards at hand (polynomial R2 > 0.9896). However, the polynomial fitting terms differed between single amino acids. Subsequently, we developed equations to relate the calibrated regression terms to physicochemical properties of the respective amino acids. First, we conducted a linear regression using the Orbitrap-derived 13C atom % of unlabeled standards against the carbon atom number of the specific amino acid-AQC derivative molecules, demonstrating great linearity (R2 = 0.9728). This linear regression curve allowed us to predict the natural 13C abundance of amino acids unavailable as isotopically labelled standards (e.g. hydroxyproline, meso-diaminopimelic acid). Consequently, based on further regressions, we could ultimately develop isotope calibration curves for those amino acids unavailable as 13C labelled standards based on the integrated isotope calibration functions. This general predictive model can be applied to comprehensively and highly sensitively (13C enrichment ~0.01 at %) quantify isotope enrichments of the whole soil amino acids profile, providing valuable insights for a better understanding of the overall fate of different amino acids in soils.

How to cite: Li, T., Li, Y., Tian, Y., Salas, E., Liu, X., and Wanek, W.: Development of a comprehensive and ultrasensitive isotope calibration method for soil amino acid profiles using Orbitrap mass spectrometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7124, https://doi.org/10.5194/egusphere-egu24-7124, 2024.

EGU24-7981 | Orals | BG2.1 | Highlight

Clumped isotopes in carbonates: state of the art and open questions  

Stefano Bernasconi, Nathan Looser, Nico Kueter, Ricarda Rosskopf, and Jordon Hemingway

Since its establishment almost 20 years ago, carbonate clumped isotope thermometry (Δ47, Δ48) has grown to the most widely applied branch of the rapidly evolving field of clumped isotope geochemistry. An increasing number of laboratories worldwide is implementing this technique and applying it to solve a broad range of Earth science questions. The introduction of carbonate-based standardisation (Bernasconi et al. 2021), together with recent efforts to improve temperature calibrations (e.g. Anderson et al. 2021), has solved inter-laboratory differences and greatly improved the confidence in temperature reconstructions based on Δ47. Discrepancies in absolute temperatures using different calibrations are now on the order of 1-2°C only. The next frontier in carbonate clumped isotopes is Δ48 which is even more analytically challenging than Δ47 but has the potential to solve long standing questions of equilibrium/disequilibrium precipitation of carbonates and better understand processes of biomineralization. An important remaining field that requires further research is related to the preservation of the original clumped isotope temperatures in deep time samples and the kinetics of C-O bond reordering. In this contribution, we will review the state-of-the-art analytical methods and calibrations and discuss open challenges in interpreting clumped isotope signatures of biogenic and inorganic carbonates with bond reordering models.

Bernasconi et al. (2021) InterCarb: A Community Effort to Improve Interlaboratory Standardization of the Carbonate Clumped Isotope Thermometer Using Carbonate Standards. Geochemistry, Geophysics, Geosystems, 22(5),e2020GC009588..

Anderson et al. (2021) A unified clumped isotope thermometer calibration (0.5–1100°C) using carbonate‐based standardization. Geophysical Research Letters, 48, e2020GL092069.

How to cite: Bernasconi, S., Looser, N., Kueter, N., Rosskopf, R., and Hemingway, J.: Clumped isotopes in carbonates: state of the art and open questions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7981, https://doi.org/10.5194/egusphere-egu24-7981, 2024.

EGU24-10068 | Posters on site | BG2.1

Improving the long-term Δ47 reproducibility of the Thermo Scientific 253 Plus 10 kV IRMS using a prototype Peltier cooling device 

László Rinyu, Andrea Czébely, Diána Kiss, Sándor Kele, and Marianna Túri

Carbonate clumped isotope analysis, a relatively new methodology, is still developing rapidly, that is well described by the frequency of changes in the applied methodological conventions. The extent of development is also characterized by the growing, sometimes special, nature of the application areas. Innovations, while promising, can present unforeseen challenges and sometimes brings unexpected difficulties, such as the integration of 1013 Ohm resistance in the amplification circuits of Thermo Scientific 253 Plus 10 kV Isotope Ratio Mass Spectrometer (IRMS).

The goal of this improvement was that even very small ion beams can be analyzed with the factor of 3 better signal to noise ratio, which is an important aspect from the point of view of clumped isotope analysis. Unfortunately, 1013 Ohm resistance has a significant temperature dependency, which highly influences the magnitude of the detected intensities as well as on the overall long-term stability of the measurement. The daily temperature fluctuation in summer is very significant in Hungary. Under extreme conditions, when the lab's air conditioning could not maintain the desired temperature range, the long-term Δ47 reproducibility of the system achieved an SD = 60 ppm value.

In order to reduce this effect a prototype Peltier cooling device has been installed on the surface of the detector house of our IRMS. To demonstrate the achieved accuracy, precision, and long-term stability (SD <= 30 ppm) of the modified measurement system, we present results of clumped isotope analyses of international carbonate standard samples and naturally formed travertine samples (known formation temperatures are in the range of 5-95°C) and compare them with formerly published data of two reputable laboratories from the clumped community, which use different measurement equipment:

  • ETHZ: Thermo Scientific MAT253 IRMS and Kiel IV automatic carbonate device [1]
  • MIT: Nu Perspective IRMS and NuCarb automated sample preparation unit [2]

Additionally, we offer insight into the infrastructure and analytical methodology of the clumped isotope laboratory established at ICER (ATOMKI, Debrecen, Hungary). The modification implemented and the attained long-term stability may serve as a valuable reference for other laboratories encountering similar challenges.

Keywords: carbonate clumped isotope, Peltier cooling, long-term reproducibility

References

[1] Bernasconi, S. M., I. A. Müller, K. D. Bergmann, et al. (2018) Reducing uncertainties in carbonate clumped isotope analysis through consistent carbonate-based standardization. Geochemistry, Geophysics, Geosystems, v. 19, 2895-2914.

[2] Anderson, N. T., J. R. Kelson, S. Kele et al. (2021) A Unified Clumped Isotope Thermometer Calibration (0.5–1,100°C) Using Carbonate-Based Standardization. Geophysical Research Letters, v. 48, e2020GL092069.

How to cite: Rinyu, L., Czébely, A., Kiss, D., Kele, S., and Túri, M.: Improving the long-term Δ47 reproducibility of the Thermo Scientific 253 Plus 10 kV IRMS using a prototype Peltier cooling device, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10068, https://doi.org/10.5194/egusphere-egu24-10068, 2024.

EGU24-10367 | Orals | BG2.1 | Highlight

Transfer of the nitrogen isotope signature from the nitrate pool to the diatom biomass and into the diatom frustule 

Anja S. Studer, Jochem Baan, and Moritz F. Lehmann

The nitrogen (N) isotopic composition of diatom frustule-bound organic matter (δ15NDB) from sedimentary archives has been used as a promising proxy indicator to reconstruct nitrate utilization in the high-latitude oceans on different timescales. The advantage of this proxy over conventional N isotopic approaches, such as measuring δ15N values of the bulk sediment, is that δ15NDB is thought to be protected from diagenetic alteration and bacterial degradation. Despite the fact that the δ15NDB proxy has been applied in palaeoceanographic research for two decades, little is known about the propagation of the δ15N signature of assimilated nitrate into biomass δ15N and subsequently into δ15NDB, and to what extent N-isotope fractionation during frustule-bound N synthesis varies among species and with environmental conditions. Only few δ15NDB data exist for living diatoms in natural environments or laboratory cultures, and implications for paleo-environmental reconstructions appear controversial between existing studies. Here, we present novel constraints on the relationship between δ15N values of nitrate, diatom bulk biomass, and diatom frustule-bound N across samples from different natural environments and from controlled mono-specific diatom cultures. While previous ground-truthing work has focussed on marine diatom species both in culture and in the ocean, we extend our study to freshwater species and lacustrine environments. We find that, in mono-specific diatom cultures, δ15NDB values are generally relatively close to biomass δ15N values, irrespective of the variable 15N-fractionation imparted by nitrate assimilation. Similarly, analysis of diatom samples from natural environments revealed little offset between δ15NDB and bulk biomass δ15N values in samples that are near mono-specific. By contrast, in more mixed-species samples, δ15NDB values can be shifted in both directions relative to biomass δ15N values, possibly as a result of i) species-specific N isotope fractionation during frustule-bound N synthesis, and/or ii) non-uniform contribution of N to the total biomass and diatom-bound N pools between different species.

How to cite: Studer, A. S., Baan, J., and Lehmann, M. F.: Transfer of the nitrogen isotope signature from the nitrate pool to the diatom biomass and into the diatom frustule, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10367, https://doi.org/10.5194/egusphere-egu24-10367, 2024.

EGU24-11056 | Posters on site | BG2.1

Investigating the effect of cation substitution and mineralogy on the dual clumped isotope composition of carbonates 

Miguel Bernecker, Magali Bonifacie, Philip Staudigel, Daniel Petrash, Eiken Haussühl, Martin Dietzel, Amelia Davies, Mattia Tagliavento, Julien Siebert, Nicolas Wehr, and Jens Fiebig

Dual-clumped isotope thermometry relies on the joint measurement of ∆47 and ∆48 in CO2 evolved from phosphoric acid digestion of carbonates (Fiebig et al., 2019). The benefit over ∆47-only measurements is its capability to identify if ∆47was affected by rate-limiting kinetics in addition to temperature, and to reconstruct accurate carbonate formation temperatures devoid of this kinetic bias (Bajnai et al., 2020).

Direct measurements of ∆63 and ∆64 in carbonates are technically not feasible. During acid digestion of carbonates, fractionations of clumped isotopes (∆63 → ∆47 and ∆64 → ∆48) occur, but the exact magnitudes of acid fractionation factors (AFFs) are not consistently established and vary across different published sources.

Theoretical models by Guo et al. (2009) indicate cation-dependent differences in AFFs for different carbonate mineralogies. Follow-up empirical studies yielded somewhat inconsistent results for ∆47 – some did not observe any differences in AFFs (e.g., Defliese et al., 2015 for calcite, aragonite, and dolomite; Bonifacie et al., 2017 for calcite and dolomite), whereas others did report differences (e.g., Murray et al., 2016 for calcite and dolomite; Müller et al., 2017 for calcite, aragonite, dolomite, and magnesite).

Advancements in gas source mass spectrometry have led to significant improvements in the long-term external repeatability of clumped isotope measurements, e.g., from > 20 ppm to 7-9 ppm for ∆47 (Bernecker et al., 2023). With this improved analytical set-up, we analyzed an assorted collection of scrambled aragonite, calcite, dolomite, siderite and witherite samples for their ∆47 and ∆48 values. We show that cation substitution and mineralogy have no effect on AFFsfor aragonite , calcite, dolomite and witherite. Moreover, the dual clumped isotope compositions of additionally investigated low-temperature aragonite and dolomite samples plot indistinguishable from the calcite equilibrium line. Altogether these findings strongly imply that the ∆47-∆48 -T framework established for calcite (Fiebig et al., 2021) is extendable to aragonite and dolomite.

 

 

Defliese, W.F. et al. Chem. Geol. 396, 51–60 (2015).

Murray, S.T. et al. Geochim. Cosmochim. Acta 174, 42–53 (2016).

Müller, I.A. et al. Chem. Geol. 449, 1–14 (2017).

Bonifacie M. et al. Geochim. Cosmochim. Acta 200, 255-279 (2017).

Fiebig, J. et al. Chem. Geol. 522, 186–191 (2019).

Bajnai, D. et al. Nat. Commun. 11, 4005 (2020).

Fiebig, J. et al. Geochim. Cosmochim. Acta 312, 235–256 (2021).

Bernecker, M. et al. Chem. Geol. 642, 121803 (2023).

How to cite: Bernecker, M., Bonifacie, M., Staudigel, P., Petrash, D., Haussühl, E., Dietzel, M., Davies, A., Tagliavento, M., Siebert, J., Wehr, N., and Fiebig, J.: Investigating the effect of cation substitution and mineralogy on the dual clumped isotope composition of carbonates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11056, https://doi.org/10.5194/egusphere-egu24-11056, 2024.

EGU24-12077 | ECS | Orals | BG2.1

Unlocking the nitrogen cycle in glacial forelands: an isotopic perspective 

Ilann Bourgeois, Jean-Christophe Clement, Lionel Bernard, Nicolas Caillon, Cedric Dentant, Leon Lepesant, Thomas Pommier, and Joel Savarino

Glacial forelands are expanding worldwide due to glacier shrinkage1, exposing new areas prone to the development of post-glacial ecosystems2,3. Nitrogen (N) is generally considered as a (co-)limiting nutrient in alpine regions, and deposition of atmospheric N, mainly emitted due to fossil fuel combustion, has for long been admitted as the main source of N4. However, other N sources such as glacial meltwaters5, long-range transport of fertilizers6 or bedrock erosion7 have recently been suspected of playing a more significant role than previously thought and could drive the establishment of pioneer microbial and plant communities in glacial forelands.

Here, we show the isotopic composition and concentration of nitrate (δ15N, δ18O, Δ17O) and ammonium (δ15N) in glacial meltwaters, soils and plants from three glacial forelands in the French Alps. Samples were collected along transects expanding from the glacier front to areas deglaciated around 60 years ago. We find that the contribution of atmospheric deposition to the nitrate pool in soils decreases as time since deglaciation increases, but never exceeds 40%, not even at the glacier front where soils are entirely mineral with no detectable nitrification enzymatic activity. This pattern suggests that bedrock nitrogen and glacial meltwaters are the main N sources in post-glacial ecosystems and calls for a better quantification of those inputs.  

 

(1)             Hugonnet, R.; McNabb, R.; Berthier, E.; Menounos, B.; Nuth, C.; Girod, L.; Farinotti, D.; Huss, M.; Dussaillant, I.; Brun, F.; Kääb, A. Accelerated Global Glacier Mass Loss in the Early Twenty-First Century. Nature 2021, 592 (7856), 726–731. https://doi.org/10.1038/s41586-021-03436-z.

(2)             Bosson, J. B.; Huss, M.; Cauvy-Fraunié, S.; Clément, J. C.; Costes, G.; Fischer, M.; Poulenard, J.; Arthaud, F. Future Emergence of New Ecosystems Caused by Glacial Retreat. Nature 2023, 620 (7974), 562–569. https://doi.org/10.1038/s41586-023-06302-2.

(3)             Ficetola, G. F.; Marta, S.; Guerrieri, A.; Gobbi, M.; Ambrosini, R.; Fontaneto, D.; Zerboni, A.; Poulenard, J.; Caccianiga, M.; Thuiller, W. Dynamics of Ecological Communities Following Current Retreat of Glaciers. Annu. Rev. Ecol. Evol. Syst. 2021, 52(1), 405–426. https://doi.org/10.1146/annurev-ecolsys-010521-040017.

(4)             Holtgrieve, G. W.; Schindler, D. E.; Hobbs, W. O.; Leavitt, P. R.; Ward, E. J.; Bunting, L.; Chen, G.; Finney, B. P.; Gregory-Eaves, I.; Holmgren, S.; Lisac, M. J.; Lisi, P. J.; Nydick, K.; Rogers, L. A.; Saros, J. E.; Selbie, D. T.; Shapley, M. D.; Walsh, P. B.; Wolfe, A. P. A Coherent Signature of Anthropogenic Nitrogen Deposition to Remote Watersheds of the Northern Hemisphere. Science 2011, 334 (6062), 1545–1548. https://doi.org/10.1126/science.1212267.

(5)             Saros, J. E.; Rose, K. C.; Clow, D. W.; Stephens, V. C.; Nurse, A. B.; Arnett, H. A.; Stone, J. R.; Williamson, C. E.; Wolfe, A. P. Melting Alpine Glaciers Enrich High-Elevation Lakes with Reactive Nitrogen. Environ. Sci. Technol. 2010, 44 (13), 4891–4896. https://doi.org/10.1021/es100147j.

(6)             Hundey, E. J.; Russell, S. D.; Longstaffe, F. J.; Moser, K. A. Agriculture Causes Nitrate Fertilization of Remote Alpine Lakes. Nat. Commun. 2016, 7 (1), 10571. https://doi.org/10.1038/ncomms10571.

(7)             Houlton, B. Z.; Morford, S. L.; Dahlgren, R. A. Convergent Evidence for Widespread Rock Nitrogen Sources in Earth’s Surface Environment. Science 2018, 360 (6384), 58–62. https://doi.org/10.1126/science.aan4399.

How to cite: Bourgeois, I., Clement, J.-C., Bernard, L., Caillon, N., Dentant, C., Lepesant, L., Pommier, T., and Savarino, J.: Unlocking the nitrogen cycle in glacial forelands: an isotopic perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12077, https://doi.org/10.5194/egusphere-egu24-12077, 2024.

EGU24-14826 | Posters on site | BG2.1

Is the sensitivity of leaf water and cellulose δ18O values sufficient for detecting effects of increasing atmospheric CO2 on stomatal conductance in plants?  

Ansgar Kahmen, Meisha Holloway-Phillips, Eva Morgener, David Basler, and Daniel B. Nelson

The oxygen isotope composition of cellulose (δ18O values) has been suggested to contain information on stomatal conductance (gs) responses to rising pCO2. The extent by which pCO2 affects leaf water and cellulose δ18O values (δ18OLW and δ18OC) and the isotope processes that determine pCO2 responses of gs in δ18OLW and δ18OC are, however, unknown. We tested the effects of pCO2 on gs, δ18OLW and δ18OCin a greenhouse experiment, where six herbaceous plant species were grown under pCO2 levels ranging from 200 to 500 ppm. An increase in pCO2 caused a decline in gs. The effects of gs on δ18OLW were caused by direct and indirect mechanisms but were generally small. The model parameter effective path length (Lm) was unaffected by changes in pCO2. pCO2 effects on δ18OLW were not directly transferred to plant δ18OC but were attenuated in grasses and amplified in dicotyledonous herbs and legumes. This is likely because of functional group specific pCO2 effects on the model parameter pxpex. Our study removes critical uncertainties for using δ18OC as a proxy for gs. At the same time, our study shows that gs effects on δ18OLW and δ18OC are rather small, possibly too small to be detected in natural settings.

How to cite: Kahmen, A., Holloway-Phillips, M., Morgener, E., Basler, D., and Nelson, D. B.: Is the sensitivity of leaf water and cellulose δ18O values sufficient for detecting effects of increasing atmospheric CO2 on stomatal conductance in plants? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14826, https://doi.org/10.5194/egusphere-egu24-14826, 2024.

EGU24-16279 | ECS | Posters on site | BG2.1

Clumped isotope temperatures from secondary carbonates in loess: comparability of different preparation methods of snail shells and earthworm biospheroids 

Andrea Czébely, Marianna Túri, Diána Kiss, Gábor Újvári, Titanilla Kertész, and László Rinyu

Quantitative reconstruction of temperature remains the major focus and challenge of paleoclimate research, especially in the terrestrial realm. This study is aimed at testing the usefulness of Δ47 of earthworm’s biospheroids (EBS) as a temperature proxy by comparing the EBS-derived T47 values to those obtained from previously studied land snails. For this purpose, the Dunaszekcső loess record in southern Hungary has been selected, which is an extensively studied section with a high resolution 14C chronology [1,2,3], revealing stadial-interstadial variations in sedimentation rates.

Sixteen samples were collected in 10 cm resolution from the loess layers between 850-770 cm and 695-615 cm representing the GI-5.1 (30.6-30.8 ka) and GI-3.1 (27.5-27.8 ka) periods and surrounding stadials [4]. The associated temperature was calculated previously between 8-15 °C [4] based on the clumped isotope compositions of mollusc shells of these layers.

The impact of sample preparation methods on Δ47 values of secondary carbonates is unknown and is a potential concern. To test this, two different sample preparation methods were applied on Trochulus hispidus shells recovered from the mentioned loess layers: 1) treatment in 1 m/m% HCl solution and 2) treatment with 3 m/m% H2O2 solution under vacuum and in ultrasonic bath in ultrapure water. The reconstructed temperatures based on the Δ47 values of the snail shells typically fell between 7-15 °C (HCl pretreatment) and 9-14 °C (H2O2 pretreatment), in very good agreement with previous published land snail T47 data [4]. The average temperatures obtained from biospheroids reveal the same stadial-interstadial temperature pattern previously reconstructed by molluscs. The mean T47 values of the two pretreatment methods are within the expected temperature range derived from the snail shells.

Clumped isotope analysis was also performed on biospheroid samples from the same layers, and the calculated temperatures were compared with those obtained from snail shells by Újvári et al. [4]. To demonstrate that the biospheroid carbonates from the same layers are of the same age as the examined molluscs, we performed radiocarbon dating on the biospheroids. Our primary goal is to investigate whether the Δ47 compositions are affected by the so-called vital effect and to what extent the formation of biospheroid carbonates is influenced by these kinetic effects. To achieve this goal, a long-term experiment is going on. We perform climate chamber experiments [5,6,7] at temperatures of 8, 11 and 15 °C. Other variables, including relative humidity, CO2 concentrations and the stable isotope compositions of diet and spray liquid are also controlled. The first results will be presented.

 

References:

[1] Újvári, G. et al. 2014, Quaternary Science Review Vol. 106, 140-154

[2] Újvári, G. et al. 2016, Quaternary Geochronology Vol. 35, 43-53

[3] Újvári, G. et al. 2019, Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 518, 72–81

[4] Újvári, G. et al. 2021, AGU, Advancing Earth and Space Science, Paleoceanography and Paleoclimatology, Volume 36, Issue 8

[5] Canti, M.G. 2009, Soil Biology & Biochemistry Vol. 41, 2588-2592

[6] Lambkin, D.C. et al. 2011, Applied Geochemistry Vol. 26, S64-S66

[7] Versteegh, E.A.A et al. 2014, Soil Biology and Biochemistry Vol. 70, 159-161

How to cite: Czébely, A., Túri, M., Kiss, D., Újvári, G., Kertész, T., and Rinyu, L.: Clumped isotope temperatures from secondary carbonates in loess: comparability of different preparation methods of snail shells and earthworm biospheroids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16279, https://doi.org/10.5194/egusphere-egu24-16279, 2024.

EGU24-18111 | ECS | Posters on site | BG2.1

Isotope fingerprinting of organically complexed chromium – the natural story of a pollutant 

Wenhao Wang, Vladislav Chrastný, Johannes Hettler, Naresh Kumar, and Stephan Kraemer

Chromium (Cr) is a redox sensitive element and Cr isotope composition (δ53Cr) has been widely utilised to reflect the extent of Cr(VI) reduction during Cr pollution mitigation, as well as changes in past atmospheric/oceanic oxygenation. Whilst redox transformations are thought to primarily drive the Cr isotopic variability in modern aquatic environments, other processes, such as ligand promoted dissolution, can occur, potentially overprinting the intrinsic δ53Cr signal.

In this study, laboratory-controlled batch and flow-through column experiments on two distinct soil materials were conducted to understand the leaching behaviour of Cr and Cr isotopes, under both oxygenated and O2-free conditions. Significant dissolution of Cr(III), together with Fe and Mn, from the solid phase in the presence of low-molecular-weight organic acids was observed over the time course of all experiments. Initial isotope analyses on Cr(III)-citrate complexes show that δ53Cr values are ~ −0.60 to −0.09‰, reflecting the pristine Cr isotopic signature of the two soil materials. In addition, whilst formation of authigenic Fe particles means that a fraction of dissolved Cr is scavenged, such that solid phase Cr may be associated with Fe, Cr does not seem to be remobilised during reductive dissolution of Fe (and Mn) oxides in these experiments.

Results from this study have several implications. Firstly, as Cr is a known carcinogen, increased levels of organic ligands, e.g., in paddy field systems, can cause increased environmental and health risks. Secondly, organic ligands may play an overlooked role in modulating the input and removal processes of dissolved Cr to/from various environments. Finally, ligand-bound Cr(III) likely has a ‘stabilised’ isotopic signature that is distinct from Cr(VI), making it possible to trace this ‘additional’ Cr in aquatic systems; it is difficult to characterise or quantify these Cr-organic complexes using conventional analytical methods.

This work is part of the CHROMA project funded by H2020-MSCA-IF (101031974).

How to cite: Wang, W., Chrastný, V., Hettler, J., Kumar, N., and Kraemer, S.: Isotope fingerprinting of organically complexed chromium – the natural story of a pollutant, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18111, https://doi.org/10.5194/egusphere-egu24-18111, 2024.

EGU24-18347 | ECS | Posters on site | BG2.1

Fresh water sources for submarine groundwater discharge to the southern Baltic Sea  

Anna-Kathrina Jenner, Rhodelyn Saban, Catia Milene Ehlert von Ahn, Julia Westphal, Patricia Roeser, Iris Schmiedinger, Jürgen Sültenfuss, and Michael Ernst Böttcher

The impact of freshwater sources like surface river and submarine groundwater discharge (SGD) on the coastal water, the element balance therein, and the associated biogeochemical transformations within the subterranean estuary is currently a matter of intense debate and investigation. A quantification of freshwater mixing in coastal areas has been found to be challenging. In this sense the combination of stable water isotopes with further (isotope) hydro(bio)geochemical tracers provides a fundamental valuable tool to identify different freshwater sources found in the mixing zone with seawater.

Here, we report the geochemical and isotopic composition of porewaters of permeable sediments in front of a coastal peatland, the Huetelmoor (southern Baltic Sea). Gradients in pore water measurements from 5 m long stationary porewater lances are used to calculate the zero-salinity (ZS) component. The application of binary mixing approaches on water isotopes and conservative elements on the compositional gradients yields temporarily relatively stable ZS compositions but with substantial isotope differences for spatially distant lances. This indicates a subterranean estuary under steady-state conditions with different fresh waters entering the coastal area. At least two freshwater sources can be identified for sediments impacted by SGD without substantial impact of short-term hydrological or meteorologic processes. These results are compared to the composition of potential endmembers, such as the local surface and groundwaters, the local meteoric water line, and the open brackish Baltic Sea.

Besides stable isotopes, also dissolved major and minor elements were used to characterize the biogeochemical processes leading to the non-conservative behavior of nutrients, the carbon system, and trace elements. In addition, tritium-noble gas dating of the pore waters allows for an estimate of the fresh water residence time before mixing with the brackish Baltic Sea water.

Results will be discussed in the context of other SGD sites along the northern German coast.

 

Acknowledgement for support by DFG RTG Baltic TRANSCOAST, DFG-KiSNet, BMBF COOLSTYLE/CARBOSTORE, DAAD, and Leibniz IOW

How to cite: Jenner, A.-K., Saban, R., Ehlert von Ahn, C. M., Westphal, J., Roeser, P., Schmiedinger, I., Sültenfuss, J., and Böttcher, M. E.: Fresh water sources for submarine groundwater discharge to the southern Baltic Sea , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18347, https://doi.org/10.5194/egusphere-egu24-18347, 2024.

EGU24-22257 | ECS | Posters on site | BG2.1

Biogeochemical Niche building of Invasive Fallopia japonica: Insights from Stable Isotope Probing 

Sierra Grange, Johanna Girardi, Clara Mendoza-Lera, Jens Dyckmanns, Katherine Muñoz, Melanie Brunn, and Hermann Jungkunst

Exploring invasive plant species, in this case the infamous Fallopia japonica, has become pivotal in understanding their impact on biogeochemical processes within ecosystems. Building upon the work of Girardi et al., who investigated how F. japonica uses polyphenols to inhibit nitrification, our study employs stable isotope analysis to delve into the biogeochemical niche-building mechanisms of this invasive species. Following Girardi et al.’s findings, which highlighted the inhibitory effects of resveratrol on potential nitrification rates in F. japonica invaded riparian ecosystems, our research takes a step further to investigate the broader implications of the success of F. japonica. We employed stable isotopes, ¹³C-CO2 and ¹⁵N-NO3 and -NH4, to shed light upon the biogeochemical dynamics associated with the invasive prowess of F. japonica and find whether Fallopia japonica exhibits a higher affinity for ammonium than nitrate when compared to the native species Urtica dioica, and whether it allocates resources predominantly to root growth.

 

Contrary to previous hypotheses, our results challenge the belief that F. japonica exhibits a higher affinity for ammonium than nitrate compared to native species. Through our labelling experiments on young F. japonica and Urtica dioica (native) plants, we discovered that F. japonica displays a lower affinity for ammonium than U. dioica. Additionally, F. japonica demonstrated higher nitrogen-use efficiency and a pronounced preference for allocating resources to root biomass, underlining its ability to efficiently utilize nitrogen resources. These findings shed light on the intricate mechanisms behind the ability of F. japonica to disrupt ecosystems, emphasizing the importance of stable isotopes in unraveling such complexities. Through the integration of stable isotope probing techniques and a comprehensive understanding of rhizosphere processes, our work contributes to the ongoing efforts to foster sustainable and efficient agricultural systems in the face of global change. Moving forward, our research trajectory aims to explore the impact of phenols on nitrification in soils. Specifically, we plan to apply phenols to soil and investigate their effects on nitrification, with potential implications for denitrification processes. This endeavor aligns with the broader goal of understanding the multifaceted interactions between invasive plant species and biogeochemical processes, contributing to the development of effective strategies for invasive species management.

 

Keywords:                      Fallopia japonica, Urtica dioica, invasive species, native species, nitrogen cycle, nitrogen use efficiency, ammonium, 15N labelling, 13C labelling, biogeochemical niche, stable isotopes

How to cite: Grange, S., Girardi, J., Mendoza-Lera, C., Dyckmanns, J., Muñoz, K., Brunn, M., and Jungkunst, H.: Biogeochemical Niche building of Invasive Fallopia japonica: Insights from Stable Isotope Probing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22257, https://doi.org/10.5194/egusphere-egu24-22257, 2024.

EGU24-548 | ECS | Posters on site | BG2.2

Isotope analysis of snowpack nitrate in coastal Antarctica; evidence of nitrate photolysis and preservation. 

Amelia Bond, Markus M. Frey, Jan Kaiser, Alina Marca, and Freya Squires

Photolysis of snowpack nitrate results in emission of the reactive nitrogen species NOx and HONO. These are important pre-cursors of HOx radicals and ozone, and thereby affect the oxidising capacity of the lower atmosphere above remote snow-covered areas. This is of particular importance in the polar regions as the usual OH radical formation pathway (ozone photolysis and reaction of O(1D) with H2O) is limited by the low water vapour concentration. Isotope analysis of atmospheric reactive nitrogen species and snow nitrate is proving to be a crucial tool for elucidating mechanisms of reactive nitrogen cycling in and above snow.

The first snowpit profiles of nitrate stable isotopes (δ15N, δ18O) and concentration at Halley VI Research Station in coastal Antarctica will be presented. The observed isotope fractionation provides evidence of photochemical loss of nitrate and allows estimation of the photolytic isotope fractionation constant at the site. At this high accumulation site, the peak in nitrate concentration from the previous summer is preserved below the snow surface, unlike at low accumulation sites on the Antarctic Plateau. Combining measurements of nitrate concentration and its isotopic compositions preserved in snow helps disentangle the isotope signature of seasonal changes in atmospheric nitrate sources from post-depositional isotope fractionation occurring even at high snow accumulation sites.

How to cite: Bond, A., Frey, M. M., Kaiser, J., Marca, A., and Squires, F.: Isotope analysis of snowpack nitrate in coastal Antarctica; evidence of nitrate photolysis and preservation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-548, https://doi.org/10.5194/egusphere-egu24-548, 2024.

EGU24-1257 | ECS | Orals | BG2.2

On the contribution of boreal wetlands to the Northern Hemisphere carbonyl sulfide sink 

Anna de Vries, Georg Wohlfahrt, Timo Vesala, and Kukka-Maaria Kohonen

Previous studies inferred a missing sink of carbonyl sulfide (COS) in high Northern latitudes. Boreal COS budgets, however, typically account solely for the contribution by forests and ignore any uptake that widespread wetland ecosystems may contribute. Here we present the first direct measurements of the ecosystem-atmosphere COS exchange of a boreal wetland and compare this with a needleleaf forest ecosystems. We then use these data to up-scale to the boreal region.

We found that the investigated wetland was a stable sink for COS during the vegetation period, taking up on average of 10 pmol m−2s−1COS. While this was just 64% of the forest COS uptake, upscaling to the boreal region using the ORCHIDEE land surface model revealed that the Northern wetland sink, c. 20 GgS/y, was on the same order of magnitude compared to the forest COS sink. Our results thus indicate that northern COS should not neglect contributions by wetland ecosystems.

How to cite: de Vries, A., Wohlfahrt, G., Vesala, T., and Kohonen, K.-M.: On the contribution of boreal wetlands to the Northern Hemisphere carbonyl sulfide sink, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1257, https://doi.org/10.5194/egusphere-egu24-1257, 2024.

EGU24-2219 | Orals | BG2.2

Leaf carbon monoxide emission under field conditions: a potential stress indicator? 

Dan Yakir, Jonathan Muller, Rafael Stern, Rafat Qubaja, and Yasmin Bohak

Carbon monoxide (CO) is produced in living plants and can act as a stress-signaling molecule in both animals and plants. While CO emissions from soil, litter decomposition, and incomplete combustion have been extensively studied, there is a scarcity of research on CO flux from living vegetation, particularly under field conditions. We present the results of continuous CO fluxes measurements (together with those of water, CO2, and COS) using twig chambers in summer-droughted and in non-droughted (irrigated) Pinus halepensis trees across the seasonal cycle. We found significant CO emissions from leaves, which were correlated with environmental parameters (radiation, leaf temperature, and VPD). It peaked under the stressful summer conditions at the study site, when CO2 exchange and leaf conductance were at a minimum.  The CO fluxes were strongly correlated to twig transpiration and were enhanced under irrigated treatment. It is speculated that leaf CO emission is related to biotic reactions, such as heme degradation, which is enhanced under stress conditions and is possibly associated with photorespiration. Our results provide a rare, high-resolution, annual scale study of the environmental factors controlling leaf CO emissions under field conditions and indicate that including it in plant gas exchange studies may provide additional means to interpret their response to stress.

How to cite: Yakir, D., Muller, J., Stern, R., Qubaja, R., and Bohak, Y.: Leaf carbon monoxide emission under field conditions: a potential stress indicator?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2219, https://doi.org/10.5194/egusphere-egu24-2219, 2024.

EGU24-3338 | ECS | Posters on site | BG2.2

Mass-Independent Fractionation Reveals the Sources and Transport of Atmospheric Particulate Bound Mercury 

Xuechao Qin, Xinyuan Dong, Congqiang Liu, Rongfei Wei, Zhenghua Tao, Hua Zhang, and Qingjun Guo

Mercury (Hg) is highly toxic and the only heavy metal that can exist in the atmosphere in gaseous form. When atmospheric Hg mixes with aerosols, it forms particulate-bound mercury (PBM). PBM can be transported and settle down quickly across regions, posing serious threats to ecosystems globally. Despite these concerns, tracking the sources and transport of atmospheric Hg remains challenging due to its global dispersal nature. However, the three-dimensional fractionation of Hg isotopes provides a feasible approach for addressing this issue. In this study, PBM2.5 and PBMTSPsamples were collected simultaneously in rural, suburban, urban, industrial, and coastal areas of the Beijing-Tianjin-Hebei (BTH) region, which is influenced by severe atmospheric pollution and the East Asian monsoon. Due to the significant influence of anthropogenic sources, the concentrations of PBM2.5 and PBMTSP were highest in the industrial and coastal areas, followed by the urban, suburban, and rural areas. The δ202Hg values of PBM2.5 and PBMTSP at the five sites were negative, overlapping with the values of most anthropogenic sources. However, most PBM2.5 and PBMTSP samples showed significantly positive Δ199Hg, significantly higher than the values of emission sources,especially for PBM2.5. The mass-independent fractionation (MIF) of Hg and sulfur isotopes showed that strong photochemical reduction happened during long-distance transport, making Δ199Hg have a positive shift. The positive changes in Δ200Hg may be due to ozone-mediated oxidation during the transport process, as shown by the interesting relationships between O3, Δ199Hg, and Δ200Hg in PBM2.5. Additionally, the analysis of backward trajectories unveiled the influence of air masses originating northwest of the BTH region through high-altitude transport. The cross-border transport of PBM, influenced by westerly and northwesterly air masses from Central Asia and Russia, markedly impacted  PBM pollution in the BTH region. Furthermore, these air masses, upon reaching the BTH area, would transport heightened PBM concentrations to the ocean through the winter monsoon. Conversely, during the summer, southeastward air masses transported from the ocean by the summer monsoon acted to mitigate the inland PBM pollution. The study results show that significant positive odd-MIF of PBM can occur in places with intensive anthropogenic emissions rather than being limited to remote areas. It implies that the odd-MIF resulting from atmospheric transport has likely been significantly undervalued. Our research offers valuable perspectives on the transport, transformation, and circulation of Hg in the environment.

How to cite: Qin, X., Dong, X., Liu, C., Wei, R., Tao, Z., Zhang, H., and Guo, Q.: Mass-Independent Fractionation Reveals the Sources and Transport of Atmospheric Particulate Bound Mercury, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3338, https://doi.org/10.5194/egusphere-egu24-3338, 2024.

EGU24-4515 | Posters on site | BG2.2

Sulfate formation in haze pollution using multiple sulfur isotopes 

Qingjun Guo, Xiaokun Han, Xinyuan Dong, Xuechao Qin, and Rongfei Wei

Air pollution has become a serious problem in some parts of the world. The mechanism of sulfate formation during haze events is still not clear. This research looks at the different sulfur isotope compositions of sulfate in PM2.5 (from 2015 to 2016) in Beijing and in seasonal samples of PM2.5, PM1.0, and TSP from rural, suburban, urban, industrial, and coastal areas of North China (in 2017). The goal is to figure out the mechanism by which SO2 oxidizes at different levels of air pollution. An obvious seasonal variation (with positive values in spring, summer, and autumn and negative values in winter) is shown by the Δ33S values of sulfate in aerosols, except for those samples collected in rural areas. The Δ33S value (S-MIF) of sulfate in PM2.5 shows a pronounced seasonality, with positive values in spring, summer, and autumn and negative values in winter. The negative Δ33S changes that happen during winter haze events are mostly caused by SO2 being oxidized by H2O2 and transition metal ion catalysis (TMI) in the troposphere, which is most likely caused by coal burning. The positive Δ33S results observed on clean days are mainly attributed to tropospheric SO2 oxidation and stratospheric SO2 photolysis. These results provide important information on sulfate formation during haze events and clean days.

How to cite: Guo, Q., Han, X., Dong, X., Qin, X., and Wei, R.: Sulfate formation in haze pollution using multiple sulfur isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4515, https://doi.org/10.5194/egusphere-egu24-4515, 2024.

EGU24-5556 | Posters on site | BG2.2

Spatial Isotopic Analysis of Airborne CO2: Insights from Etna Volcano and Madonie Mountains, Italy, Surveys 

Sergio Gurrieri and Roberto M.R. Di Martino

Climate change is intricately linked to the carbon cycle. Both phenomena are examined across various temporal and spatial scales to clarify the processes of carbon exchange between the atmosphere and the Earth's surface in response to increasing greenhouse gas emissions, primarily CO2. Anthropogenic CO2 emissions emerge as the main driver of global warming, while natural CO2 emissions into the atmosphere constitutes approximately 1% of annual CO2 emissions, mainly resulting from volcanic activity.

This study relies on datasets gathered during surveys at Etna volcano and the Madonie mountains, Italy, to identify spatial variations in stable isotope composition and the concentration of airborne CO2. The dataset was collected along a path specifically designed from the urban areas of Catania and Cefalù, both in Italy, to high altitudes (i.e., ~2200 m a.s.l.) at Mount Etna and the Madonie mountains, Italy, respectively. This dataset facilitates exploration of spatial variations in the sources of atmospheric CO2 and patterns in the isotopic composition and concentration of airborne CO2 with altitude.

The study's findings indicate that the primary sources of airborne CO2 exhibit a biogenic isotopic carbon signature at Etna and the Madonie mountains, although a more 13C-enriched CO2 source influences the isotopic signature of airborne CO2 at Mount Etna. The concentration of airborne CO2 and the carbon isotopic signature remain independent of altitude. However, a high correlation between altitude and oxygen isotopic signature suggests that variations in hydrology significantly impact the airborne CO2.

Furthermore, the study underscores the complex relationship between environmental variables and airborne CO2 concentration, indicating that the pattern in airborne CO2 cannot be comprehensively investigated solely through concentration analysis due to the high background CO2 concentration compared to relative spatial variations. Additionally, the carbon isotopic signature of CO2 enables the differentiation of multiple sources of CO2 at Mount Etna and the distinction of 13C-enriched volcanic CO2 from background air at low airborne CO2 concentrations.

How to cite: Gurrieri, S. and Di Martino, R. M. R.: Spatial Isotopic Analysis of Airborne CO2: Insights from Etna Volcano and Madonie Mountains, Italy, Surveys, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5556, https://doi.org/10.5194/egusphere-egu24-5556, 2024.

EGU24-6354 | ECS | Orals | BG2.2

Interannual variations in Δ(17O) of atmospheric CO2 suggest a strong link with stratospheric input 

Pharahilda Steur, Hubertus A. Scheeren, Gerbrand Koren, Getachew A. Adnew, Wouter Peters, and Harro A. J. Meijer

We present multiple year records of the triple oxygen isotope signature Δ(17O) of atmospheric CO2 conducted with laser absorption spectroscopy, from Lutjewad in the Netherlands (53° 24’N, 6° 21’E) and Mace Head in Ireland (53° 20’ N, 9° 54’ W). Measurements were done on flask samples covering the period 2017-2022. The average uncertainty of 0.07 is about 3 times smaller than the total observed variability. A positive Δ(17O) originates from intrusions of stratospheric CO2, whereas values close to zero result from equilibration of CO2 and water, predominantly happening inside plants due to enhanced dissolution in the presence of carbonic anhydrase. A biosphere driven seasonal signal is, however, not observed in the records. Both records show significant interannual variability, of up to 0.3 . The total range covered by smoothed monthly averages from the Lutjewad record is -0.065 to 0.046 , which is significantly higher than the range of -0.009 to 0.036 that was simulated with a 3-D transport model. One of the major model uncertainties is the representation of the stratospheric influx of Δ(17O). We modified the model using the 100 hPa 60-90° North monthly mean temperature anomaly as a proxy to scale stratospheric downwelling. This results in a strong improvement of the correlation coefficient of the simulated and the observed year-to-year Δ(17O) variations at Lutjewad over 2019 and 2022 from 0.37 to 0.81 (N=22). To infer terrestrial carbon fluxes, the contribution of the stratosphere to the observed signal should therefore be considered. In fact, as the Δ(17O) of atmospheric CO2  seems to be dominated by stratospheric influx, it might be used as a tracer for stratosphere-troposphere exchange. To further study the potential of Δ(17O) of atmospheric CO2 as a tracer for stratosphere-troposphere exchange at Lutjewad, we installed a laser absorption spectrometer at the measurement station for in-situ measurements. At Lutjewad numerous other atmospheric species are monitored, such as N2O, Rn and 14C. This will enable us to deepen our knowledge on the mechanisms that drive the interannual variability of Δ(17O) of atmospheric CO2  that we observe at Lutjewad.

 
 

How to cite: Steur, P., Scheeren, H. A., Koren, G., Adnew, G. A., Peters, W., and Meijer, H. A. J.: Interannual variations in Δ(17O) of atmospheric CO2 suggest a strong link with stratospheric input, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6354, https://doi.org/10.5194/egusphere-egu24-6354, 2024.

We present a project aiming to provide a new estimate of the parameter known as "climate sensitivity" (symbol γL in the models) which is essential to constrain models of future climate change. This parameter describes how the amount of carbon sequestered by terrestrial ecosystems depends on temperature. Predictions of future climate by models show significant uncertainties associated with the estimates of carbon sequestration by terrestrial ecosystems with future temperature increases. Quantifying γL with data measured in the industrial era is very complicated because the terrestrial part of the carbon cycle is dominated by the effect of the increase in atmospheric CO2 (the so-called anthropogenic “fertilization” or CO2 concentration feedback, symbol βL in the models), while the effect of temperature is smaller. We will derive γL from measurements of ultra-trace gases trapped in polar ice cores in pre-industrial times.

The Little Ice Age (i.e. the period that roughly covers the centuries 1400-1800 AD) was characterized by temperatures lower than the average of the last millennium, due to intense volcanic activity and reduced solar activity. The global decrease in temperature has coincided with a decrease in the atmospheric concentration of CO2, mainly caused by sequestration from terrestrial ecosystems. Low CO2 concentrations contributed negligibly to the decrease in temperature, making the Little Ice Age a suitable time to derive γL.

Why CO2 decreased during the Little Ice Age is debated. On the one hand, considerations deriving from models that simulate the amount of carbon present in terrestrial ecosystems suggest that primary productivity increased during the Little Ice Age because of an anthropogenic effect. This increase would have been caused by pandemics and colonial conquests in America which led to a depopulation of cultivated lands and a regrowth of tree species. On the other hand, measurements of carbonyl sulphate (COS) and numerical calculations capable of closing the COS budget suggest that primary productivity naturally decreased during the Little Ice Age. In this second case, the decrease in CO2 would be caused by the fact that the respiration of terrestrial ecosystems decreased to a greater extent than the decrease in primary productivity. Therefore, if this second hypothesis is correct, it would be possible to derive γL from COS data covering the Little Ice Age.

Unfortunately, COS measurements covering the Little Ice Age have great uncertainty. It is therefore necessary to carry out new measurements of COS concentration during the Little Ice Age. The COS measurements will be accompanied by CO2 and δ13C-CO2 measurements, necessary to confirm, on the one hand, the working hypothesis, and, on the other, the quality of the ice samples used. Finally, future developments could build on measurements of COS isotopes in ice samples.

Rubino M., et al. Terrestrial uptake due to cooling responsible for low atmospheric CO2 during the Little Ice Age, Nature Geoscience, 9, 691-694 (2016)

How to cite: Iazzetta, D. and Rubino, M.: Quantification of the climate sensitivity of terrestrial ecosystems through the analysis of ultra-trace gases in ice cores over the last millennium, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7270, https://doi.org/10.5194/egusphere-egu24-7270, 2024.

EGU24-10052 | ECS | Posters on site | BG2.2

Atmospheric O2 and CO2 measurements at a single height provide weak constraint on the surface carbon exchange. 

Kim Faassen, Ingrid Luijkx, Jordi Vilà-Guerau de Arellano, Raquel González-Armas, Bert Heusinkveld, Ivan Mammarella, and Wouter Peters

The ratios of atmospheric tracers are often used to interpret the local CO2 budget, where measurements at a single height are assumed to represent local flux signatures. Alternatively, these signatures can be derived from direct flux measurements or using fluxes derived from measurements at multiple heights. In this study, we contrast interpretation of surface CO2 exchange from tracer ratio measurements at a single height versus measurements at multiple heights. Specifically, we analyse the ratio between atmospheric O2 and CO2 (exchange ratio, ER) above a forest canopy. We consider two alternative approaches: the exchange ratio of the forest (ERforest) obtained from the ratio of the surface fluxes of O2 and CO2, derived from their vertical gradients measured at multiple heights, and the exchange ratio of the atmosphere (ERatmos) obtained from changes in the O2 and CO2 mole fractions over time measured at a single measurement height. We investigate the diurnal cycle of both ER signals, with the goal to relate the ERatmos signal to the ERforest signal and to understand the biophysical meaning of the ERatmos signal. We combined CO2 and O2 measurements from Hyytiälä, Finland during spring and summer of 2018 and 2019 with a conceptual land-atmosphere model and a theoretical relationship between ERatmos and ERforest to investigate the behaviour of ERatmos and ERforest during different environmental conditions. We show that the ERatmos signal rarely directly represents the forest exchange, mainly because it is influenced by entrainment of air from the free troposphere into the atmospheric boundary layer. The resulting ERatmos signal is not the average of the contributing processes, but rather an indication of the influence of large scale processes such as entrainment or advection. We conclude that the ERatmos only provides a weak constraint on local scale surface CO2 exchange, because large scale processes confound the signal. Single height measurements therefore always require careful selection of the time of day and should be combined with atmospheric modelling to yield a meaningful representation of forest carbon exchange. More generally, we recommend to always measure at multiple heights when using multi-tracer measurements to study surface CO2 exchange.

How to cite: Faassen, K., Luijkx, I., Vilà-Guerau de Arellano, J., González-Armas, R., Heusinkveld, B., Mammarella, I., and Peters, W.: Atmospheric O2 and CO2 measurements at a single height provide weak constraint on the surface carbon exchange., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10052, https://doi.org/10.5194/egusphere-egu24-10052, 2024.

EGU24-10688 | Posters on site | BG2.2

A comprehensive model for COS isotope discrimination during leaf COS uptake 

Nerea Ubierna, Sophie L. Baartman, María Elena Popa, Jérôme Ogée, Maarten C. Krol, and Lisa Wingate

Anthropogenically emitted CO2 is warming the earth’s climate to temperatures that already exceed pre-industrial levels by more than 1.2 oC. Terrestrial vegetation has slowed the rate of climate change by removing part of this anthropogenic emission. Accurate estimations of the present and future terrestrial carbon sink are still needed for forecasting climate and for informing policies for climate stabilization. This requires precise knowledge of the photosynthetic C uptake over land (gross primary production, GPP), independently of the C released through plant and soil respiration. The gas carbonyl sulfide (COS) has emerged as a promising tracer for GPP. This is because both CO2 and COS are a substrate for carbonic anhydrase (CA), the first enzyme involved in photosynthesis, so that the uptake by foliage of COS and CO2 often covaries. Estimating GPP from COS measurements and atmospheric budgets also requires quantifying ocean and industrial COS sources, which is challenging. Isotopic constrained COS tropospheric mass balances can help quantify the relative contribution of these sources if the isotope discrimination during COS uptake by terrestrial vegetation (the main COS sink) is known. However, little is known about plant-atmosphere COS isotope exchange; measurements are challenging and theory to interpret these measurements is limited. Herein, we present a new comprehensive model for discrimination during COS uptake by plants (∆34S) and use it to revisit existing COS isotope datasets and atmospheric budgets. Our ∆34S model expands Davidson et al. (2022) pioneer framework by accounting for leaf COS production. By analogy with the well-established model for photosynthetic discrimination against 13CO2, Davidson et al. ∆34S model stated that COS discrimination occurs as COS diffuses into the leaf and binds to CA. Leaf COS emission was not considered, although it has been reported in species ranging from bryophytes to wheat and trees. Because it is uncertain where these emissions occur, we tested different leaf-level COS emission scenarios - including zero emissions - in various leaf compartments (cuticle, intercellular space, cytosol), alone or in combination. We used this comprehensive model to generate predictions for ∆34S in C3 and C4 species and discussed implications for determining a global plant uptake fractionation factor. Our mechanistic model provides a framework to interpret vegetation-atmosphere COS isotope exchange that can prove useful to improve COS uptake-based GPP estimates and our understanding of plant function, especially when combined with other isotopes (C, O, H).

How to cite: Ubierna, N., Baartman, S. L., Popa, M. E., Ogée, J., Krol, M. C., and Wingate, L.: A comprehensive model for COS isotope discrimination during leaf COS uptake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10688, https://doi.org/10.5194/egusphere-egu24-10688, 2024.

EGU24-11359 | ECS | Orals | BG2.2

Investigating the dust-induced N2O production in ice cores using bulk and position-specific isotope analysis 

Lison Soussaintjean, Jochen Schmitt, Joël Savarino, Andy Menking, Edward Brook, Barbara Seth, Thomas Röckmann, and Hubertus Fischer

Ice cores represent the only direct paleo-atmospheric archive that allow the reconstruction of greenhouse gas concentrations such as N2O. However, processes in the ice can alter the atmospheric information stored in air bubbles, for example by adding extra N2O by in situ production. This in situ production of N2O is especially severe in mineral dust-rich ice core sections corresponding to glacial periods. Understanding the production process and its link to the mineral dust content is key to systematically detecting altered samples and correcting for the in situ contribution. Isotope analysis is particularly useful for characterizing these processes and thus isolating the paleoclimatic signal from archived data. 

We measured the bulk nitrogen and oxygen isotopic composition of N2O in Antarctic and Greenland ice cores from glacial periods. The isotopic signatures of N2O produced in situ, calculated using a mass balance approach, differ from that of the atmospheric N2O. In addition, enrichment or depletion in 15N and/or 18O relative to atmospheric values varies with drilling site, snow accumulation rate, and properties of the snow-ice transition. Interestingly, isotopic signatures of nitrate (NO3-) exhibit similar dependencies. It is well established that NO3- is drastically altered by post-depositional processes in low accumulation areas. Joint isotopic analysis of N2O and NO3- in samples from the EDC and EDML ice cores revealed a correlation between δ15N values of NO3- and in situ N2O, pointing to NO3- as a potential precursor for in situ production. While being linearly correlated, the nitrogen isotopic signature of NO3- is twice as enriched as in situ produced N2O. This suggests that the two N atoms of N2O originate from two distinct sources and only one is likely derived from nitrate.

We additionally measured the site preference of 15N in N2O in ice core samples (SP = δ15Nα - δ15Nβ, where α is the central and β the terminal N atom in the N2O molecule). Previous work on SP suggests that SP might be indicative of the N2O formation pathway provided both N atoms are derived from the same N precursor. The SP signature in Vostok samples ranges from +57 to +242 ‰, and the δ15Nα values from +92 to +234 ‰, which is comparable to the δ15N values of NO3- at Vostok. Although similar reaction pathways were expected in different ice cores, in situ N2O from Taylor Glacier samples exhibits very different SP values from -17 to -7 ‰, with δ15Nα values from -45 to -32 ‰. Given that the difference in δ15N of NO3- is also up to 200 ‰ between these two locations, our findings suggest that the center-position nitrogen (α) of in situ N2O comes from NO3- and the terminal-position nitrogen (β) from another N-bearing compound. Thus, the SP signature seems to reflect not the N2O formation pathway but the difference in δ15N of the two nitrogen pools involved in the reaction.

Gaining a thorough understanding of the N2O production in ice marks a significant advancement towards interpretation of the N2O record and possibly correction for in situ production.

How to cite: Soussaintjean, L., Schmitt, J., Savarino, J., Menking, A., Brook, E., Seth, B., Röckmann, T., and Fischer, H.: Investigating the dust-induced N2O production in ice cores using bulk and position-specific isotope analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11359, https://doi.org/10.5194/egusphere-egu24-11359, 2024.

EGU24-13219 | ECS | Orals | BG2.2

Deciphering the origin of methane in fracture fluids at Virginia gas field using clumped isotope tracers. 

Orestis Gazetas, Andrew Houston, Matthieu Clog, Issaku Kohl, and Fin Stuart

The Witwatersrand Basin is a well-known area due to the immense gold mineralisation and mining activities, which have been ongoing since the late 19th century. The Virginia Gas Field, located in the southernmost extent of the basin, has recently gained further attention due to the discovery of gases with remarkable helium content of up to 12% and methane content between 75-99%. While the helium generation is likely straightforward and linked to the U-rich Dominion (2.9-3.0 Ga) and Central Rand (2.7-2.8 Ga) groups (Lippmann-Pipke et al., 2003), the origin of methane seems more complex but ultimately significant, with economic potential and implications for the evolution of life .

Stable isotopic compositions of carbon and hydrogen (δ13C and δD) along with molecular compositions (C1/C2+) are traditionally considered useful for understanding the origin of methane in natural gas reservoirs but can often be ambiguous or misleading. The recent development of HR-IRMS allows us to delve deeper into the distribution of isotopes beyond bulk ratios by introducing two additional tracers, the clumped isotopic compositions Δ13CH3D and Δ12CH2D2. These novel tracers offer two additional dimensions which can potentially provide insights into the formation pathways and formation or re-equilibration temperature of methane.

For this study, we measured bulk and clumped isotopic compositions along with molecular compositions for samples collected from shallow boreholes (300-700m depth) within the Virginia gas field production area. Here, we present evidence that the bulk and clumped isotopic compositions are governed by the microbial cycling of CH4 due to the presence of ancient microbial communities of methanogens and methanotrophs at depths below 1km (Omar et al., 2003). We also consider the possibility of mixing microbial methane with abiotic gas resulting from water-rock interactions occurring in the deep subsurface.

References

1. Lippmann-Pipke, J., Stute, M., Torgersen, T., Moser, D.P., Hall, J., Lin, L., Borcsik, M., Bellamy, R.E.S. and Onstott, T.C., 2003. Dating ultra-deep mine waters with noble gases and 36Cl, Witwatersrand, South Africa. Geochimica Cosmoshimica Acta, 67, pp.4597-4619.

2. Omar, G.I., Onstott, T.C. and Hoek, J., 2003. The origin of deep subsurface microbial communities in the Witwatersrand Basin, South Africa as deduced from apatite fission track analyses. Geofluids, 3(1), pp.69-80.

 

How to cite: Gazetas, O., Houston, A., Clog, M., Kohl, I., and Stuart, F.: Deciphering the origin of methane in fracture fluids at Virginia gas field using clumped isotope tracers., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13219, https://doi.org/10.5194/egusphere-egu24-13219, 2024.

EGU24-13866 | Posters on site | BG2.2

Laser absorption spectroscopy-based ultraportable analyzer for δ18O and δ2H in water. 

Akshay Nataraj, Susan Fortson, Frederic Despagne, Julio Lobo Neto, and Doug Baer

Stable isotope analysis of water 2H2O and H218O are powerful tracers to understand the different hydrological processes like ecohydrological processes, and hydroclimatic processes [1]. The measurement of δ2H and δ18O in water samples using laser-based absorption techniques is adopted increasingly in hydrologic and environmental studies. In contrast to the conventional Isotope ratio mass spectrometry (IRMS) technique, optical absorption spectroscopic techniques allow the realization of isotopologue-specific, non-destructive, and compact spectrometers with short analysis times with high-precision capabilities.

ABB’s ultraportable water analyzers are compact, portable field-deployable laser spectrometers capable of making continuous, high-frequency measurements of δ18O and δ2H from multiple water sources. The instrument is based on Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) technique [2]. These analyzers are capable of measuring liquid water (GLA132-LWIA) or vapor (GLA132-WVIA).  They are rugged and designed to handle both natural and isotopically enriched water samples.  Users can leverage the precision and speed of the GLA132-LWIA by coupling it with a portable auto-injector to perform automated, unattended injection patterns on multiple samples.

An important asset of this innovative approach based on OA-ICOS technology coupled with the portable auto-injector technology is its sample throughput, which allows one to measure approximately 90 samples a day corresponding to 720 injections each with a sample volume of 0.5 µL per injection per day. The precision (1σ) achieved corresponds to 0.6 ‰ for δ2H and 0.2 ‰ for δ18O. The analyzer’s ease of use, field portability, durability, and high throughput make it an excellent choice for reliable, high-performance measurement of freshly collected samples in the field, thereby opening a plethora of applications to understand the different processing governing the earth’s climate.

[1] Tian, C.,et al., Sci Rep 8, 6712 (2018). https://doi.org/10.1038/s41598-018-25102-7

[2] A. O’Keefe, et al., Chemical Physics Letters, vol. 307, no. 5, pp. 343–349, Jul. 1999, doi: 10.1016/S0009-2614(99)00547-3.

How to cite: Nataraj, A., Fortson, S., Despagne, F., Lobo Neto, J., and Baer, D.: Laser absorption spectroscopy-based ultraportable analyzer for δ18O and δ2H in water., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13866, https://doi.org/10.5194/egusphere-egu24-13866, 2024.

 Nitrous oxide (N2O), known for its ozone-depleting potential and characterized by a long residence time of 120 years in the atmosphere, is the third most significant anthropogenic greenhouse gas after CO2 and CH4. Primary sources of N2O include nitrification and denitrification processes in soils and aquatic systems, as well as from direct anthropogenic sources such as fossil fuel combustion and wastewater treatment plants. The increase in N2O emissions due to agricultural activities and urbanization is complex, given the high variability of these emissions. To characterize anthropogenic N2O sources, we collected air samples from tunnels and wastewater treatment plants. Additionally, to establish the background levels for Seoul, a megacity in South Korea, we collected ambient air from three sites (Mt Gwanak, Mt Nam, and Olympic Park) monthly throughout the year 2023. These air samples were measured for greenhouse gas concentrations (CO2, CH4, and N2O), and the stable isotopic compositions of N2O (δ15Nbulk, δ18O, and SP values) were analyzed using IRMS. The stable isotopic ratios of N2O emitted from the vehicles were determined as 6.0 ± 1.2 ‰ for δ15Nbulk, 34.4 ± 11.7 ‰ for δ18O, and 6.0 ± 4.2 ‰ for SP values. Furthermore, N2O from wastewater treatment plant water tank air exhibited variations dependent on dissolved oxygen levels. Notably, the stable isotopic compositions of N2O from anthropogenic sources were consistently depleted compared to the ambient air of Seoul (δ15Nbulk: 5.9± 0.2 ‰, δ18O: 43.8 ± 0.1 ‰, SP: 18.6 ± 0.3 ‰ (S.E.)). Intriguingly, while δ15Nbulk and δ18O values of ambient air were depleted relative to the global average, SP values exhibited a wide range and significant variability. This suggests the presence of pronounced spatial and temporal variabilities in N2O emissions, underscoring the need for further research to understand the extent of anthropogenic impacts.

How to cite: Kim, J., Ahn, J., and Toyoda, S.: Nitrous oxide emissions and stable isotopic composition in urban sources and ambient air in Seoul, South Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13954, https://doi.org/10.5194/egusphere-egu24-13954, 2024.

EGU24-15555 | ECS | Orals | BG2.2

Tracing diurnal variations of carbon and water cycle tracers over a tropical and temperate forest 

Gerbrand Koren, Kim A. P. Faassen, Raquel González-Armas, Getachew Agmuas Adnew, Hella van Asperen, Hugo de Boer, Santiago Botía, Oscar Hartogensis, Lucas Hulsman, Ronald W. A. Hutjes, Sam P. Jones, Shujiro Komiya, Ingrid T. Luijkx, Wouter Mol, Michiel van der Molen, Robbert Moonen, Thomas Röckmann, and Jordi Vilà-Guerau de Arellano

Diurnal temperature and carbon dioxide ranges are key metrics to quantify the impact of regional climate changes in forests. These ranges depend on biophysical processes, surface heat, water and carbon exchange, and boundary-layer dynamics. A crucial and elusive process is the entrainment of air from the free troposphere and residual air layers into the atmospheric boundary layer. Here we provide observational constraints on entrainment for two contrasting measurement sites: the Amazon Tall Tower Observatory (ATTO) in central Amazonia and the Loobos flux tower (NL-Loo) in a temperate forest in the Netherlands. We used radio soundings, air samples from tall towers and aircraft data in combination with surface air measurements and ecophysiological data. Fluxes and concentrations were measured for biophysical-process tracers  CO2, O2/N2, δ13C, δ18O (in CO2) and δ18O (in water). These novel tracers are proposed to partition gross carbon and water fluxes and for estimating plant properties and we present a unique dataset with our interpretation. Our analysis enables us to unravel the role of entrainment on the diurnal ranges and how this is controlled by surface and entrainment fluxes. By means of a coupled forest-atmosphere model constrained by the comprehensive observations, we perform a sensitivity study on the surface flux partitioning (photosynthesis versus soil respiration; soil evaporation versus plant transpiration, sensible versus heat flux) under a wide range of leaf traits, surface and boundary-layer dynamic conditions. Our results are useful to assess the performance of carbon-climate models in tropical and temperate forests.

How to cite: Koren, G., Faassen, K. A. P., González-Armas, R., Adnew, G. A., van Asperen, H., de Boer, H., Botía, S., Hartogensis, O., Hulsman, L., Hutjes, R. W. A., Jones, S. P., Komiya, S., Luijkx, I. T., Mol, W., van der Molen, M., Moonen, R., Röckmann, T., and Vilà-Guerau de Arellano, J.: Tracing diurnal variations of carbon and water cycle tracers over a tropical and temperate forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15555, https://doi.org/10.5194/egusphere-egu24-15555, 2024.

EGU24-15916 | ECS | Orals | BG2.2

Source apportionment of sulfate aerosols over South Asia using δ34S 

Sean Clarke, Henry Holmstrand, Krishnakant Budhavant, Manoj Remani, and Örjan Gustafsson

Sulfate aerosols are short lived climate forcers that cool the climate, but at the cost of human health and the environment. Their short lifetime leads to an unequal global distribution, with massive emissions in South Asia, resulting in some of the highest atmospheric loadings. These emissions originate from natural and anthropogenic sources, with their relative contributions uncertain, due to emissions being short lived and diffuse. However, the stable isotopic composition (δ34S), holds some promise of improved apportionment of sulfate sources. The aim was to leverage this isotopic composition to distinguish sources of sulfate aerosols intercepted at the Maldives Climate Observatory Hanimaadhoo (MCOH). This site is strategically located to intercept a wide footprint of the outflow from South Asia.

The results demonstrated that non-sea salt sulfate was largely of anthropogenic origin, contributing 93±21%, 85±14%, 61±20% in winter, spring, and summer, respectively. This study also found a moderate to strong correlation (r2 = 0.68) between continental anthropogenic (winter and spring) sulfate (δ34S) and fossil fuel black carbon (δ13C, Δ14C). This study provides improved constraints on sulfate sources in South Asia using stable δ34S isotopic analysis, which builds a foundation for future investigations aimed at unravelling the nexus of sulfate emissions in South Asia.

How to cite: Clarke, S., Holmstrand, H., Budhavant, K., Remani, M., and Gustafsson, Ö.: Source apportionment of sulfate aerosols over South Asia using δ34S, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15916, https://doi.org/10.5194/egusphere-egu24-15916, 2024.

EGU24-16015 | ECS | Posters on site | BG2.2

From over to under, a story about the vertical within-canopy variation of the leaf relative uptake rate of COS 

Felix M. Spielmann, Albin Hammerle, Katharina Scholz, Gil Putz, Lorenz Hänchen, Anna De-Vries, and Georg Wohlfahrt

The gross primary productivity (GPP), which represents the gross uptake of carbon dioxide (CO2) by plants, cannot be directly measured at the ecosystem level. It must instead be inferred either by applying models or by measuring proxies. A notable proxy is the trace gas carbonyl sulfide (COS), which is particularly interesting because it follows a pathway into plant leaves similar to CO2 and, unlike CO2, is generally not reemitted.

To utilize COS as a tracer for GPP, the leaf relative uptake (LRU)—the ratio of the deposition velocities of COS to CO2 at the leaf level—must be known a priori. Initial studies suggested that LRU values were relatively constrained, around 1.7. However, it has been observed that LRU varies between plant species and is influenced by environmental factors such as drought, vapor pressure deficit (VPD), and photosynthetically active radiation (PAR).

The variation in LRU related to PAR is due to COS primarily being catalyzed by the enzyme carbonic anhydrase in a light-independent reaction, contrasting with CO2 uptake via photosynthesis, which is dependent on PAR. Consequently, LRU increases under lower light conditions, even when stomatal control on both gases is similar.

This light dependency prompts questions about LRU variation within canopies. While most LRU chamber measurements have been conducted under laboratory conditions or in canopy crowns, additional data on LRU variability within canopies, particularly in lower light conditions, are necessary. A comprehensive understanding of LRU, encompassing both crown and shadow-adapted leaves at various canopy positions and considering stand species composition, is essential for accurately calculating GPP at the ecosystem scale using eddy covariance (EC) measurements.

To investigate how LRU varies within the canopy, particularly in response to environmental factors like PAR and VPD, and to compare the LRUs from different chamber measurements to EC measurements, we conducted a measurement campaign in an Austrian Pine forest. This included ongoing eddy covariance measurements of COS, CO2, and H2O, supplemented by manual measurements of the same gases using branch chambers at three levels within the Pinus sylvestris canopy and three additional chambers of Juniperus communis.

Above 400 µmol photons m² s PAR, where we consider the LRU to be light independent, the LRU reached 1.61±0.3 at the top of the crown and decreased to 1.55±0.4 and 1.56±0.3 going consecutively deeper into the canopy of Pinus sylvestris. In contrast, the LRU of Juniperus communis in the understory was notably lower, at 1.41±0.4. Between 100 and 400 µmol photons m² s PAR, the LRUs increased to 1.81±0.3 and 1.69±0.5 for the upper and middle canopy layers, respectively, while decreasing to 1.43±0.2 and 1.19±0.2 in the lower parts of Pinus sylvestris and Juniperus communis, respectively. This decrease in LRU deeper within the canopy is attributed to a greater reduction in COS compared to CO2 deposition velocity of the leaves. The median LRU above 800 µmol photons m² s PAR, based on classical daytime flux partitioning for the summer month of 2022, was 2.5±0.7, indicating the need for further investigation into the observed discrepancy in LRU.

How to cite: Spielmann, F. M., Hammerle, A., Scholz, K., Putz, G., Hänchen, L., De-Vries, A., and Wohlfahrt, G.: From over to under, a story about the vertical within-canopy variation of the leaf relative uptake rate of COS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16015, https://doi.org/10.5194/egusphere-egu24-16015, 2024.

EGU24-16376 | ECS | Orals | BG2.2

Development and verification of preconcentrator to measure clumped isotopologues (Δ13CH3D and Δ12CH2D2) of methane from the atmosphere and sources 

Sara Defratyka, Chris Rennick, Freya Wilson, Matthieu Clog, Andrew Houston, and Tim Arnold

Bulk isotopic signatures (δ13C-CH4 and δD-CH4) are widely used for determination of methane source types and relative contributions. For example, these measurements are implemented as additional tracers in top-down studies. However, for some sources, for example certain fossil fuels sources in Europe and waste sector, the bulk isotopic signatures are overlapping, thus some methane sources remain indistinguishable1–4.

The multiply substituted (clumped) isotopes can be used as additional tracers to better distinguish methane sources, and potentially, better understand methane sinks. Measurement of methane clumped isotopes, Δ13CH3D and Δ12CH2D2 is more challenging than measurements of bulk isotopes and requires more advanced instruments 3,5–8. Currently, a NERC project called POLYGRAM aims to develop the sample preparation (automated preconcentration) and measurement infrastructure to measure atmospheric air samples using High Resolution - Isotope Ratio Mass Spectrometer (HR-IRMS), to determine clumped isotopes from air samples collected at the world-recognised global monitoring sites at Cape Point, South Africa and station Zeppelin, Svalbard. Moreover, the project also aims to determine the clumped isotopes ratios of methane sources, like wetlands, agriculture or coal mines, as currently clumped isotopes database is constrained.

Use of custom-built preconcentrator is a key step in the measurement chain, as HR-IRMS requires ultra-pure methane samples to measure clump isotopes. For ambient air studies, our aim is to obtain, at ambient pressure, a 150 ml sample containing at least 1% of methane from hundreds of litres of ambient air, where CH4 mole fraction is less than 2 ppm. To achieve it, we aim to concentrate methane in our sample by up to 62500 times. Additionally, we develop our preconcentrator to prepare samples containing at least 1% of methane from gas samples containing <1% CH4, like air in coal mines, landfill emissions, etc. During the conference, we will be focused on overcoming technical and scientifical challenges and made progress in developing CH4 preconcentrator. We will present the results of validation exercises to ensure repeatability and lack of fractionation effects, both for ambient air and methane source samples.

References:

  • Turner, A. J., Frankenberg, C. & Kort, E. A. Interpreting contemporary trends in atmospheric methane. Proc. Natl. Acad. Sci. 116, 2805–2813 (2019).
  • Saunois, M. et al. The Global Methane Budget 2000–2017. Earth Syst. Sci. Data 12, 1561–1623 (2020).
  • Chung, E. & Arnold, T. Potential of Clumped Isotopes in Constraining the Global Atmospheric Methane Budget. Glob. Biogeochem. Cycles 35, (2021).
  • Menoud, M. et al. New contributions of measurements in Europe to the global inventory of the stable isotopic composition of methane. Earth Syst. Sci. Data 14, 4365–4386 (2022).
  • Douglas, P. M. J. et al. Methane clumped isotopes: Progress and potential for a new isotopic tracer. Org. Geochem. 113, 262–282 (2017).
  • Haghnegahdar, M. A., Schauble, E. A. & Young, E. D. A model for 12CH2D2 and 13CH3D as complementary tracers for the budget of atmospheric CH4. Glob. Biogeochem. Cycles 31, 1387–1407 (2017).
  • Sivan, M. & Röckmann, T. Extraction, purification, and clumped isotope analysis of methane (Δ13CDH3 and Δ12CD2H2) from sources and the atmosphere. (2023).
  • Haghnegahdar, M. A. et al. Tracing sources of atmospheric methane using clumped isotopes. 120, (2023).

How to cite: Defratyka, S., Rennick, C., Wilson, F., Clog, M., Houston, A., and Arnold, T.: Development and verification of preconcentrator to measure clumped isotopologues (Δ13CH3D and Δ12CH2D2) of methane from the atmosphere and sources, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16376, https://doi.org/10.5194/egusphere-egu24-16376, 2024.

EGU24-20240 | Posters on site | BG2.2

Pros and cons of methane clumped isotope analysis by high-resolution isotope-ratio mass spectrometry and laser absorption spectroscopy 

Naizhong Zhang, Ivan Prokhorov, Nico Kueter, Stefano Bernasconi, Mayuko Nakagawa, Alexis Gilbert, Yuichiro Ueno, Béla Tuzson, Lukas Emmenegger, and Joachim Mohn

Bulk isotope analytical methods of CH4 quantify carbon and hydrogen isotope ratios (δ13C and δD) to provide information on the sources and sinks of CH4 in natural environments. A more extensive tracing of CH4 pathways, especially when multiple processes and sources are involved, has been realized by novel measurements techniques capable of methane clumped isotope analysis (termed as Δ13CH3D and Δ12CH2D2) during the past decade. These paired datasets can either be used as proxy for exploring CH4 formation temperatures under thermodynamic equilibrium, or studying contributions of kinetically controlled processes during CH4 formation and consumption1.

Currently, methane clumped isotope analysis is performed by two different techniques: isotope-ratio mass spectrometry (e.g. 253 Ultra from Thermo Fisher Scientific2 or Panorama from Nu Instruments1) or laser absorption spectroscopy (e.g. QCLAS from Aerodyne Research3,4), both of which have demonstrated a precision better than 0.5‰ for Δ13CH3D and 1.5‰ for Δ12CH2D2, which is sufficient for most applications. This work will provide insights about the main instrumental features, measurement protocols and performance of the 253 Ultra HR-IRMS at Tokyo Institute of Technology (Japan)2,5, and the QCL absorption spectrometer at Empa (Switzerland)4. Furthermore, advantages and limitations of both techniques during current applications in natural methane samples are discussed. Finally, perspectives for future applications at low CH4 concentrations, such as atmospheric monitoring, are provided.

 

References:

  • Young et al., 2017, Geochimica et Cosmochimica Acta; 2. Dong et al., 2020, Thermo Scientific white paper; 3. Gonzalez et al., 2019, Analytical Chemistry; 4. Prokhorov and Mohn, 2022, Analytical Chemistry; 5. Zhang et al., 2021, Geochimica et Cosmochimica Acta

How to cite: Zhang, N., Prokhorov, I., Kueter, N., Bernasconi, S., Nakagawa, M., Gilbert, A., Ueno, Y., Tuzson, B., Emmenegger, L., and Mohn, J.: Pros and cons of methane clumped isotope analysis by high-resolution isotope-ratio mass spectrometry and laser absorption spectroscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20240, https://doi.org/10.5194/egusphere-egu24-20240, 2024.

EGU24-20419 | ECS | Orals | BG2.2

Stratospheric observations of carbonyl sulfide using AirCore and LISA 

Alessandro Zanchetta, Steven van Heuven, Jin Ma, Maarten Krol, and Huilin Chen

Carbonyl sulfide (COS) is a long-lived sulfur compound present in the atmosphere with an average mole fraction of around 450-500 ppt, and is considered as a potential tracer to partition gross primary production (GPP) and net ecosystem exchange (NEE) in plants’ photosynthesis, possibly by satellite observations. However, its sources and sinks  are not fully understood, and remote sensing observations of COS still require validation and need to be linked with a reference measurement scale, e.g., NOAA’s. In this work, we present vertical profiles of COS mole fractions obtained in Trainou, France (47°58' N, 2°06' E) in June 2019, in Kiruna, Sweden (67°53' N, 21°04' E) in August 2021, and in Sodankylä, Finland (67°22'N, 26°37'E) in August 2023 using AirCore samplers and two versions of the lightweight stratospheric air (LISA) sampler. Additionally, simultaneous measurements of CO2, CO, CH4 and N2O have been made. Measurement methods (i.e., LISA vs AirCore) will be compared. Moreover, the retrieved COS profiles will be compared with COS FTIR remote sensing observations and COS simulations from the TM5-4DVAR modeling system, to get a better understanding of the behavior of these species in the stratosphere, i.e., the sources and the sinks of COS, as well as vertical structures due to atmospheric transport. Furthermore, these stratospheric observations could be used to estimate the stratospheric lifetime of COS. These findings will improve our understanding of the budget and the variabilities of COS in the stratosphere, and advance the use of remote sensing observations of COS from satellite and ground-based spectrometers to study the global cycle of COS.

How to cite: Zanchetta, A., van Heuven, S., Ma, J., Krol, M., and Chen, H.: Stratospheric observations of carbonyl sulfide using AirCore and LISA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20419, https://doi.org/10.5194/egusphere-egu24-20419, 2024.

EGU24-21410 | ECS | Posters on site | BG2.2

Characterization of the isotopic signature in methane from several biogenicsources in the central Amazon 

Santiago Botía, Shujiro Komiya, Sam P. Jones, Ingrid Chanca, Viviana Horna, Gisela Dajti, Getachew A. Adnew, Sipko Bulthuis, Jochen Schöngart, Maria Teresa Fernandez Piedade, Florian Wittmann, Daniel Magnabosco Marra, Michael Rothe, Heiko Mossen, Armin Jordan, Thomas Röckmann, Jost Lavric, Carlos Sierra, Susan Trumbore, and Hella van Asperen

The decreasing global trend in 𝛿13𝐶 − 𝐶𝐻4 suggests that rising biogenic sources of methane are a plausible explanation for the current methane atmospheric growth rate. Furthermore, tropical wetlands represent one of the largest sources of uncertainty in the global methane budget and the Amazon basin plays a crucial role in this context as approximately 20% of its area is annually flooded. However, the availability of methane isotopic composition data for tropical wetlands is scarce, undermining our understanding of these tropical sources.

In this study, we present results from two sampling campaigns during the dry season, one in September 2019 and the other in August 2022. During each campaign, we collected air samples at different locations within the area around the Amazon Tall Tower Observatory (ATTO), such as in a black-water seasonally flooded forest (i.e. igapó), in an upland swampy valley (i.e. baixio), at the Uatumã black-water river and on the 80-m tower located on the upland terra-firme forest at the ATTO site. Air samples were collected with pressurized glass flasks and pre-evacuated vials and were analyzed for the isotopic composition of methane (𝛿13𝐶 and 𝛿𝐷 ) with gas source isotope ratio mass spectrometer. We estimated isotopic source signatures of CH4 emissions from the four different sites using the intercept of an orthogonal fit in a Keeling plot.

Relative to the Amazon atmospheric background value of -59 ‰ per mill (Beck et al., 2012), our isotopic source signatures are more depleted in 𝛿13𝐶 ranging from -60 ‰ to -68 ‰, which confirms -as expected- a strong wetland-related biogenic source. Within this range, methane source signatures from areas near the Uatumã river (-68 ‰) and a periodically flooded valley (representing small streams of the region) have more depleted signatures (- 66 ‰). Using this range of source 𝛿13𝐶 signatures we explore the possibility of identifying different biogenic sources at the Tower based on continuous measurements (in-situ) of

𝛿13𝐶 − 𝐶𝐻4 and a Lagrangian atmospheric transport model to obtain the isotopic background (i.e. the isotopic signature of the air masses before entering the continent). Our results contribute valuable insights into the methane isotopic signature for different ecosystem types in central Amazonia, which could serve as a reference for measurement-based source attribution studies as well as a based on measurements and also for atmospheric transport modeling estimates.

How to cite: Botía, S., Komiya, S., Jones, S. P., Chanca, I., Horna, V., Dajti, G., Adnew, G. A., Bulthuis, S., Schöngart, J., Fernandez Piedade, M. T., Wittmann, F., Marra, D. M., Rothe, M., Mossen, H., Jordan, A., Röckmann, T., Lavric, J., Sierra, C., Trumbore, S., and van Asperen, H.: Characterization of the isotopic signature in methane from several biogenicsources in the central Amazon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21410, https://doi.org/10.5194/egusphere-egu24-21410, 2024.

EGU24-5205 | ECS | Orals | BG2.4

Late Holocene hydroclimate dynamics in the northern Alps based on compound-specific δ2H from Schliersee, Germany 

Maximilian Prochnow, Katharina Dulias, Paul Strobel, Marcel Bliedtner, Gerhard Daut, Sönke Szidat, Gary Salazar, Sudip Acharya, Rodrigo Martinez-Abarca, Anja Schwarz, Antje Schwalb, and Roland Zech

A comprehensive understanding of Holocene hydroclimate variability in the European Alps remains challenging because of the great spatial and temporal disparities between the northern and southern Alps, mainly caused by changes in atmospheric circulation patterns and different climate settings. Most of the hydroclimate studies are based on lake level and high-resolution flood reconstructions that can be potentially biased by catchment-specific effects and anthropogenic impacts. Moreover, floods are only single events and just one important aspect of paleohydrology. Phases of enhanced evaporation, transpiration and droughts are equally important ecologically and can occur between flooding events. Stable isotopes (δ18O) in speleothems and lake carbonates were applied to track past changes in atmospheric circulation and hydrology, but in the northern Alps, such studies mainly focus on the Late Glacial and Early Holocene.

We present the first compound-specific δ2H record based on terrestrial (n-C31) and aquatic (n-C25) n-alkanes from a sediment core collected from Schliersee, a pre-alpine lake located in Bavaria (Germany), and covering the Late Holocene (past ~4.3 ka). Based on previous calibration studies and new data, we use the δ2H record of n-C31 as a proxy for the isotopic composition of precipitation. We find that δ2Hn-C31 from Schliersee shows depleted values between ~1200 and ~500 cal. yr BP and enriched values before (2500 – 1200 cal. yr BP) and thereafter (500 cal. yr BP until today). This pattern is in good agreement with speleothem δ18O from Spannagel cave, Austria, and compound-specific δ2H from Lake Ghirla, southern Alps and was previously interpreted to reflect changes in moisture source. Therefore, our results support the concept that northern hemispheric cooling and changes in the North Atlantic Oscillation cause changes in moisture source related to shifts in the position of the Westerlies. Based on our results we conclude that this mechanism seem to have affected the isotopic composition of precipitation in both northern and southern Alps.

Moreover, aquatic δ2Hn-C25 is enriched by several tens of permille compared to terrestrial δ2Hn-C31, because of evaporative enrichment of lake water (Grafenstein & Labuhn, 2021 in: Ramstein et al., Springer Cham). Thus, we use their isotopic difference, expressed by Δaq–terr, as a proxy for evaporative enrichment. Our Δaq–terr shows a striking coincidence with tree-ring based drought reconstructions for Europe since the Medieval. This highlights that a “warm and dry” hydroclimate occurred during the Medieval (~1000 cal. yr BP), whereas “cool and wet” conditions prevailed during the Little Ice Age (~600 cal. yr BP). Furthermore, minima in Δaq–terr during the Little Ice Age seem to correspond to minima in solar forcing. High evaporative enrichment coincides with the observed anthropogenic warming during the last 250 years.

Our δ2H-record from Schliersee is consistent with other regional reconstructions and provides additional insights into the paleohydrology of the northern Alps. This highlights the potential of compound-specific δ2H analyses as a powerful tool for paleohydrological reconstructions and helps to better understand the hydroclimate dynamics across the Alps.

How to cite: Prochnow, M., Dulias, K., Strobel, P., Bliedtner, M., Daut, G., Szidat, S., Salazar, G., Acharya, S., Martinez-Abarca, R., Schwarz, A., Schwalb, A., and Zech, R.: Late Holocene hydroclimate dynamics in the northern Alps based on compound-specific δ2H from Schliersee, Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5205, https://doi.org/10.5194/egusphere-egu24-5205, 2024.

EGU24-7306 | ECS | Orals | BG2.4

Stable Middle Miocene seawater isotopes in the eastern North Atlantic Ocean 

Katrin Haettig, Stefan Schouten, and Marcel T.J. van der Meer

The Middle Miocene is a phase of gradual climate cooling, CO2 decline and major episodes of seaward Antarctic ice expansion across the Middle Miocene Climate Transition. The global benthic foraminifera oxygen isotopes (δ18Obenthic) show a long-term increase by approximately 1‰, reflecting bottom water cooling and increase in global ice volume, although the latter is subject of debate. Here, we used a relatively new proxy based on hydrogen isotopes of long-chain alkenones (δ2HC37), produced by Haptophyte algae, to reconstruct surface seawater isotopes (e.g., Schouten et al., 2006; Weiss et al., 2019; Gould et al., 2019). This proxy is, in contrast to δ18Obenthic, not temperature dependent. Enabling us to reconstruct the isotopic evolution of the surface seawater from marine sedimentary records up to 40 Million years ago.

Here, we compare foraminifera based oxygen isotope and alkenone based hydrogen isotope reconstructions of seawater from a shallow sediment record covering the Middle Miocene (IODP Site U1318, 409 m water depth, eastern North Atlantic Ocean, Sangiorgi et al., 2021). The local δ18Obenthic record shows a strong long-term increase across the Middle Miocene Climate Transition in agreement with global benthic stacks. However, our reconstructed surface seawater δ2H shows no long-term increasing trend and when correcting the local δ18Obenthic record for subsurface temperature with TEXH86, the bottom seawater δ18O record also shows no long-term trend. Our findings are in line with recently published records using clumped isotope temperatures which suggest a long-term decrease in temperature during the Middle Miocene large enough to explain the trend in oxygen isotopic composition of the benthic foraminifera without the need for a change in ice volume.

How to cite: Haettig, K., Schouten, S., and van der Meer, M. T. J.: Stable Middle Miocene seawater isotopes in the eastern North Atlantic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7306, https://doi.org/10.5194/egusphere-egu24-7306, 2024.

EGU24-8785 | Orals | BG2.4

A novel method for analyzing δ18O by laser ablation IRMS 

Elina Sahlstedt, Neil Loader, and Katja Rinne-Garmston

Fine-scale variations in the oxygen isotope composition (δ18O) of organic matrices, such as tree rings, provide an important proxy for past environmental conditions. In practice, however, sampling at high resolution is resource intensive and time consuming, requiring the precise cutting, processing, and weighing of sequential samples prior to mass spectrometry. These factors have limited the production of high-resolution δ18O data for research purposes. We have developed a novel method for analyzing δ18O in organic matrices using laser ablation mass spectrometry. This “online” method directly couples a UV laser ablation unit with an isotope ratio mass spectrometer (IRMS). Measurements are conducted on carbon monoxide (CO) gas produced during the laser ablation process. Thus, we sidestep the requirement for separate sample cutting and weighing steps and can take advantage of the high resolution and accurate positioning capabilities of the laser with significantly increased sample throughput and effectively non-destructive sampling. Preliminary results, conducted by analyzing woody materials, indicate a typical measurement precision of ≤0.5 ‰ at spatial resolution of 100µm (spot size). Running a single analysis with the new method takes approximately 15 minutes, which is comparable to a δ18O analysis run by conventional, thermal conversion IRMS. In the future, the new method is expected to provide a valuable tool for investigating fine-scale variation in δ18O in organic matrices.

How to cite: Sahlstedt, E., Loader, N., and Rinne-Garmston, K.: A novel method for analyzing δ18O by laser ablation IRMS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8785, https://doi.org/10.5194/egusphere-egu24-8785, 2024.

EGU24-8937 | Posters on site | BG2.4

A promising approach in isotope geochemistry: 87Sr/86Sr in human teeth and hair to study dietary and environmental effects. 

Ilenia Arienzo, Valeria Di Renzo, Carlo Pelullo, and Massimo D'Antonio

In recent years Sr isotope geochemistry has provided a huge contribution to environmental and food traceability studies. This is possible because soils, plants and water are characterized by a specific Sr isotopic signature (expressed through the 87Sr/86Sr ratio), which derives from the local geological substratum which, in turn, depends on geological processes and on the age and initial rubidium (Rb) content of the rocks, given that 87Rb decays to 87Sr over time. Since the relative abundance of Sr isotopes does not change during the path through the food chain, the 87Sr/86Sr ratio in human tissues reflects that of the “environment” in which people live and feed. In particular, tooth enamel (which forms during the first years of life) does not exchange with external Sr after mineralization. For this reason, its isotopic composition mostly reflects the 87Sr/86Sr of the food intake that individuals used for energy, growth and maintaining the processes of life, during their childhood.

In this work, the Sr isotopic characterization of deciduous human teeth and hair, water, soil, plants and food was carried out. Donors are all born and currently residing in Campania (Southern Italy), of different age and sex. The 87Sr/86Sr of deciduous teeth provides a direct link to the mother’s milk, or to the artificial milk, which are the first foods for the newborn individuals, whereas the 87Sr/86Sr of hair is directly related to the diet in adulthood. Moreover, the mother’s milk is in part related to the local geological substratum and in part to the diet that has become no longer local, but global. Despite adult individuals have different diets, the isotopic fingerprint of enamel teeth is similar for all breastfeed children. Results from this study have scientific implications also for human mobility studies.

How to cite: Arienzo, I., Di Renzo, V., Pelullo, C., and D'Antonio, M.: A promising approach in isotope geochemistry: 87Sr/86Sr in human teeth and hair to study dietary and environmental effects., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8937, https://doi.org/10.5194/egusphere-egu24-8937, 2024.

EGU24-9025 | ECS | Orals | BG2.4

A new lipid-based proxy for the reconstruction of past phytoplankton ecological dynamics 

Antonia Klatt, Cindy De Jonge, Daniel B. Nelson, Marta Reyes, Ricardo N. Santos, Fatemeh Ajallooeian, Carsten J. Schubert, Nathalie Dubois, and S. Nemiah Ladd

The composition of lacustrine phytoplankton communities plays a key role for biogeochemical cycling of carbon, nitrogen, and phosphorus. Through the linkage between lakes and terrestrial ecosystems, especially via carbon cycling and freshwater supply, changes in algal ecology can affect even non-aquatic habitats. To investigate past phytoplankton dynamics, paleolimnologists often rely on microscopic algal remains preserved in the sediment, e.g., diatom frustules. However, only few taxa produce fossil remains, and might not be fully representative for the phytoplankton community. Other studies have reconstructed phytoplankton dynamics based on source-specific algal lipids, but many lipids are not as source-specific as initially thought. Rather than focusing on specific lipid biomarkers, a more holistic analysis of algal lipid distributions and their isotopic composition might highlight shifts in the past phytoplankton community with a greater robustness.

In this study, we introduce a new lipid-based proxy to reconstruct past phytoplankton community changes based on the abundance and hydrogen isotope ratios (δ2H) of short-chain fatty acids, phytosterols and phytol. Previous culturing and mesocosm experiments have shown that the relative offset between δ2H values of different algal lipids (εlipid1-lipid2) strongly differs among phytoplankton groups. For instance, εpalmitic acid-phytol values for green algae and cyanobacteria were ~150 ‰ higher than for other taxa. To validate these results in a natural system, we collected algal biomass samples from the water column of Lake Rot, a small eutrophic lake in central Switzerland, every second week from 2019 to 2020. Phytoplankton and microplankton cell counts were conducted for every sampling date. εlipid1-lipid2 values and algal lipid distributions were measured and related to biovolume changes of different algal groups. We used algal δ2Hlipid values from previous culturing studies weighted by phytoplankton biovolume in Lake Rot to model algal εlipid1-lipid2 values. To assess the potential heterotrophic impact on εlipid1-lipid2 values, we created a second model to simulate εlipid1-lipid2 values incorporating δ2Hlipid values from algae and microplankton. For this, we included hydrogen isotope fractionation between algal and plankton lipids as well as microplankton biovolume in Lake Rot. Modeled εlipid1-lipid2 values showed generally a good agreement with measured εlipid1-lipid2 values, validating εlipid1-lipid2 values as a potential proxy for phytoplankton dynamics. Moreover, measured εlipid1-lipid2 values were clearly represented by modeled algal εlipid1-lipid2 values suggesting that δ2Hlipid values in eutrophic lakes primarily reflect phytoplankton community composition with a negligible impact from microplankton. Our analysis of algal lipid distributions in the water column of Lake Rot revealed a significant positive correlation between the ratios of phytol and phytosterols (phytol:sterol ratio) as well as the sum of C18 fatty acids and C16:0 (C18:C16 ratio) and cyanobacterial biovolume.

We further apply our new lipid-based approach to a ~14 m long sediment core from Lake Rot, enabling a paleoecological reconstruction of phytoplankton community dynamics during the past ~13 kyr. Sedimentary phytol:sterol ratios, C18:C16 ratios, and εpalmitic acid-phytol indicate rising cyanobacterial biovolume during the last ~4000 years. Moreover, we compare the magnitude of change in the algal community in response to 20th century eutrophication with the natural variability throughout the Holocene.

How to cite: Klatt, A., De Jonge, C., Nelson, D. B., Reyes, M., Santos, R. N., Ajallooeian, F., Schubert, C. J., Dubois, N., and Ladd, S. N.: A new lipid-based proxy for the reconstruction of past phytoplankton ecological dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9025, https://doi.org/10.5194/egusphere-egu24-9025, 2024.

EGU24-9906 | ECS | Posters on site | BG2.4

Unveiling geological identities: use of 87Sr/86Sr in food and beverages traceability, focusing on wines from Solopaca (Campania, Italy) 

Piergiorgio Tranfa, Valeria Di Renzo, Francesco Izzo, Alessio Langella, Mariano Mercurio, Vincenzo Mercurio, Piergiulio Cappelletti, and Massimo D'Antonio

Research on food and beverages traceability, i.e., assessing their environmental origin, has advanced significantly in recent years thanks in large part to strontium isotope geochemistry. The unique Sr isotope signature (87Sr/86Sr) found in soils, plants, and waters makes the relation between food/beverages and environment achievable. This signature is derived from the local geological substratum and is influenced by age and initial concentration of rubidium in the rocks, and to geological processes. The release of strontium ions from the bedrock due to weathering processes, resulting from the interaction of circulating fluids with rocks, contributes to the accumulation of Sr in waters and soils. Part of this Sr is bioavailable and its 87Sr/86Sr ratio can be used as a valid tracer to identify the region of origin of wines. Considering an original 87Sr/86Sr ratio in rocks and soil of a given locality, it is demonstrated that strontium is first absorbed by plant roots, then by grapes, and finally by wine, without isotopic fractionation. As a result, the analysis of the wine' Sr isotope ratio establishes a precise connection between the product and its geological provenance, giving each wine a unique geofingerprint. This study aims to verify the strong relationship between the product (wine) and its region by building on these foundations. The final objective is to make the wine recognizable and distinguishable from comparable products so that it can be protected from fraud and adulteration. Using the 87Sr/86Sr systematics, coupled with traditional analyses such as thermal, XRD and FTIR analyses, 24 samples (8 soil samples, 8 grape samples and 8 microvinification samples) from Solopaca (Campania, Italy) were investigated. In order to provide a thorough Sr-isotopic characterization, soil samples were analyzed for both total and bioavailable Sr fractions. This method improves the investigation of environmental processes at every stage of the wine-making process.

How to cite: Tranfa, P., Di Renzo, V., Izzo, F., Langella, A., Mercurio, M., Mercurio, V., Cappelletti, P., and D'Antonio, M.: Unveiling geological identities: use of 87Sr/86Sr in food and beverages traceability, focusing on wines from Solopaca (Campania, Italy), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9906, https://doi.org/10.5194/egusphere-egu24-9906, 2024.

EGU24-10248 | ECS | Posters on site | BG2.4

The hydrogen isotope footprint of source water in tree lignin methoxy groups 

Anna Wieland, Marco M. Lehmann, Claudia Guidi, Valentina Vitali, Paul Handrack, and Frank Keppler

The stable hydrogen isotope values of tree lignin methoxy groups (δ2Hmeth) show a robust relationship with source water hydrogen isotopes (δ2HSW), enabling the reconstruction of the source water origin using an average hydrogen isotopic fractionation (ε) of around -200 mUr between δ2Hmeth and δ2HSW values (Greule et al., 2021; Keppler et al., 2007). Reconstructed δ2HSW is currently mainly used for climatic reconstruction of temperature but could also be used to better understand ecohydrological processes such as root water uptake. As the use of lignin methoxy groups as a source water proxy is relatively new, there are still uncertainties regarding additional influences on δ2Hmeth interfering the reconstruction of δ2HSW. Factors such as temporal changes in the isotopic composition of source water, soil moisture, and changes in root system and biomass may influence lignin methoxy fractionation, and a better understanding of these factors is important to improve the application of this proxy.

Here, we analyzed wood samples collected from a dry pine forest in Switzerland, where an extensive irrigation experiment was conducted. The site was divided into eight plots and since 2003 four of these plots received irrigation during the growing season from a nearby channel fed by the Rhone River, doubling the annual precipitation amount in the irrigated (1200mm) compared to the control stands (600 mm). Irrigation water is about 46 ± 9 mUr more depleted in 2H than the soil water, resulting in average δ2H values of -76 vs -68 mUr in irrigated and control soil water (0-10 cm) (Guidi et al., 2023).

We present results of δ2Hmeth measurements from four irrigated and four control trees analyzed annually from 1990 to 2023. We observed a significant 2H depletion in the irrigated trees compared to the control trees, supporting the use of this proxy to reconstruct source water changes. By further comparing δ2Hmeth values of irrigated and control trees, including root and leaf samples, we gain additional insight into hydrogen isotope fractionation processes in trees, improving our understanding of the influences of biological processes on δ2Hmeth. With our study, we hope to contribute to the further development of a new ecohydrological proxy that potentially allows the reconstruction of past variations in root water uptake of plants.

References:

Greule, M., Wieland, A., Keppler, F., 2021. Measurements and applications of δ2H values of wood lignin methoxy groups for paleoclimatic studies. Quat. Sci. Rev. 268, 107107. https://doi.org/10.1016/j.quascirev.2021.107107

Guidi, C., Lehmann, M.M., Meusburger, K., Saurer, M., Vitali, V., Peter, M., Brunner, I., Hagedorn, F., 2023. Tracing sources and turnover of soil organic matter in a long-term irrigated dry forest using a novel hydrogen isotope approach. Soil Biol. Biochem. 184, 109113. https://doi.org/10.1016/j.soilbio.2023.109113

Keppler, F., Harper, D.B., Kalin, R.M., Meier-Augenstein, W., Farmer, N., Davis, S., Schmidt, H.L., Brown, D.M., Hamilton, J.T.G., 2007. Stable hydrogen isotope ratios of lignin methoxyl groups as a paleoclimate proxy and constraint of the geographical origin of wood. New Phytol. 176, 600–609. https://doi.org/10.1111/j.1469-8137.2007.02213.x

How to cite: Wieland, A., Lehmann, M. M., Guidi, C., Vitali, V., Handrack, P., and Keppler, F.: The hydrogen isotope footprint of source water in tree lignin methoxy groups, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10248, https://doi.org/10.5194/egusphere-egu24-10248, 2024.

EGU24-10626 | Posters on site | BG2.4

The hydrogen isotope composition of nocturnal sucrose does not reflect the 2H-depletion of remobilized leaf starch 

Meisha Holloway-Philips, Anina Wacker, Daniel B. Nelson, Guillaume Tcherkez, Marco Lehmann, and Ansgar Kahmen

The hydrogen isotope composition (δ2H) of cellulose is inherently linked to that of sucrose synthesised in leaves. During the daytime, sucrose is synthesised from photosynthetic products, and at night, from remobilised starch. From theory, the δ2H of starch should be 2H-depleted relative to triose-phosphates generated during photosynthesis. Consequently, sucrose δ2H values should diurnally vary so that on a flux-weighted basis, cellulose δ2H values could provide a sensitive proxy for the partitioning of photoassimilates between sucrose and starch. However, this hypothesis is yet to be tested.

We made diel measurements of sucrose and starch δ2H in three species – Vicia faba (bean), Raphanus sativus (radish), and Helianthus annuus (sunflower) differing in their sucrose/starch dynamics. Plants were grown under controlled environment conditions to minimise variation in leaf water δ2H and physiology, so that changes in sucrose δ2H could be attributed to day/night shifts in photoassmiliates vs transitory starch used for sucrose synthesis. We confirmed that transitory starch in leaves was 2H-depleted compared with sucrose, on average by around 100 ‰. However, whilst there were species-specific trends in daytime sucrose δ2H, surprisingly, there was no significant day-night difference in the three species. Several explanations are discussed for the lack of day/night variation in the δ2H of sucrose, including the signal being subsequently overwritten in the cytosolic processing of sugars or masked by 2H-enrichment at other positions to counteract the 2H-depleted starch signature. We qualify the latter possibility with a simplified steady-state isotopic model.

How to cite: Holloway-Philips, M., Wacker, A., Nelson, D. B., Tcherkez, G., Lehmann, M., and Kahmen, A.: The hydrogen isotope composition of nocturnal sucrose does not reflect the 2H-depletion of remobilized leaf starch, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10626, https://doi.org/10.5194/egusphere-egu24-10626, 2024.

EGU24-11920 | Posters on site | BG2.4

Hydrogen and oxygen isotopes in tree-ring cellulose as indicators of source water variations 

Marco Lehmann, Haoyu Diao, Meisha Holloway-Phillips, Fabian Bernhard, Katrin Meusburger, Georg von Arx, Arthur Gessler, and Matthias Saurer

Although the hydrogen (δ2H) and oxygen (δ18O) isotopic signature of tree rings is dependent on the environmental water, such as precipitation and soil water that trees have taken up (i.e. “source water”), estimating the spatio-temporal origin of water sources through analysis of water stable isotopes in tree rings is not a straightforward approach. This is because 1) our knowledge on the contribution and the variability of individual isotopic fractionation steps between source water and tree rings is limited, and 2) in situ measurements that consider the seasonality of the isotopic composition of source water and cellulose synthesis are rare.

Within the framework of the EU Cost Action WATSON (#CA19120 - WATer isotopeS in the critical zONe), we analyzed (1) δ2H and δ18O in tree-ring cellulose and stem sugar, (2) δ2H and δ18O in soil water at shallower (15 cm) and deeper (80 cm) depths in up to bi-weekly resolution and (3) modelled isotopic variations in precipitation, soil water, stem xylem water, and leaf water using mechanistic and process-based models for three long-term forest monitoring sites in Switzerland over 20 years. We used this data to explain intra-annual (2021-2022) and inter-annual (2003-2022) δ2H and δ18O variations in tree-ring cellulose of beech (Fagus sylvatica) and spruce (Picea abies).

At the intra-annual scale, preliminary findings indicate a pronounced isotopic enrichment in the second half of the growing season and marked seasonal variations in the isotopic composition of soil water at shallower depths compared to deeper layers. However, such fluctuations were strongly dampenend in the intra-annual δ2H and δ18O variations observed in the tree-ring cellulose and stem sugars of both tree species, which may indicate the use of deeper soil water sources or scrambling of the source water isotope signal because of isotope fractionation before cellulose synthesis. In further analyses at the inter-annual scale, we will investigate how well δ2H and δ18O in tree rings can function as indicators of source water through time-window correlation analysis between water and tree-ring stable isotopes and comparisons between measured and modelled data.

Our study aims to enhance models of hydrogen and oxygen isotope fractionation. This will improve the use of both elements in tree rings as innovative ecohydrological proxies for retrospectively reconstructing environmental water sources.

How to cite: Lehmann, M., Diao, H., Holloway-Phillips, M., Bernhard, F., Meusburger, K., von Arx, G., Gessler, A., and Saurer, M.: Hydrogen and oxygen isotopes in tree-ring cellulose as indicators of source water variations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11920, https://doi.org/10.5194/egusphere-egu24-11920, 2024.

EGU24-12594 | ECS | Orals | BG2.4

In situ estimation of hydrogen isotope fractionation associated with sucrose and cellulose synthesis from leaves to roots 

Jochem Baan, Meisha Holloway-Phillips, Daniel B. Nelson, and Ansgar Kahmen

Plant cellulose hydrogen (H) stable isotope compositions (δ2H) integrate hydrological and biochemical information, and therefore measurements from archives such as tree rings can be valuable for understanding past climate and plant metabolic responses to environmental change. Although the hydrological component that is integrated into cellulose δ2H values is relatively well understood, the biochemical reactions that can alter δ2H values of metabolites used for cellulose biosynthesis remain cryptic. Attempts at establishing models to simplify the interpretation of cellulose δ2H values have been made, like the widely used cellulose δ2H model by Roden et al. (2000) using the terms quantified by Yakir & DeNiro (1990). However, independent quantification of the parameters in this model, and assessment of their variability with respect to plant C metabolism, has been limited.

The cellulose δ2H model uses the δ2H compositions of leaf water and source water, autotrophic and heterotrophic 2H-fractionation (εA and εH, respectively), and the proportion of carbon (C) bound H that exchanges with xylem water during cellulose biosynthesis (ƒ) to explain variation in cellulose δ2H values. By growing plants along a gradient of source water δ2H values under autotrophic and heterotrophic conditions, the original, εA, εH, and ƒ were determined for the aquatic plant Lemna gibba L.. One drawback of this approach is that it assumes these terms are the same when plants are grown in the light vs the dark. We recently reassessed the model for terrestrial plants by measuring δ2H values of leaf sucrose and found species variation in εA (Holloway-Phillips et al., 2022), but were unable to resolve variation associated with ƒ and εH.

In the present experiment we assessed a new experimental approach to quantify all model parameters for autotrophically grown plants using regression analysis. This required growing plants with variation in the isotopic offset between xylem water and leaf water (∆LW) and measuring sucrose and cellulose δ2H values from leaves and roots. In a previous study we determined that mutation-induced inhibition of starch synthesis in leaves resulted in higher cellulose δ2H values compared with the wildtype, which was hypothesized to occur preceding sucrose synthesis in the leaves (Baan et al., 2023). Using this new approach, we tested whether this effect was indeed mostly established in source cells during de novo sucrose synthesis (εA), or was a result of 2H-fractionating processes in sink cells prior to cellulose synthesis (εH and ƒ). Preliminary analyses show an increase in leaf sucrose δ2H values in the mutant relative to the wild type, implying that εA is also dependent on plant C metabolism within a given species.

How to cite: Baan, J., Holloway-Phillips, M., Nelson, D. B., and Kahmen, A.: In situ estimation of hydrogen isotope fractionation associated with sucrose and cellulose synthesis from leaves to roots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12594, https://doi.org/10.5194/egusphere-egu24-12594, 2024.

EGU24-12750 | Posters on site | BG2.4

Varying amounts of isotopic exchange among dual water hydrogen isotope exchange methods indicate different pools of exchangeable hydrogen  

Daniel B. Nelson, Meisha Holloway-Phillips, and Ansgar Kahmen

The hydrogen isotopic composition of organic compounds carries information relating to the isotopic composition of biosynthetic source water, as well as source-organism biochemistry. This has led to diverse applications in areas such as paleoclimatology, ecology, and criminal forensics. Yet, measurement poses a unique isotopic challenge because hydrogen bound to oxygen or nitrogen can exchange with ambient water or vapor, unlike the hydrogen that is bound to carbon. This creates a need to account for this so-called exchangeable hydrogen. In some cases, this can be done by permanent replacement via chemical derivatization, but this is often not convenient or even possible. This has led to the development of dual water equilibration methods in which the exchangeable hydrogen in a sample is equilibrated with water with a known isotopic composition in a controlled manner as the last step in sample preparation prior to measurement. Dual water equilibration methods have facilitated applications in a range of subdisciplines, especially for applications focused on plant carbohydrate-rich materials such as cellulose and bulk wood, and on keratin in animal migration and ecology.

 

The term “exchangeable hydrogen” has generally been used inconsistently in environmental applications. In some cases, the term is used to describe only the hydrogen that can freely exchange with ambient vapor at room temperature conditions, while in other cases the term directly refers to all hydrogen that is not covalently bound to carbon and can therefore theoretically undergo isotopic exchange. These two definitions are inconsistent with one another because in many biomolecules, such as cellulose and keratin, a large portion of the hydrogen that is not carbon-bound is engaged in hydrogen bonding and is important for the macromolecular structure of the material. This bridging hydrogen, although not carbon-bound, is more difficult to isotopically exchange, and has the potential to be excluded by some types of dual water equilibration approaches. As a consequence, the fraction of hydrogen that is measured as exchangeable varies between sample types and methodologies, resulting in different hydrogen isotope values.

 

In this study we compared hydrogen isotope values after dual water equilibrations on plant carbohydrates and animal keratins using two different analytical approaches, one of which targeted only the freely exchangeable hydrogen pool, and the other of which targeted the theoretically exchangeable hydrogen pool. For all sample types, we observed large differences in the calculated fraction of exchangeable hydrogen, with the freely exchangeable approach yielding exchange rates 10-15 % smaller than those from the theoretically exchangeable approach. The data also showed a greater range of hydrogen isotope values for the approach that achieved higher degrees of hydrogen exchange, suggesting that the range in bridging hydrogen isotope values among samples was lower than that of carbon-bound hydrogen. We suggest modification of the term “exchangeable” in dual water equilibration studies to indicate whether the freely or the potentially exchangeable hydrogen is being targeted, and therefore the extent to which the bridging hydrogen has been isotopically exchanged.

How to cite: Nelson, D. B., Holloway-Phillips, M., and Kahmen, A.: Varying amounts of isotopic exchange among dual water hydrogen isotope exchange methods indicate different pools of exchangeable hydrogen , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12750, https://doi.org/10.5194/egusphere-egu24-12750, 2024.

EGU24-12823 | Posters on site | BG2.4

Nitrogen Isotopic Studies in an Urban Estuary: Not Just a story of Anthropogenic Influences 

Peter Swart, Amel Saied, Maribeth Gidley, Aliza Karim, Elzabeth Kelly, Rachel Silverstein, Chistopher Sinigalliano, Tiffany Troxler, and Sean Ahearn

Over a twelve-month period, between June 2021 and June 2022, a study was carried out that investigated possible causes of water quality decline in northern Biscayne Bay (South Florida, USA).  During this investigation a large number of different water quality parameters were monitored at 22 sites and waterways feeding into the Bay (Miami River, Little River, Biscayne Canal, and Snake Creek) in this area. Additional samples were also collected in the central region of Biscayne Bay around Virginia Key and Key Biscayne, Coconut Grove, and Matheson Hammock. At each site water and vegetation samples were collected.  Water samples were analyzed for standard nutrient parameters (TN, TP, NO3-, NH4, chlorophyll, turbidity, salinity, and dissolved oxygen content) and vegetation samples analyzed for their δ15N and δ13C values, and CN ratios. A smaller number of additional water samples were collected for the analysis of the δ18O and δ15N values of the NO3- and sediment samples were analyzed for their dδ15N values at each site. This presentation concentrates principally on the nitrogen isotopic portion of the study. The highest δ15N values were found in algae and plants collected from the Biscayne Canal, Little River, and Miami River sites, while lower values were measured at the central Biscayne Bay sites.  The Little River sites showed a strong seasonality with δ15N values ranging from +8 ‰ in the wet season to over +13‰ at the start of the dry season, while Miami River and Biscayne Canal sites remained at values of between +9 to +13‰ throughout the year.   While elevated δ15N  values are associated with the input of anthropogenic waste, leaking from septic tanks along the canals, elevation of the d15N values in excess of typical human δ15N values is driven by fractionation during nitrification and incorporation by assimilation. We propose that nitrogen derived from septic tanks ,with elevated δ15N  values, mixes with nitrogen derived from the natural environment as well as from artificial fertilizers (both with lower δ15N values) to produce a pool of nitrogen with intermediate δ15N values.  This reservoir is then further enriched in 15N during the process of assimilation and nitrification which fractionates the δ15N  value of the residual NO3-

How to cite: Swart, P., Saied, A., Gidley, M., Karim, A., Kelly, E., Silverstein, R., Sinigalliano, C., Troxler, T., and Ahearn, S.: Nitrogen Isotopic Studies in an Urban Estuary: Not Just a story of Anthropogenic Influences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12823, https://doi.org/10.5194/egusphere-egu24-12823, 2024.

EGU24-12841 | Orals | BG2.4

Photosynthesis results in 2H-depleted carbohydrates, but why? 

Roland A. Werner and Meisha Holloway-Phillips

When you grow plants in the light, the hydrogen isotopic composition (δ2H) of plant compounds such as cellulose show lower δ2H values (are 2H-depleted) relative to plants grown heterotrophically in the dark. Therefore, it is logical to assume that photosynthetic reactions introduce 2H-depleted hydrogen atoms into carbohydrates. But where in the C reductive pathway (Calvin-Benson-Bassham cycle, CBB) does this occur? Or more interestingly, can we interpret the degree of 2H-depletion of plant compounds with respect to this key reaction(s)? With the recent resurgence of studies offering hydrogen isotopes as a new proxy for plant central carbon and energy metabolism, such a fundamental question seems pertinent to answer.

We 1) examine the stereospecific mechanism of hydride transfer via NADP(H) catalyzed by oxidoreductases (ferredoxin-NADP+ reductase, glyceraldehyde 3-phosphate dehydrogenase) as a key reason why photoproduced NADPH is not directly the source of 2H-depletion of autotrophically produced carbohydrates, 2) reconcile the site-specific deuterium abundance pattern differences between C3 and C4 (NADP-ME) species of hydrogen bound to position C-4 in glucose, and 3) urge greater investment in position-specific and complimentary metabolomic analyses to progress the development of hydrogen isotopes as a metabolic proxy.

How to cite: Werner, R. A. and Holloway-Phillips, M.: Photosynthesis results in 2H-depleted carbohydrates, but why?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12841, https://doi.org/10.5194/egusphere-egu24-12841, 2024.

EGU24-12882 | ECS | Posters on site | BG2.4

Comparison of lipid biomarkers and their hydrogen isotopic values in submerged vascular macrophytes and charophytes 

Ricardo N. Santos, Bernhard Aichner, Daniel B. Nelson, Sabine Hilt, and Sarah N. Ladd

Submerged macrophytes incorporate lake water directly during lipid synthesis, making the δ2H values of their lipids a crucial tool for reconstructing past hydrology and lake states. Despite this significance, the lipid biomarkers of aquatic plants have received less attention compared to terrestrial plants. In particular, in the context of organic geochemical applications, submerged aquatic plants are typically considered as a single group, ignoring potential differences in lipid distributions and hydrogen isotope composition between vascular macrophytes and macroalgae such as charophytes. This gap limits the use of lipid biomarkers in lake sediments to understand past lake water isotopes and vegetation dynamics.

In this study, we analyzed the lipid contents and δ2H values of fatty acids, n-alkanes, and the chlorophyll side-chain phytol from paired vascular macrophytes and charophytes collected from 12 oligo-mesotrophic hardwater lakes in northeast Germany. We aim to assess differences between macrophyte groups and their relation to environmental factors and lake water properties, such as lake water δ2H values and pH levels.

Our preliminary results reveal a notable predominance of fatty acids over n-alkanes in both macrophyte groups. Vascular macrophytes tended to exhibit a higher, albeit variable, abundance of n-alkanes, fatty acids, and phytol concentrations compared to charophytes. The n-alkanes profiles were mainly comprised of mid to long-chain hydrocarbons (n-C23 to n-C27) and exhibited striking variability among macrophytes. Nonetheless, charophytes were notably characterized by a prominent dominance of n-C27. While the C16:0 fatty acid was the most abundant hydrocarbon in both macrophyte types, vascular macrophytes exhibit a greater abundance of long-chain (C24 toC30) fatty acids. However, our data revealed marked differences in the relative abundance of these long-chained compounds. The overall disparities in the lipid profiles point to distinct lipid biosynthesis pathways or environmental adaptations among the studied aquatic plants. Despite the differences in lipid distributions, no systematic differences were observed in the δ2H values for any studied compound class between the two macrophyte groups, Our results suggest that reconstructions of lake water isotopes based on δ2H values of aquatic plant lipids are unlikely to be influenced by changes in the relative contributions from vascular macrophytes and charophytes.

How to cite: N. Santos, R., Aichner, B., B. Nelson, D., Hilt, S., and N. Ladd, S.: Comparison of lipid biomarkers and their hydrogen isotopic values in submerged vascular macrophytes and charophytes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12882, https://doi.org/10.5194/egusphere-egu24-12882, 2024.

EGU24-15515 | Orals | BG2.4

Comparing the strontium isotope signatures of human urinary stones, drinking waters and environmental matrices: A first case study from Italy 

Izzo Francesco, Langella Alessio, Di Renzo Valeria, D'Antonio Massimo, Tranfa Piergiorgio, Widory David, Salzano Luigi, Germinario Chiara, Grifa Celestino, Varricchio Ettore, and Mercurio Mariano

Urolithiasis is a rather common pathology among the adult population and the biominerals it produces, i.e., urinary stones, may represent a potential proxy to characterize the environmental matrices that surrounded patients before being diagnosed. The objective of the present investigation (recently published in Izzo et al., 2024) was to use 87Sr/86Sr, a peculiar geochemical tracer routinely used for interpreting geological processes, to correlate the characteristics of patients’ urolith and their lifestyle habits, trying to identify correlations with direct or indirect contacts with their geological and environmental surroundings (water, soil, rock, etc.). Analyzed samples consisted of 21 kidney and bladder stones that were collected at the Department of Urology of the San Pio Hospital (Benevento, Italy) from patients living in Campania Region admitted between 2018 and 2020. Investigation was also extended to a vital food for humans such as water. Local tap waters and bottle waters (38 samples) from totally different Italian areas were here analyzed in order to highlight if and how different geological and hydrogeological settings could influence their Sr isotope ratio characterizing the connections existing between humans and their surrounding environment.

The 87Sr/86Sr ratios of uroliths ranged from 0.70761 for an uricite sample to 0.70997 for a weddellite one and seem to be partly discriminated based on the mineralogy. The comparison with the isotope characteristics of Italian drinking waters shows a general overlap in 87Sr/86Sr with the biominerals. However, on a smaller geographic area (Campania Region), we observe small 87Sr/86Sr differences between the biominerals and local waters. This may be explained by external Sr inputs for example from agriculture practices, inhaled aerosols (i.e., particulate matter), animal manure and sewage, non-regional foods. Nevertheless, biominerals of patients that stated to drink and eat local water/wines and foods every day exhibited a narrower 87Sr/86Sr range roughly matching the typical isotope ratios of local geological materials and waters, as well as those of archaeological biominerals from the same area. This preliminary study evidences how the strontium isotope ratio of urinary stones records that of the patient's surrounding environmental matrices, although further investigations will be necessary to confirm this hypothesis.

 

Izzo F., Di Renzo V., Langella A., D’Antonio M., Tranfa P., Widory D., Salzano L., Germinario C., Grifa C., Varricchio E., Mercurio M. (2024) Investigating strontium isotope linkage between biominerals (uroliths), drinking water and environmental matrices. Environmental Pollution, https://doi.org/10.1016/j.envpol.2024.123316  

How to cite: Francesco, I., Alessio, L., Valeria, D. R., Massimo, D., Piergiorgio, T., David, W., Luigi, S., Chiara, G., Celestino, G., Ettore, V., and Mariano, M.: Comparing the strontium isotope signatures of human urinary stones, drinking waters and environmental matrices: A first case study from Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15515, https://doi.org/10.5194/egusphere-egu24-15515, 2024.

EGU24-17441 | ECS | Posters on site | BG2.4

Toward using δ2H values for investigating marine mixotrophy 

Marc-Andre Cormier, Jean-Baptiste Berard, Daniel Nelson, Kevin Flynn, Richard Lampitt, and Gael Bougaran

Hydrogen isotope ratios (δ2H) measured on lipids extracted from aquatic and terrestrial organisms are widely applied for studying past hydro-climatic conditions. A growing body of evidence suggests that δ2H values of lipids integrate not only climatic, but also metabolic information. Metabolic effects hinder the reconstruction of climatic conditions based on δ2H values from archives and urges for a better understanding of the key drivers of δ2H values in organic compounds. Once disentangled, such non-climatic information in δ2H values may become key for investigating misunderstood eco-physiological behaviours. One such behaviour is marine mixotrophy.

While science requires tools to measure the contributions of phototrophic and heterotrophic growth in plankton, my colleagues and I have already shown that lipid δ2H values are uniquely sensitive to the expression of heterotrophy relative to photosynthesis in plants. This presentation will discuss groundwork experiments performed with chlorophytes and dinoflagellates exploring whether δ2H values of diverse compounds produced by protists are similarly sensitive to their central metabolic pathway. New δ2H analyses performed on fatty acids, phytols and sterols from these experiments, using an isotope ratio mass spectrometer (IRMS) coupled to a gas chromatograph (GC), will be discussed. Our data suggest that lipids δ2H values are indeed sensitive to the level of heterotrophic growth in diverse protists.

If this relation can be confirmed and calibrated, compound specific H isotope analyses could provide a powerful means to study the role of mixotrophy on the global carbon cycle and the occurrences of HABs.

How to cite: Cormier, M.-A., Berard, J.-B., Nelson, D., Flynn, K., Lampitt, R., and Bougaran, G.: Toward using δ2H values for investigating marine mixotrophy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17441, https://doi.org/10.5194/egusphere-egu24-17441, 2024.

EGU24-18348 | ECS | Posters on site | BG2.4

Robustness of the relationship between needle n-alkane δ²H and leaf water evaporative enrichment, amidst seasonally variable relationships between non-structural carbohydrate δ²H and respiration rate, in a boreal forest 

Charlotte Angove, Guido Wiesenberg, Marco Lehmann, Matthias Saurer, Yu Tang, Elina Sahlstedt, Tatjana Speckert, Pauliina Schiestl-Aalto, and Katja Rinne-Garmston

Stable isotopes of n-alkanes are important and rapidly developing tools for understanding paleoecology and past climatic conditions. However, there are knowledge gaps surrounding the physiological and environmental δ2H signals of n-alkanes. In this study, we investigated whether biosynthetic processes interfere with the consistency of the environmental signal in needle n-alkane δ²H. Therefore, we sampled two needle generations (one year-old needles, current-year needles) from five Pinus sylvestris trees at the boreal forest in Hyytiälä, Finland, during the 2019 growing season and analyzed δ2H of leaf non-structural carbohydrates (NSCs), starch, n-alkanes, and combined data with published leaf water isotope and shoot gas exchange measurements. We explored (1) time-integrated relationships between environmental variables and measured organic compound δ2H, and (2) evaluated whether the δ²H data of this study align with model predictions for NSC and leaf n-alkane δ²H values based on a process-based model for NSC δ2H hybridized with different leaf water heavy isotope enrichment and n-alkane models. Our findings suggest that NSC δ²H has temporally variable relationships to environmental variables which are related to needle generation and season, because current-year needle NSC δ²H was more closely correlated to respiration rate than a needle water isotope signal while one year-old needle NSC δ²H was more closely related to a leaf water evaporative enrichment signal. Interestingly, n-alkane δ²H did not exhibit the same seasonally variable relationship to respiration rate and were instead more closely related to a leaf water evaporative enrichment signal. Overall, results suggest that water compartmentalization in leaves can have a prominent enough role during n-alkane synthesis, that its effects can be observed at seasonal scale, which shows promise to the role of leaf n-alkane δ²H as a leaf evaporative enrichment signal without substantial interference by source water δ²H. However, we also highlight the role of signal dampening, by time integration and new needle growth.

 

How to cite: Angove, C., Wiesenberg, G., Lehmann, M., Saurer, M., Tang, Y., Sahlstedt, E., Speckert, T., Schiestl-Aalto, P., and Rinne-Garmston, K.: Robustness of the relationship between needle n-alkane δ²H and leaf water evaporative enrichment, amidst seasonally variable relationships between non-structural carbohydrate δ²H and respiration rate, in a boreal forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18348, https://doi.org/10.5194/egusphere-egu24-18348, 2024.

EGU24-18459 | Orals | BG2.4

Long-term ecophysiological signals from isotopomers: Principles and applications.  

Jürgen Schleucher, Lenny Haddad, Pieter Zuidema, Benjamin Smith, Mats Öquist, and John Marschall

Understanding plant responses to increasing CO2 is essential for predictions of plant productivity and of future climate (Walker et al. 2020). Isotope ratios (13C/12C and 2H/1H) have long been used in plant ecophysiology and for reconstruction of environmental variables. But it has also been known since decades that heavy isotopes are distributed unevenly WITHIN biological metabolites, i.e. that the abundances of 2H and 13C isotopomers vary. Because isotopomer variation is caused by enzyme isotope fractionation, it carries signals on the regulation of biochemical pathways. If such signals can be recovered from archives of plant material, they can report on plant-climate interactions on time scales from decades to millennia.

We use NMR (nuclear magnetic resonance) to analyze isotopomers of the glucose units of plant archives, and I will describe the principles and practicalities of isotopomer measurements. First, in manipulation experiments we calibrate isotopomer responses to environmental drivers, in particular CO2 and T. Second, we analyse isotopomers in plant archives such as tree-ring series over previous decades of rising CO2, and use the calibrations from the manipulation experiments to deduce shifts in photosynthetic metabolism over decades. We will present results on 2H and 13C isotopomer variation and associated ecophysiological signals.

We present data on 13C isotopomers in tree-ring cellulose and annual plants (Wieloch et al 2018). The results have implications for interpretation of the d13C of respired CO2. Furthermore, we show how 13C isotopomers give new insight into the pathways of C metabolism (Wieloch et al 2023).

Photorespiration is a side reaction of photosynthesis that reduces C assimilation in most vegetation. Photorespiration is reduced by increasing CO2 yet exacerbated by rising T, so its evolution under climate change and implications for global C fluxes are highly uncertain. We present data showing how 2H isotopomers can be used to track photorespiration in response to CO2 and T. The opposing effects of CO2 and T on photorespiration will determine if forests will in the future be a sink or source of CO2 (Van der Sleen et al. 2015; Sperry et al. 2019). For select tree species, we compare results from FACE experiments and from decades-long tree ring series, to detect possible acclimation of gas exchange of broad-leaved trees over

In summary, the presentation will describe how isotopomers can improve mechanistic understanding of plant function on long time scales, to be incorporated into Dynamic global vegetation models to improve predictions of C fluxes under climate change scenarios.

References

Walker et al., 2020 https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.16866.

Van der Sleen et al., 2015. https://doi.org/10.1038/ngeo2313.

Sperry et al., 2019. https://doi.org/10.1073/pnas.1913072116.

Wieloch et al., 2018 https://www.nature.com/articles/s41598-018-23422-2

Wieloch et al., 2023 https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.18965

 

How to cite: Schleucher, J., Haddad, L., Zuidema, P., Smith, B., Öquist, M., and Marschall, J.: Long-term ecophysiological signals from isotopomers: Principles and applications. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18459, https://doi.org/10.5194/egusphere-egu24-18459, 2024.

EGU24-19894 | ECS | Orals | BG2.4

Hydrogen isotope fractionation is controlled by CO2 in coccolithophore lipids 

Hongrui Zhang, Ismael Torres-Romero, Reto Wijker, Alexander Clakr, Madalina Jaggi, and Heather Stoll

Hydrogen isotope ratios (d2H) represent an important natural tracer of metabolic processes, but quantitative models of processes controlling H-fractionation in aquatic photosynthetic organisms are lacking. Here we elucidate the underlying physiological controls of 2H/1H fractionation in algal lipids by systematically manipulating temperature, light and, for the first time, CO2(aq) in continuous cultures of the haptophyte Gephyrocapsa oceanica. We analyze the hydrogen isotope fractionation in alkenones (aalkenone), a class of acyl lipids specific to this species and other haptophyte algae. We find a strong decrease in the aalkenone with increasingCO2(aq), and confirm aalkenone correlates with temperature and light. Based on the known biosynthesis pathways, we develop a new cellular model of the d2H of algal acyl lipids to evaluate processes contributing to these controls on fractionation. Simulations show that longer residence times of NADPH in the chloroplast favor greater exchange of NADPH with 2H-richer intracellular water, increasing aalkenone. Higher chloroplast CO2(aq) and temperature shorten NADPH residence time by enhancing the carbon fixation and lipid synthesis rates. The inverse correlation of aalkenone toCO2(aq) in our cultures suggests that carbon concentrating mechanisms (CCM) do not achieve a constant saturation of CO2 at the Rubisco site, but rather that chloroplast CO2 varies with external CO2(aq). The pervasive inverse correlation of aalkenone with CO2(aq) in the modern and preindustrial ocean also suggests that natural populations may not attain a constant saturation of Rubisco with the CCM. Rather than reconstructing growth water, aalkenone may be a powerful tool to elucidate carbon limitation of photosynthesis.

How to cite: Zhang, H., Torres-Romero, I., Wijker, R., Clakr, A., Jaggi, M., and Stoll, H.: Hydrogen isotope fractionation is controlled by CO2 in coccolithophore lipids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19894, https://doi.org/10.5194/egusphere-egu24-19894, 2024.

EGU24-20065 | ECS | Posters on site | BG2.4

Non-Exchangeable Hydrogen Stable Isotope Analysis In Mango (Mangifera indica L.) Pectin Methoxy Groups 

Aiman Abrahim, Markus Greule, Peter Rinke, Christina Vlachou, and Simon Kelly

Hydrogen stable isotope analysis of fruits can provide valuable information about their geographical origin, growing conditions, and the underlying environmental factors. The isotopic ratios of Hydrogen in fruits are related to the water they absorb and incorporate during photosynthesis. Nevertheless, measuring non-exchangeable hydrogen isotope ratios in plant-related organic compounds such as carbohydrates and polysaccharides face well-known analytical challenges (1). One strategy to overcome this challenge is by an established method which determines the hydrogen isotope ratios in non-exchangeable methoxy groups of organic compounds (e.g., lignin, pectin) (2). Pectin is a type of polysaccharide that is naturally occurring in the cell walls of fruits and vegetables and has the potential to be useful for food traceability. We have adapted the site-specific hydrogen stable isotope method, originally developed for wood lignin, to the extraction and δ2H measurement of pectin in mango fruits cultivated in different countries to assess the feasibility of applying the data to geographical origin assignment.

Reference.

(1) Sauer, P. E., Schimmelmann, A., Sessions, A. L., & Topalov, K. (2009). Simplified batch equilibration for D/H determination of non‐exchangeable hydrogen in solid organic material. Rapid Communications in Mass Spectrometry: An International Journal Devoted to the Rapid Dissemination of Up‐to‐the‐Minute Research in Mass Spectrometry, 23(7), 949-956.

(2) Keppler, F., Harper, D. B., Kalin, R. M., Meier‐Augenstein, W., Farmer, N., Davis, S., ... & Hamilton, J. T. (2007). Stable hydrogen isotope ratios of lignin methoxyl groups as a paleoclimate proxy and constraint of the geographical origin of wood. New Phytologist176(3), 600-609.

How to cite: Abrahim, A., Greule, M., Rinke, P., Vlachou, C., and Kelly, S.: Non-Exchangeable Hydrogen Stable Isotope Analysis In Mango (Mangifera indica L.) Pectin Methoxy Groups, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20065, https://doi.org/10.5194/egusphere-egu24-20065, 2024.

EGU24-1261 | Orals | GM3.1

Machine-learning based 3D point cloud classification and multitemporal change analysis with simulated laser scanning data using open source scientific software 

Bernhard Höfle, Ronald Tabernig, Vivien Zahs, Alberto M. Esmorís Pena, Lukas Winiwarter, and Hannah Weiser

AIM: We will present how virtual laser scanning (VLS), i.e., simulation of realistic LiDAR campaigns, can be key for applying machine/deep learning (ML/DL) approaches to geographic point clouds. Recent results will be shown for semantic classification and change analysis in multitemporal point clouds using exclusively open source scientific software.

MOTIVATION: Laser scanning is able to deliver precise 3D point clouds which have made huge progress in research in geosciences over the last decade. Capturing multitemporal (4D: 3D + time) point clouds enables to observe and quantify Earth surface process activities, their complex interactions and triggers. Due to the large size of 3D/4D datasets that can be captured by modern systems, automatic methods are required for point cloud analysis. Machine learning approaches applied to geographic point clouds, in particular DL, have shown very promising results for many different geoscientific applications [1,2].

METHODS & RESULTS: While new approaches for deep neural networks are rapidly developing [1], the bottleneck of sufficient and appropriate training data (typically annotated point clouds) remains the major obstacle for many applications in geosciences. Those data hungry learning methods depend on proper domain representation by training data, which is challenging for natural surfaces and dynamics, where there is high intra-class variability. Synthetic LiDAR point clouds generated by means of VLS, e.g., with the open-source simulator HELIOS++ [3], can be a possible solution to overcome the lack of training data for a given task. In a virtual 3D/4D scene representing the target surface classes, different LiDAR campaigns can be simulated, with all generated point clouds being automatically annotated. VLS software like HELIOS++ allows to simulate any LiDAR platform and settings for a given scene, which offers high potential for data augmentation and the creation of training samples tailored to specific applications. In recent experiments [1], purely synthetic training data could achieve similar performances to costly labeled training data from real-world acquisitions for semantic scene classification.

Furthermore, surface changes can be introduced to create dynamic VLS scenes (e.g., erosion, accumulation, movement/transport). Combining LiDAR simulation with automatic change analysis, such as offered by the open-source scientific software py4dgeo [5], enables to perform ML for change analysis in multitemporal point clouds [6]. Recent results show that rockfall activity mapping and classification for permanent laser scanning data can be successfully implemented by combining HELIOS++, py4dgeo and the open-source framework VL3D, which can be used for investigating various ML/DL approaches in parallel.

CONCLUSION: Expert domain knowledge (i.e., definition of proper 3D/4D scenes) and the power of AI can be closely coupled in VLS-driven ML/DL approaches to analyze 3D/4D point clouds in the geosciences. Open-source scientific software already offers all required components (HELIOS++, VL3D, py4dgeo). 

REFERENCES:

[1] Esmorís Pena, A. M., et al. (2024): Deep learning with simulated laser scanning data for 3D point cloud classification. ISPRS Journal of Photogrammetry and Remote Sensing. under revision.

[2] Winiwarter, L., et al. (2022): DOI: https://doi.org/10.1016/j.rse.2021.112772 

[3] HELIOS++: https://github.com/3dgeo-heidelberg/helios

[4] VL3D framework: https://github.com/3dgeo-heidelberg/virtualearn3d

[5] py4dgeo: https://github.com/3dgeo-heidelberg/py4dgeo

[6] Zahs, V. et al. (2023): DOI: https://doi.org/10.1016/j.jag.2023.103406

How to cite: Höfle, B., Tabernig, R., Zahs, V., Esmorís Pena, A. M., Winiwarter, L., and Weiser, H.: Machine-learning based 3D point cloud classification and multitemporal change analysis with simulated laser scanning data using open source scientific software, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1261, https://doi.org/10.5194/egusphere-egu24-1261, 2024.

EGU24-1640 | ECS | Posters on site | GM3.1

Automatic Classification of Surface Activity Types from Geographic 4D Monitoring Combining Virtual Laser Scanning, Change Analysis and Machine Learning 

Vivien Zahs, Bernhard Höfle, Maria Federer, Hannah Weiser, Ronald Tabernig, and Katharina Anders

We advance the characterization of landscape dynamics through analysis of point cloud time series by integrating virtual laser scanning, machine learning and innovative open source methods for 4D change analysis. We present a novel approach for automatic identification of different surface activity types in real-world 4D geospatial data using a machine learning model trained exclusively on simulated data.

Our method focuses on classifying surface activity types based on spatiotemporal features. We generate training data using virtual laser scanning of a dynamic coastal scene with artificially induced surface changes. Scenes with surface change are generated using geographic knowledge and the concept of 4D objects-by-change (4D-OBCs) [1, 2], which represent spatiotemporal subsets of the scene that exhibit change with similar properties. A realistic 3D scene modelling is essential for accurately replicating the dynamic nature of coastal landscapes, where morphological changes are driven by both natural processes and anthropogenic activities.

The Earth's landscapes exhibit complex dynamics, spanning large spatiotemporal scales, from high-mountain glaciers to sandy coastlines. The challenge lies in effectively detecting and classifying diverse surface activities with varying magnitudes, spatial extents, velocities, and return frequencies. Effective characterization of these dynamics is crucial for understanding the underlying environmental processes and their interplay with human activities. Supervised machine learning classification of surface activities from point cloud time series is challenging due to the limited availability of comprehensive and diverse real-world datasets for training and validation. Our approach combines virtual laser scanning with machine learning-based classification, enabling the generation of comprehensive training datasets covering the full spectrum of expected change patterns [3].

In our approach, the simulation of LiDAR point clouds is performed in the open-source framework HELIOS++ [4, 5]. HELIOS++ allows the flexible simulation of custom LiDAR campaigns with diverse acquisition modes and settings together with automatic annotations of artificially induced surface changes. We train a supervised machine learning model to classify synthetic 4D-OBCs into typical surface activity types of a sandy beach (e.g. dune erosion/accretion, sediment transport, etc.). Moreover, we investigate descriptors for 4D-OBCs, assessing their suitability for representing general types of surface activity (transferable between use cases) and types specific to particular surface processes.

We evaluate our model for 4D-OBC classification in terms of its capacity to discriminate surface activity types in a real-world dataset of a sandy beach in the Netherlands [6]. 4D-OBCs are extracted, classified into our target classes and validated with manually labelled reference data based on expert evaluation.

Our study showcases the efficacy of coupling virtual laser scanning, innovative open-source 4D change analysis methods, and machine learning for classifying natural surface changes [7]. Our findings not only contribute to advancing the understanding of landscape dynamics but also provide a promising approach to mitigating environmental challenges.

REFERENCES

[1] Anders et al. (2022): DOI: https://doi.org/10.5194/egusphere-egu22-4225

[2] py4dgeo: https://github.com/3dgeo-heidelberg/py4dgeo 

[3] Zahs et al. (2022): DOI: https://doi.org/10.1016/j.jag.2023.103406

[4] HELIOS++: https://github.com/3dgeo-heidelberg/helios

[5] Winiwarter et al. (2022): DOI: https://doi.org/10.1016/j.rse.2021.112772 

[6] Vos et al. (2022): DOI: https://doi.org/10.1038/s41597-022-01291-9

[7] CharAct4D: www.uni-heidelberg.de/charact4d

How to cite: Zahs, V., Höfle, B., Federer, M., Weiser, H., Tabernig, R., and Anders, K.: Automatic Classification of Surface Activity Types from Geographic 4D Monitoring Combining Virtual Laser Scanning, Change Analysis and Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1640, https://doi.org/10.5194/egusphere-egu24-1640, 2024.

The acquisition of aerial photographs for cartographic applications started in the 1930s, and more intensively after World War II. Such old, often panchromatic, imagery offers metre to sub-metre scale spatial resolution over landscapes that have significantly evolved over the decades. Before the appearance of the first digital aerial camera systems at the end of the 20th Century, surveys were performed with analogue metric cameras, with images acquired on films or glass plates and, next, developed on photo papers. In Europe and North America, several institutions hold unique collections of historical aerial photographs having local, national and, in some cases, colonial coverages. They represent invaluable opportunities for environmental studies, allowing the comparison with today’s land use land cover, and the analysis of long-term surface displacements.

Initially, the photogrammetric processing of analogue aerial photographs would require expensive equipment, specialised operators, and significant processing time. Thanks to the digital revolution of the past two decades and the development of modern digital photogrammetric approaches, the processing of this type of image datasets has become less cumbersome, time consuming and expensive, at least in theory. In practice, this is more complex, with digitising and processing issues related to the ageing and quality of conservation of the aerial photographs, the potential distortions created during the digitising process, and the lack of ancillary data, such as, flight plans, and camera calibration reports. The limited overlap between photographs, typically 60 % and 10-20 %, along-track and across-track, respectively, make their processing with Structure-from-Motion Multi-View Stereo (SfM-MVS) photogrammetry poorly reliable to accurately reconstruct the topography and orthorectify the images. Given the fact that some collections reach up to millions of historical aerial photographs, the digitising, pre-processing, and photogrammetric processing of these images remain a challenge that must be properly tackle if we would like to ensure their preservation and large-scale valorisation.

In the present work, we describe the mass-digitising, digital image pre-processing and photogrammetric processing approaches implemented at the Royal Museum for Central Africa (RMCA, Belgium) to preserve and valorise the collection of >320,000 historical aerial photographs conserved in this federal institution. This imagery was acquired between the 1940’s and the 1980’s, over Central Africa, and mostly D.R. Congo, Rwanda and Burundi. For the digitising, a system of parallelized flatbed scanners controlled by a Linux computer and a self-developed software allows speeding-up the scanning of the entire collection in only few years. A series of Python scripts were developed and combined to allow a swift pre-processing that prepare and optimise the digitised images for photogrammetric processing. Finally, a SfM-MVS photogrammetric approach adapted to historical aerial photos is used. Examples of application for geo-hydrological hazards studies in the western branch of the East African Rift are shown.

How to cite: Smets, B., Dille, A., Dewitte, O., and Kervyn, F.: Digitising, pre-processing and photogrammetric processing of historical aerial photographs for the production of high resolution orthomosaics and the study of geohazards, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2356, https://doi.org/10.5194/egusphere-egu24-2356, 2024.

EGU24-4399 | ECS | Posters on site | GM3.1

Evaluating the efficacy of multitemporal TLS and UAS surveys for quantifying wind erosion magnitudes of sand dune topography 

László Bertalan, Gábor Négyesi, Gergely Szabó, Zoltán Túri, and Szilárd Szabó

Wind erosion constitutes a prominent land degradation process in regions of Hungary characterized by low annual precipitation. In these areas, it poses significant challenges to agricultural productivity and adversely impacts soil and environmental quality. Presently, human activities exert a more pronounced influence on the endangered areas of Hungary in comparison to climate-related factors. It is noteworthy that the wind erodibility of Hungarian soils not only poses a soil conservation challenge but also gives rise to economic ramifications, such as nutrient loss, as well as environmental and human health concerns. Within agricultural landscapes, wind erosion contributes to the removal and transportation of the finest and biologically active soil fractions, rich in organic matter and nutrients.

High-resolution topographic surveys have become integral for assessing volumetric changes in sand dune mobility and mapping wind erosion. While Unmanned Aerial Systems (UAS) surveys have been extensively employed for erosion rates exceeding the decimeter scale, Terrestrial Laser Scanning (TLS) surveys have demonstrated efficiency in capturing more extensive negative erosional forms, even in a vertical orientation. To enhance the field of view, a mounting framework can be implemented to elevate the TLS. However, determining centimeter-scale material displacement in flat terrain conditions remains challenging and requires an increased number of scanning positions.

To identify optimal settings for surveying centimeter-scale wind erosion magnitudes, we conducted combined multi-temporal TLS and UAS surveys at the Westsik experimental site near Nyíregyháza during the spring of 2023. This site features dune topography with a height of 6 meters. Our investigations encompassed various UAS image acquisition modes, involving different flight altitudes and camera settings, utilizing a DJI Matrice M210 RTK v2 drone and a Zenmuse X7 24 mm lens. Additionally, we generated diverse point clouds through various scanning scenarios using a Trimble X7 TLS device. In the data processing phase, we explored multiple co-registration algorithms to address the challenge of larger Root Mean Square Error (RMSE) in Digital Terrain Models (DTMs) from UAS Structure from Motion (SfM) compared to the actual wind erosion rates.

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The research is supported by the NKFI K138079 project.

How to cite: Bertalan, L., Négyesi, G., Szabó, G., Túri, Z., and Szabó, S.: Evaluating the efficacy of multitemporal TLS and UAS surveys for quantifying wind erosion magnitudes of sand dune topography, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4399, https://doi.org/10.5194/egusphere-egu24-4399, 2024.

EGU24-5142 | Posters on site | GM3.1 | Highlight

Four nationwide Digital Surface Models from airborne historical stereo-images 

Christian Ginzler, Livia Piermattei, Mauro Marty, and Lars T. Waser

Historical aerial images, captured by film cameras in the previous century, have emerged as valuable resources for quantifying Earth's surface and landscape changes over time. In the post-war period, historical aerial images were often acquired to create topographic maps, resulting in the acquisition of large-scale aerial photographs with stereo coverage. Using photogrammetric techniques on stereo-images enables extracting 3D information to reconstruct Digital Surface Models (DSMs), and orthoimages.

This study presents a highly automated photogrammetric approach for generating nationwide DSMs for Switzerland at 1 m resolution using aerial stereo-images acquired between 1979 and 2006. The 8-bit scanned images, with known exterior and interior orientation, were processed using BAE Systems' SocetSet (v5.6.0) with the "Next-Generation Automatic Terrain Extraction" (NGATE) package for DSM generation. The primary objective of the study is to derive four nationwide DSMs for the epochs 1979-1985, 1985-1991, 1991-1998, and 1998-2006. The study assesses DSM quality in terms of vertical accuracy and completeness of image matching across different land cover types, with a focus on forest dynamics and management research.

The elevation accuracy of the generated DSMs was assessed using two reference datasets. Firstly, the elevation differences between a nationwide reference Digital Terrain Model (DTM - swissAlti3d 2017 by Swisstopo) and the generated DSMs were calculated on points classified as "sealed surface". Secondly, elevation values of the DSMs were compared to approximately 500 independent geodetic points distributed across the country. Six study areas were chosen to assess completeness, and it was calculated as the percentage of successfully matched points to the potential total number of matched points within a predefined area. This assessment was conducted for six land cover classes based on the land cover/land-use statistics dataset from the Federal Office of Statistics.

Across the entire country, the median elevation accuracy of the DSMs on sealed points ranges between 0.28 to 0.53 m, with a Normalized Median Absolute Deviation (NMAD) of around 1 m (maximum 1.41 m) and an RMSE of a maximum of 3.90 m. The elevation differences between geodetic points and DSMs show higher accuracy, with a median value of a maximum of 0.05 m and an NMAD smaller than 1 m. Completeness results reveal mean completeness between 64 % to 98 % for the classes "glacial and perpetual snow" and "sealed surfaces," respectively and 93 % specifically for the “closed forest” class.

This work demonstrates the feasibility of generating accurate DSM time series (spanning four epochs) from historical scanned images for the entire Switzerland in a highly automated manner. The resulting DSMs will be available upon publication, providing an excellent opportunity to detect major surface changes, such as forest dynamics.

How to cite: Ginzler, C., Piermattei, L., Marty, M., and Waser, L. T.: Four nationwide Digital Surface Models from airborne historical stereo-images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5142, https://doi.org/10.5194/egusphere-egu24-5142, 2024.

EGU24-5670 | ECS | Posters on site | GM3.1

Enhancing 3D Feature-based Landslide Monitoring Efficiency by Integrating Contour Lines in Laser Scanner Point Clouds 

Kourosh Hosseini, Jakob Hummelsberger, Daniel Czerwonka-Schröder, and Christoph Holst

Landslides are a pervasive natural hazard with significant societal and environmental impacts. In addressing the critical need for accurate landslide detection and monitoring, our previous research introduced a feature-based monitoring method enhanced by histogram analyses, straddling a middle ground between point-based and point cloud-based methods. This paper expands upon that foundation, introducing an innovative contour line extraction technique from various epochs to precisely identify areas prone to deformation. This refined focus diverges from conventional methodologies that analyze entire point clouds. By applying on regions where contour lines do not match, indicating potential ground movement, we significantly elevate the efficiency and precision of our feature-based monitoring system.

 

One of the principal challenges of feature-based monitoring is managing a substantial number of outliers. Our prior research tackled this issue effectively by integrating feature tracking with histogram analysis, thereby filtering these outliers from the final results. However, the process of extracting features from each patch and matching them with corresponding patches from different epochs was time-intensive.

 

The incorporation of contour line extraction into our workflow, using high-resolution laser scanner data, allows for a more focused and efficient analysis. We can now identify and analyze areas of landscape alteration with greater accuracy. This approach limits the application of feature tracking and histogram analysis to these critical areas, thus streamlining the process and significantly reducing computational demands. This focused methodology not only accelerates data processing but also enhances the accuracy of landslide predictions.

 

Our findings indicate a substantial improvement in the efficiency of landslide monitoring methods. This methodology represents a promising advancement in geospatial analysis, particularly for environmental monitoring and risk management in regions susceptible to landslides. This research contributes to the ongoing efforts to develop more effective, efficient, and accurate approaches to landslide monitoring, ultimately aiding in better informed and timely decision-making processes for hazard mitigation and risk management.

How to cite: Hosseini, K., Hummelsberger, J., Czerwonka-Schröder, D., and Holst, C.: Enhancing 3D Feature-based Landslide Monitoring Efficiency by Integrating Contour Lines in Laser Scanner Point Clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5670, https://doi.org/10.5194/egusphere-egu24-5670, 2024.

EGU24-5674 | ECS | Orals | GM3.1

Piecewise-ICP: Efficient Registration of 4D Point Clouds for Geodetic Monitoring 

Yihui Yang, Daniel Czerwonka-Schröder, and Christoph Holst

The permanent terrestrial laser scanning (PLS) system has opened the possibilities for efficient data acquisition with high-temporal and spatial resolution, thus allowing for improved capture and analyses of complex geomorphological changes on the Earth's surface. Accurate georeferencing of generated four-dimensional point clouds (4DPC) from PLS is the prerequisite of the following change analysis. Due to the massive data volume and potential changes between scans, however, efficient, robust, and automatic georeferencing of 4DPC remains challenging, especially in scenarios lacking signalized and reliable targets. This georeferencing procedure can be typically realized by designating a reference epoch and registering all other scans to this epoch. Addressing the challenges in targetless registration of topographic 4DPC, we propose a simple and efficient registration method called Piecewise-ICP, which first segments point clouds into piecewise patches and aligns them in a piecewise manner.

Assuming the stable areas on monitored surfaces are locally planar, supervoxel-based segmentation is employed to generate small planes from adjacent point clouds. These planes are then refined and classified by comparing defined correspondence distances to a monotonically decreasing distance threshold, thus progressively eliminating unstable planes in an efficient iterative process as well as preventing local minimization in the ICP process. Finally, point-to-plane ICP is performed on the centroids of the remaining stable planes. We introduce the level of detection in change analysis to determine the minimum distance threshold, which mitigates the influence of outliers and deformed areas on registration accuracy. Besides, the spatial distribution of empirical registration uncertainties on registered point clouds is derived based on the variance-covariance propagation law.

Our registration method is demonstrated on two datasets: (1) Synthetic point cloud time series with defined changes and transformation parameters, and (2) a 4DPC dataset from a PLS system installed in the Vals Valley (Tyrol, Austria) for monitoring a rockfall. The experimental results show that the proposed algorithm exhibits higher registration accuracy compared to the existing robust ICP variants. The real-time capability of Piecewise-ICP is significantly improved owing to the centroid-based point-to-plane ICP and the efficient iteration process.

How to cite: Yang, Y., Czerwonka-Schröder, D., and Holst, C.: Piecewise-ICP: Efficient Registration of 4D Point Clouds for Geodetic Monitoring, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5674, https://doi.org/10.5194/egusphere-egu24-5674, 2024.

EGU24-5757 | Posters on site | GM3.1

Arctic puzzle: pioneering a shrimp habitat model in topographically complex Disko Bay (West Greenland) 

Diana Krawczyk, Tobias Vonnahme, Ann-Dorte Burmeister, Sandra Maier, Martin Blicher, Lorenz Meire, and Rasmus Nygaard

Our study focuses on the geologically, topographically, and oceanographically complex region of Disko Bay in West Greenland. Disko Bay is also considered a marine biodiversity hotspot in Greenland. Given the impact of commercial fishing on seafloor integrity in the area, seafloor habitats studies are crucial for sustainable use of marine resources. One of the key fishery resources in Greenland, as well as in the North Atlantic Ocean, is northern shrimp.

In this study we analyzed multiple (1) monitoring datasets from 2010 to 2019, including data from shrimp and fish surveys, commercial shrimp fishery catches, satellite chlorophyll data, and (2) seafloor models, encompassing high-resolution (25 x 25 m) multibeam data with a low-resolution (200 x 200 m) IBCAO grid. Using multivariate regression analysis and spatial linear mixed-effect model we assessed the impact of physical (water depth, bottom water temperature, sediment type), biological (chlorophyll a, Greenland halibut predation), and anthropogenic factors (shrimp fishery catch and effort) on shrimp density in the area. The resulting high-resolution predictive model of northern shrimp distribution in Disko Bay is the first model of this kind developed for an Arctic area.

Our findings reveal that shrimp density is significantly associated with static habitat factors, namely sediment type and water depth, explaining 34% of the variation. The optimal shrimp habitat is characterized by medium-deep water (approximately 150-350 m) and mixed sediments, primarily in the north-eastern, south-eastern, and north-western Disko Bay. This pioneering study highlights the importance of seafloor habitat mapping and modeling, providing fundamental geophysical knowledge necessary for long-term sustainable use of marine resources in Greenland.

The developed high-resolution model contributes to a better understanding of detailed patterns in northern shrimp distribution in the Arctic, offering valuable insights for stock assessments and sustainable fishery management. This novel approach to seafloor habitat mapping supports the broader goal of ensuring the responsible utilization of marine resources, aligning with principles of environmental conservation and fisheries management. Our work serves as a foundation for ongoing efforts to balance economic interests with the preservation of marine ecosystems, fostering a harmonious coexistence between human activities and the fragile Arctic environment.

How to cite: Krawczyk, D., Vonnahme, T., Burmeister, A.-D., Maier, S., Blicher, M., Meire, L., and Nygaard, R.: Arctic puzzle: pioneering a shrimp habitat model in topographically complex Disko Bay (West Greenland), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5757, https://doi.org/10.5194/egusphere-egu24-5757, 2024.

EGU24-10361 | ECS | Orals | GM3.1

A Time-Series Analysis of Rockfall Evolution in a Coastal Region Using Remote Sensing Data 

Aliki Konsolaki, Emmanuel Vassilakis, Evelina Kotsi, Michalis Diakakis, Spyridon Mavroulis, Stelios Petrakis, Christos Filis, and Efthymios Lekkas

The evolution of technology, particularly the integration of Unmanned Aerial Systems (UAS), earth observation datasets, and historical data such as aerial photographs, stand as fundamental tools for comprehending and reconstructing surface evolution and potential environmental changes. In addition, the active geodynamic phenomena in conjunction with climate crisis and the increasing frequency of extreme weather phenomena can cause abrupt events such as rockfalls and landslides, altering completely the morphology on both small and large scales.

This study deals generally with the temporal evolution of landscapes and specifically focuses on the detection and quantification of a significant rockfall event that occurred at Kalamaki Beach on Zakynthos Island, Greece – a very popular summer destination. Utilizing UAS surveys conducted in July 2020 and July 2023, this research revealed a rockfall that has significantly altered the coastal morphology. During this period, two severe natural phenomena occurred, one of which could potentially be the cause of this rockfall event. Initially, the Mediterranean hurricane (‘medicane’) ‘Ianos’ made landfall in September 2020, affecting a large part of the country including the Ionian Islands. The result was severe damage to property and infrastructures, along with human casualties, induced by intense precipitation, flash flooding, strong winds, and wave action. Second, in September of 2022, an ML=5.4 earthquake struck between Cephalonia and Zakynthos Islands in the Ionian Sea, triggering considerable impact in both islands. The study employs satellite images postdating these natural disasters, to detect the source of the rockfall in Kalamaki Beach. Additionally, historical analog aerial images from 1996 and 2010 were used as assets for understanding the surface’s evolution. For the quantitative analysis, we applied 3D semi-automated change detection techniques such as the M3C2 algorithm, to estimate the volume of the rockfall.

The results provide insights into the complex interplay between natural disasters and geological processes, shedding light on the dynamic nature of landscapes and the potential implications for visitor-preferred areas.

This research not only contributes to our understanding of landscape evolution but also underscores the importance of integrating modern and historical datasets to decipher the dynamic processes shaping the Earth's surface. The methodology proposed, serves as a valuable approach for assessing and managing geological hazards in coastal regions affected by both climatic events and geodynamic activities.

How to cite: Konsolaki, A., Vassilakis, E., Kotsi, E., Diakakis, M., Mavroulis, S., Petrakis, S., Filis, C., and Lekkas, E.: A Time-Series Analysis of Rockfall Evolution in a Coastal Region Using Remote Sensing Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10361, https://doi.org/10.5194/egusphere-egu24-10361, 2024.

EGU24-10373 | Orals | GM3.1

A database for ancillary information of three-dimensional soil surface microtopography measurements. 

Kossi Nouwakpo, Anette Eltner, Bernardo Candido, Yingkui Li, Kenneth Wacha, Mary Nichols, and Robert Washington-Allen

Understanding the complex processes occurring at the soil surface is challenging due to the intricate spatial variability and dynamic nature of these processes. An effective tool for elucidating these phenomena is three-dimensional (3D) reconstruction, which employs advanced imaging technologies to create a comprehensive representation of the soil surface at high spatial resolution, often at the mm-scale. Three-dimensional reconstruction techniques are increasingly available to scientists in the fields of soil science, geomorphology, hydrology, and ecology and many studies have employed these novel tools to advance understanding of surface processes. Much of the data being collected in these studies are however not interoperable, i.e., 3D data from one study may not be directly combined with 3D data from other studies thus limiting the ability of researchers to advance process understanding at a broader scope. The limited interoperability of existing data is due in part to the fact that 3D surface reconstruction data are influenced by many factors including experimental conditions, intrinsic soil properties and accuracy and precision limits of the 3D reconstruction technique used. These ancillary data are crucial to any broad-scope efforts that leverage the increasing number of 3D datasets collected by scientists across disciplines, geographic regions, and experimental conditions. We have developed a relational database that archives and serves ancillary data associated with published high-resolution 3D data representing soil surface processes. This presentation introduces the structure of the database with its required and optional variables. We also provide analytics on the currently available records in the database and discuss potential applications of the database and future developments.

How to cite: Nouwakpo, K., Eltner, A., Candido, B., Li, Y., Wacha, K., Nichols, M., and Washington-Allen, R.: A database for ancillary information of three-dimensional soil surface microtopography measurements., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10373, https://doi.org/10.5194/egusphere-egu24-10373, 2024.

EGU24-11949 | ECS | Posters on site | GM3.1

Employng satellite immagery interpretation tools to detect land-use land-change dynamics in Italian historical rural landscapes 

Virginia Chiara Cuccaro, Claudio Di Giovannantonio, Giovanni Pica, Luca Malatesta, and Fabio Attorre

Rural landscapes inherited from the past are marked by a strong interaction between man and nature, a relationship rooted in a long history that testifies to the importance of the landscape as one of the most historically representative expressions of a country's cultural identity.

In this broad context, olive groves markedly characterize the agricultural landscape of many European rural areas, particularly in the Mediterranean region. Along with other rural landscapes, they form a semi-natural environment that can contribute to biodiversity conservation, soil protection and ecosystem resilience.

In addition to the global increase in temperatures, the main threats affecting these agrarian landscapes include the abandonment of traditional practices and the intensification of cultivation through the installation of irregular, intensive and overly dense planting beds.

The Land Cover classification and change-detection can provide useful indications for the restoration, conservation, and enhancement of olive groves

The objective of this work was to identify , rural landscapes in the Lazio region with characteristics of historical interest and determine their level of conservation. In particular, it was investigated the olive landscape of Cures (historic province of Sabina) trough a multi-temporal analysis of literature and cartographic information (e.g. orthophotos from the Italian Aeronautical Group flight of 1954)

The technique concerns the VASA (Historical Environmental Assessment) methodology, which allows the temporal evaluation of a given landscape and can inform on how agricultural practices and land use have changed over time.

Softwares  Collect Earth and Google Earth were employed to manipulate the historical series of high-resolution satellite images and implement photointerpretation. The coverage of identitied land units  was then estimated to address the configuration of the target landscape.

Landscape evolution over time was achieved by overlaying the 1954 and 2022 land use polygons, resulting in a merging database, in which an evolutionary dynamic was associated with each land use change.

The approach generated in-depth insights on the significant elements of the CURES olive landscape and informed on the dynamics of the area in relation to the risk of their disappearance, making it possible to identify what are the "landscape emergencies," i.e., the land uses that have seen the most̀ reduction in their area.

The methodologies employed have proven reliability in improving the knowledge ng target landscapes.  It might be useful to promote  sustainable agricultural practices for better preservation and management of rural environments so that cultural traditions can be preserved as well, and the environmental balance of the agrarian land can be maintained.

How to cite: Cuccaro, V. C., Di Giovannantonio, C., Pica, G., Malatesta, L., and Attorre, F.: Employng satellite immagery interpretation tools to detect land-use land-change dynamics in Italian historical rural landscapes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11949, https://doi.org/10.5194/egusphere-egu24-11949, 2024.

EGU24-12105 | ECS | Orals | GM3.1 | Highlight

Unleashing the archive of aerial photographs of Iceland, 1945-2000. Applications in geosciences  

Joaquín M. C. Belart, Sydney Gunnarson, Etienne Berthier, Amaury Dehecq, Tómas Jóhannesson, Hrafnhildur Hannesdóttir, and Kieran Baxter

The archive of historical aerial photographs of Iceland consists of ~140,000 vertical aerial photographs acquired between the years 1945 and 2000. It contains an invaluable amount of information about human and natural changes in the landscape of Iceland. We have developed a series of automated processing workflows for producing accurate orthomosaics and Digital Elevation Models (DEMs) from these aerial photographs, which we’re making openly available in a data repository and a web map visualization service. The workflow requires two primary inputs: a modern orthomosaic to automatically extract Ground Control Points (GCPs) and an accurate DEM for a fine-scale (sub-meter) alignment of the historical datasets. We evaluated the accuracy of the DEMs by comparing them in unchanged terrain against accurate recent lidar and Pléiades-based DEMs, and we evaluated the accuracy of the orthomosaics by comparing them against Pléiades-based orthomosaics. The data are becoming available at https://loftmyndasja.lmi.is/. To show the potential applications of this repository, we present the following showcases where these data reveal significant changes the landscape in Iceland in the past 80 years: (1) volcanic eruptions (Askja 1961, Heimaey 1973 and the Krafla eruptions, 1975-1984), (2) decadal changes of Múlajökull glacier from 1960-2023, (3) Landslides (Steinsholtsjökull 1967, Tungnakvíslarjökull 1945-present) and (4) coastal erosion (Surtsey island).

How to cite: Belart, J. M. C., Gunnarson, S., Berthier, E., Dehecq, A., Jóhannesson, T., Hannesdóttir, H., and Baxter, K.: Unleashing the archive of aerial photographs of Iceland, 1945-2000. Applications in geosciences , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12105, https://doi.org/10.5194/egusphere-egu24-12105, 2024.

EGU24-14087 | ECS | Posters on site | GM3.1

A point-cloud deep learning model based on RGB-D images: Application of riverbed grain size survey 

Bo Rui Chen and Wei An Chao

The water level and discharge of river are crucial parameters to understand the variance in riverbed scour. The detail behavior of scouring can be studied by the hydraulic simulation. The grain-size distribution of riverbed is also one of crucial parameter for modeling. Thus, how to investigate the grain-size of riverbed efficiently and swiftly is the urgent issue. However, the conventional measurement methods including Wolman counts (particles sampled at a fixed interval) which are a long and laborious task cannot survey the grain-size efficiently in the large area. In recent years, with an advantage of image segmentation and recognition has been applied to the investigation of grain-size, for example, capturing images through UAV and generating orthoimage is one of commonly used image technique. Although above the method can investigate the grain-size in the large area, it does not provide the information in the field immediately. Hence, a recent study developed the low-cost portable scanner to obtain the information of grain-size distribution in the field. However, the calibrating parameters of camera (e.g., height camera capture) are necessary before survey, and the uncertainties in calculation of image resolution will significantly affect the accuracy of grain-size analysis. Therefore, this study provides the additional algorithm to analyze the grain-size by using RGB-D image as inputs. The application of RGB-D can be categorized into two-dimensional (2D) and three-dimensional (3D) spaces. In a case of 2D, it integrates depth information with traditional RGB image processing to separate the grain-size of riverbed from the background (e.g., bottomland). Furthermore, depth information is also applied for grain-size edge detection. In a case of 3D, the collected RGB-D image information is transformed into point cloud data, then extract 3D features of grain particle by Deep learning, specifically PointNet. Our study demonstrates that clustering of 3D features can achieve the automatic identification of particle. The grain-size of particle can also be estimated by fitting 3D ellipsoid geometry. In the end, results show the grain-size distribution curves with the RGB、RGB-D、PointNet recognition, and compare with the true observations. 3D image information provides the cloud points of grain object, leading the possibility of estimating the 3D geometric morphology of the object. Our study successfully overcomes the limitations of conventional RGB-based process, which could only capture size and shape information in 2D planar. RGB-D-based image recognition, is an innovative technique for the hydraulic problem, not only advances survey efficiency but also addresses the intricate steps required for field investigations.

 

Key words: Riverbed grain size, RGB-D image, Point cloud, Deep Learning

How to cite: Chen, B. R. and Chao, W. A.: A point-cloud deep learning model based on RGB-D images: Application of riverbed grain size survey, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14087, https://doi.org/10.5194/egusphere-egu24-14087, 2024.

EGU24-14680 | Orals | GM3.1

Using current 3D point clouds as a tool to infer on past geomorphological processes 

Reuma Arav, Sagi Filin, and Yoav Avni

Examining deposition and erosion dynamics during the late Pleistocene and Holocene is crucial for gaining insights into soil development, erosion, and climate fluctuations. This urgency intensifies as arable lands face escalating degradation rates, particularly in arid and semi-arid environments. Nevertheless, as the destructive nature of erosional processes allows only for short-term studies, long-term processes in these regions are insufficiently investigated. In that respect, the ancient agricultural installations in the arid Southern Levant offer distinctive and undisturbed evidence of long-term land dynamics. Constructed on a late Pleistocene fluvial-loess section during the 3rd-4th CE and abandoned after 600-700 years, these installations record sediment deposition, soil formation, and erosion processes. The challenge is to trace and quantify these processes based on their current state. In this presentation, we demonstrate how the use of 3D point cloud data enables us to follow past geomorphological processes and reconstruct trends and rates. Utilizing data gathered in the immediate vicinity of the UNESCO World Heritage Site of Avdat (Israel), we illustrate how these point clouds comprehensively document the history of soil dynamics in the region. This encompasses the initial erosion phase, subsequent soil aggradation processes resulting from anthropogenic interruption, and the ongoing reinstated erosion. The unique setting, which uncovers the different fluvial sections, together with the detailed 3D documentation of the site, allows us to develop means for the reconstruction of the natural environment in each of the erosion/siltation stages. Therefore, by utilizing the obtained data, we can recreate the site during its developmental stages till the present day. Furthermore, we utilize terrestrial laser scan data sequence acquired in the past decade (2012-2022) to compute current erosion rates. These are then used to determine past rates, enabling inferences about the climatic conditions prevalent in the region over the last millennium. The in-depth examination of these installations provides valuable insights into approaches for soil conservation, sustainable desert living, and strategies to safeguard world-heritage sites subjected to soil erosion. As the global imperative to address soil erosion intensifies, this case study gains heightened relevance.

How to cite: Arav, R., Filin, S., and Avni, Y.: Using current 3D point clouds as a tool to infer on past geomorphological processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14680, https://doi.org/10.5194/egusphere-egu24-14680, 2024.

EGU24-15439 | ECS | Orals | GM3.1 | Highlight

Utilizing historical aerial imagery for change detection in Antarctica 

Felix Dahle, Roderik Lindenbergh, and Bert Wouters

Our research explores the potential of historical images of Antarctica for change detection in 2D and 3D. We
make use of the TMA Archive, a vast collection of over 330,000 black and white photographs of Antarctica taken
between 1940 to 1990. These photographs, available in both nadir and oblique, are systematically captured
from airplanes along flight paths and offer an unprecedented historical snapshot of the Antarctic landscape.
Detecting changes between past and present observations provides a unique insight into the long-term impact
of changing climate conditions on Antarctica’s glaciers, and their dynamical response to ice shelf weakening and
disintegration. Furthermore, it provides essential validation data for ice modelling efforts, thereby contributing
to reducing the uncertainties in future sea level rise scenarios.

In previous work, we applied semantic segmentation to these images [1]. By employing classes derived from this
segmentation, we can focus on features of interest and exclude images with extensive cloud coverage, enhancing
the accuracy of change analyses. In the next step, we geo-referenced the images: We assigned the images to
their actual position, scaled them to their true size, and aligned them with their genuine orientation. This
presents novel opportunities for detecting environmental changes in Antarctica, particularly in the retreat of
glaciers and sea ice.

Furthermore, the combination of these two steps allows for the first time a large scale reconstruction of these
images in 3D through Structure from Motion (SfM) techniques, which enables further multidimensional change
detection by comparing historical 3D models with contemporary ones. Due to the high number of images,
manual processing is impractical. Therefore, we are investigating the possibility of automatizing this process.
We utilize MicMac, an open-source software developed by the French National Geographic Institute for the
creation of the 3D models. Its high modularity allows for necessary customizations to automate the SfM
process effectively. Further adaptions are required due to the poor image quality and monotonous scenery. By
comparing historical 3D models with contemporary ones, we can assess alterations in elevation due to factors
such as glacial isostatic adjustments and glacier retreat.

We have already employed geo-referenced images for detecting changes on the Antarctic peninsula and are in the
process of creating initial 3D models. Our presentation will outline the workflow we developed for this process
and showcase the initial results of the change detection, both in 2D and 3D formats. This approach marks a
significant step in understanding and visualizing the impacts of climate change on the Antarctic landscape.

Acknowledgements
This work was funded by NWO-grant ALWGO.2019.044.

References
[1] F. Dahle, R. Lindenbergh, and B. Wouters. Revisiting the past: A comparative study for semantic segmen-
tation of historical images of Adelaide Island using U-nets. ISPRS Open Journal of Photogrammetry and
Remote Sensing, 11:100056, 2024.

How to cite: Dahle, F., Lindenbergh, R., and Wouters, B.: Utilizing historical aerial imagery for change detection in Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15439, https://doi.org/10.5194/egusphere-egu24-15439, 2024.

EGU24-15896 | Orals | GM3.1

Classification and segmentation of 3D point clouds to survey river dynamics and evolution  

Laure Guerit, Philippe Steer, Paul Leroy, Dimitri Lague, Dobromir Filipov, Jiri Jakubinsky, Ana Petrovic, and Valentina Nikolova

3D data for natural environments are now widely available via open data at large scales (e.g., OpenTopography) and can be easily acquired on the field by terrestrial LiDAR scan (TLS) or by structure-from-motion (SFM) from camera or drone imagery. The 3D description of landscapes gives access to an unprecedented level of details that can significantly change the way we look at, understand, and study natural systems. Point clouds with millimetric resolution even allow to go further and to investigate the properties of riverbed sediments: dedicated algorithms are now able to extract the sediment size distribution or their spatial orientation directly from the point cloud. 

Such data can be real game changers to study for example torrential streams prone to flash floods or debris flows. Such events are usually associated with heavy rainfall events, while conditioned by the geomorphological state of a stream (e.g., channel geometry, vegetation cover). The size and the shape of the grains available in the river also strongly influence river erosion and sediment transport during a flood. 3D data can thus help to design prevention and mitigation measures in streams prone to torrential events. 

However, it is not straightforward to go from data acquisition to river erosion or to grain-size distributions. Indeed, isolating and classifying the areas of interest can be complex and time-consuming. This can be done manually, at the cost of time and absence of reproducibility. We rather take advantage of state-of-the-art classification method (3DMASC) to develop a general classifier for point clouds in fluvial environments designed to identify five classes usually found in such settings: coarse sediments, sand, bedrock, vegetation and human-made structures. We also improved the G3Point sediment segmentation algorithm, developed by our team, to make it more efficient and straightforward to use in the CloudCompare software, which is dedicated to point cloud visualization and analysis. We apply it to the coarse sediments class identified by 3DMASC to provide a more accurate description of grain size and orientation. We also make a profit of the sand class to estimate its relative areal distribution that can then be compared to the coarse sediment class. This provides valuable information about the type of flows which are also important for planning torrential events mitigation measures.

We illustrate this combined approach with two field examples. The first one is based on SFM data acquired along streams prone to torrential events in Bulgaria and in Serbia where we documented sediment size and orientation. The second one is based on TLS data acquired along a bedrock river in France that experienced a major flood which induced dramatic changes in the river morphology. 

This work has been partially funded by PHC Danube n° 49921ZG/ n° KP-06-Danube/5, 14.08.2023 (National Science Fund, Bulgaria) and the H2020 European Research Council (grant no. 803721). 

How to cite: Guerit, L., Steer, P., Leroy, P., Lague, D., Filipov, D., Jakubinsky, J., Petrovic, A., and Nikolova, V.: Classification and segmentation of 3D point clouds to survey river dynamics and evolution , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15896, https://doi.org/10.5194/egusphere-egu24-15896, 2024.

EGU24-16939 | ECS | Posters on site | GM3.1 | Highlight

Integrating structure-from-motion photogrammetry with 3D webGIS for risk assessment, mapping and monitoring of coastal area changes in the Maltese archipelago 

Emanuele Colica, Daniel Fenech, Christopher Gauci, and George Buhagiar

The Maltese coasts extend for approximately 273km, representing a notable resource for the country and of one of its pillar economies, the tourism sector. Natural processes and anthropic interventions continue to threaten Malta's coastal morphology, shaping its landscape and triggering soil erosion phenomena. Therefore, many research projects (Colica et al., 2021, 2022 and 2023) have concentrated their work on the investigation and monitoring of the instability of cliffs and the erosion of pocket beaches. The results of such activities can be widely disseminated and shared with expert and non-expert users through web mapping, which has only been used in a very limited way in collaborative coastal management and monitoring by different entities in Malta. This study describes the performance of a WebGIS designed to disseminate the results of innovative geomatic investigations for monitoring and analyzing erosion risk, performed by the Research and Planning Unit within the Public Works Department of Malta. While aiming to include the entire national coastline, three study areas along the NE and NW regional coasts of the island of Malta have already been implemented as pilot cases. This WebGIS was generated using ArcGIS pro software by ESRI and a user-friendly interactive interface has been programmed to help users view in 2D and 3D, satisfying both multi-temporal and multi-scale perspectives. It is envisaged that through further development and wider dissemination there will be a stronger uptake across different agencies involved in coastal risk assessment, monitoring and management.

References

Colica, E., D’Amico, S., Iannucci, R., Martino, S., Gauci, A., Galone, L., ... & Paciello, A. (2021). Using unmanned aerial vehicle photogrammetry for digital geological surveys: Case study of Selmun promontory, northern of Malta. Environmental Earth Sciences, 80, 1-14.

Colica, E. (2022). Geophysics and geomatics methods for coastal monitoring and hazard evaluation.

Colica, E., Galone, L., D’Amico, S., Gauci, A., Iannucci, R., Martino, S., ... & Valentino, G. (2023). Evaluating Characteristics of an Active Coastal Spreading Area Combining Geophysical Data with Satellite, Aerial, and Unmanned Aerial Vehicles Images. Remote Sensing, 15(5), 1465.

How to cite: Colica, E., Fenech, D., Gauci, C., and Buhagiar, G.: Integrating structure-from-motion photogrammetry with 3D webGIS for risk assessment, mapping and monitoring of coastal area changes in the Maltese archipelago, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16939, https://doi.org/10.5194/egusphere-egu24-16939, 2024.

EGU24-17822 | ECS | Posters on site | GM3.1

Evaluating Ordnance Survey sheets (1890s – 1957) for shoreline change analysis in the Maltese Islands  

Daniel Fenech, Jeremie Tranchant, Christopher Gauci, Daniela Ghirxi, Ines Felix-Martins, Emanuele Colica, and George Buhagiar

 

Jeremie' Tranchant1, Daniel Fenech1, Christopher Gauci1, Daniela Ghirxi1, Ines Felix Martins1, Emanuele Colica1, George Buhagiar1

1  Research and Planning Unit, Ministry for Transport, Infrastructure and Public Works, Project House, Triq Francesco    Buonamici, Floriana, FRN1700, Malta

The assessment of coastal erosion through shoreline change analysis, is an exercise of national utility undertaken in many countries. The Maltese Islands are particularly vulnerable to coastal erosion given the economic value of coastal activities and their high ratio of coast-to-land surface. The integration of historical cartographic material is often used to hindcast shoreline change across long periods of time, as well as to model future erosion rates. The Public Works Department have produced detailed 1:2500 maps of Malta in collaboration with the British Ordnance Survey from the end of the 19th century to 1957, however these maps have never been scientifically assessed. The initial research carried out evaluated the usefulness of the two oldest 25-inches Maltese maps series (early 20th century and 1957) for shoreline change analysis.  The two series were digitised, georeferenced, and compared in a GIS environment to assess their differences. The inaccuracies of the original drawings, absent shoreline indicators, and the absence of a geographic coordinate system (datum and projection) were identified as limitations for their use in evaluating small gradual changes, but were ideal for the identification of stochastic, large-scale historic erosion events using difference maps. This assessment showed that the two series are highly congruous and any changes between the two series are largely attributed to changes in infrastructure. There were, however, minor exceptions and these need to be explored on a case-by-case basis. These methods and the insights garnered from their production will function as scientific steppingstones towards developing a holistic coastal erosion national monitoring program.  

How to cite: Fenech, D., Tranchant, J., Gauci, C., Ghirxi, D., Felix-Martins, I., Colica, E., and Buhagiar, G.: Evaluating Ordnance Survey sheets (1890s – 1957) for shoreline change analysis in the Maltese Islands , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17822, https://doi.org/10.5194/egusphere-egu24-17822, 2024.

EGU24-21396 | ECS | Orals | GM3.1

Automatic detection of river bankfull parameters from high density lidar data 

Alexandre Rétat, Nathalie Thommeret, Frédéric Gob, Thomas Depret, Jean-Stéphane Bailly, Laurent Lespez, and Karl Kreutzenberger

The European Water Framework Directive (WFD), adopted in 2000, set out requirements for a
better understanding of aquatic environments and ecosystems. In 2006, following the transposition of
the WFD into French law (LEMA), France began work on a field protocol for the geomorphological
characterization of watercourses, as part of a partnership between the Centre National de la Recherche
Scientifique (CNRS) and the Office Français de la Biodiversité (OFB). This protocol, known as "Carhyce"
(For « River Hydromorphological Caracterisation »), has been tested, strengthened and approved over
the last 15 years at more than 2500 reaches. It consists of collecting standardised qualitative and
quantitative data in the field, essential for the caracterisation of a watercourse: channel geometry,
substrate, riparian vegetation... However, certain rivers that are difficult to survey (too deep or too
wide) pose problems for data collection.
To address these issues, and to extend the analysis to a wider scale (full river section), using
remote sensing, and in particular LiDAR data, was considered. The major advantages of LiDAR over
passive optical sensors are better geometric accuracy and especially under vegetation. For a long time,
LiDAR data rarely exists at national scale with data density similar to passive imagery. Today, the French
LiDAR HD dataset (10 pulses per meter square) program run by the French mapping agency offers an
unprecedented amount of data at this scale. Thanks to them, a national 3D coverage of the ground can
be used, and numerous geomorphological measurements can be carried out on a more or less large
scale. This is the case for hydromorphological parameters such as water level and width.
The aim of this study is therefore to use this high-density lidar to automatically determine the
hydromorphological parameters sought in the Carhyce protocol. In particular, we have developed a
lidar-based algorithm to reconstruct the topography from point cloud and automatically identify the
bankfull level at reach scale. Designed to be applicable to every French river, the method must be
robust to all river features such as longitudinal slope, width, sinuosity, multi-channel etc... For
validation purposes, the bankfull geometry calculated by the algorithm has been compared with field
measurements at some twenty Carhyce stations across France. To determine the test stations, we
looked for the diversity of situations in terms of river characteristics describe above to observed the
influence of this features on the results.

How to cite: Rétat, A., Thommeret, N., Gob, F., Depret, T., Bailly, J.-S., Lespez, L., and Kreutzenberger, K.: Automatic detection of river bankfull parameters from high density lidar data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21396, https://doi.org/10.5194/egusphere-egu24-21396, 2024.

EGU24-22358 | ECS | Orals | GM3.1 | Highlight

UAV’s to monitor the mass balance of glaciers 

Lander Van Tricht, Harry Zekollari, Matthias Huss, Philippe Huybrechts, and Daniel Farinotti

Uncrewed Aerial Vehicles (UAVs) are increasingly employed for glacier monitoring, particularly for small to medium-sized glaciers. The UAVs are mainly used to generate high-resolution Digital Elevation Models (DEMs), delineate glacier areas, determine surface velocities, and map supraglacial features. In this study, we utilise UAVs across various sites in the Alps and the Tien Shan (Central Asia) to monitor the mass balance of glaciers. We present a workflow for calculating the annual geodetic mass balance and obtaining the surface mass balance using the continuity-equation method. Our results demonstrate generally a close alignment between the determined mass balances and those obtained through traditional glaciological methods involving intensive fieldwork. We show that utilising UAV data reveals significantly more spatial details, such as the influence of debris and collapsing ice caves, which are challenging to capture using conventional methods that strongly rely on interpolation and extrapolation. This underscores the UAV's significance as a valuable add-on tool for quantifying annual glacier mass balance and validating glaciological assessments. Drawing on our experience in on-site UAV glacier surveys, we discuss the methodology's advantages, disadvantages, and potential pitfalls. 

How to cite: Van Tricht, L., Zekollari, H., Huss, M., Huybrechts, P., and Farinotti, D.: UAV’s to monitor the mass balance of glaciers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22358, https://doi.org/10.5194/egusphere-egu24-22358, 2024.

EGU24-837 | ECS | Orals | EMRP3.4

Identifying probable signatures of hydrothermal activity from the Carlsberg ridge sediments using rock magnetic properties 

Sambhabana Lenka, Pratima Kessarkar, Lina Fernandes, and Concy Gomes

The Carlsberg Ridge (CR) is a slow-spreading ridge occurs along divergent plate boundary, with the reports of three active and one extinct hydrothermal vent sites. For the present study eight spade cores (SCs) were collected from the CR, of which three are in the vicinity of Tianxiu hydrothermal field and one on the ridge flank. The hydrothermal sites are known to be associated with metalliferous sediments with Fe being the one of the dominant element. We measured rock magnetic properties of sediments that depend on iron bearing minerals, along with X-ray diffractometry (XRD), and microscopic observations to distinguish metalliferous sediments, that may be associated with the active/extinct hydrothermal activity at the CR. Magnetic susceptibility (χlf) of sediments ranges between 1.3 and 37.1 x10-8 m3kg-1. Low χlf signatures suggesting low metalliferous sediments are observed on flank and two cores from the ridge valley indicating, the absence of hydrothermal activity. Whereas sediments closer to the Tianxiu hydrothermal vent field are associated with high χlf, signifying higher metalliferous sediments and are also having high satuaration isothermal remanent magnetization (SIRM), hard isothermal remanent magnetization (HIRM), and low anhysteretic remanent magnetic susceptibility (χARM)/SIRM, coarse stable single domain (SSD)  and fine SSD & mixture grains characteristics. Two more spade cores ~ 250 km south of the Tianxiu vent field also showed similar signatures indicating new active/relict site/sites in the vicinity. Identifying/locating metalliferous hydrothermal sediment/sites along extensive Mid Ocean Ridge (MOR) is expensive and time-consuming; rock magnetic could be a non-destructive method to shortlist the areas for detailed studies.

How to cite: Lenka, S., Kessarkar, P., Fernandes, L., and Gomes, C.: Identifying probable signatures of hydrothermal activity from the Carlsberg ridge sediments using rock magnetic properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-837, https://doi.org/10.5194/egusphere-egu24-837, 2024.

A correlation between Earth’s magnetic field and climate change has been debated for over forty years, despite significant ~100- and ~41-kyr periods in both the stacked relative paleointensity and inclination records. In this paper, we construct a master relative intensity curve (SPIS-150) over the past ~150 kyr by stacking the data from one new core (PC27) with published intensity curves for the northern South China Sea. Additionally, we calculate the Dole effect from the sea surface temperature (SST) and d18O of planktonic foraminifera based on two cores, PC83 and PC27, and use it as a precipitation proxy. The results of this study show that geomagnetic field intensity lows are related to rich rainfall. During the ~23 kyr period, the relative intensity shows in-phase variations with simulating 0-30°N terrestrial precipitation, which shows that the superimposed effect of insolation and geomagnetic fields influences low-latitude precipitation. The strong summer monsoon predominated by insolation carries rich water vapor, which forms low cloud cover under one cloud-formation physical process where the geomagnetic field modulates galactic cosmic rays (GCRs) and leads to aerosol-related cloud condensation nuclei (CCN) formation. Deeper cloud cover produces strong rainfall in low-latitude regions.

How to cite: Yang, X.: Are there any links between geomagnetic field variations and hydrological cycles in the South China Sea since the Late Pleistocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2855, https://doi.org/10.5194/egusphere-egu24-2855, 2024.

EGU24-3158 | ECS | Posters on site | EMRP3.4

Paleomagnetism and calcite U-Pb geochronology from the Penglaitan GSSP section, South China 

Min Zhang, Huafeng Qin, Chenglong Deng, Shu-zhong Shen, and Yongxin Pan

The Guadalupian-Lopingian boundary (GLB) interval is characterized by the Pangea breakup, dramatic sea-level change, Emeishan Basalt volcanism, and biotic turnover. We conducted magnetostratigraphic, mineralogical, and calcite U-Pb geochronological studies at the Penglaitan Global Stratotype Section and Point section in South China. Rock-magnetic results indicate that magnetite and rare hematite are the dominant remanence carriers. After removing the viscous remanent magnetization, three components were isolated from the limestone at the Penglaitan section. The high-temperature remanence components were isolated from the tuffaceous limestone and yielded a mean direction of Ds/Is = 195.3°/+5.6° (α95s = 5.3°, ks = 22.8, n = 34) after tilt correction. It defined a reversed magnetozone from the top of conodont Jinogondolella granti Zone to the lower part of the Clarkina. dukouensis Zone, straddling the GLB. Additionally, intermediate-temperature components represent the Jurassic and Triassic remagnetization, also supported by the in-situ calcite U-Pb dating (~133-166 Ma and ~213-224 Ma), pyrite-to-magnetite alteration, or magnetite oxidization to maghemite and hematite. The new paleomagnetic results and calcite U-Pb dating provide new insights into Mesozoic multi-remagnetization in the South China Block and refine the GLB positioned in a reversed magnetozone.

How to cite: Zhang, M., Qin, H., Deng, C., Shen, S., and Pan, Y.: Paleomagnetism and calcite U-Pb geochronology from the Penglaitan GSSP section, South China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3158, https://doi.org/10.5194/egusphere-egu24-3158, 2024.

Situated along the Adriatic coast of southern Apulia (Italy), Grotta Romanelli (40.02o N, 18.43o E) is a natural coastal cave considered as a key site for understanding the Middle Pleistocene-Holocene geomorphological, palaeoenvironmental and stratigraphic evolution of the Mediterranean area. Its sedimentary fillings, extremely rich in archaeological and palaeontological findings have been long investigated for their stratigraphical and palaeontological aspects while efforts, mainly based on radiocarbon and pollen analyses, have been focused on better understanding their chronological framework. In this study, we propose a new age model based on the palaeomagnetic record of the uppermost Stratigraphical Unit IUS5 of Grotta Romanelli, also known as Terre Brune. Stepwise alternating field demagnetization provided well-defined directions, which were compared with the reference geomagnetic field curves calculated from the SHA.DIF.14k global geomagnetic field model directly at the cave’s geographic coordinates. A continuous age model was determined taking into consideration the principle of stratigraphic superposition. A selection of reliable, previously published, radiocarbon ages from animal teeth, bones and charcoal was also used for comparison. The proposed age-depth model covers the 14ka-8ka BP period, offering new insights on the chronology of the sedimentation and frequentation of the cave before its complete infilling. This chronological frame enables new considerations on the palaeoenvironmental evolution and climate changes that took place during the transition from the Late Pleistocene to the Holocene, and offers new insights on the dating of the Grotta Romanelli fossil remains, human rests and archaeological artifacts, including lithic tools and rock art.

How to cite: Tema, E., Lanci, L., Pieruccini, P., Mazzini, I., and Sardella, R.: Palaeomagnetic dating of the Grotta Romanelli (Apuglia, Italy) upper sedimentary filling: Insights on the Late Pleistocene-Holocene palaeoenvironment and human settings in the Mediterranean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4536, https://doi.org/10.5194/egusphere-egu24-4536, 2024.

EGU24-5396 | Orals | EMRP3.4

Rock magnetic record of environmental changes over the last 40.000 years in the Westermost Mediterranean: the Alboran Sea sedimentary record 

Victor Villasante Marcos, Silvia Beltrán de Heredia García-Nieto, Francisca Martínez Ruiz, Santiago Casanova Arenillas, and Francisco Javier Rodríguez Tovar

We present here a high-resolution rock magnetic study of deep-sea marine sediments from the Alboran Sea (Westernmost Mediterranean). The analyzed sediment  record, core GP03, 889 cm in length, covers the last 40.000 years from upper Pleistocene glacial times through the Last Glacial Maximum, subsequent deglaciation, Younger Dryas cooling reversal and the whole Holocene up to the current Industrial Period. The sediment core was sampled at high resolution, and 379 samples were measured for their bulk magnetic susceptibility, frequency-dependent susceptibility, hysteresis cycles and Isothermal Remanent Magnetization (IRM) direct and reverse acquisition curves. A subset of 125 samples were subjected to thermomagnetic experiments up to 700º C in order to reveal Curie and thermal transformation temperatures and to support the identification of the precise magnetic mineralogy. The variations in the magnetic mineralogy along the analyzed record, together with previously published geochemical data, have allowed to track the main paleoenvironmental and paleoclimatic changes in the studied region over the last 38 ka, as well as documenting a very strong reductive dissolution horizon affecting magnetic phases in the Younger Dryas sediments, which points to a significant deoxygenation event. A strong correlation of magnetic parameters and stadial-interstadial fluctuations during the last glaciation, especially between 25 and 38 ka, is observed, pointing to variations in riverine vs. aeolian terrigenous input. In modern sediments (approximately the last 200 years), a sharp increase in magnetite abundance in the sediments has been recognized, coinciding with the timespan of the Industrial Period. We conducted magnetic extraction to concentrate the ferromagnetic fraction of these sediments, followed by Scanning Electron Microscopy and EDS analysis, and identified strongly ferromagnetic microspherules with textures typical of rapid crystallization from high temperature melts. These microspherules, rich in magnetite, are indistinguishable from typical fly ash magnetic microspherules of industrial origin, which support they are the magnetic fingerprint of anthropogenic industrial ferromagnetic phases in this marine setting that superimposed on the natural paleoenvironmental changes during the uppermost Pleistocene and Holocene.

How to cite: Villasante Marcos, V., Beltrán de Heredia García-Nieto, S., Martínez Ruiz, F., Casanova Arenillas, S., and Rodríguez Tovar, F. J.: Rock magnetic record of environmental changes over the last 40.000 years in the Westermost Mediterranean: the Alboran Sea sedimentary record, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5396, https://doi.org/10.5194/egusphere-egu24-5396, 2024.

EGU24-5451 | ECS | Posters on site | EMRP3.4

Time-series analysis of rock magnetic data from sediments spanning the last 40.000 years in the Western Mediterranean: strong paleoenvironmental cyclicities during the last glaciation 

Silvia Beltrán de Heredia García-Nieto, Víctor Villasante Marcos, Francisca Martínez Ruiz, Santiago Casanova Arenillas, and Francisco Javier Rodríguez Tovar

Time-series analysis of high-resolution rock magnetic data from deep-sea marine sediments (piston core GP03, Alboran Sea, Westernmost Mediterranean), spanning the last 40.000 years, has been performed to reveal paleoenvironmental cyclicities and climate variability in this region during the uppermost Pleistocene and Holocene. We have applied both the classical Fast Fourier Transform (FFT), after regularizing our data by linear interpolation, and the Lomb-Scargle periodogram, which is well suited to analyze non-regular time series, as is the case. In addition to the usual Lomb-Scargle periodogram, we have also tested a modification of the periodogram that takes into account the experimental errors of the analyzed parameters. Also, in addition to the power spectrum and its peak spectral frequencies/periods, we have computed the Achieved Confidence Level (or false positive rate) of the different spectral peaks by a Monte Carlo evaluation of the permutation test, restricting our further analysis to those spectral peaks with Achieved Confidence Levels greater than 95%. The obtained results through these different approaches show a high degree of coherency, proving the reliability not only of the methods, but also of the modifications introduced and of the obtained results. Our results highlight the presence of characteristic cyclicities with periods in the range of 1600-4500 years during the last glaciation, especially between 25 and 38 ka. The most intense spectral peak has a period around 2 ka, which is consistent with the characteristic periods of Dansgaard-Oeschger (D-O) climate fluctuations. This strong 2 ka signal is clearly arising from the observed match between high magnetic susceptibility and saturation remanent magnetization values with D-O warm phases (interstadials). These relative maxima in magnetic mineral abundance are correlated with high S-ratio values, pointing to an increase in magnetite vs. hematite abundance in the sediments. Conversely, cold D-O phases (stadials) seem to be related to low susceptibility, low saturation remanence and lower S-ratio, indicating a decrease in the contribution of low coercivity phases (like magnetite) and an increase in the relative importance of high coercivity phases like hematite. We suggest this is connected with variations in the relative importance of riverine vs. aeolian terrigenous input. In contrast, Holocene rock magnetic data do not show this 2 ka peak, but instead cyclicities with periods around 2800, 3800 and 5500 years are recognized. To our knowledge, this is the first report of such a remarkable relationship between marine sedimentary rock magnetic data and paleoclimatic cyclicities in the frequency range of the Dansgaard-Oeschger or stadial-interstadial events in the Western Mediterranean over the last glaciation, pointing to the interest of further rock magnetic studies.

How to cite: Beltrán de Heredia García-Nieto, S., Villasante Marcos, V., Martínez Ruiz, F., Casanova Arenillas, S., and Rodríguez Tovar, F. J.: Time-series analysis of rock magnetic data from sediments spanning the last 40.000 years in the Western Mediterranean: strong paleoenvironmental cyclicities during the last glaciation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5451, https://doi.org/10.5194/egusphere-egu24-5451, 2024.

The hidden link between the geomagnetic field and climate is gradually being noted for its unexpected consistency. However, the unclear linking mechanisms and questions regarding whether geomagnetic reconstructions entirely exclude climatic influences have sparked controversy surrounding this relationship. Here, we analyze a high-resolution geomagnetic paleosecular variation record since 30 ka in the northern South China Sea and find a good correlation between its climate-independent inclination record with the regional temperature and precipitation.

The studied core, SCS-5, was obtained from the northern South China Sea (21.21°N, 118.04°E) at a water depth of 1600 m, twenty AMS 14C ages were used to establish the age framework since ~30 ka, with an overall sedimentation rate exceeding 30cm/kyr. Detailed rock magnetic and environmental magnetic analysis determined that the sedimentary environment of the core is stable and homogeneous. Reliable characteristic remanent magnetization directions are established, with all the maximum angular deviations less than 3. The inclination has fluctuated considerably over the last 30 ka period, but is more moderate during 20-10 ka. Reconstructed paleointensity shows an overall upward trend except for a slight decrease during 15-12 ka, with several significant shallowing of the inclination corresponding to the low values of the field intensity, which may be related to the role of geomagnetic reverse flux patches.

Comparing the local precipitation δ18Osw local record of the core and the paleotemperature record from South China, we observe that as the geomagnetic field strength decreases with shallower inclination, regional precipitation increases significantly, while the land temperature decreases. We hypothesize that the decline in geomagnetic strength may have regulated the regional hydroclimate through the mediation of cosmic rays, aerosols, and cloud cover. The weakening field could have induced increased cloudiness, leading to a parasol effect and greater precipitation. Additionally, the correlation between rainfall and the geomagnetic field is evident throughout the Late Pleistocene-Holocene, whereas the relationship between temperature and the geomagnetic field is more pronounced in the Holocene. It suggests that the forcing mechanism of the geomagnetic field on climate change is complex and nonlinear, which may differ in glacial and interglacial periods due to low-latitude processes or other forcing mechanisms.

How to cite: Wu, S. and Yang, X.: Unveiling the Covert Linkage Between Geomagnetic Dynamics and Climate in the Northern South China Sea Over the Last 30 ka, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5734, https://doi.org/10.5194/egusphere-egu24-5734, 2024.

EGU24-5780 | Posters on site | EMRP3.4

Rock magnetic anomaly caused by the pyritization linking to the gas hydrate dissociation off SW Taiwan 

Yin-Sheng Huang, Chorng-Shern Horng, Chih-Chieh Su, Shu-Kun Hsu, Wen-Bin Doo, and Jing-Yi Lin

      In the study, we present the rock magnetic property from three sediment cores collected by the R/V Marion Dufresne (MD) during the cruise MD214 off SW Taiwan, and two of these cores, MD18-3542 and MS18-3543, have collected shallow hydrate samples. Core site MD18-3542 is on the South Yuan-An East Ridge, where an unconformity covered by fine-silt sediments lies at ~5.5 m below the seafloor, and the core site MD18-3543 is close to the Good-Weather Ridge with a gas-related pockmark and authigenic carbonates near shallow strata. The other core MD18-3548 was obtained at a basin with relatively stable deposition settings to get the background information. Rock magnetic measurements, including magnetic susceptibility (MS) and hysteresis parameters, are used to describe the downcore variations of the magnetic features, while the Day Plot and XRD analysis are applied to classify and identify the dominance of core magnetic components. Both cores MD18-3542 and MD18-3543 show the attractive anomaly with dramatic value-drop in the records of MS and hysteresis parameters, and the feature looks absent in the core MD18-3548. Such signature may link to the pyritization caused by the gas hydrate dissociation. The dissociated methane with hydrogen sulfide trapped under the structures (an unconformity at site MD18-3542 and authigenic carbonates at site MD18-3543) would form an anoxic setting and activate the pyritization at shallow layers. Detrital magnetite would be gradually turned into authigenic iron sulfides, and thus could cause the attractive anomaly in the MS and hysteresis records.

How to cite: Huang, Y.-S., Horng, C.-S., Su, C.-C., Hsu, S.-K., Doo, W.-B., and Lin, J.-Y.: Rock magnetic anomaly caused by the pyritization linking to the gas hydrate dissociation off SW Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5780, https://doi.org/10.5194/egusphere-egu24-5780, 2024.

EGU24-7855 | ECS | Orals | EMRP3.4

A new protocol for fingerprinting cultural ochre sources using mineral magnetism 

Maddison Crombie, Agathe Lise-Pronovost, Marcus Giansiracusa, Colette Boskovic, Amy Roberts, n/a River Murray and Mallee Aboriginal Corporation, and Rachel Popelka-Filcoff

Provenance studies in ochre research are used to characterise the “fingerprint” of different ochre sources, providing the opportunity to trace the cultural movement of ochre in the archaeological past. Ochre pigment composition, and therefore the “fingerprint”, often varies between sites leading to source discrimination, but in many cases the composition can also vary within a site, and therefore presents an analytical challenge to develop methods that can differentiate this “fingerprint”. This work presents a novel protocol for the analysis of iron-based archaeological ochres from known sources within Australia and Kenya using geological mineral magnetism methods to disentangle complex mineral assemblages1. Magnetic properties have been largely unexplored as a tool for ochre provenance. However, the use of measurements such as room temperature – saturation isothermal remnant magnetisation (RT-SIRM), Hysteresis loops and zero field cooled, field cooled (ZFC-FC) allow for the identification of different magnetic minerals in the ochre samples, which can, in turn, be used to fingerprint ochre sources. This approach works towards understanding (1) the variation within and between sites and how this may differ based on source geologies and (2) the larger goal of tracing the movement of ochre from their sources to archaeological contexts and related ochre cultural exchange.

(1) Lagroix, F.; Guyodo, Y. A new tool for separating the magnetic mineralogy of complex mineral assemblages from low temperature magnetic behavior. Frontiers in Earth Science 2017, 5, 61.

How to cite: Crombie, M., Lise-Pronovost, A., Giansiracusa, M., Boskovic, C., Roberts, A., River Murray and Mallee Aboriginal Corporation, N., and Popelka-Filcoff, R.: A new protocol for fingerprinting cultural ochre sources using mineral magnetism, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7855, https://doi.org/10.5194/egusphere-egu24-7855, 2024.

EGU24-10469 | ECS | Orals | EMRP3.4

Magnetobiochronology of the Izaga section (South Pyrenean foreland basin) and its chronological implications: searching for a potential candidate for the Bartonian GSSP 

Pablo Sierra-Campos, Pablo Calvín, Gilen Bernaola, Manuel Montes, Aránzazu Luzón, José Ignacio Pérez-Landazábal, Cristina Gómez-Polo, Aitor Payros, Maria Pilar Mata, Eva Bellido, Emilio L. Pueyo, and Juan C. Larrasoaña

Here we introduce a new magnetobiostratigraphic section in the Jaca-Pamplona Basin, the Izaga section, which was studied in order to shed light on the chronology of the Lutetian/Bartonian boundary and the possibility of proposing it to host the Bartonian Global Stratotype Section and Point (GSSP). The Izaga section is located in the northern limb of the eastern termination of the Izaga syncline (South Pyrenean foreland basin) and is composed by a total of 1116 m of marine sediments that include the uppermost 450 m of the Jaca Turbidites and ~660 m of the prodeltaic marls of the Larrés (500 m), Urroz (110 m) and Pamplona (56 m) Formations. The uppermost Jaca Turbidites include the youngest South Pyrenean Eocene Carbonate Megabreccia (SPECM) identified in the basin to date, and the uppermost part of the Larrés Formation hosts ferroan dolomitic nodules whose formation can be linked to early diagenetic methanogenesis. Previously published biostratigraphic data based on planktic foraminifers broadly place the Lutetian/Bartonian boundary within the middle part of the Larrés Formation. A total of 173 magnetostratigraphic sites were sampled throughout the succession with an average 6.5 m spacing. Thermal demagnetization reveals the presence of two stable components: 1) a low temperature component that is identified <250ºC and is interpreted as present-day field overprint; and 2) a high-temperature component, that unblocks from 250-300ºC up to 425ºC and is identified as the ChRM. Paleo- and rock-magnetic data point to the dominant contribution of magnetite to the ChRM, although an additional drop in NRM intensity between 300-350ºC suggests the additional contribution by magnetic iron sulphides. To avoid problems with a likely diagenetic origin of magnetic iron sulphides, we established the polarity sequence of the Izaga section by using only ChRM directions associated to magnetite. The local polarity sequence comprises a normal (N1) magnetozone in the uppermost 286 m of the section and a reverse (R1) one spanning its remaining middle and lower parts. The analysis of calcareous nannofossil aseemblages allow the identification of zones CNE14 and CNE15 in the lower/middle and upper part of the succession, respectively. Overall, these new results enable the correlation of R1 and N1 with chrons C18r and C18n.2n, respectively. We have found no evidence for the presence of chron C19n, the proposed marker for the Lutetian/Bartonian boundary, within R1, which indicates that the whole studied section was deposited during the Bartonian and, therefore, has no bearings on the definition of the Bartonian GSSP. Our results also indicate: 1) that sedimentation rates (of >80 cm/kyr) in the South Pyrenean foreland basin increased towards the west; 2) that the SPECM found within the Jaca Turbidites extend the processes of SPECM formation well into the Bartonian; and 3) that the ferroan dolomitic nodules found in the uppermost part of the Larrés Formation can be considered as the sedimentological expression of the Middle Eocene Climate Optimum (MECO) in the basin.

How to cite: Sierra-Campos, P., Calvín, P., Bernaola, G., Montes, M., Luzón, A., Pérez-Landazábal, J. I., Gómez-Polo, C., Payros, A., Mata, M. P., Bellido, E., Pueyo, E. L., and Larrasoaña, J. C.: Magnetobiochronology of the Izaga section (South Pyrenean foreland basin) and its chronological implications: searching for a potential candidate for the Bartonian GSSP, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10469, https://doi.org/10.5194/egusphere-egu24-10469, 2024.

EGU24-13888 | ECS | Posters on site | EMRP3.4

Rock Magnetic and Mineralogical Analysis of IODP Expeditions 390 and 393 Basement Cores and their Implications for Fluid-Rock Interaction along the Mid-Atlantic Ridge Flank   

Gilbert Hong and Sang-Mook Lee and the The South Atlantic Transect IODP Expedition 390 & 393 Scientists

During the International Ocean Drilling Program (IODP) expeditions 390 and 393 - also referred to as the South Atlantic Transect (SAT), basement cores have been drilled from a total of 6 holes which penetrates around 150 – 300 meters of the uppermost South Atlantic seafloor. The cores mainly consist of basalts of varying age (~7 to 61 Ma) and alteration states. Some intervals of sedimentary breccia were found in older cores as well. Analyzing how these rocks have been altered and characterizing it based on age and depth are crucial to understanding how the oceanic crust along the South Atlantic has evolved throughout spreading and how fluid-rock interaction has influenced the process. Magnetic minerals can be a useful proxy of such alteration as its effects can be observed in both rock magnetism and mineralogy.   

In this study, we observed the composition and microstructure of magnetic minerals within basaltic samples of varying alteration degrees using a scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). These observations were then compared with shipboard rock magnetic data to determine which property shows correlation with the mineralogical characteristics. Magnetic minerals within the SAT basalt samples are mostly titanomaghemites with Fe content of 20 – 36 at% and Ti content of 5 – 13 at%. Ti content is generally lower in more altered samples, with some highly oxidized samples showing very low percentage (< 3 at%). In addition, heavily altered samples show smaller (< 3 μm) and elongated magnetic mineral grains. Such mineralogical properties show correlation with key rock magnetic properties such as magnetic susceptibility and coercivity of remanence (Bcr). It is also notable that samples with high alteration degree also show reversals in remanence directions caused by strong secondary magnetization that persists after 20 mT demagnetization. This finding implies that production of secondary magnetic minerals may have occurred along with the oxidation of existing grains during the alteration of basalts.

How to cite: Hong, G. and Lee, S.-M. and the The South Atlantic Transect IODP Expedition 390 & 393 Scientists: Rock Magnetic and Mineralogical Analysis of IODP Expeditions 390 and 393 Basement Cores and their Implications for Fluid-Rock Interaction along the Mid-Atlantic Ridge Flank  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13888, https://doi.org/10.5194/egusphere-egu24-13888, 2024.

Loess paleosol sequences carry valuable information on global climate change during the Quaternary. The main geochemical paleoenvironmental proxies rely on the well established sequence of mineral weathering and its products under earth surface conditions. On the other hand, mineral magnetic signal of the loess – paleosol sequences represent easily measurable and sensitive tool for identification and semi-quantification of the degree of secondary alterations of the initial loess substrate. We have analyzed geochemical and magnetic properties of a collection of loess – paleosol sediments from North Bulgaria from 8 profiles, spanning the time interval of the last 800 kyrs. Weathering indices calculated from the bulk geochemical data on major oxides indicate that loess samples are characterized by wide range of Chemical Index of Alteration (CIA) values – from 57.8 to 83.5 with the highest values typically obtained in the oldest deposits, formed during marine oxygen isotope stages (MIS) 16 and 18.  On the other hand, CIA values for paleosols are restricted in the range 73.4 – 82, indicating an intermediate weathering degree. Classic ternary A-CN-K diagram implies dominant role of plagioclase weathering. Magnetic signature of the studied collection shows typical widely observed magnetic enhancement in paleosols as compared to weakly magnetic non weathered loess material. The content of ultra fine grained superparamagnetic magnetite/maghemite give rise to the percent frequency dependent magnetic susceptibility, which shows linear relationship with CIA values, proving the genetic linkage between weathering and pedogenic magnetic fraction. On the other hand, calculated background magnetic susceptibilities χbg for the loess-paleosol couplets included in the study show reverse linear relationship with CIA values for the loess samples. Searching for possible effect of changing dust source areas, we observe decreasing χbg for sites located progressively eastward (longitudes varying from 23oE to 29oE) along with linear increase of χbg with increasing Cr/V ratio, indicative for increasing contribution of mafic component. At the same time, samples from loess horizons with the lowest χbg are characterized by the highest Al2O3/SiO2 values, e.g clay content. Thus, decreasing χbg along W – E transect probably reflects combined effects of dust source change and grain size fining during aeolian dust transportation. The relationships between CIA, χbg and pedogenic magnetic signatures suggest that aeolian dust material was already weathered before its deposition. As a result, the following periods of paleosol formation during interglacial epochs occurred under supply – limited weathering regimes.

This contribution is supported by project No KP-06-H34/2 of the Bulgarian National Science Fund

How to cite: Jordanova, D. and Jordanova, N.: Effects of dust source change, weathering and pedogenesis on loess sediments revealed by combined magnetic and geochemical studies – opportunities and challenges, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14612, https://doi.org/10.5194/egusphere-egu24-14612, 2024.

EGU24-15097 | ECS | Posters on site | EMRP3.4

Rock Magnetic Studies of The Early Jurassic Middle Eocene Volcanic and Sedimentary Rocks of the Eastern Pontides 

Bahadırhan Sefa Algur, Sercan Kayın, Abdurrahman Dokuz, Z. Mümtaz Hisarlı, and Turgay İşseven

In this research, we revealed the findings from rock magnetic analyses, including Isothermal Remanent Magnetization (IRM) and High-Temperature Susceptibility (HTS), conducted on various volcanic and sedimentary rocks from the Early Jurassic – Middle Eocene located in the Eastern Pontides. These magnetic studies offer valuable insights into the minerals causing magnetization, as well as the composition and changes in magnetic minerals within these rocks. The experiments were carried out at the Doç.Dr. Yılmaz İspir Paleomagnetism Laboratory, Istanbul University-Cerrahpaşa.

For the Isothermal Remanent Magnetization (IRM) studies, samples were collected from 57 sites in the Eastern Pontides, ensuring representation of each rock type. The analysis revealed that “Hematite”, “Magnetite”, and a combination of “Hematite + Magnetite” are the minerals responsible for magnetization in the selected samples. Moreover, it was discovered that in 41 out of the 57 sites, the samples reached saturation magnetization, indicating that "Magnetite" is the predominant mineral responsible for magnetization. The magnetic susceptibility of the rocks was examined during the heating and cooling stages in these high-temperature susceptibility measurements. High-temperature susceptibility measurements were used to assess whether the minerals responsible for magnetization in the rocks underwent any changes due to temperature, to determine the Curie temperatures, and to understand the domain structure. For this aspect of the study, 23 sites representing various ages and types of rocks were chosen for high-temperature susceptibility studies. It can be said that some rocks are rich in "Ti-Magnetite". It is observed that mineral phase transformation occurs in some rocks as a result of heating phases.

This study was supported by the project of the Scientific Research Projects Commission of Gümüşhane University with Project Number: 21.B0126.01.01.

How to cite: Algur, B. S., Kayın, S., Dokuz, A., Hisarlı, Z. M., and İşseven, T.: Rock Magnetic Studies of The Early Jurassic Middle Eocene Volcanic and Sedimentary Rocks of the Eastern Pontides, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15097, https://doi.org/10.5194/egusphere-egu24-15097, 2024.

The East Asian Winter Monsoon (EAWM) is driven by the dry and cold north-westerly winds blowing from central Asia towards the Western Pacific Ocean as atmospheric high-pressure cell develops over Siberia and Mongolia due to low continental temperatures during boreal winter. Today, the EAWM surface winds together with the prevailing mid-latitude upper troposphere westerly jet (WJ) winds transport hundreds of millions of tons of dust every year across East Asia and/or to the North Pacific and further. Various records of past EAWM and/or WJ variability are available but well-resolved records with (sub)orbital resolution to investigate the dynamics of and relationships between EAWM and WJ are rare. The Japan Sea, as the largest marginal sea located in mid-latitude East Asia, is significantly under the influence of the EAWM and WJ. Previous studies suggest that the composition, concentration, and size of magnetic particles in sediments are sensitive to changes in aeolian dust input. Here, we study the magnetic mineralogy and reconstruct high-resolution continuous environmental magnetic records spanning the last 500 kyrs using sediments cored during Integrated Ocean Drilling Program (IODP) Expedition 346 (Asian Monsoon) at Site U1424 in the Japan Sea. Our results suggest that magnetite is the dominant magnetic phase at Site U1424 and there is a significantly increased contribution of high-coercivity magnetic phase, presumably hematite transported through aeolian dust, in samples from glacial periods. Magnetic grain size proxy (kARM/k) of Site U1424 sediments appears to covary with the population of coarse particles (> ~14 μm) that are dominated by aeolian dust, and shows a striking similarity to published EAWM records, especially during the interglacials and glacial inceptions. During the glacial maxima, largely enhanced EAWM indicated by published records are, however, not shown in the Site U1424 kARM/k record. We suggest that Site U1424 kARM/k is a proxy for dust transportation to the Japan Sea modulated by EAWM intensity as well as interactions between EAWM and the WJ. During the interglacials and glacial inceptions when the main axis of WJ frequently reaches Northern China close to the dust source region of the EAWM, interactions between the EAWM and WJ during winter/spring at mid-level troposphere enable long-distance transportation of coarse dust particles (mainly modulated by EAWM) to the Japan Sea. During the glacial maxima, when the WJ main axis no longer frequently reaches the EAWM source regions, reduced interaction between WJ and EAWM prevented long-distance transportation of coarse dust particles. A conceptual model is also presented to summarise the consequences of changes in EAWM and WJ and their interactions over glacial and interglacial cycles at different locations along the Asian dust transportation pathway.

How to cite: Wang, J., Xuan, C., and Wilson, P.: East Asian winter monsoon variability during the last 500 thousand years recorded by environmental magnetism of sediments in the Japan Sea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19484, https://doi.org/10.5194/egusphere-egu24-19484, 2024.

EGU24-19599 | ECS | Posters on site | EMRP3.4

Preliminary results of paleomagnetism, rock magnetism and AMS in a soot-layered speleothem from Cueva Mayor (Atapuerca, Spain) 

Elisa María Sánchez-Moreno, Eneko Iriarte, Manuel Calvo-Rathert, Eric Font, Maria-Felicidad Bógalo, and Ángel Carrancho

Speleothem are excellent recorders of the Earth’s magnetic field and climate variation. The nature and origin of the magnetic minerals trapped into the calcite laminae are controlled by climate and environmental processes acting on the surface soils and inside the cave.

In this work, we analysed samples from a stalagmite from Cueva Mayor in the archaeological site of Atapuerca (Burgos, Spain). Cueva Mayor site hosts a very important record of Pleistocene human occupation. Finding speleothems that record signs of human activity is unusual. However, in the karst system of the Sierra de Atapuerca, different works on speleothems revealed a significant human fossil record. The stalagmite studied has a small size, the sampled section measures 10 cm from base to top and is not oriented. It shows a calcite laminae alternation with darker micritic and/or ash-rich laminae, composed of aggregates of soot/smoke in the last 2.7 cm to the top. These black soot laminae are interpreted as derived from anthropogenic fires. The remaining part the stalagmite is a sequence of whitish and brownish laminae. A high detrital fraction is inferred from the brown layers. Available U-Th age data on a nearby stalagmite indicate that they grew during the last 14 kyr approximately.

In order to characterize the magnetic properties in a stalagmite of special interest considering its record of human activity, we have carried out experiments on paleomagnetism, rock magnetism, and anisotropy of magnetic susceptibility. We obtained paleomagnetic directions for most samples of calcite laminae with high detrital content and laminae with soot by alternating field demagnetization. Isothermal remanent magnetization acquisition curves of and hysteresis cycles show the presence of low coercivity ferromagnetic minerals in the soot-bearing samples, while the magnetization intensity in the rest of the samples is too weak to show clear results. The thermomagnetic curves reveal magnetite in both brownish-white and soot-containing samples. Other very low Curie temperature magnetic phases also appear in the soot samples. Finally, AMS shows a triaxial magnetic fabric with magnetic foliation pseudo-parallel to the calcite lamellae and horizontal lineation.

Acknowledgments: This work was funded by the Agencia Estatal de Investigación (España) (PID2019-105796GB-100), the postdoctoral program María Zambrano 2021 (España), the Junta de Castilla y León (España) (project BU037P23) and the Fundação para a Ciência e a Tecnologia (Portugal) (PTDC/CTA-GEO/0125/2021).

How to cite: Sánchez-Moreno, E. M., Iriarte, E., Calvo-Rathert, M., Font, E., Bógalo, M.-F., and Carrancho, Á.: Preliminary results of paleomagnetism, rock magnetism and AMS in a soot-layered speleothem from Cueva Mayor (Atapuerca, Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19599, https://doi.org/10.5194/egusphere-egu24-19599, 2024.

EGU24-20050 | ECS | Posters on site | EMRP3.4

Magnetic response of marine sediments to climate variations over the last 40 ka in the western equatorial Pacific. 

Louise Dauchy-Tric, Julie Carlut, Franck Bassinot, Laure Meynadier, and Jean-Pierre Valet

Magnetic properties from marine sediment cores, combined with other proxies, make it possible to study climatic variations. The type, concentration and grain size of magnetic minerals can be used as proxies of precipitation and deep oceanic circulation changes.  

In this study, we focus on core MD01-2385 retrieved on the northwest margin of Papua-New Guinea, in the western equatorial Pacific Ocean. This area is located in the Indo-Pacific Warm Pool (IPWP), which is a major source of heat and moisture to the atmosphere and plays an important role on global climate. The western Indo-Pacific climate is complex, being affected by the El Nino-Southern Oscillation (ENSO) and the Australian-Indonesian monsoon.

 

Core MD01-2385 was dated using 14C. The studied interval covers the last 40 ka with an average sedimentation rate of 30 cm/ka. We took samples every 2 cm (time resolution ~ 70 years). Magnetic granulometry proxies (ARM/SIRM and Karm/K) show a gradual decrease in grain size from the last glacial-interglacial transition (~17 ka) before a stabilization with fine grains from 8 ka. The records show variations associated with Heinrich events and the Younger Dryas. In the ~40 to 13 ka interval, the ARM/SIRM ratio is correlated with the d18O curve from EPICA-EDML ice cores (Antartica), whereas over the last 13 ka the ARM/SIRM ratio appears correlated to d18O curve of the NGRIP ice cores (Greenland).This observation suggests a stronger climatic influence of the Southern Hemisphere than the Northern Hemisphere in this region from 40 to 13 ka, followed since 13 ka by a period in which remote climatic influences originate from northern high latitudes.

Our magnetic results were combined with geochemical analyses carried out by Yu et al. (2023) on the same core (Rb/Sr ratio, chemical index of alteration (CIA), and the smectite/(illite + chlorite) ratio). These data indicate that heinrichs events (HS) are associated, in this region, with lower precipitation (Yu et al., 2023) and also correspond to lower magnetic concentrations, suggesting a dominant physical weathering in northwest Papua-New Guinea.

An interval with coarse magnetic grains and glass shards was dated at ~ 25 ka, suggesting the recording of a volcanic eruption during HS2. It could be the Oruanui supereruption from Taupo volcano, in New Zealand, dated at ~25.5 ka.

How to cite: Dauchy-Tric, L., Carlut, J., Bassinot, F., Meynadier, L., and Valet, J.-P.: Magnetic response of marine sediments to climate variations over the last 40 ka in the western equatorial Pacific., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20050, https://doi.org/10.5194/egusphere-egu24-20050, 2024.

EGU24-20274 | Posters on site | EMRP3.4

Selective transport and deposition of magnetic particles during speleothem growth 

Eric Font, Ana Raquel Brás, Joshua Feinberg, Ramon Egli, Ana Sofia Reboleira, Rui Melo, and Paulo Fonseca

During the last decades, advances in the field of speleothem’s magnetism opened a new door to investigate high-resolution and short-lived features of the Earth’s magnetic field. Due to the rapid precipitation of calcite/aragonite, the lock-in time of the detrital remanent magnetization resulting from the physical alignment of the magnetic minerals parallel to the Earth’s magnetic field is acquired almost instantaneously. The magnetic particles trapped into the speleothem usually originate from the soils capping the cave and are transported into the cave by dripwaters. Authigenic magnetic particles may also precipitate under conditions likely to prevail during speleothem growth. Here we investigate the magnetic mineralogy of a stalagmite from the Gruta da Ceramica of Central Portugal. We also analyzed the host carbonate, the cave sediments and the soils capping the cave. We measured concentration- and grainsize-dependent magnetic proxies, including natural remanent magnetization, anhysteretic remanent magnetization, isothermal remanent magnetization, mass specific magnetic susceptibility, FORC and hysteresis curves.  Results show that magnetic and hematite are the main magnetic carriers in all samples. A gradual enrichment of hematite relative to magnetite is observed following the transportation path from the soils to the cave sediments up to the stalagmite. The higher contribution of hematite relative to magnetite in the speleothem may reflect precipitation of authentic hematite during speleothem growth or the selective transport of finer particles from the soil to the cave.  

 

Acknowledgments: This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (refs. PTDC/CTA-GEO/0125/2021), (PIDDAC) – UIDB/50019/2020, UIDP/50019/2020 and LA/P/0068/2020

How to cite: Font, E., Brás, A. R., Feinberg, J., Egli, R., Reboleira, A. S., Melo, R., and Fonseca, P.: Selective transport and deposition of magnetic particles during speleothem growth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20274, https://doi.org/10.5194/egusphere-egu24-20274, 2024.

EGU24-344 | ECS | Posters on site | CL1.1.5

Paleoenvironmental and paleoecological changes during the early GABI in the Argentine Pampas: a stable isotope approach 

Dánae Sanz Pérez, Claudia I. Montalvo, Adriana E. Mehl, Rodrigo L. Tomassini, Manuel Hernández Fernández, and Laura Domingo

The analysis of stable isotopes in fossil mammals is a powerful tool to reconstruct paleoenvironmental and paleoecological conditions. Nevertheless, there are few works of this type focused on the Neogene of South America, specifically, on the Argentine Pampas. In this context, we perform an integrative approach for the Late Miocene-Early Pliocene of this region combining new U-Pb zircon dating and carbon and oxygen stable isotope analysis, to contextualize the paleoenvironmental and paleoecological evolution of the region. The δ13C values are used to reconstruct the diets and preferred habitats of the taxa, while changes in the δ18O values of animals forced to drink reflect variations in δ18O of meteoric water, controlled by temperature and evaporation rate. We selected a total of 270 bioapatite samples of δ13CCO3 and δ18OCO3 from eight localities of La Pampa and Buenos Aires provinces. Radioisotopic ages for six of them allowed us to pin down maximum deposition ages and a time interval of ca. 5 million years for our study (from 9.7±0.3 Ma at Arroyo Chasicó to 4.5±0.2 Ma at Farola Monte Hermoso), including the Chasicoan, Huayquerian, and Montehermosan stages/ages. We studied genera of Litopterna, Notoungulata, Rodentia, Pilosa, and Cingulata orders. During the Chasicoan Stage/Age, herbivore δ13C values point to mixed C3–C4 diets, evidencing the existence of favorable habitats for C4 plants before their great expansion. By contrast, during the Huayquerian Stage/Age, taxa show values indicative of feeding preferentially on C3 plants, except for some rodents that continued including C4 plants in their diets (possibly related to an early specialization of this group). In the latest Huayquerian-Montehermosan stages/ages, herbivorous taxa incorporated a higher percentage of C4 plants in their diets, coinciding with the global expansion of this type of vegetation. This change in δ13C values also reflects an increase in aridity and/or temperature since the Late Miocene-Early Pliocene in the area, coincident with results of other proxies. The δ18O values of the notoungulates support these interpretations, evidenced by higher δ18O values during the Chasicoan and latest Huayquerian–Montehermosan stages/ages; on the contrary, there is no trend recorded in litopterns, while only a slight decrease in δ18O values was obtained in rodents. These differences are possibly linked to the fact that each order records conditions at different scales; litopterns might register global hydrological conditions, notoungulates regional conditions, and rodents more local conditions. In addition, the difference with rodents is probably due to the fact that they obtained part of the water to cover their physiological needs by eating, in contrast to the notoungulates which needed to drink to meet these requirements.

This study was financed by the projects: PGC2018–094955–A–I00 and PID2022-138275NB-I00 (Ministerio de Ciencia e Innovación, Spain), 13G and 21G (FCEyN, UNLPam, Argentina), PGI 24 H/154 (Secretaría de Ciencia y Tecnología, UNS, Argentina). DSP acknowledges a predoctoral grant PRE2019–089848 and AEM and RLT funding from LA. TE. Andes – CONICET (2020-2021). This is a contribution of the research group UCM 910607 on Evolution of Cenozoic Mammals and Continental Palaeoenvironments.

How to cite: Sanz Pérez, D., Montalvo, C. I., Mehl, A. E., Tomassini, R. L., Hernández Fernández, M., and Domingo, L.: Paleoenvironmental and paleoecological changes during the early GABI in the Argentine Pampas: a stable isotope approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-344, https://doi.org/10.5194/egusphere-egu24-344, 2024.

This study examines marine sediment samples from Ocean Drilling Program Site 1195, Hole B (Lat 20°24.28'S; Long 152°40.24'E; water depth 420 m), located beneath the present-day pathway of the East Australian Current (EAC) on the shelf of Northeast Australia. The EAC represents the western boundary current of the South Pacific subtropical gyre. It originates from the bifurcation of the southern arm of the South Equatorial Current between 15°S and 20°S. The East Australian Current's evolution is linked to the tectonic reorganization of the Indonesian Gateway and the expansion of the West Pacific Warm Pool over geological time. Our analysis of foraminiferal relative abundance data revealed the existence of high surface productivity and reduced subsurface productivity during the 7.5–6.4 Ma Our findings suggest that the northward movement of Papua New Guinea may have commenced after 6.4 Ma, inferred from the consistent thinning of the mixed layer and shallowing of the thermocline. This aligns with the hypothesis proposing the formation of the New Guinea Coastal Undercurrent, potentially caused by the entrapment of a significant portion of the South Equatorial Current against the Papua boundaries, directing it northward. Additionally, we observe a significant decline in the relative abundance of Globigerinoides ruber and a shoaling of the thermocline during the Mid-Pleistocene Transition, coinciding with high surface productivity.

How to cite: Palei, R. R. and Gupta, A.: Paleoceanographic reconstruction of the NE shelf of Australia: Insights from surface and subsurface dynamics of the East Australian Current, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-462, https://doi.org/10.5194/egusphere-egu24-462, 2024.

Given its stance as the harbinger of modern-day climatic conditions 1, the Miocene epoch (23.03 – 5.33 Ma) is perhaps, climatologically, the most important epoch in the Cenozoic era. Within this epoch, the Middle to Late Miocene transition offers a time window to study the effects of plummeting atmospheric CO2 levels and consequent global cooling on ecosystems. Currently, we are witnessing a reversal of this scenario, namely global warming, which makes studying this transition crucial for verifying the model predictions regarding the future of our ecosystems. Herein, such a study documenting the paleoclimatic record preserved in the fossiliferous section of the Kutch region (India), a hitherto unexplored area, is presented. It spans two localities: Palasava (~14 Ma) & Tappar (~10 Ma), one each from the Middle and Late Miocene sub-epoch and utilises the carbonate phase from enamel remains of megafaunal herbivore mammals (Proboscideans & Rhinocerotids) as the investigatory tool. Enamel δ13C signature is indicative of ambient vegetation type due to the differential assimilation of C isotopes in diet plant tissue as a function of different carbon fixing mechanisms in C3 and C4 plants 2. δ18O signal, on the other hand, is reflective of the environmental rainfall intensity and seasonality because the rainfall isotopic composition is a function of temperature and amount effect during precipitation. Large-bodied obligate drinker mammals are most efficient for these reconstructions 3, which justifies the choice of mammals in this study.

The Palasava and Tappar samples have ranges of +0.20‰ to +4.24‰ and -3.97‰ to +5.47‰, respectively, for δ18O values. The larger scatter within the latter indicates higher seasonality in the Late Miocene relative to the Middle Miocene, which aligns well with the idea of intensification of the Indian summer monsoon regime during the younger sub-epoch4. Parallelly, the δ13C signature for Palasava samples ranges from -11.23‰ to -9.42‰ while the Tappar ones are between -12.95‰ and -10.64‰. The former represents woodland browsing, whereas the latter indicates forest-woodland browsing. Both localities imply C3-dominated environments. Since Tappar straddles the beginning of the Late Miocene, it is acceptable to think that C3-dominated habitats must have persisted up till this time, and it was only much later and perhaps fuelled by enhanced rainfall seasonality that C4 grasses became abundant and eventually, grassland expansion took place.

Conclusively, the observed trends agree with the ones seen for contemporaneous Siwalik samples and comply with the hypothesis of increasing rainfall seasonality towards the Late Miocene sub-epoch followed by eventual, and perhaps consequential, expansion of C4 grasses during the later part of Late Miocene.

References:

  • Steinthorsdottir, M. et al. The Miocene: The Future of the Past. Paleoceanography. Paleoclimatology 36, (2021).
  • Patnaik, R., Singh, N. P., Paul, D. & Sukumar, R. Dietary and habitat shifts in relation to climate of Neogene-Quaternary proboscideans and associated mammals of the Indian subcontinent. Quat. Sci. Rev. 224, 105968 (2019).
  • Daniel Bryant, J. & Froelich, P. N. A model of oxygen isotope fractionation in body water of large mammals. Geochim. Cosmochim. Acta 59, 4523–4537 (1995).
  • Raymo M.E. & Ruddiman W.F. Tectonic Forcing of Late Cenozoic Climate. Nature 359, 117–122 (1992).

How to cite: Priya, B., Patnaik, R., and Ghosh, P.: A stable isotope record documenting the Middle to Late Miocene climate transition from the Kutch Tertiary group, Gujarat (India), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1393, https://doi.org/10.5194/egusphere-egu24-1393, 2024.

EGU24-2807 | ECS | Posters virtual | CL1.1.5

Stable isotopes and palaeo-hydrological implications of Tunisian laminar calcretes during the late Pliocene - early Pleistocene 

Farah Jarraya, Barbara Mauz, Mike Rogerson, Nejib Kallel, Nouredidne Elmejdoub, and Abdeljalil Sghari

During the late Pliocene-early Pleistocene Tunisian calcretes were formed in a soil environment. Fabrics at the macro and micro scale show that these deposits are similar to rhizogenic modern analogue systems forming in Spain. We infer that a similar climate prevailed in Tunisia in the past, specifically winter-season rainfall and a dry summer with annual rainfall close to 430 mm/year in the center of Tunisia. Here, we provide further constraints on the climate under which the Tunisian calcrete formed by looking at vegetation structure, water advection and amount of seasonal rainfall.

To investigate (1) the palaeo-vegetation type(s) if they are C3 or C4 plants and (2) the source(s) of meteoric water of Tunisian calcretes during that era, stable isotopes of C and O were analysed in 25 samples taken from 5 horizontal laminar calcretes cores, from 3 sites: North (N36º.43.713; E10º.06.681’), Center (N35º.07.077’; E10º.14.545’), South (N33º.28.898’; E10º.23.602’). Results are expressed relative to the VPDB reference.
In the North, the δ18O samples show values varying from – 4.78 ‰ to -6.91 ‰. Likewise, central site cores are characterised by δ18O values ranging from -5.32 ‰ to -6.97 ‰. In contrast, the δ18O values from the South are more depleted (-8.82 ‰ to -7.20 ‰). Concerning the carbon isotope results, both central and southern sites show similarly enriched δ13C values with an average of -6 ‰, while the North site shows more depleted values (-11.3 ‰ to -9.6 ‰). The δ18O values are similar to those determined in the last deglaciation/early Holocene speleothem carbonates from caves in the Tunisian Atlas Mountains, indicating a North Atlantic source. The north-to-south difference in both isotope systems reveals a decoupling between precipitation δ18O and vegetation effects. The southern site shows more depleted water isotopes (a consequence of internal water recycling effects) and more enriched δ13C, consistent with C4 vegetation and/or lower soil respiration. The central site shows low water recycling, but southern-like dryland vegetation. The northern site shows low water recycling and C3 vegetation and/ or higher soil respiration. Consequently, although there is enhanced humidity in all three sites, the sites do not record the same amount of rainfall and the same response of the landscape to form calcretes.

How to cite: Jarraya, F., Mauz, B., Rogerson, M., Kallel, N., Elmejdoub, N., and Sghari, A.: Stable isotopes and palaeo-hydrological implications of Tunisian laminar calcretes during the late Pliocene - early Pleistocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2807, https://doi.org/10.5194/egusphere-egu24-2807, 2024.

The Middle Miocene Climatic Optima (MMCO; 17–14.5 Ma) is warmest over the last 23 Myrs, with higher pCO2 (400–500 ppmv; Foster et al., 2012, Super et al., 2018), ~6 °C warming in a mid-latitude compared to the present (Flower and Kennett, 1994), and a large reduction (30–36 m) in Antarctic ice volume (Gasson et al., 2016). The eruption of CO2 from the Columbia River flood basalt has been suggested as a primary cause of the MMCO. However, the mechanisms of the progressive global cooling after the MMCO remain highly controversial. Here, we provide novel paleoceanographic information on the Antarctic Intermediate Water (AAIW) in the Pacific sector of the Southern Ocean to improve our understanding of climate–ocean conditions during the MMCO. In this study, we analyzed the middle Miocene biopelagic sediments (> 90% CaCO3 contents) from ODP Site 1120 (50°3.8′S, 173°22.3′E), located on the central Campbell Plateau off the South Island of New Zealand (Ando et al., 2011). Because the middle Miocene paleo-water depth at Site 1120 is estimated to be similar to the present water depth (~600 m), analyses of oxygen and carbon isotopic compositions of benthic foraminifer and neodymium (Nd) isotopes of fossil fish teeth/debris allow us to characterize the AAIW during the deposition. We present newly measured 17.5–8.5 Myr records of Nd isotopes of fossil fish teeth/debris, planktonic foraminiferal δ18O, δ13C, Mg/Ca, and Ba/Ca from Site 1120. The εNd values ranged from -7.5 to -3.2 at 17.5–8.5 Ma. In contrast, during the Middle Miocene Climate Transition (MMCT, 14.5–13.5 Ma), εNd values shifted rapidly toward more radiogenic values (~-3.2) and then gradually returned to less radiogenic values (-7 to -6). Such a large long-term variation of εNd values has not been reported in previous datasets, which is the first records to represent the characteristics of the AAIW in the Pacific sector of the Southern Ocean during the MMCT. We argue for the two possible causes of these εNd changes in the AAIW: 1) there might have been an anomalous supply of radiogenic Nd due to the intense physical weathering in West Antarctica caused by the onset of glaciation and 2) the equatorial surface water, characterized by high εNd values, might have expanded toward the high latitudes and a part of the water mass was incorporated into the intermediate layer in the Southern Hemisphere.

How to cite: Khim, B.-K., Horikawa, K., and Asahara, Y.: Anomalous eNd change of the Antarctic Intermediate Water in the Pacific sector of the Southern Ocean during the Middle Miocene Climate Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3364, https://doi.org/10.5194/egusphere-egu24-3364, 2024.

EGU24-6785 | ECS | Orals | CL1.1.5 | Highlight

High-resolution multi proxy records across the Plio-Pleistocene boundary: a central Mediterranean perspective 

Elena Zanola, Sergio Bonomo, Patrizia Ferretti, Eliana Fornaciari, Alessandro Incarbona, Teresa Rodrigues, and Luca Capraro

The central Mediterranean region is traditionally acknowledged as a key reference area for investigating the Northern Hemisphere climate variability over the last few million years.

Specifically, the expanded and highly fossiliferous open-marine succession currently exposed along the shoreline of Southern Italy and Sicily offers a pristine sedimentary record of the Neogene to Quaternary interval, which can be tightly constrained in time and deeply investigated by means of a manifold array of paleoenvironmental and paleoclimatic proxies (e.g., Cita et al., 2008; Capraro et al., 2017, 2022).

In this context, the Monte San Nicola (MSN) section, located in Southern Sicily, provides an exceptional stratigraphic record for studying the climate evolution throughout the Piacenzian to Gelasian interval. The MSN succession hosts the GSSP for the Gelasian Stage (ca. 2.58 Ma; Rio et al., 1998), which presently marks the base of both the Pleistocene Serie and the Quaternary System (Head et al., 2008). The section is currently under revision, especially in the interval straddling the Gelasian GSSP, which includes the definitive establishment of the Northern Hemisphere Glaciation (NHG), at around 2.6 Ma. This cooling event is marked by a triplet of glacial stages (i.e., MIS 100, 98 and 96) that are found just above the Piacenzian-Gelasian boundary.

In the wake of the emerging interest towards the MSN section, we are currently committed to reconstructing a high-resolution multi-proxy record (foraminiferal δ18O and δ13C, Alkenones-derived SSTs, C37total and Alcoholic index) in the lower part of the “Mandorlo” section at MSN (Capraro et al., 2022; Zanola et al., 2024). Results achieved so far provide new insights on the paleoceanographic and paleoclimatic evolution of the central Mediterranean at the sub-orbital scale at the beginning of the NHG.

How to cite: Zanola, E., Bonomo, S., Ferretti, P., Fornaciari, E., Incarbona, A., Rodrigues, T., and Capraro, L.: High-resolution multi proxy records across the Plio-Pleistocene boundary: a central Mediterranean perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6785, https://doi.org/10.5194/egusphere-egu24-6785, 2024.

EGU24-7348 | ECS | Orals | CL1.1.5

Multicellular eukaryotes followed:MOE or life stagnation 

Ruihan Duan, Pengchen Ju, Ruliang He, Jinlong Yao, and Guochun Zhao

The discovery of the fossils of decimetre-scale multicellular eukaryotes in the Mesoproterozoic from the 1.56-Gyr-old Gaoyuzhuang Formation in the North China Craton indicates that eukaryotes have evolved to a high level, but the evolution of life after it is still unclear due to the lack of definitive fossil evidence. Multi-proxies suggests that a pulsed oxygenation event was recorded during1.56-1.57 Ga, but the subsequent ocean oxygen levels are unequivocal. Here we report I/(Ca+Mg) ratios, carbonate C-O isotopes, and Ce anomaly across the ca. 1.56-1.50 Ga in the North China Platform. The results showed that the evolution of ocean oxygen content could be divided into four stages: (1)The δ13Ccarb values remained stable at 0‰ , and the I/(Ca+Mg) ratios was near detection limit, with no Ce anomaly from 1.56 to 1.53Ga, indicating that the ocean was anoxic; (2)The I/(Ca+Mg) ratios increased to 1.2μmol/mol with an excursion from 0‰ to -2.6‰ negative δ13Ccarb anomaly, and a negative Ce anomaly to 0.56 in 1.52Ga, which may be the result of the oxidation of the dissolved organic carbon(DOC) in the ocean, and the ocean changed from anoxic to oxic;(3) The C isotope composition 0‰ , with I/(Ca+Mg) ratios maintained at 0μmol/mol-0.5μmol/mol, and there was no Ce anomaly in 1.51Ga. Oxygen consumption through oxidation of DOC may have quickly lowered marine O2 levels to suboxic.(4) A positive shift in  δ13Ccarb from 0 ‰ to +2.1‰, and the I/(Ca+Mg) increased to 1μmol/mol, without obvious Ce anomaly, which may be a certain degree of biological flourishing leading to the increase of oxygen content in the ocean. Although the ocean in 1.52Ga was oxic, the oxygen levels were low, which may be a key factor restricting the evolution of eukaryotes.

How to cite: Duan, R., Ju, P., He, R., Yao, J., and Zhao, G.: Multicellular eukaryotes followed:MOE or life stagnation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7348, https://doi.org/10.5194/egusphere-egu24-7348, 2024.

EGU24-7606 | Posters on site | CL1.1.5 | Highlight

Spring distribution in Quaternary deposits, South Carpathians, Romania: isotope composition, chemistry and radiocarbon dating 

Ana-Voica Bojar, Stanislaw Chmiel, Hans-Peter Bojar, Carmen Varlam, Victor Barbu, and Andrzej Pelc

The investigated area is part of a plateau situated at around 350m elevation in the south-western part of the South Carpathians. The area is crossed from north-west to south-east by dry valleys, which cut Pleistocene and Quaternary clastic deposits. Water is flowing across these valleys temporarily, after strong storms or during rainy periods. A groundwater geochemistry study was carried out on water samples collected from different springs and wells. The study was motivated by the fact that springs have represented the only source of potable water in the region, only recently completed by a few wells.

Spring distributions and geological data reveal the presence of a multi-layered system situated in the Lower Quaternary deposits. Precipitations and meteorological parameters were monitored in the region for a period over 10 years. The mean δ18O and δD values of groundwater reflect the yearly weighted mean of the isotopic composition of precipitation, demonstrating locally derived recharge. The aquifers are situated at different depths in clastic deposits; the shallower aquifers are affected by evaporations during the drought periods of the summer.

The water samples have concentrations of 157 to 852 mg/l for anion and 55 to 308 mg/l for cations, with TDS between 212 and 1157 mg/l. The total dissolved salts limit proposed in the guideline of WHO is 1200 mg/l, above the limit water having a bad taste, all the measured samples are below this limit.

The Piper ternary diagrams for spring water indicate that the dominant hydrochemical types is HCO3--Ca+2-Mg+2 with transition toward higher SO4-2 and Mg+2  contents to the deeper aquifer. The anions vary from HCO3- with transition to no dominant- and with Cl- contents higher for the shallower aquifer. The sequence of abundance of cations is generally Ca2+>Mg+2>K+>Na+ and for anions: HCO3->SO4-2>Cl->NO3->F-. The Gibbs diagrams indicate rock weathering as a major driving force for driving the groundwater ionic chemistry in the study area. Radiocarbon dating of DIC (dissolved inorganic carbon) indicates a sub recent recharge of the aquifers.

The vertical and lateral variations in groundwater chemistry may vary, and are influenced by lateral lithologic variation of the Quaternary clastic deposits. This is an unpredictable quality factor when taking the decision for the drinking water drill locations.

How to cite: Bojar, A.-V., Chmiel, S., Bojar, H.-P., Varlam, C., Barbu, V., and Pelc, A.: Spring distribution in Quaternary deposits, South Carpathians, Romania: isotope composition, chemistry and radiocarbon dating, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7606, https://doi.org/10.5194/egusphere-egu24-7606, 2024.

EGU24-7711 | Orals | CL1.1.5 | Highlight

A Versatile Water Vapor Generation Module for Vapor Isotope Calibration and Liquid Isotope Measurements 

Hans Christian Steen-Larsen and Daniele Zannoni

A versatile vapor generation module has been developed for the purpose of both field water vapor isotope calibrations and laboratory liquid water isotope measurements. The vapor generation module is fully scalable allowing in principle an unlimited number of standards or samples to be connected, opening up the possibility for calibrating with multiple standards during field deployment. Compared to a standard autosampler system, the vapor generation module has a more than 2 times lower memory effect. The vapor generation module can in principle generate a constant stream of vapor with constant isotopic composition indefinitely. We document an Allan Deviation for 17O-excess (Δ17O) of less than 2 per meg for an approximate 3 hour averaging time. For similar averaging time the Allan Deviation for 𝛿17O, 𝛿18O, 𝛿D, d-excess is 0.004, 0.006, 0.01, 0.03 ‰. Measuring unknown samples for Δ17O show that it is possible to obtain an average standard deviation of 3 per meg leading to an average standard error (95 % confidence limit) using 4-5 replicates of 5 per meg.

Using the vapor generation module we document that an enhancement in the Allan Deviation above the white noise level for integration times between 10 minutes and 1 hour is caused by cyclic variations in the cavity temperature. We further argue that increases in Allan Deviation for longer averaging times could be a result of memory effects and not only driven by instrumental drifts as it is often interpreted as.

The vapor generation module as a calibration system have been document to generate a constant water vapor stream for a period of more than 90 hours showing the feasibility of being used as an autonomous field vapor isotope calibration unit for more than 3 months.

How to cite: Steen-Larsen, H. C. and Zannoni, D.: A Versatile Water Vapor Generation Module for Vapor Isotope Calibration and Liquid Isotope Measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7711, https://doi.org/10.5194/egusphere-egu24-7711, 2024.

EGU24-8232 | Posters on site | CL1.1.5 | Highlight

On the radiocesium distribution on the Romanian territory 30 years after the Chernobyl disasters 

Octavian G. Duliu, Ana-Maria Blebea-Apostu, Romul Mircea Margineanau, Diana Persa, and Maria-Claudia Gomoiu

The Chernobyl 1986 accident, considered one of the worst of its kind, occupies the highest 7th position on the seven levels IAEA International Nuclear and Radiological Event Scale. Following the thermal explosions which took parts, an impressive amount of new and spent nuclear fuel, rich in fission and neutron activation products was dispersed into the atmosphere at an altitude up to a few km, but without reaching the stratosphere. In this way, about 20 to 40 % of the total radiocesium inventory estimated to be 280 PBq of 137Cs was transported by the atmospheric circulation contaminating significant areas of Ukraine, Belarus, Russia, Scandinavian countries, Central and Eastern Europe. Its presence was signaled also in Japan, Canada, and the United States.

Due to the geographical position of Romania in the vicinity of Ukraine, the total 137Cs contamination of Romanian territory was estimated immediately after the Chernobyl accident at 51 ± 2 TBq, an estimation based on more detailed measurements performed during the 1993 y on 62 locations.

Under these circumstances, and for a more accurate estimation of the 137Cs contamination, 747 soil samples covering the entire Romanian territory were collected, and the radiocesium inventory was measured by gamma-ray high-resolution spectroscopy performed in the low backgrounder laboratory located in the Slanic-Prahova former salt mine. Soil sampling and radiometric measurements were performed between 2016 and 2018 years, all data being recalculated for May 2016, i.e. 30 years after the Chernobyl accident.

The results showed for the 2016 radiocesium distribution an irregular pattern containing four maxima of which positions were quite different from the 1993 ones. Concerning the 137Cs inventory, its total value decreased from 43 ± 2 TBq in May 1993 to 14.1± 0.7 TBq in May 2016, i.e. by a factor of 3 ± 0.3, twice of natural disintegration. This finding could be explained by taking into account that a significant amount of radiocesium was washed out by precipitation and, in a lower measure, was incorporated into plants.

The same data permitted evaluation of the total contribution of 137Cs to the population exposure. Accordingly, in 1993 and even more so in 2016, the average supplementary annual effective dose did not exceed 1 mSv, i.e. the maximum annual effective dose considered not harmful for the unexposed population.

How to cite: Duliu, O. G., Blebea-Apostu, A.-M., Margineanau, R. M., Persa, D., and Gomoiu, M.-C.: On the radiocesium distribution on the Romanian territory 30 years after the Chernobyl disasters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8232, https://doi.org/10.5194/egusphere-egu24-8232, 2024.

EGU24-8530 | ECS | Orals | CL1.1.5

Isotopic signatures from the weathering of ophiolitic massifs and volcanic deposits in the Zambales region, Philippines. 

Chris Tsz Long Cheung, Ryan McKenzie, Juan Miguel Guotana, Brian Beaty, Yonghui Qin, Giancarlo DeFrancesco, Bianca Maria Laureanna Pedrezuela, Dan Asael, Noah Planavsky, and Decibel V. Faustino-Eslava

Lithium isotopes (d7Li) are a useful proxy to track silicate weathering, the fundamental process in which carbon is removed from Earth’s surface. Here we present d7Li and elemental data from 14 riverine localities in the Zambales region, Philippines. The warm, humid climate coupled with monolithic rivers draining ophiolitic massifs and volcanic deposits (from the major 1991 Pinatubo eruption) allows for the comparison of silicate weathering and riverine geochemistry across different lithologies. The most striking part of our dataset is that all rivers draining ophiolitic terranes have heavier d7Lidiss values (range from 22.8 to 37.1‰) than those draining Pinatubo volcanic deposits (range from 8.9 to 18.4‰). As all rivers feature similar topographic relief and hydrological conditions, this suggests a strong lithological influence on d7Lidiss values despite both bedrock lithologies being highly weatherable. We postulate that the mafic and ultramafic composition of the ophiolite terrain significantly enhances incongruent weathering and clay mineral formation, increasing Li fractionation, and leading to the heavier d7Lidiss values. Conversely, the lighter d7Lidiss values for the Pinatubo rivers could be explained by the more felsic composition and unconsolidated nature of the volcanic deposits leading to increased congruent weathering and low clay formation, and thus low Li fractionation. Notable differences in major element concentrations are also observed. The Mg2+ is the dominant cation in ophiolitic-draining rivers reflecting the weathering of Mg-rich mafic and ultramafic minerals. Meanwhile, Na+ and Ca2+ dominate in rivers flowing off the Pinatubo volcanic deposits. The ophiolitic-draining rivers also have total major cation concentrations ([Na+] + [Mg2+] + [K+] + [Ca2+]) almost 3.5 times lower than those draining the volcanic deposits (~1600 vs ~5600 µM). Despite the composition of the ophiolites consisting of highly weatherable mafic and ultramafic minerals, the volcanic deposits are seemingly even more favorably weathered. This is interpreted to be caused by the freshness of the material deposited from the recent eruption. Overall, our study shows that despite all rivers in this study draining highly weatherable lithologies, their intrinsic lithological differences can lead to significantly contrasting d7Lidiss and major cation signatures. New clay mineralogical data from riverine sediments will further inform us on silicate weathering processes in the region.

How to cite: Cheung, C. T. L., McKenzie, R., Guotana, J. M., Beaty, B., Qin, Y., DeFrancesco, G., Pedrezuela, B. M. L., Asael, D., Planavsky, N., and Faustino-Eslava, D. V.: Isotopic signatures from the weathering of ophiolitic massifs and volcanic deposits in the Zambales region, Philippines., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8530, https://doi.org/10.5194/egusphere-egu24-8530, 2024.

EGU24-9747 | ECS | Orals | CL1.1.5

Westerly jet shifts over the last glacial cycle revealed by provenance of Japan Sea dust   

Lingle Chen, Chuang Xuan, Anya J. Crocker, and Paul A. Wilson

Asian deserts are major sources of dust loading to the atmosphere, second only to those of North Africa. Today, dust activation in central and eastern Asia and convective rainfall over eastern China are preconditioned by the seasonal weakening of the Siberian High-Pressure system and migration of the Westerly Jet (WJ) northwards of the Tibetan Plateau during spring. Once activated, East Asian dust is transported over long distances to the North Pacific Ocean and to Greenland. Downcore records from locations on the dust transportation pathway provide valuable information about changes in past aridity and wind systems. Recent studies suggest that the westerlies were weaker and shifted towards more poleward latitudes than today during the warm Pliocene. However, the available data are too sparse to evaluate variability on glacial-interglacial timescales and often of questionable attribution (uncertain provenance). Here we report new downcore radiogenic isotope (Nd, Sr) records of dust provenance change over the last glacial cycle (150 kyrs to present) from the Japan Sea. Our records benefit from a thorough treatment protocol to remove the imprint of contaminating marine phases (including barite) and non-dust material and show remarkably clean glacial-interglacial structure. We report a marked shift in East Asian dust sources from glacial to interglacial conditions that has important implications for our understanding of the behaviour of the Siberian High-Pressure system and the westerly jet in response to changes in atmospheric carbon dioxide concentrations and ice sheet extent on geological timescales.

How to cite: Chen, L., Xuan, C., J. Crocker, A., and A. Wilson, P.: Westerly jet shifts over the last glacial cycle revealed by provenance of Japan Sea dust  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9747, https://doi.org/10.5194/egusphere-egu24-9747, 2024.

EGU24-9896 | ECS | Posters on site | CL1.1.5

Testing the efficacy of grain size-sorted sediment for biomarker analysis to reconstruct palaeoclimate 

Joe Hingley, P. Sargent Bray, Gavin Foster, Jessica Whiteside, Bridget Wade, and Gordon Inglis

Following the announcement of the retirement of the JOIDES Resolution drilling platform, it has become even more important to efficiently utilise the finite resource of marine sediment stored in IODP repositories. Marine sediments processed for inorganic geochemical analysis are often separated into fine (<0.63 µm) and coarse (>0.63 µm) fractions to help isolate benthic and planktonic foraminifera. However, organic matter can be associated with different particle size fractions and may have experienced different transport and diagenetic processes. Previous studies have suggested that sieving sediments into different size fractions does not affect the distribution of isoprenoidal [1,2] and branched glycerol dialkyl glycerol tetraethers (GDGTs) [3]. However, this has never been systematically investigated across a wide range of sample types (e.g., age, depositional environment, thermal maturity). It is also unclear whether size processing affects other lipid biomarker proxies (e.g., leaf waxes, alkenones).

Here we test whether processing marine sediments into different size fractions influences lipid distributions by separating sediments into fine (<0.63 µm) and coarse (> 0.63 µm) fractions and comparing these to corresponding bulk un-sieved sediments. Temperature reconstruction using the marine sea surface temperature proxy TEX86 shows relatively minimal deviation (average ±0.12 TEX86 units, or ~2-3 °C) between the bulk un-sieved sediment (i.e,. control) and fine (<63 µm) fraction, suggesting isoGDGTs are well preserved in the fine fraction. In contrast, relatively more variation is seen in the coarse fraction (±0.25 TEX86 units, or >10 °C). We also analysed leaf wax derived n-alkanes extracted from the marine sediment to evaluate the impact on terrestrial biomarkers. The average chain length shows similar deviation in both the fine (±0.21 units) and coarse (±0.21 units) fractions relative to the bulk sediment, suggesting that either fraction is suitable for interpreting first-order changes in vegetation type.  Moving forward, our results suggest that the fine fraction of grain size-sorted sediment yield similar lipid distributions compared to the bulk un-washed sediment. However, coarse fractions often show large deviations from the bulk sediment across different proxies, perhaps making these unsuitable for biomarker-based climate reconstruction.

References
[1] Zachos et al., Geology, 34, 9, pp 737-740 (2006)
[2] Xiao et al., Global Biogeochemical Cycles, 37, e2022GB007648 (2023)
[3] Peterse and Eglinton, Frontiers in Earth Science, 5, 49 (2017)

How to cite: Hingley, J., Bray, P. S., Foster, G., Whiteside, J., Wade, B., and Inglis, G.: Testing the efficacy of grain size-sorted sediment for biomarker analysis to reconstruct palaeoclimate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9896, https://doi.org/10.5194/egusphere-egu24-9896, 2024.

EGU24-12864 | ECS | Posters on site | CL1.1.5

A radiogenic isotope framework to study palaeoaridity in the Middle East 

Kai Zhang, Tereza Kunkelova, Anya J. Crocker, Amelia Gale, Chuang Xuan, and Paul A. Wilson

Dust plays a vital role in global climate and environmental change by influencing the Earth’s radiation budget and providing nutrients to marine and terrestrial ecosystems. Modern dust emissions are dominated by North Africa, the Middle East and West Asia, which together provide ~80% of total global atmospheric dust. Geological deposits of dust can also act as valuable archives to study hydroclimate variability across a range of global states, with marine sediments in particular able to preserve high resolution and continuous records of past dust emissions. For example, dust preserved in Arabian Sea sediments has been used to provide climatic context for hominin evolution in East Africa, however, there is little understanding of where the deposited sediments originate and hence whether they truly record an African signal. Tracing the provenance of the lithogenic fraction in marine sediments is made particularly challenging by the lack of geochemical data in key potential source areas such as Mesopotamia, one of the most active dust emission regions in the Middle East. Here we present new radiogenic isotope data (Sr and Nd) from surface sediment samples, integrated with the satellite-derived dust source activation frequency (DSAF) maps and other published radiogenic data to characterise the geochemical fingerprint of dust-producing regions in the circum Arabian Sea. Our results provide a framework to trace sources of dust in geological archives including marine sediments, speleothems and ice cores and to identify the provenance of archaeological artefacts. We exemplify the utility of our approach by comparing our data to strategically positioned marine cores in the Arabian Sea to shed new light on key regional palaeoclimate reconstructions.

How to cite: Zhang, K., Kunkelova, T., Crocker, A. J., Gale, A., Xuan, C., and Wilson, P. A.: A radiogenic isotope framework to study palaeoaridity in the Middle East, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12864, https://doi.org/10.5194/egusphere-egu24-12864, 2024.

EGU24-13265 | ECS | Orals | CL1.1.5 | Highlight

Climate, fire, and vegetation history from loess-palaeosol sequences in Southern Tajikistan, Central Asia during early Palaeolithic: Reconstruction using organic biomarkers and stable isotopes 

Aljasil Chirakkal, David K Wright, Calin Constantin Stiendal, Jago Jonathan Birk, Redzhep Kurbanov, and Jan-Pieter Buylaert

We reconstruct palaeoenvironmental conditions with multi-proxy records from loess-palaeosol settings in Tajikistan, Central Asia. Landscape conditions in this area are poorly characterised, ambiguous, and difficult to determine, which confounds models of human dispersal out of Africa. This region has been the focus of Russian-Tajik archaeological projects since the 1970s, as it contains evidence of some of the earliest (~600-400 ka) hominin occupations in Central Asia and has yielded numerous Lower Palaeolithic artifacts. In the present study, fire and vegetation biomarkers and stable isotopes have been used to reconstruct fire and vegetation histories in loess-palaeosol samples of early Palaeolithic sites in the vicinities of the Obi-Mazar River in the Khovaling district of southern Tajikistan. Samples from four loess-palaeosol documented profiles were analysed for linear chain alkanes (n-alkanes) and polycyclic aromatic hydrocarbons (PAHs) together with soil stable isotopes (δ13C, δ15N). The fluctuations in the values of n-alkane derived indices showed vegetation changes in concert with glacial-interglacial variability. The δ13C values fell between -20‰ and -25‰ (vs. PDB) and revealed mixed input of C3 and C4 plant organic matter into loess-palaeosol sediments, while δ15N values varied between 3.5‰ and 6.5‰ (vs. AIR) indicating high litter content and tree abundance. The fluctuations in total PAH abundance and increased low to high molecular weight ratio values revealed fire activity and lower temperature burning events during interglacial periods relative to glacial periods.  Moreover, the strong positive correlation between PAHs and deposits that hosted the densest artifact assemblages signals early hominin use of fire in the catchment during MIS 11, 13, and 15. Therefore, our study demonstrates substantial hominin influences on the environment dating to over 500 ka indicating human-ecological processes far predate the modern era.

How to cite: Chirakkal, A., K Wright, D., Constantin Stiendal, C., Jonathan Birk, J., Kurbanov, R., and Buylaert, J.-P.: Climate, fire, and vegetation history from loess-palaeosol sequences in Southern Tajikistan, Central Asia during early Palaeolithic: Reconstruction using organic biomarkers and stable isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13265, https://doi.org/10.5194/egusphere-egu24-13265, 2024.

EGU24-15805 | ECS | Orals | CL1.1.5

Investigating ophiolite weathering via lithium isotopes in the Indo-Burma range of northeast India 

Giancarlo DeFrancesco, Ryan McKenzie, Chris Tsz Long Cheung, Nongmaithem Lakhan Singh, Yengkhom Raghumani Singh, Brian Beaty, Dan Asael, Jed Oliver Kaplan, and Noah Planavsky

The weathering of silicate minerals regulates climate on million-year timescales. Some silicate bedrock, particularly ophiolites, are more susceptible to enhanced weathering than other lithologies. Lithium isotopes (δ7Li) are a proxy that can be used to help track weathering processes due to the fractionation of Li during secondary clay mineral formation. Here we present data collected from tributaries that source the Nagaland-Manipur Ophiolite Complexes in northeastern India, which ultimately flow into the Irrawaddy River in Myanmar, to test the hypothesis that the weathering of ultramafic terrains generated by arc-continent collisions can drive rapid atmospheric carbon drawdown. Major cations, anions, trace elements, δ7Li, and clay mineralogical compositions were measured from river water, bedload, and suspended sediment to gain insight into silicate weathering processes in the region. Our results show streams and rivers in this region contain δ7Li values that range from 20.6 to 31.2‰, with the ophiolitic-sourced tributaries being heavier than the global riverine average of ~23‰. This indicates that rivers draining ultramafic lithologies in warm humid climates are experiencing higher degrees of weathering intensity than other drainages comprised of more felsic lithologies. Additionally, XRD results show that most river bedload contains smectite clays, which may help promote organic carbon burial. These data combined highlight new pathways toward understanding silicate weathering as it relates to atmospheric CO2 drawdown.

How to cite: DeFrancesco, G., McKenzie, R., Cheung, C. T. L., Singh, N. L., Singh, Y. R., Beaty, B., Asael, D., Kaplan, J. O., and Planavsky, N.: Investigating ophiolite weathering via lithium isotopes in the Indo-Burma range of northeast India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15805, https://doi.org/10.5194/egusphere-egu24-15805, 2024.

EGU24-18475 | ECS | Posters on site | CL1.1.5 | Highlight

Chromium isotope compositions of sediments from the global oceans 

Sylvie Bruggmann, Patrick Blaser, and Samuel Jaccard

The chromium (Cr) isotope system (δ53Cr) is a promising tool to reconstruct changes in marine redox conditions and biological productivity through geological time, but uncertainties remain regarding the pathway of Cr from the water column to the sediment record (Janssen, 2021; Huang et al., 2021; Bruggmann et al., 2023). While sediment Cr concentration and isotope data are available from continental margin sites and oxygen minimum zones (e.g., Gueguen et al., 2016; Bruggmann et al., 2019), modern sediments from open marine settings are understudied. Such sediments can provide key information to understand how Cr from the water column or across the sediment-water interface accumulates in the sediment.

We will investigate the response of Cr concentrations and isotope compositions (i) in the authigenic fraction of different types of pelagic sediments (carbonate-rich versus clay-rich) (ii) from the North Atlantic to the North Pacific to complement published seawater δ53Cr values, and (iii) their changes during well-characterised climate changes in the Quaternary, specifically the Last Glacial Maximum (LGM). The database of Cr isotope compositions in the modern global oceans resulting from this study will significantly enhance the interpretation of Cr isotope changes in sediments from the geological record.

 

References

Bruggmann S., Severmann S. and McManus J. (2023) Geochemical conditions regulating chromium preservation in marine sediments. Geochimica et Cosmochimica Acta 348, 239–257.

Gueguen B., Reinhard C. T., Algeo T. J., Peterson L. C., Nielsen S. G., Wang X., Rowe H. and Planavsky N. J. (2016) The chromium isotope composition of reducing and oxic marine sediments. Geochimica et Cosmochimica Acta 184, 1–19.

Huang T., Moos S. B. and Boyle E. A. (2021) Trivalent chromium isotopes in the eastern tropical North Pacific oxygen-deficient zone. Proc. Natl. Acad. Sci. U.S.A. 118.

Janssen D. J. (2021) Release from biogenic particles, benthic fluxes, and deep water circulation control Cr and δ53Cr distributions in the ocean interior. Earth and Planetary Science Letters 574,117163.

How to cite: Bruggmann, S., Blaser, P., and Jaccard, S.: Chromium isotope compositions of sediments from the global oceans, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18475, https://doi.org/10.5194/egusphere-egu24-18475, 2024.

EGU24-18743 | ECS | Posters on site | CL1.1.5

Interpolating proxy observations to high-resolution XRF data 

Patrick Blaser, Jörg Lippold, Sylvie Bruggmann, Michael Bollen, Xavier Crosta, and Samuel Jaccard

Proxy observations are the fundament for many insights in geosciences, such as the reconstruction of past environmental conditions from sediment cores. However, the labor-intensive nature of producing proxy data often renders high-resolution records prohibitively expensive. In contrast, state-of-the-art XRF analyses offer an efficient means of generating high-quality and very high-resolution elemental concentration data. Although these data initially provide only qualitative information about the bulk sample composition, their high-resolution renders them invaluable as a foundation for subsequent studies.

Here we explore the potential utility of high-resolution XRF data as a foundation for interpolating more scarce sedimentological, geochemical, and environmental analyses to the same high-resolution. We base the investigation on a long sediment core obtained from the Crozet Plateau in the Indian sector of the Southern Ocean, where changes in surface productivity, dust influx, and delivery of detritus from the nearby island dominate the sedimentological and geochemical signals.

We test different statistical methods for sediment classification and the interpolation of proxy data and discuss their reliability and limitations. For instance, application of a random forest model for the interpolation of carbonate and opal concentration conspicuously reveals the presence of distinct detrital layers. These layers are not readily discernible in the original XRF data or the sparse original opal and carbonate measurements.

We propose these straight-forward statistical methods have potential to be used on many other sediment records for which high-quality and high-resolution XRF data and certain proxy observations are available. Such an approach can streamline the interpretation of XRF data and enhance the investigation of specific environmental proxy observations at a high-resolution.

How to cite: Blaser, P., Lippold, J., Bruggmann, S., Bollen, M., Crosta, X., and Jaccard, S.: Interpolating proxy observations to high-resolution XRF data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18743, https://doi.org/10.5194/egusphere-egu24-18743, 2024.

Sun-climate connection is a well-documented expression of earth´s climate system. Higher sensitivity to solar forcing is evident in many paleoclimate records, ranging from decadal to millennial time scales. Considering the Indian monsoon domain, Summer Monsoon show asynchronous variations with energy output of the Sun throughout Holocene, however the response of its winter counterpart is not well understood. This study aims to explore the variability of the Indian Winter Monsoon in association with solar activity during Holocene. Monsoon reconstruction was based on trace elements and lanthanide geochemistry of lagoon sediments from south-eastern Sri Lanka.  A 5.1 m sediment core acquired from Pottuvil Lagoon was logged for concentrations of K, Rb, Mg, Al, Ti and rare earth elements at a 5cm interval using ICP-MS. The chronology of the core was established by Bacon 2.2 age-depth modelling based on calibrated AMS 14C dates. Reconstructed monsoon signal was compared with Holocene records of 14C and 10Be nuclide production rates which are considered as proxies for solar activity. Results revealed a distinct millennial scale variability of Indian Winter Monsoon during mid-late Holocene with three strong monsoon activity phases at 2553-2984 yrs BP, 3899-5021 yrs BP, and at 5244-5507 yrs BP. Further, the millennial-bands detected in Pottuvil monsoon record are closely matched with shifts in cosmogenic nuclide production rates, showing coherence with solar output. The existence of millennial scale variability is further reinforced by occurrence of dominant 1600 and 1000-year periodicities in Lomb-Scargle power spectra of element proxies. In particular, 1000-year periodic band is consistent with Eddy solar cycle. Thus, this study suggests a possible link to solar influence on millennial scale variability of Indian winter monsoon from mid to late Holocene.

How to cite: Premaratne, K. M. and Chandrajith, R.: Solar influence on Millennial-scale variability of Indian Winter Monsoon during mid-late Holocene: Evidence from coastal sediments from Southeastern Sri Lanka , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18843, https://doi.org/10.5194/egusphere-egu24-18843, 2024.

EGU24-19482 | ECS | Posters on site | CL1.1.5

Deciphering the Central African Copperbelt sedimentary succession: Chemostratigraphy of the Neoproterozoic metasedimentary sequences at Lubambe, Zambia 

Aileen Doran, Jon Stacey, Koen Torremans, Murray Hitzman, Victor Vincent, Laura Hepburn, and Adrian J. Boyce

A +1.6 km borehole, southeast of the Lubambe Copper Mine, Zambia has intersected a seemingly continuous sedimentary sequence spanning the Neoproterozoic Kantanga Supergroup sedimentary succession within the Central African Copperbelt. This extensive sequence encompasses the Mindola Clastics Formation of the Lower Roan Subgroup, through the Upper Roan Subgroup, and the lower Nguba Group (including the Grand Conglomérat of the Mwale Formation and overlying Kakontwe Limestone). Lithofacies and mineralogical studies of this drillcore have revealed numerous sedimentary cycles, with clear evidence for evaporite formation during sedimentation and diagenetic processes throughout (e.g., bedded/vein anhydrite, chicken-wire textures, relic cements & pseudomorphs). Siliciclastic red-bed lithologies at the base transition into repeated cycles of shales/siltstones-dolostone-evaporite, succeeded by deeper water carbonate and siltstone intervals. Diamictites of the Mwale Formation (Grand Conglomérat unit) cap these cycles at the base of Nguba Group, interbedded with several thick carbonate beds (peloidal grainstones, dolostones +/- bioherm textures).

To explore the Upper Roan to Nguba Group carbonate successions, detailed mineral chemistry mapping (Tescan TIGER MIRA3 FEG-SEM, µXRF, pXRF) and C-O isotopic analysis were undertaken, with a focus on understanding global trends associated with the onset of diamictite formation. Mineral chemistry analysis revealed the influence of post-depositional processes on the sequence, including dolomite and silica alteration. Silicification selectively preserved peloids above the first diamictite occurrence while the original carbonate matrix dissolved, with later cement formation (hydrothermal?) associated with elevated Mn-Fe relative to earlier carbonates. However, most of the carbonate units from the upper successions are composed of dolomite grains/cement, with original textures often preserved (e.g., stromatolites, disrupted reefs).

Isotope sampling targeted the ‘least-altered’ carbonates from the upper Roan to lower Nguba Group, to minimize post-depositional alternation effects. The initial analysis revealed variable δ13C isotopic values, with ~negative trending excursions below the main diamictite body. The lack of notable covariance with corresponding O isotope values suggests representation of the original seawater composition, not impacted by local diagenetic/hydrothermal alterations. Further, the largest negative excursion is associated with a lithofacies change from non-stromatolite- to stromatolite-bearing dolomitic siltstones, suggesting local lithofacies changes may influence the isotope profile. Specifically, δ13C isotopic values drop from ~+4.2 ‰ to +0.37 ‰, before returning to ~+4.7 ‰ below the diamictite contact. While these units do not record the more extreme negative excursion (<-5 ‰) typically associated with the Sturtian glaciation recorded elsewhere, the overall curve may represent the Islay anomaly recorded globally in Cryogenic sections beneath the Sturtian diamictite. This negative excursion, in line with global C isotope trends (<-5 ‰) has also been identified within Copperbelt on both the Zambian and Democratic Republic of Congo sides (ongoing work), but with a more significant decrease in C isotope values, in line with global trends. The lack of exact duplication may be the result of local sedimentological factors, as shown by the association in lithofacies variation, an incomplete sample record, or perhaps the influence of the Sturtian is not fully recorded in the stratigraphy underlying these diamictites.

How to cite: Doran, A., Stacey, J., Torremans, K., Hitzman, M., Vincent, V., Hepburn, L., and Boyce, A. J.: Deciphering the Central African Copperbelt sedimentary succession: Chemostratigraphy of the Neoproterozoic metasedimentary sequences at Lubambe, Zambia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19482, https://doi.org/10.5194/egusphere-egu24-19482, 2024.

EGU24-20288 | Posters virtual | CL1.1.5 | Highlight

From an Ocean-like to Methanogenesis-dominated carbon cycle in the Dziani Dzaha Lake 

Pierre Cadeau, Magali Ader, Pierre Cartigny, Ivan Jovovic, Pierre Adam, and Vincent Grossi

Over geological times, the evolution of carbon isotope composition of carbonates (δ13Ccarb) in the sedimentary record is punctuated by numerous positive isotopic excursions (CIEs), which reflect significant perturbations of the carbon cycle on Earth surface environments. Such isotopic events are mainly interpreted as a consequence of an increase of organic carbon burial in sediments. However, the significant spatial and temporal variability observed in many Proterozoic sedimentary successions recording positive CIEs still challenge this postulate. Among others, the potential influence of methanogenesis has been raised to explain at least a part of the variability observed during CIEs.

The Dziani Dzaha is a shallow tropical volcanic crater lake located on the Petite Terre Island of Mayotte (Comoros Archipelago, Indian Ocean). Its water most likely originate from the nearby ocean through bedrock seepage thanks to the fracturation associated with the phreatomagmatic eruption at that formed the crater 7 to 4 Kyr ago. Based on numerous analogies, this atypical modern lacustrine system was considered as an analogue of Proterozoic environments, and more specifically of those having recorded strongly positive δ13C values, such as for example the Lomagundi-Jatuli event. A previous study demonstrated the significant role of methane in the Dziani Dzaha carbon cycle through an intense organic matter degradation by methanogenesis associated with methane degassing into the atmosphere. Here, in order to investigate the processes responsible for the onset of this methanogenic activity, we present coupled C and S isotope records in a sediment core of the lake.

Based on geochemical and sedimentological evidences, four different units have been identified in the sediment core. From the bottom to the top, carbon and sulfur isotopic signatures in the first unit are similar to modern oceanic values (δ13Corg ~ -25‰, δ13Ccarb ~ 0‰ and δ34Spy ~ -20‰), which is consistent with a marine origin of the lake water. In the second unit, the δ34Spy increases progressively from -20‰ to -10‰ while the δ13C of organic and inorganic carbon remain constant, which is consistent with a progressive consumption of the sulfate pool through the degradation of organic matter by sulfatoreduction in a restricted environment. The δ34Spy shifts sharply to 35‰ at the transition with the third unit where it remains constant up to the top, while both organic and inorganic carbon isotopic signatures increase progressively from -25‰ to -14‰ and from 0‰ to almost 20‰, respectively. This turning point most likely results from a depletion of the initial sulfate pool to a point allowing part of the organic matter to be remineralized through methanogenesis with a degassing of methane into the atmosphere. These results highlight the potential of C-S-isotope coupling to identify a potential impact of methanogenesis on the carbon-isotope signatures observed in the sedimentary record through geological times.

How to cite: Cadeau, P., Ader, M., Cartigny, P., Jovovic, I., Adam, P., and Grossi, V.: From an Ocean-like to Methanogenesis-dominated carbon cycle in the Dziani Dzaha Lake, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20288, https://doi.org/10.5194/egusphere-egu24-20288, 2024.

Reconstruction of the history of bottom-water redox conditions in the climatically sensitive Southern Ocean can provide comprehensive information regarding oceanic circulation, global carbon cycling, and global climate changes. Here we present high-resolution sedimentary redox records over the last ~35 ka in the deep Protector Basin (~4,100 m water depth) of the southern Scotia Sea. Sedimentary δ34S and redox-sensitive trace metals were comprehensively analyzed and compared with 230Th-normalized Ba- and opal-based export fluxes to constrain bottom-water or sedimentary redox and bottom-water oxygenation conditions. The results demonstrate tight coupling of redox state proxies (sulfur isotopes and trace metals) over the glacial–interglacial cycle; the presence of oxidizing conditions during glacial periods rapidly transitions to reducing conditions during interglacial periods. Our findings indicate that absolute control of sedimentary redox variability in the study area involves climate-forced primary production, rather than the deep circulation and ventilation dynamics previously highlighted in the Antarctic Zone. Signs of climate-driven redox changes are also evident in two episodic cold events superimposed on the warm Holocene climate. The glacial–interglacial pattern of redox changes observed in this study contrasts with previous observations in the Southern Ocean, including the Antarctic Zone, suggesting spatial heterogeneity of bottom-water and sediment conditions during orbital-scale climate cycles. This study may help to elucidate paleoenvironmental changes in the Southern Ocean, such as changes in the dynamics of Antarctic Bottom Water production and Holocene climate instability.

How to cite: Kim, J., Lim, D., and Yoo, K.: Climate-driven redox changes in the Antarctic region: New insights from sedimentary sulfur isotopes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21485, https://doi.org/10.5194/egusphere-egu24-21485, 2024.

EGU24-2305 | Posters on site | HS1.2.5

Pedotransfer functions and their impact on water dynamics simulation and yield prediction 

Pablo Rosso, Kurt-Christian Kersebaum, Janis Groh, Horst Gerke, Kurt Heil, and Robin Gebbers

The dynamics of water availability for plant growth is particularly important for crop productivity simulation. Critical for the prediction of crop growth and development is the accurate simulation of soil moisture variation time. Soil capacity-based models assume that the vertical movement of water in the soil is mostly controlled by the intrinsic soil water retention capacities (WRCs), mainly field capacity (FC) and wilting point (WP). However, FC and WP are difficult to measure directly. Pedotransfer functions (PTFs) have been developed to determine these parameters from basic, more readily available soil attributes such as texture and soil organic carbon content. Functional evaluation, a procedure to assess the appropriateness of a PTF, entails testing the sensitivity of the different PTFs to model’s target simulation outcomes. This study constitutes an attempt to quantify and understand the impact of different PTFs on crop yield in a soil capacity-based model.

Six PTFs were used in the crop model HERMES to test their ability to simulate soil water dynamics and to determine their effect on yield simulation. This study, carried out in Germany, included three sandy soil sites in Brandenburg and a silty soil site in Bavaria. Five lysimeters at a site in Brandenburg provided a complete record for assessing the performance of PTFs. Measured soil texture and organic carbon were used as inputs in HERMES, which by applying the PTFs under study, produced the corresponding estimates of WRPs used for soil water dynamic simulations and yield predictions. Soil water records were statistically compared with model outputs to assess the accuracy of each PTF-based simulation. Differences in yield predictions were measured to estimate the sensitivity of the crop model to the PTFs tested.

Not a single PTF performed best in all sites. PTFs by Batjes and Rosetta were the best performers at the three Brandenburg sites. At Duernast, Bavaria, all PTFs resulted in higher errors than at the other sites. At this site, the measured soil water content maxima during the rainy months appeared very variable from year to year, which was unexpected if assumed that the maxima should stay around FC and be fairly constant. In general, HERMES simulations followed the trends in measured soil water dynamics regardless of the PTF applied, whereas differences between PTFs appear on the magnitude of the water maxima during the winter months. This shows that the accuracy of PTFs largely depended on their ability to correctly estimate FC. The highest variability in yield prediction for the different PTFs was observed in the three Brandenburg sites, which also corresponded with higher differences in FC estimation. A closer look at the sandy sites, and simulations with a synthetic soil database showed that differences in yield simulation between PTFs increased proportionally with soil sand percent. This points out at the empirical nature of PTFs and the care that needs to be taken when applied in new situations.

How to cite: Rosso, P., Kersebaum, K.-C., Groh, J., Gerke, H., Heil, K., and Gebbers, R.: Pedotransfer functions and their impact on water dynamics simulation and yield prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2305, https://doi.org/10.5194/egusphere-egu24-2305, 2024.

Nitrate pollution of groundwater is still an issue of concern at many drinking water wells located in the Swiss lowlands, where agricultural areas are the main pollution source. Extensification measures (e.g. conversion of arable land to extensive grassland, reduction of vegetable/potato areas in favor of cereals) are generally considered to be effective to reduce nitrate leaching to groundwater. However, these measures are also associated with large losses in agricultural productivity and can thus only be implemented on small focused areas within contribution zones of drinking water wells. It is hypothesized here that the trade-offs between agricultural production and groundwater protection can better be managed if more nuanced mitigation strategies are implemented at a broader scale. Such strategies would target at an improved synchrony between plant nitrogen demands and soil nutrient availabilities (e.g. by inclusion of cover crops and optimizing crop rotations, through reduced soil management and demand-driven fertilization practices). Since evaluating the effects of such strategies is anything but trivial given the high complexity of the process interactions and the strong influence of climatic variability, it is the aim of this work to train a mechanistic field scale model that simulates soil water and nutrient dynamics at a field scale in response to soil, climate and management drivers (DAISY model). The calibration builds on an extensive dataset from the lysimeter station Zurich Reckenholz including detailed data since 2009 on nitrate leaching, seepage water generation, soil moisture, water tension, soil temperature, and crop yields for a series of different experiments including non-inversion tillage, cover cropping as well as different fertilization types and amounts. The calibration strategy and selected calibration/validation results will be presented and discussed in context with implications for model applications.

How to cite: Holzkämper, A.: Managing the trade-off between agricultural productivity and groundwater protection in Switzerland – a model-approach based on long-term lysimeter data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2703, https://doi.org/10.5194/egusphere-egu24-2703, 2024.

EGU24-2783 | ECS | Posters on site | HS1.2.5

Critical Soil Moisture Content Estimated from Lysimeter Time Series for Different Soil, Vegetation and Weather conditions 

Xiao Lu, Jannis Groh, Thomas Pütz, Alexander Graf, Mathieu Javaux, Harry Vereecken, and Harrie-Jan Hendricks Franssen

Evapotranspiration (ET) is a crucial terrestrial ecosystem process that links water, energy, and carbon cycles. ET can be limited by either energy or water availability. The transition between water- and energy-limited regimes is associated with the soil moisture content, and can be postulated as the soil moisture content reaching a threshold, denoted as critical soil moisture (θcrit). Knowledge of θcrit is important for improving land surface, hydrological and crop models and predicting hydroclimate extremes such as droughts and heatwaves. However, the quantification of θcrit and the factors that impact θcrit are still not well understood. Here we used precise lysimeter observations to quantify θcrit by analyzing the relationship between soil moisture content and evaporative fraction (EF), as well as the relationship between soil moisture content and the actual ET/ potential ET ratio during drydowns. We estimated θcrit not only at the surface layer using in situ soil moisture measurements at 10 cm depth, but also for the root zone using vertically integrated in situ soil moisture (0–50 cm) observations. We estimated θcrit across various soil textures (e.g., sandy loam, silty loam, clay loam), vegetation types (grass, crop), as well as weather conditions from western and eastern Germany (spatial distances: 10 ~ 600 km). Especially, with some lysimeters that were taken from their original environment and translocated to other regions, we can identify the shift of θcrit with the same soil and vegetation but under different weather conditions, which can provide implication on changes of θcrit under global warming. We would expect a dependence of θcrit on soil texture and weather condition. We found for example that at the same site with the same crop rotation on the lysimeters but different soils, the sandy loamy soil experienced a lower θcrit (approximate 0.15 m3/m3) than the silty loamy soil (approximate 0.17 m3/m3), indicating that the higher content of sand would lead to the lower θcrit. In addition, an increase in θcrit was observed when the lysimeter was translocated from a site with a lower potential ET to a site with a higher potential ET.

How to cite: Lu, X., Groh, J., Pütz, T., Graf, A., Javaux, M., Vereecken, H., and Hendricks Franssen, H.-J.: Critical Soil Moisture Content Estimated from Lysimeter Time Series for Different Soil, Vegetation and Weather conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2783, https://doi.org/10.5194/egusphere-egu24-2783, 2024.

EGU24-3404 | ECS | Orals | HS1.2.5

Effects of changes in climatic conditions on soil water storage patterns 

Annelie Ehrhardt, Jannis Groh, and Horst H. Gerke

The soil water storage (SWS) defines crop productivity of a soil and varies under differing climatic conditions. Pattern identification and quantification of these variations remains difficult due to the non-linear behaviour of SWS changes over time.

We hypothesize that these patterns can be revealed by applying wavelet analysis to an eight-year time series of SWS, precipitation (P) and actual evapotranspiration (ETa) in similar soils of lysimeters in a colder and drier location and a warmer and wetter location within Germany. Correlations between SWS, P and ETa at these sites might reveal the influence of altered climatic conditions but also from subsequent wet and dry years on SWS changes.

We found that wet and dry years exerted influence on SWS changes by leading to faster or slower response times of SWS changes to precipitation in respect to normal years. This might be explained by a higher soil water content and the related higher soil hydraulic conductivity. Time shifts in correlations between ETa and SWS became smaller at the wetter and warmer site over time in comparison to the cooler and drier site where they stayed constant. This could be attributed to an earlier onset of the vegetation period over the years and thus to an earlier ETa peak every year and reflects the direct impact of changing climate on soil water budget parameters. 

How to cite: Ehrhardt, A., Groh, J., and Gerke, H. H.: Effects of changes in climatic conditions on soil water storage patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3404, https://doi.org/10.5194/egusphere-egu24-3404, 2024.

EGU24-9112 | Posters on site | HS1.2.5

Investigating herbicide transport and fate in vegetated lysimeters with numerical modeling and stable carbon isotopes 

Arno Rein, Anne Imig, Lea Augustin, Jannis Groh, Thomas Pütz, Martin Elsner, and Florian Einsiedl

The application of pesticides can induce severe impacts to the vadose zone, groundwater, and their ecosystems. A study was carried out on two lysimeters located in Wielenbach, Germany. Different soil textures were considered within the soil cores, consisting of sandy gravel and clayey sandy silt. The lysimeters were vegetated with maize, and four different herbicides were applied according to common agricultural practice. Over a period of 4.5 years, concentrations of the herbicides and selected metabolites were monitored in the lysimeter drainage. In addition, stable carbon isotopes (δ13C) were analyzed for investigating biodegradation influences of two of the applied herbicides.

In a first step, we characterized unsaturated flow in the lysimeters based on stable water isotope measurements (δ2H and δ18O) combined with modeling. Different setups within the numerical model HYDRUS-1D were compared, including single and dual porosity approaches. Then, the unsaturated flow models were extended for describing reactive transport of the herbicides, and simulations were interpreted in combination with measured δ13C values. 

At the end of the observations, 0.9 to 15.9% of the applied herbicides (up to 20.9% for herbicides plus metabolites) were recovered in lysimeter drainage. Some metabolites were observed to accumulate in drainage, and biodegradation was indicated by small isotopic shifts in δ13C to less negative values in the leached herbicides. In the later sampling campaign (7.5 months after herbicide application), a higher increase in δ13C (less negative values) compared to earlier sampling (19 days after application) points towards stronger biodegradation. This can be explained by a higher biodegradation potential when the infiltrated water and the herbicides were affected by longer mean transit times in the unsaturated zone.

Observations were reproduced by modeling, where the overall dynamics of herbicide concentration in the lysimeter drainage could be covered well by the model setups. The concentration peaks were partly associated with heavy precipitation, which in turn indicates that the transport was influenced by preferential flow. Limitations were found for describing preferential flow events by using single and dual porosity models, as some concentration peaks were over- or underestimated. The use of δ13C for compound-specific isotope analysis allowed obtaining some evidence on biodegradation of the two herbicides in the unsaturated zone, which was also validated with the model results. 

How to cite: Rein, A., Imig, A., Augustin, L., Groh, J., Pütz, T., Elsner, M., and Einsiedl, F.: Investigating herbicide transport and fate in vegetated lysimeters with numerical modeling and stable carbon isotopes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9112, https://doi.org/10.5194/egusphere-egu24-9112, 2024.

The ongoing global concern regarding climate change necessitates innovative approaches to understand its complex dynamics. This presentation outlines the evolution of lysimeters and ecotrons, culminating in the development of a cutting-edge platform designed for comprehensive research on climate change parameters in both laboratory and field environments.

Lysimeters, traditionally employed to measure water movement and nutrient transport in soil, have undergone significant advancements. Enhanced instrumentation and sensor integration now allow for precise monitoring of multiple environmental factors, including soil moisture, temperature, and gas exchange. These improvements enable researchers to simulate and analyze various climate change scenarios in a controlled laboratory setting.

Simultaneously, ecotrons, specialized chambers designed to replicate natural ecosystems, have evolved to provide a more realistic representation of climate interactions. By incorporating advanced technologies such as remote sensing, automated data acquisition, and controlled environmental conditions, ecotrons now offer a holistic approach to studying the impact of climate change on ecosystems.

The integration of lysimeters under natural conditions and ecotrons into a unified platform represents a paradigm shift in climate change research. This new platform facilitates a seamless transition between controlled laboratory experiments and real-world field studies, allowing for a more comprehensive understanding of the intricate relationships between climate change parameters.

Researchers can now explore the effects of elevated temperatures, altered precipitation patterns, and increased greenhouse gas concentrations on soil health, plant growth, and ecosystem dynamics with unprecedented precision. The platform's adaptability and versatility make it a valuable tool for addressing urgent questions related to climate change impact mitigation and adaptation strategies.

In conclusion, the fusion of outdoor lysimeters and indoor ecotrons into a unified platform signifies a milestone in climate change research. This innovative approach provides researchers with a powerful tool to investigate and address the complex challenges posed by climate change, fostering a more sustainable and resilient future.

How to cite: Reth, S.: Advancements in Lysimeters and Ecotrons: A Novel Platform for Investigating Climate Change Parameters in Laboratory and Field Settings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9489, https://doi.org/10.5194/egusphere-egu24-9489, 2024.

EGU24-9685 | ECS | Orals | HS1.2.5 | Highlight

The need for realistic experimental setups in controlled environments: insights from a two-year ecotron experiment on earthworms’ impact on ecosystem H2O, CO2 and N2O dynamics 

Joana Sauze, Oswaldo Forey, Clément Piel, Emmanuel S. Gritti, Sébastien Devidal, Abdelaziz Faez, Olivier Ravel, Yvan Capowiez, Damien Landais, Jacques Roy, and Alexandru Milcu

Recent studies have highlighted the potential role of earthworms in modulating soil greenhouse gas (GHG) emissions, yet the complexity of natural ecosystems and the lack of high-resolution temporal data have limited our understanding. To bridge this gap, a two-year experiment was undertaken in a controlled ecotron setting, utilizing large-scale lysimeters (5 square meters in area and 1.5 meters in soil depth) in the Macrocosms experimental platform of the Montpellier European Ecotron (CNRS). This study aimed to provide an understanding of the impact of earthworms (specifically endogeic and anecic ecotypes) on water and greenhouse gas emissions in a realistically simulated agricultural ecosystem undergoing a three-crop rotation.

We employed continuous, high-frequency monitoring to measure ecosystem-level exchanges of CO2, N2O, and H2O. While temporary increases in CO2 fluxes were noted in earthworm-inhabited replicates, the cumulative data over the entire study period did not demonstrate a significant increase in CO2 emissions. Interestingly, the presence of endogeic earthworms was correlated with a notable reduction in N2O emissions during wheat cultivation (by 44.6%), although this effect did not persist throughout the entire experimental timeline. Additionally, while earthworms had an impact on water infiltration along the soil profile, no consistent patterns were observed in terms of ecosystem evapotranspiration or water use efficiency (WUE) changes attributable to earthworm activity.

Our findings provide critical insights into the role of earthworms in terrestrial GHG dynamics, particularly in agricultural settings. Contrary to prevailing assumptions, this study suggests that earthworm activity does not lead to a significant increase in greenhouse gas emissions over a period of two years under conditions that closely emulate agricultural environments. These results underscore the importance of conducting long-term, high-resolution studies in realistically simulated ecosystems to better comprehend the intricate relationships between soil biota and greenhouse gas emissions.

How to cite: Sauze, J., Forey, O., Piel, C., Gritti, E. S., Devidal, S., Faez, A., Ravel, O., Capowiez, Y., Landais, D., Roy, J., and Milcu, A.: The need for realistic experimental setups in controlled environments: insights from a two-year ecotron experiment on earthworms’ impact on ecosystem H2O, CO2 and N2O dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9685, https://doi.org/10.5194/egusphere-egu24-9685, 2024.

EGU24-11233 | Orals | HS1.2.5 | Highlight

Influence of climate and land management on water, carbon and nitrogen cycling in grasslands of the pre-alpine region of southern Germany 

Ralf Kiese, Marcus Schlingmann, Katrin Schneider, Sophie Reinermann, Anne Schucknecht, Jincheng Han, Thomas Koellner, Carolin Boos, and Michael Dannenmann

Pre-alpine grasslands provide important economic value through forage for milk and meat production. Grassland soils also support ecosystem services such as carbon and nitrogen storage, water retention, erosion control and biodiversity. These functions are currently threatened by climate change, which is likely to accelerate in the coming decades. In addition to climate change, management decisions such as mowing and fertilisation frequency have a major impact on grassland yields, biodiversity and soil C and N dynamics. In this presentation we will summarise results from long-term monitoring of control and translocated grassland soil monoliths (1m2; 1.4m height) as operated in TERENO and studied in detail in the SUSALPS project.

From 2012, moderate climate change (plus 2°C) has increased grassland productivity, unless water stress has reversed the temperature stimulating effect. However, this increase in plant growth is only possible because increased N mineralisation rates under climate change allow increased N demand to be met. As plant N uptake is already in the range of total N fertilisation rates under current climate conditions, N losses to the environment, such as microbial N2O emissions and nitrate leaching from montane grassland soils, are comparatively low. If other ecosystem N losses such as NH3 and N2 emissions are considered, it becomes clear that even under the present climatic conditions substantial N has to be provided by mineralisation of soil organic N, indicating soil N (and C) mining. As the latter is associated with negative effects on soil fertility/productivity, C sequestration and GHG exchange, as well as filtering functions to protect water bodies, this trend poses risks to key soil functions in the long term. The detailed investigations from long-term monitoring sites were essential for testing a process-based model (LandscapeDNDC), which was used together with remote sensing information for spatial and temporal upscaling of the results.

How to cite: Kiese, R., Schlingmann, M., Schneider, K., Reinermann, S., Schucknecht, A., Han, J., Koellner, T., Boos, C., and Dannenmann, M.: Influence of climate and land management on water, carbon and nitrogen cycling in grasslands of the pre-alpine region of southern Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11233, https://doi.org/10.5194/egusphere-egu24-11233, 2024.

EGU24-11711 | Orals | HS1.2.5

The Deep Soil Ecotron – A Facility to Explore, Model, and Sense Deep Soil 

Zachary Kayler, Michael Strickland, David Williams, Rodrigo Vargas, Zeli Tan, Caley Gasch, Susan Crow, and Noah Fierer

The Deep Soil Ecotron will give researchers the unparalleled ability to investigate and experiment with deep soils while complementing established ecotrons across the globe. This facility, composed of twenty-four, highly instrumented ecounits, will allow for soil profiles up to three meters in depth to be repeatedly sampled and continuously monitored. This facility will be the first modern ecotron facility in the United States and as such will provide research infrastructure that this country currently lacks. The Deep Soil Ecotron will enable researchers to address the following four broad research needs using approaches and instrumentation that have been unattainable under more common field and laboratory experiments. First, the Deep Soil Ecotron will reveal how deep soil communities and processes affect and interact with surface soils to influence whole ecosystems. Second, the Deep Soil Ecotron will allow researchers to determine how deep soils and associated vegetation respond to global and land-use change, such as increasing soil temperature and agricultural management practices. Third, information gained from the Deep Soil Ecotron will be integrated into earth system models to improve model representation of soil carbon cycling. Fourth, the Deep Soil Ecotron will provide a testbed for the development of sensors for the in-situ monitoring of deep soils. This presentation will provide an overview of the Deep Soil Ecotron's design, capacity, and preliminary research agenda.

How to cite: Kayler, Z., Strickland, M., Williams, D., Vargas, R., Tan, Z., Gasch, C., Crow, S., and Fierer, N.: The Deep Soil Ecotron – A Facility to Explore, Model, and Sense Deep Soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11711, https://doi.org/10.5194/egusphere-egu24-11711, 2024.

EGU24-12759 | Orals | HS1.2.5

Enhanced understanding of water cycling processes of dwarf shrubs using high-precision lysimeters and climate manipulations 

Georg Leitinger, Elena Tello-García, Lucía Laorden-Camacho, Lisa Ambrosi, Karl Grigulis, Bello Mouhamadou, Christiane Gallet, Ursula Peintner, Ulrike Tappeiner, and Sandra Lavorel

Throughout European mountains, changes in livestock production systems since the 1950s have resulted in the gradual segregation between more accessible, flatter, and productive grasslands with intensified fodder production, and more remote, steeper, and less productive meadows used for extensive grazing, and some abandoned. After cessation of grazing in subalpine grasslands, secondary succession promotes the gradual colonization of species and functionally diverse herbaceous communities by shrubs. Although shrub encroachment is considered a ‘Plant Functional Type transformation’, our knowledge about the impact of climate change on shrub encroached ecosystems is still limited. Mechanistic analyses of alpine grassland responses to drought have focused on carbon fluxes, and a few studies have targeted components of the ecosystem water budget or nutrient cycling. However, these studies are focused on herbaceous functional groups, and shrubs are usually neglected. Moreover, despite the prevalence of this original climate change driver in mountains, snow manipulations are still rare.

To improve understanding of nitrogen and water cycling processes of shrubs with expected increased drought and advanced snowmelt, small high-precision lysimeters (SFL®, Meter Group AG, Munich, Germany) were used to analyze the effects and mechanisms of climate change on shrub species. In a garden experiment in the LTSER-site Stubai Valley (970 m a.s.l.), Tyrol Austria, two congeneric shrubs contrasting a deciduous (Vaccinium myrtillus) and evergreen (Vaccinium vitis-idaea) were planted into 16 lysimeters. In a split-plot design of 3.5m x 3.5m each, two plots were subject to either (1) control, (2) earlier snowmelt, or (3) summer drought treatments.

The manipulative experiments indicate that a shortening of the period with snow cover at the end of winter affects soil freezing and hence, soil nitrogen (N) and carbon (C) availability. Results further highlight the interacting effects of climate manipulations on key plant traits, and their consequences for N- and water availability. Furthermore, summer drought seems to additionally affect biogeochemical cycling and evapotranspiration for both investigated shrub types. This study's results reveal the importance of addressing the impact of shrub encroachment not only from a land management perspective but also to increasingly raise awareness about climate change effects on shrubs. Moreover, it provides valuable insights into challenges and chances of growing shrubs in lysimeters, being a promising approach for future climate impact studies. The study was conducted as part of the LUCSES project, ANR-FWF (ANR-20-CE91-0009 and FWF-I 4969-B).

How to cite: Leitinger, G., Tello-García, E., Laorden-Camacho, L., Ambrosi, L., Grigulis, K., Mouhamadou, B., Gallet, C., Peintner, U., Tappeiner, U., and Lavorel, S.: Enhanced understanding of water cycling processes of dwarf shrubs using high-precision lysimeters and climate manipulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12759, https://doi.org/10.5194/egusphere-egu24-12759, 2024.

EGU24-14816 | ECS | Posters on site | HS1.2.5

Can we bring alpine climate into ecotrons? 

Harald Crepaz, Johannes Klotz, Marco Cavalli, Ulrike Tappeiner, and Georg Niedrist

Climate change is advancing at an unprecedented pace, impacting terrestrial ecosystems, particularly those in alpine regions. Consequently, there is a growing need to comprehend the associated impacts, underlying mechanisms, and implications. Long-term monitoring may face challenges in capturing the effects of accelerated climate change, and in-situ experiments in remote alpine areas often grapple with logistical constraints. Furthermore, attributing vegetative responses to specific manipulated variables proves challenging, especially under extreme alpine conditions such as low atmospheric pressure, low temperatures, or high radiation levels.

Using a specially designed ecotron called 'TerraXcube' (Bozen, Italy), we investigated the feasibility of realistically reproducing harsh alpine conditions and explored the interactions among various parameters. For our measurements, we equipped the chamber with temperature and relative humidity probes, a spectrometer, barometer, and anemometer positioned at different heights within the chamber. We tested the spatial and temporal homogeneity of the variables— atmospheric pressure, temperature, relative humidity (RH), and radiation—independently, as well as their interactions over time and in space, by simulating various realistic alpine climatic scenarios.

The measurements, conducted between -20°C and +25°C with relative humidity ranging from 10% to 95%, yielded satisfactory results. Over several hours, the largest difference at a specific position was 0.6°C and 4.3% RH, while the maximum difference between two sensors simultaneously was 1°C and 7% RH. At a height of 170 cm, the LED system emitted radiation at an intensity of 1,002 W/m² within the wavelength range of 280 to 900 nm; however, with a sharp decrease in intensity from the light source. The photosynthetically active radiation (PAR) at the chamber's center reached 1,883 μmol·m−2·s−1, achieving 77% of the potential annual maximum measured at 2,400 m a.s.l. This enables us to replicate the PAR level for 97% of the days throughout the year. Despite the high light intensity, the heating effect of the LED system was limited to a maximum of 2°C in the upper 40cm of the chamber. Pressure manipulation, with the highest technical demand, nonetheless resulted in high temporal homogeneity up to 4,000m a.s.l., corresponding to 618.9 mbar.

In conclusion, the results emphasize the potential and utility of ecotrons in simulating a suitable climate for alpine ecological experiments. However, as in many ecotrons, it is crucial to acknowledge that minor island effects and irregularities are inevitable. Even more sophisticated parameters such as wind effects or pollinator function are currently not sufficiently addressed. A combined in- and outdoor usage of mobile field lysimeters might be a further step to bridge this gap between experimental results obtained in ecotrons and in the field.

How to cite: Crepaz, H., Klotz, J., Cavalli, M., Tappeiner, U., and Niedrist, G.: Can we bring alpine climate into ecotrons?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14816, https://doi.org/10.5194/egusphere-egu24-14816, 2024.

EGU24-15212 | ECS | Posters on site | HS1.2.5

Effects of land use change on dry heathland soil moisture in a changing climate 

René Shaeffer, Francois Rineau, and Nadia Soudzilovskaia

Conversion of natural and semi-natural systems to agricultural use is one of the largest conservation
challenges of our time. As the world’s population continue to grow at unprecedented rates,
multinational organizations like the United Nations and its subsidiary the Food and Agriculture
Organization call for higher crop production and the expansion of existing agriculture to ensure future
food security, especially in the face of changing climate. However, these efforts will most likely endanger
numerous landscapes of historical and cultural value, including those found in northwest Europe. How
these possible changes in land use may alter the functions of these ecosystems and the associated
services they provide are questions that need to be answered before any policy decisions can be made.


Using a state-of-the-art ecotron facility, we compared soil moisture profiles between an intact dry
heathland system and heathland soils that had been cleared for cereal agriculture, both of which were
subjected to climate conditions projected for the year 2070, in line with the IPCC RCP8.5. After
continuously monitoring moisture changes in the top 1.5 meters of soil for three years, we found that
there are significant differences between the two modes of land use. Soils used for cereal crops were
significantly drier (up to >60%) in the upper 10-20cm than intact heathland soils, and significantly wetter
(up to >500%) at the lowest soil levels (140cm). This redistribution of moisture within the soil column
under different land use schemes can have serious implications for overall ecosystem functioning,
particularly with regard to potentially mitigating heathland soils’ ability to store and capture carbon and
exacerbating detrimental soil-climate feedbacks under agricultural use.

How to cite: Shaeffer, R., Rineau, F., and Soudzilovskaia, N.: Effects of land use change on dry heathland soil moisture in a changing climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15212, https://doi.org/10.5194/egusphere-egu24-15212, 2024.

EGU24-15321 | ECS | Posters on site | HS1.2.5

A practical approach to link lysimeter and large-scale measurement systems. 

Gunther Liebhard, Peter Strauss, Peter Cepuder, and Reinhard Nolz

An accurate and reliable measurement system is essential for analysing transport processes within the soil-plant-atmosphere continuum and for calibrating and validating ecosystem or hydrological models. Weighing lysimeters are very suitable tools for these purposes, as they are the most direct tools to reliably and precisely measure water mass balance components such as rainfall and non-rainfall water inputs, evapotranspiration, and percolation at the system boundaries. Investigating the ecosystem by use of lysimeters is more or less limited to point measurements, though. Approaches are therefore required to link lysimeter mesurements to the landscape scale. We present our experimental approach to link point and large-scale parameter assessment at an experimental station in Groß-Enzersdorf, Austria. In particular, we use soil water content data across the soil profiles from capacitance sensors and t-test statistics to check the representativeness of the conditions in the lysimeter body with the surrounding field and to assess soil hydraulic properties for numerical modeling of water fluxes. Based on this, we transfer measurement data with high measurement accuracy and temporal resolution from the lysimeter scale to the large-scale measurement systems such as eddy covariance, scintillometry, or isotope hydrology. On the other hand, we are able to incorporate parameters from areal measurements and from measurements using disturbed and undisturbed soil samples into the lysimeter measurement system.

How to cite: Liebhard, G., Strauss, P., Cepuder, P., and Nolz, R.: A practical approach to link lysimeter and large-scale measurement systems., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15321, https://doi.org/10.5194/egusphere-egu24-15321, 2024.

EGU24-15370 | Posters on site | HS1.2.5

What you do not know, and what you should know about lysimeter experiments 

Thomas Puetz, Horst H. Gerke, Nicolas Brueggemann, Harry Vereecken, and Jannis Groh

For many studies in the fields of soil, hydrology, agriculture, ecology, meteorology, and environmental sciences and across disciplines, conventional field experiments are inadequate because the variables cannot be measured properly or controlled experimentally. In the soil-plant-atmosphere continuum, lysimeters can be used as an integrative experimental approach that enables precise measurements of water and matter fluxes in combination with field crops. The term lysimeter basically refers to two different types of experimental equipment. Porous suction cups, as well as containers/vessels filled with soil substrates or other materials, are termed lysimeters. Lysimeters are vessels of various sizes filled with ecosystem compartments, taking a holistic approach as each compartment interacts dynamically within the biosphere.

Lysimeter experiments are carried out in a wide variety of designs. To optimize the scientific exploitation of lysimeter data, various prerequisites should be met. The complexity of lysimeter experiments will be explained in more detail, the advantages of lysimeters, but also the restrictions and limitations will be examined in more detail. We would like to suggest some hints, norms, and rules for conducting lysimeter experiments that can optimize and increase the benefit and profit of lysimeter experiments. Special attention is paid to the important technical details that can significantly influence the quality of lysimeter measurements. The latest technical developments are also briefly presented.

How to cite: Puetz, T., Gerke, H. H., Brueggemann, N., Vereecken, H., and Groh, J.: What you do not know, and what you should know about lysimeter experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15370, https://doi.org/10.5194/egusphere-egu24-15370, 2024.

EGU24-16315 | Posters on site | HS1.2.5

Aluminum fate in forest soils developed from magmatic and metamorphic rock of mid-mountain areas in Germany 

Roukaya Eid, Katharina Lehmann, Karin Eusterhues, and Kai Totsche

Climate and land use change affect weathering and pedogenesis with potential consequences for the fate of Al-bearing minerals and the potential export of Aluminum to groundwater resources. These changes might result in strong acidification, originally known for “acid rain” affecting these areas until the second but last decade of the past century. To explore the fate of Al in areas now affected by climate and land use change, we investigated two sites of different geology in North-Bavaria. Site 1 is located on granitic rocks under a reforested 6-year-old Norway spruce forest. Site 2 is a hilltop site located on metamorphic rocks under a 60-80-year-old spruce forest. Soil samples (< 2mm) and clay fractions were analyzed by hydrochemical and spectroscopic techniques. Zero tension controlled lysimeter and automated tension controlled lysimeters were installed for monitoring the soil solution volume and composition at the topsoil-subsoil and the subsoil-regolith boundary. Monitoring started in June 2018. Since then, 85 sampling campaigns have been completed that amounted to 1500 individual lysimeter samples. Analysis comprised among others EC, pH, elemental composition major anions and cations, and carbon sum parameters (DOC, TOC, DIC, TIC).

Recent climate at the sites differs markedly from the 1961-1990 period, indicating a transient climate at the sites. Mean soil pH ranged from 3.2 to 4.7 at both sites and was comparable to values published in 1995 by Franken et al. (3.4 to 4.2). Thus, recent soil pH is as low as used to be under the conditions of strong acid precipitation of the last century. Soils developed from magmatic rock showed higher contents of variable Al phases than those developed from metamorphic rocks.

At both sites pyrophosphate extractable Al is the dominant Al pool accounting 19.4% of total Al in site 1(14.1 g/kg in Bs horizon), and 6.9% of total Al in site 2 (4.9 g/kg in Bs horizon).

Noteworthy, hydrological summer was more important for seepage generation than the hydrologic winter: Roughly 68% of the total annual seepage volume was found in the hydrological summer. As a result, the TOC flux from the subsoil in summer is 35.66 ± 20 mg/year, and only 13.88 ± 13.8 mg/year in winter. Similarly, the Al flux in summer is 1.02 ± 0.7 mg/year and only 0.43 ± 0.4 mg/year in winter.

Variation partitioning analysis showed that the seasonal variation and the difference between topsoil and subsoil combined explained less than 5 % of the particle-related soil solution properties ((pH, ∑LMWO, TOC, Al and Si(mg/L)) and less than 1% of the hydrochemical properties (TIC, Cl, SO42−, Ca, Mg, Na (mg/L)). Difference between the two sites explained 13.84% and 6.48% of the two sets, respectively and the sampling year explained 4.52% and 4.74%. We conclude that the Al system at our sites is controlled by climatic conditions and site properties (lithology, slope, vegetation..). There are no indications that the released Al is immobilized in any secondary immobile Al-phase in the subsoil or downstream, pointing to the potential transport of Al and other unwanted substances to the aquifers.

How to cite: Eid, R., Lehmann, K., Eusterhues, K., and Totsche, K.: Aluminum fate in forest soils developed from magmatic and metamorphic rock of mid-mountain areas in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16315, https://doi.org/10.5194/egusphere-egu24-16315, 2024.

EGU24-20671 | Posters on site | HS1.2.5 | Highlight

Effect of climate change on functioning of natural and agricultural ecosystems: an ecotron study 

Francois Rineau and Nadejda Soudzilovskaia and the Ecotron consortium team

Ecotrons represent enclosed systems in which macrocosms are subjected to controlled environmental conditions, and their responses are closely monitored at a high frequency. This makes them particularly well-suited for investigating the impact of climate change on ecosystem functioning. In this presentation, we demonstrate the utilization of the UHasselt ecotron to examine the effects of climate change on two distinct ecosystems: a natural heathland and an agricultural pear orchard.

We delve into the results obtained thus far, covering aspects such as carbon balance, water balance, greenhouse gas emissions, soil water nutrients, plant biomass, phenology, soil microbial communities, and soil fauna. Additionally, we explore the strengths and limitations associated with ecotron-based approaches. The presentation concludes by identifying future challenges in this field.

How to cite: Rineau, F. and Soudzilovskaia, N. and the Ecotron consortium team: Effect of climate change on functioning of natural and agricultural ecosystems: an ecotron study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20671, https://doi.org/10.5194/egusphere-egu24-20671, 2024.

EGU24-20967 | Orals | HS1.2.5

Determining the soil water balance at a large-scale lysimetric facility with 60 years of uninterrupted data comprising a grassland basin, oak/beech and a pine basin 

Marcel Gaj, Stephan Costabel, Michèle Erlach, Julia Frank, Viktoriya Tarasyuk, Stephan Peth, and Vera Schimetzek

The research facility St. Arnold presented here consists of three individual lysimeters with an area of 400m² and 3.5m depth each. They are similar in soil types but differ in vegetation cover. This unique setup allows the direct comparison of the water balance of grassland, oak/beech forest and pine forest under the same climatic and topographic boundary conditions. The later site were cut after a significant storm occurred in 2007. Since a pioneer forest developed. 

The data collection of precipitation, groundwater recharge, temperature, humidity and sunshine duration started in 1964. In addition, stem diameter at certain trees has been determined once a year.  All data until 1997 were collected manually. After that automated collection of hydro climatic data were established and transmitted directly into the database of LANUV. From the data, evaporation rates were calculated with Penman-Montheith. More recently in October 2023 undisturbed soil cores where collected and analyses for their saturated and unsaturated hydraulic conductivity. In addition, the investigation of the water balance has been done with HYDRUS 3D.

The data shows significant trends. Further, it can be observed how storm damage and/ or clear-cut of forested areas impact the soil water balance.  The long-term average of the period 1965 to 2007 showed, the grassland basin turns more than half of its annual incoming precipitation into leachate and only 36% into evaporation while the deciduous forest exhibits a ratio of 36% leachate and 56% for evapotranspiration. The evergreen coniferous forest shows the highest evaporation rate 65% and the lowest leachate rate with 26%. (Harsch et al., 2009)

An upgrade of the entire facility with state of the art measurements devices is in progress. This will initiated with a geophysical survey in the beginning of 2024 along with the installation of soil moisture and tensiometer sensors. Depending on funding permanent and long term geophysical measurements and stable isotope analysis will be conducted all data will be available open source. We welcome collaborators for joint research at the facility.

 Harsch, N., Brandenburg, M., & Klemm, O. (2009). Large-scale lysimeter site St. Arnold, Germany: analysis of 40 years of precipitation, leachate and evapotranspiration. Hydrology and earth system sciences13(3), 305-317.

How to cite: Gaj, M., Costabel, S., Erlach, M., Frank, J., Tarasyuk, V., Peth, S., and Schimetzek, V.: Determining the soil water balance at a large-scale lysimetric facility with 60 years of uninterrupted data comprising a grassland basin, oak/beech and a pine basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20967, https://doi.org/10.5194/egusphere-egu24-20967, 2024.

EGU24-21932 | Orals | HS1.2.5

Heat transport model simulations of Lysimeter/Ecotron systems 

Gernot Klammler, Janja Vrzel, and Hans Kupfersberger

Soil temperature plays a central role in the complex processes in the vadose zone, particularly in connection with water and solute transport. As a major thermal factor, soil temperature influences not only the physical properties of the soil, but also the biochemical reactions responsible for the transport of water and solutes. The variation of soil temperature can have significant effects on the mobility of nutrients and pollutants and thus plays a key role in understanding and controlling important soil processes.

Ecotrons in combination with weighable lysimeters are generally able to investigate complex ecological processes (e.g. evapotranspiration, nutrient dynamics) under controlled conditions. However, the requirement for this is that the temperature control of the soil column can be simulated with sufficient accuracy over the entire height and cross-section. Furthermore, it must also be ensured that the required rates of temperature change in the soil column, which can vary depending on the scientific question, can be simulated.

In the course of the abstract submitted here, we would like to present the results of 3D heat transport model simulation for selected examples, which contribute to the optimization of the technical design of Lysimeter/Ecotron systems (e.g. with regard to insulation thickness, heat exchanger area, required inlet temperature in the heat exchanger, etc.).

How to cite: Klammler, G., Vrzel, J., and Kupfersberger, H.: Heat transport model simulations of Lysimeter/Ecotron systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21932, https://doi.org/10.5194/egusphere-egu24-21932, 2024.

EGU24-6080 | Posters on site | CL5.3

U-Th dating of gypsum: methodology and reference materials 

Xuefeng Wang, Lisheng Wang, Zhibang Ma, Wuhui Duan, and Jule Xiao

Gypsum is a common evaporate mineral in a wide variety of geological settings, especially in arid and semi-arid areas. It often precipitated from the natural brine systems with trace amounts of U and almost no Th, rendering it a potentially valuable U-Th geochronometer. However, U-Th dating of gypsum is often challenging, such as how to quickly and completely digest gypsum into solution, and avoid the re-crystallization of gypsum particles during the digestion and chromatography process. Here we present a rapid and practical method for high-precision U-Th dating of gypsum using the (NH4)2CO3 exchange reaction and double-spike method by MC-ICPMS. Our developed protocol addresses these conventional challenges by using the chemical reaction between calcium sulfate and carbonate, resulting in the (NH4)2SO4 solution and CaCO3 precipitate. Then the CaCO3 could be easily digested by diluted acid. With the solid-liquid separation, Ca2+ and SO42- ions are also effectively separated, minimizing the recrystallization of gypsum. The (NH4)2CO3 median, the gypsum/carbonate molar ratio of 1: 4, and the exchange reaction duration of 1.5 ~ 2 hours are suggested in this protocol. Since there is no gypsum U-Th dating reference materials to validate the accuracy of different approaches and ensure methods are repeatable across laboratories. We also prepared and characterized two natural gypsum U-Th dating reference materials (PXCG-1, PXCG-2) from PiXiao Cave, southwest China. Data from three different laboratories exhibit good agreement with both 238U content, δ234U, 230Th/238U activity ratio, and the 230Th ages. The 230Th ages of PXCG-1, PXCG-2 RMs proposed are 66.97 ± 0.31 ka, 260.82 ± 3.39 ka, respectively.

How to cite: Wang, X., Wang, L., Ma, Z., Duan, W., and Xiao, J.: U-Th dating of gypsum: methodology and reference materials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6080, https://doi.org/10.5194/egusphere-egu24-6080, 2024.

EGU24-10443 | Posters on site | CL5.3

14C bomb peak and the onset of the Anthropocene 

Irka Hajdas, Carley Crann, Kristine DeLong, Barbara Fiałkiewicz-Kozieł, Juliana Ivar Do Sul, Jerome Kaiser, Francine M.G. McCarthy, Simon Turner, Allison Stenger, Colin Waters, and Jens Zinke

The unprecedented environmental changes resulting from anthropogenic activities initiated during the Great Acceleration of the mid-20th century can be traced using radiocarbon analysis. The cosmogenic isotope 14C, which is produced in the atmosphere, is well-known as the geochronological tool applied to archives of the last 55 thousand years. However, during the last 200 years, the natural signal of 14C in the atmosphere and connected reservoirs (biosphere, ocean, soils, etc.,) has been perturbed by human activities. Two anthropogenic effects are observed: a decreasing trend observed in 14C concentration of the atmosphere (Suess effect) which has been temporarily reversed by aboveground thermonuclear tests of the 1950/60s.

The excess of the artificially produced 14C (bomb pulse) is a useful time marker for the mid-20th century and the detection of the bomb peak in natural archives has thus been proposed as a tool to locate and date the onset of a proposed new epoch, the Anthropocene [1].

Here we present the results of radiocarbon analysis conducted as a part of the research dedicated to establishing the Global boundary Stratotype Section and Point (GSSP) for the proposed Anthropocene series. The studied sites include corals (Flinders Reef, AU and Flower Garden Banks, USA)[2, 3], peat (Śnieżka peatland, PL)[4], lake sediment (Crawford Lake, CA and Searsville Lake, USA)[5, 6] and marine sediment (East Gotland Basin, Baltic Sea)[7]. The variety of records (different carbon reservoirs) required site and sample-specific treatment prior to analysis and site-specific interpretation of the measured 14C. Nevertheless, the mid-20th century bomb peak was detected at all but one of these sites (Searsville Lake)[6]. In all records, the observed onset of the 14C bomb peak always postdates 1954, the year of the first atmospheric 14C bomb increase. The specific reservoir effects and corrections will be discussed.

References

The Anthropocene Review, 2023. 10(1):

1.    Waters, C.N., et al. (Eds.), Candidate sites and other reference sections for the Global boundary Stratotype Section and Point of the Anthropocene series.  p. 3-24.

2.    Zinke, J., et al., North Flinders Reef (Coral Sea, Australia) Porites sp. corals as a candidate Global boundary Stratotype Section and Point  for the Anthropocene series.  p. 201-224.

3.    DeLong, K.L., et al., The Flower Garden Banks Siderastrea siderea coral as a candidate Global boundary Stratotype Section and Point  for the Anthropocene series. p. 225-250.

4.    Fiałkiewicz-Kozieł, B., et al., The Śnieżka peatland as a candidate for the Global boundary Stratotype Section and Point  for the Anthropocene series.  p. 288-315.

5.    McCarthy, F.M.G., et al., The varved succession of Crawford Lake, Milton, Ontario, Canada as a candidate Global boundary Stratotype Section and Point for the Anthropocene series.  p. 146-176.

6.    Stegner, M.A., et al., The Searsville Lake Site (California, USA) as a candidate Global boundary Stratotype Section and Point for the Anthropocene Series. p. 116-145.

7.    Kaiser, J., et al., The East Gotland Basin (Baltic Sea) as a candidate Global boundary Stratotype Section and Point for the Anthropocene series. p. 25-48.

How to cite: Hajdas, I., Crann, C., DeLong, K., Fiałkiewicz-Kozieł, B., Ivar Do Sul, J., Kaiser, J., McCarthy, F. M. G., Turner, S., Stenger, A., Waters, C., and Zinke, J.: 14C bomb peak and the onset of the Anthropocene, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10443, https://doi.org/10.5194/egusphere-egu24-10443, 2024.

EGU24-13250 | Posters on site | CL5.3

Assessing Gol-e-Zard Cave (GZS) and Bergen Speleothem Standards (BSS) for U/Th Geochronometry Using MC-ICP-MS 

Altug Hasözbek, Fernando Jiménez-Barredo, Arash Sharifi, Ali Pourmand, Regina Mertz-Kraus, Michael Weber, Denis Scholz, Stein-Erik Lauritzen, Josep M. Parés, and Silviu Constantin

Recent advancements in MC-ICPMS technology have significantly enhanced the application of U/Th geochronometry in both biogenic and chemically precipitated carbonate rocks of almost middle Pleistocene to upper Holocene. This burgeoning use, particularly in the study of late Pleistocene earth surface processes, underscores the need for standardized reference materials with a broad age spectrum with different uranium and thorium concentrations. Addressing this need, our study evaluates speleothem specimens, Gol-e-Zard Cave Standard (GZS) and Bergen Speleothem Standard (BSS), as potential reference materials.

BSS-2 was processed as a homogenized powder and dissolved aliquot for U-Th dating using MC-ICP-MS analysis. We employed various digestion and ion-resin chromatography separation methods, followed by U-Th dating using MC-ICP-MS at CENIEH, University of Miami, and University of Mainz. The ion chromatography protocols yielded recovery rates ranging from 85% to over 95%. U-series analyses of powdered BSS-2 indicated uncertainties between 0.2-1.5%, attributed to variations in the Beta-factor and the specific U and Th standard bracketing procedures used across laboratories. The dissolved BSS-2 aliquots yield between 1.5-2% of uncertainty. Obtained U-Th ages were 122.8 ± 3.3 ka (University of Miami), 124.5 ± 0.3 ka (University of Mainz), and 123.9 ± 3.2 ka (CENIEH) in the powdered samples. Furthermore, in dissolved samples, the Th-ages vary between 126.9 ± 2.9 to 127.9 ± 3.1 (CENIEH & University of Miami). GZS was prepared as a dissolved standard and the Th-date results obtained from this stalagmite are 3967 ± 0.1 to 3988 ± 0.1 (University of Miami), and 3967 ± 0.1 to 4060 ± 0.4 (CENIEH).

All Th-dates required no correction as activity ratios [230Th/232Th] exceeded 500 and 150 for BSS-2 and GZS, respectively. The consistency of these preliminary results across different laboratories suggest that GZS and BSS-2 are promising reference materials for U-Series analysis of calcium carbonate.

How to cite: Hasözbek, A., Jiménez-Barredo, F., Sharifi, A., Pourmand, A., Mertz-Kraus, R., Weber, M., Scholz, D., Lauritzen, S.-E., M. Parés, J., and Constantin, S.: Assessing Gol-e-Zard Cave (GZS) and Bergen Speleothem Standards (BSS) for U/Th Geochronometry Using MC-ICP-MS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13250, https://doi.org/10.5194/egusphere-egu24-13250, 2024.

EGU24-17301 | ECS | Posters on site | CL5.3

Refining the age-depth model of a marine sediment record in the Laptev Sea using Beryllium-10 

Arnaud Nicolas, Gesine Mollenhauer, Maylin Malter, Jutta Wollenburg, and Florian Adolphi

In order to correctly determine leads and lags in the climate system and compare different proxy records over long time periods, it is important to build robust chronologies that can provide the temporal foundation for paleoclimate correlations between marine, terrestrial and ice-core records. One of the main challenges for building reliable radiocarbon-based chronologies in the marine realm is to estimate the regional marine radiocarbon reservoir age correction. Estimates of the local marine reservoir effect, ΔR, during the deglaciation can be obtained by 14C-independent dating methods such as synchronization to other well-dated archives. The cosmogenic radionuclide 10Be provides such a synchronization tool. Its atmospheric production rate is globally modulated by changes in the cosmic ray flux caused by changes in solar activity and geomagnetic field strength. The resulting variations in the meteoric fallout of10Be are recorded in sediments and ice cores and can thus be used for their synchronization.

In this study we use for the first time the authigenic 10Be/9Be record of a Laptev Sea sediment core and synchronize it to the 10Be records from absolutely dated ice cores. Based on the resulting absolute chronology, the ΔR  was then estimated for the Laptev Sea during the deglaciation. The deglacial estimate for the benthic ΔR value for the Laptev Sea is 345±60 14C years, corresponding to a marine reservoir age of 864±90 14C years. We discuss the obtained ΔR in comparison to modern ΔR estimates from the literature and its consequences for the age-depth model. Our refined age-depth model can be used as a reference for the Laptev Sea and the wider Siberian regions of the Arctic Ocean.    

How to cite: Nicolas, A., Mollenhauer, G., Malter, M., Wollenburg, J., and Adolphi, F.: Refining the age-depth model of a marine sediment record in the Laptev Sea using Beryllium-10, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17301, https://doi.org/10.5194/egusphere-egu24-17301, 2024.

EGU24-18258 | Posters on site | CL5.3

Advancing Quaternary Geochronology: Impact of Sample Preparation and Analytical Techniques on Natural Radioactive Dose Assessment in Stream Sediments 

Fernando Jimenez, Altug Hasozbek, Mathieu Duval, Josep M. Pares, M. Isabel Sarró-Moreno, Ana I. Barrado-Olmedo, Estefania Conde-Vila, Marta Fernández-Díaz, Jose Manuel Cobo, Martin Perez-Estebanez, and Javier Alonso-Garcia

Keywords: Geochronology, Sediment, Uranium, Thorium, Microwave Digestion, HR-ICP-MS

In Quaternary geochronology, accurately estimating natural radiation exposure is crucial for dating materials using Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL). Traditional methods like gamma and alpha spectrometry, despite their utility, are limited by sample size requirements and time inefficiency, especially in low-radiation contexts. This study explores the efficacy of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Plasma Mass Spectrometry (ICP-MS), including both Quadrupole (ICP-QMS) and High-Resolution (HR-ICP-MS), for analyzing uranium, thorium, and potassium concentrations in sediments.

We compared various acid digestion methods using standard hot-blocks, microwave digestion, and single cell microwave technology on Sediment Reference Materials (NIST BRS 8704, OREAS 24d). Potassium detection was more accurate with ICP-OES (96% precision) than ICP-QMS (80%). In contrast, HR-ICP-MS significantly outperformed ICP-QMS in measuring uranium and thorium (U and Th recoveries of 99% and 94% vs. 83% and 81%, respectively). Moreover, microwave-assisted digestion methods showed slight advantages in uranium and thorium recovery.

Our findings suggest that a four-acid microwave-assisted digestion, combined with potassium measurement via ICP-OES in radial mode and uranium and thorium quantification using HR-ICP-MS, offers the most accurate and time-efficient approach for natural dose determination in sediment dating. This methodology is particularly relevant for cave, river, and stream sediments even with expected low uranium levels.

How to cite: Jimenez, F., Hasozbek, A., Duval, M., Pares, J. M., Sarró-Moreno, M. I., Barrado-Olmedo, A. I., Conde-Vila, E., Fernández-Díaz, M., Cobo, J. M., Perez-Estebanez, M., and Alonso-Garcia, J.: Advancing Quaternary Geochronology: Impact of Sample Preparation and Analytical Techniques on Natural Radioactive Dose Assessment in Stream Sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18258, https://doi.org/10.5194/egusphere-egu24-18258, 2024.

EGU24-18925 | Posters on site | CL5.3

μGraphiline: a high-throughput, low-maintenance, fully automated 14C graphitization system 

Konrad Tudyka, Kacper Kłosok, Maksymilian Jedrzejowski, Andrzej Rakowski, Sławomira Pawełczyk, Alicja Ustrzycka, Sebastian Miłosz, and Aleksander Kolarczyk

μGraphiline is an innovative, fully automated graphitization system designed for radiocarbon dating using accelerator mass spectrometry. This system streamlines the conversion of samples into CO2 and subsequently into graphite. The standard configuration of μGraphiline is capable of preparing 24 targets daily, demonstrating its high throughput. It achieves a graphitization efficiency of over 95% for 1 mg graphite targets. μGraphiline also offers additional modules for stepped combustion, ramped pyrolysis, and oxidation, all of which can be operated at user-defined temperatures. Furthermore, its design ensures a low background and reproducibility, significantly enhancing the accuracy and reliability of radiocarbon measurements.

 

One of the notable advantages of the system is its low maintenance requirements. It operates efficiently without the need for working gasses such as helium (He), argon (Ar), oxygen (O2), explosive hydrogen (H2) or liquid nitrogen, which simplifies its operation and enhances safety. This feature, coupled with its modular design and high efficiency, virtually no cross-contamination between modules and samples makes μGraphiline an advanced solution for radiocarbon dating. Lastly, the system's repeatability and reliability are backed by reference materials measurements from the International Atomic Energy Agency, demonstrating good repeatability. 

 

This demonstrates μGraphiline's capability to deliver fast, consistent and accurate results, making it a valuable tool for various scientific and research applications.

How to cite: Tudyka, K., Kłosok, K., Jedrzejowski, M., Rakowski, A., Pawełczyk, S., Ustrzycka, A., Miłosz, S., and Kolarczyk, A.: μGraphiline: a high-throughput, low-maintenance, fully automated 14C graphitization system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18925, https://doi.org/10.5194/egusphere-egu24-18925, 2024.

EGU24-19089 | Posters on site | CL5.3

230Th/U and 234U/238U dating of cold-water corals: Approaching the disequilibrium theory 

Norbert Frank and the DCWC

U-series disequilibrium dating or more specifically 230Th/U - dating of cold-water corals is a major absolute chronological toolbox to study the evolution of coral reefs through time and to determine absolute time scales for climate proxies. Advances in multi-collector inductively coupled ion source mass spectrometry (MC-ICPMS) have continuously improved precision of Th and U isotopic measurements over the past decades thanks the development of new high ohmic resistors for Faraday cups. Consequently, isotopic measurements and absolute precision levels are in epsilon ranges for 234U/238U ratios and in the case of materials older than a few tens of thousands of years also for 230Th/238U ratios. To obtain accurate ages the corals isotope ratios need to evolve as a U series closed system and must be free of initial 230Th and non-carbonate materials. The latter being often traced using the natural most abundant 232Th isotope. Coral diagenesis, bio-erosion, residual ferromanganese coatings, recrystallization, and recoil displacement of U isotopes are known sources of age disturbances and U series open system behavior. Here, I want to advocate, however, that such cold-water corals can be ideal dating objects opening far reaching perspectives of marine climate science and for past ecosystem studies. Based on approx. 1200 coral ages and isotope ratios of reef-forming cold-water corals, which correspond to strict quality criteria, a perfect agreement with theoretical predictions of a closed U series system can be found. The resulting oceanic initial (234U/238U) activity ratio for the past 510 ka varies by at most 6.7 ‰ (2s) surrounding the mean of modern seawater and of all reconstructed values of 146.5 ‰ (HU1 reference material is assumed here to be in secular radioactive equilibrium). Consequently, the 234U/238U ratios may be used for dating of old cold-water corals to expand the dating range to more than 1.2 million years. Moreover, any significant deviation between closed system 234U/238U ages and 230Th/238U ages may be used to detect U series open - system behavior. Based on the combined age determination, more consistent chronologies can be derived for cold-water coral reefs beyond 350 ka and theoretically the quality of this archive has opened a path for absolutely dated marine climate proxy records since the Mid Pleistocene Transition.

How to cite: Frank, N. and the DCWC: 230Th/U and 234U/238U dating of cold-water corals: Approaching the disequilibrium theory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19089, https://doi.org/10.5194/egusphere-egu24-19089, 2024.

EGU24-21472 | ECS | Posters on site | CL5.3

Lyoluminescence: a potential tool for dating evaporites up to the Middle-Pleistocene? 

Magdalena Biernacka and Sebastian Kreutzer

Lyoluminescence (LL) is light emission during the solvation of previously irradiated crystals in the liquid-solid interface (Atari, 1980). Our aim is the breakthrough development of lyoluminescence as a dating tool on halite (here: sodium chloride and potassium chloride) for application in Earth Sciences. The positive correlation between radiation dose and LL light emission makes crystal lattice defects viable natural ionizing radiation dosimeters. With a saturation dose of ~10 kGy (e.g. Atari et al., 1973) for sodium chloride dissolved in pure water and for realistic dose rates of ~4 Gy/ka (e.g., Han et al., 2014), the LL signal from salt minerals potentially may determine an age up to 2.5 Ma.
We hypothesize that LL, naturally observable in salt minerals, will allow dating the last recrystallization event significantly beyond the age limits of conventional luminescence-dating methods. In the past, the potential of halite as a material for optical luminescence dating had been suggested, e.g. Bailey et al., (2000); Zhang et al., (2005). However, LL may offer an additional luminescence-dating tool for routine use in geochronology but targeting the crystallization instead of heat or light exposure event. Moreover, it may enable tapping into different archives and subsurface processes where only the event of the last hydration is of interest.
In our contribution, we present the first basic design of a measurement prototype using 3D printing and preliminary experimental results of salts easily soluble in water.

References
Atari, N.A., 1980. Lyoluminescence mechanism of gamma and additively coloured alkali halides in pure water. Journal of Luminescence 21, 305–316. https://doi.org/10.1016/0022-2313(80)90009-5
Atari, N.A., Ettinger, K.V., Fremlin, J.H., 1973. Lyoluminescence as a possible basis of radiation dosimetry. Radiation Effects 17, 45–48. https://doi.org/10.1080/00337577308232596
Bailey, R.M., Adamiec, G., Rhodes, E.J., 2000. OSL properties of NaCl relative to dating and dosimetry. Radiation Measurements 32, 717–723. https://doi.org/10.1016/S1350-4487(00)00087-1
Han, W., Ma, Z., Lai, Z., Appel, E., Fang, X., Yu, L., 2014. Wind erosion on the north‐eastern Tibetan Plateau: constraints from OSL and U‐Th dating of playa salt crust in the Qaidam Basin. Earth Surf Processes Landf 39, 779–789. https://doi.org/10.1002/esp.3483
Zhang, J.F., Yan, C., Zhou, L.P., 2005. Feasibility of optical dating using halite. Journal of Luminescence 114, 234–240. https://doi.org/10.1016/j.jlumin.2005.01.009
 

How to cite: Biernacka, M. and Kreutzer, S.: Lyoluminescence: a potential tool for dating evaporites up to the Middle-Pleistocene?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21472, https://doi.org/10.5194/egusphere-egu24-21472, 2024.

EGU24-24 | Orals | NP4.1

The fractional Sinusoidal wavefront Model (fSwp) for time series displaying persistent stationary cycles 

Gael Kermarrec, Federico Maddanu, Anna Klos, and Tommaso Proietti

In the analysis of sub-annual climatological or geodetic time series such as tide gauges, precipitable water vapor, or GNSS vertical displacements time series but also temperatures or gases concentrations, seasonal cycles are often found to have a time-varying amplitude and phase.

These time series are usually modelled with a deterministic approach that includes trend, annual, and semi-annual periodic components having constant amplitude and phase-lag. This approach can potentially lead to inadequate interpretations, such as an overestimation of Global Navigation Satellite System (GNSS) station velocity, up to masking important geophysical phenomena that are related to the amplitude variability and are important for deriving trustworthy interpretation for climate change assessment.

We address that challenge by proposing a novel linear additive model called the fractional Sinusoidal Waveform process (fSWp), accounting for possible nonstationary cyclical long memory, a stochastic trend that can evolve over time and an additional serially correlated noise capturing the short-term variability. The model has a state space representation and makes use of the Kalman filter (KF). Suitable enhancements of the basic methodology enable handling data gaps, outliers, and offsets. We demonstrate our method using various climatological and geodetic time series to illustrate its potential to capture the time-varying stochastic seasonal signals.

How to cite: Kermarrec, G., Maddanu, F., Klos, A., and Proietti, T.: The fractional Sinusoidal wavefront Model (fSwp) for time series displaying persistent stationary cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-24, https://doi.org/10.5194/egusphere-egu24-24, 2024.

On some maps of the first military survey of the Habsburg Empire, the upper direction of the sections does not face the cartographic north, but makes an angle of about 15° with it. This may be due to the fact that the sections were subsequently rotated to the magnetic north of the time. Basically, neither their projection nor their projection origin is known yet.

In my research, I am dealing with maps of Inner Austria, the Principality of Transylvania and Galicia (nowadays Poland and Ukraine), and I am trying to determine their projection origin. For this purpose, it is assumed, based on the archival documentation of the survey, that these are Cassini projection maps. My hypothesis is that they are Graz, Cluj Napoca or Alba Julia and Lviv. I also consider the position of Vienna in each case, since it was the main centre of the survey.

The angle of rotation was taken in part from the gufm1 historical magnetic model back to 1590 for the assumed starting points and year of mapping. In addition, as a theoretical case, I calculated the rotation angle of the map sections using coordinate geometry. I then calculated the longitude of the projection starting point for each case using univariate minimization. Since the method is invariant to latitude, it can only be determined from archival data.

Based on these, the starting point for Inner Austria from the rotation of the map was Vienna, which is not excluded by the archival sources, and since the baseline through Graz also started from there, it is partly logical. The map rotation for Galicia and Transylvania also confirmed the starting point of the hypothesis.  Since both Alba Julia and Cluj Napoca lie at about the same longitude, the method cannot make a difference there; and the archival data did not provide enough evidence. In comparison, the magnetic declination rotations yielded differences of about 1°, which may be due to an error in the magnetic model.

On this basis, I have given the assumed projections of the three maps with projection starting points, and developed a method for determining the projection starting points of the other rotated grid maps. The results suggest that there is a very high probability that the section network was rotated in the magnetic north direction, and thus provide a way to refine the magnetic declination data at that time.

With this method I managed to give new indirekt magnetic declinations data from Central-East Europe, which can help to improve the historical magnetic field models. The main reason for this is that we don’t have any measurement from that region.

Furthermore the difference beetwen the angle of the section north and the declination data from gufm1 always 0.8-1°. Maybe there are systematical data error at that region.

Supported by the ÚNKP-23-6 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund.

How to cite: Koszta, B. and Timár, G.: A possible cartographical data source for historical magnetic field improvement: The direction of the section north of the Habsburg first military survey, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-582, https://doi.org/10.5194/egusphere-egu24-582, 2024.

EGU24-1988 | ECS | Posters on site | NP4.1

Predictive ability assessment of Bayesian Causal Reasoning (BCR) on runoff temporal series 

Santiago Zazo, José Luis Molina, Carmen Patino-Alonso, and Fernando Espejo

The alteration of traditional hydrological patterns due to global warming is leading to a modification of the hydrological cycle. This situation draws a complex scenario for the sustainable management of water resources. However, this issue offers a challenge for the development of innovative approaches that allow an in-depth capturing the logical temporal-dependence structure of these modifications to advance sustainable management of water resources, mainly through the reliable predictive models. In this context, Bayesian Causality (BC), addressed through Causal Reasoning (CR) and supported by a Bayesian Networks (BNs), called Bayesian Causal Reasoning (BCR) is a novel hydrological research area that can help identify those temporal interactions efficiently.

This contribution aims to assesses the BCR ability to discover the logical and non-trivial temporal-dependence structure of the hydrological series, as well as its predictability. For this, a BN that conceptually synthesizes the time series is defined, and where the conditional probability is propagated over the time throughout the BN through an innovative Dependence Mitigation Graph. This is done by coupling among an autoregressive parametric approach and causal model. The analytical ability of the BCR highlighted the logical temporal structure, latent in the time series, which defines the general behavior of the runoff. This logical structure allowed to quantify, through a dependence matrix which summarizes the strength of the temporal dependencies, the two temporal fractions that compose the runoff: one due to time (Temporally Conditioned Runoff) and one not (Temporally Non-conditioned Runoff). Based on this temporal conditionality, a predictive model is implemented for each temporal fraction, and its reliability is assessed from a double probabilistic and metrological perspective.

This methodological framework is applied to two Spanish unregulated sub-basins; Voltoya river belongs to Duero River Basin, and Mijares river, in the Jucar River Basin. Both cases with a clearly opposite temporal behavior, Voltoya independent and Mijares dependent, and with increasingly more problems associated with droughts.

The findings of this study may have important implications over the knowledge of temporal behavior of water resources of river basin and their adaptation. In addition, TCR and TNCR predictive models would allow advances in the optimal dimensioning of storage infrastructures (reservoirs), with relevant substantial economic/environmental savings. Also, a more sustainable management of river basins through more reliable control reservoirs’ operation is expected to be achieved. Finally, these results open new possibilities for developing predictive hydrological models within a BCR framework.

How to cite: Zazo, S., Molina, J. L., Patino-Alonso, C., and Espejo, F.: Predictive ability assessment of Bayesian Causal Reasoning (BCR) on runoff temporal series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1988, https://doi.org/10.5194/egusphere-egu24-1988, 2024.

EGU24-3857 | ECS | Posters on site | NP4.1 | Highlight

Spatial-Temporal Analysis of Forest Mortality 

Sara Alibakhshi

Climate-induced forest mortality poses an increasing threat worldwide, which calls for developing robust approaches to generate early warning signals of upcoming forest state change. This research explores the potential of satellite imagery, utilizing advanced spatio-temporal indicators and methodologies, to assess the state of forests preceding mortality events. Traditional approaches, such as techniques based on temporal analyses, are impacted by limitations related to window size selection and detrending methods, potentially leading to false alarms. To tackle these challenges, our study introduces two new approaches, namely the Spatial-Temporal Moran (STM) and Spatial-Temporal Geary (STG) approaches, both focusing on local spatial autocorrelation measures. These approaches can effectively address the shortcomings inherent in traditional methods. The research findings were assessed across three study sites within California national parks, and Kendall's tau was employed to quantify the significance of false and positive alarms. To facilitate the measurement of ecosystem state change, trend estimation, and identification of early warning signals, this study also provides "stew" R package. The implications of this research extend to various groups, such as ecologists, conservation practitioners, and policymakers, providing them with the means to address emerging environmental challenges in global forest ecosystems.

How to cite: Alibakhshi, S.: Spatial-Temporal Analysis of Forest Mortality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3857, https://doi.org/10.5194/egusphere-egu24-3857, 2024.

Iram Parvez1, Massimiliano Cannata2, Giorgio Boni1, Rossella Bovolenta1 ,Eva Riccomagno3 , Bianca Federici1

1 Department of Civil, Chemical and Environmental Engineering (DICCA), Università degli Studi di Genova, Via Montallegro 1, 16145 Genoa, Italy (iram.parvez@edu.unige.it,bianca.federici@unige.it, giorgio.boni@unige.it, rossella.bovolenta@unige.it).

2 Institute of Earth Sciences (IST), Department for Environment Constructions and Design (DACD), University of Applied Sciences and Arts of Southern Switzerland (SUPSI), CH-6952 Canobbio, Switzerland(massimiliano.cannata@supsi.ch).

3 Department of Mathematics, Università degli Studi di Genova, Via Dodecaneso 35, 16146 Genova, Italy(riccomag@dima.unige.it).

The deployment of hydrometeorological sensors significantly contributes to generating real-time big data. The quality and reliability of large datasets pose considerable challenges, as flawed analyses and decision-making processes can result. This research aims to address the issue of anomaly detection in real-time data by exploring machine learning models. Time-series data is collected from IstSOS - Sensor Observation Service, an open-source software that stores, collects and disseminates sensor data. The methodology consists of Gated Recurrent Units based on recurrent neural networks, along with corresponding prediction intervals, applied both to individual sensors and collectively across all temperature sensors within the Ticino region of Switzerland. Additionally, non-parametric methods like Bootstrap and Mean absolute deviation are employed instead of standard prediction intervals to tackle the non-normality of the data. The results indicate that Gated Recurrent Units based on recurrent neural networks, coupled with non-parametric forecast intervals, perform well in identifying erroneous data points. The application of the model on multivariate time series-sensor data establishes a pattern or baseline of normal behavior for the area (Ticino). When a new sensor is installed in the same region, the recognized pattern is used as a reference to identify outliers in the data gathered from the new sensor.

How to cite: Parvez, I.: Exploring Machine Learning Models to Detect Outliers in HydroMet Sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4280, https://doi.org/10.5194/egusphere-egu24-4280, 2024.

EGU24-5268 | ECS | Orals | NP4.1

Unveiling Geological Patterns: Bayesian Exploration of Zircon-Derived Time Series Data 

Hang Qian, Meng Tian, and Nan Zhang

For its immunity to post-formation geological modifications, zircon is widely utilized as chronological time capsule and provides critical time series data potential to unravel key events in Earth’s geological history, such as supercontinent cycles. Fourier analysis, which assumes stationary periodicity, has been applied to zircon-derived time series data to find the cyclicity of supercontinents, and wavelet analysis, which assumes non-stationary periodicity, corroborates the results of Fourier Analysis in addition to detecting finer-scale signals. Nonetheless, both methods still prognostically assume periodicity in the zircon-derived time-domain data. To stay away from the periodicity assumption and extract more objective information from zircon data, we opt for a Bayesian approach and treat zircon preservation as a composite stochastic process where the number of preserved zircon grains per magmatic event obeys logarithmic series distribution and the number of magmatic events during a geological time interval obeys Poisson distribution. An analytical solution was found to allow us to efficiently invert for the number and distribution(s) of changepoints hidden in the globally compiled zircon data, as well as for the zircon preservation potential (encoded as a model parameter) between two neighboring changepoints. If the distributions of changepoints temporally overlap with those of known supercontinents, then our results serve as an independent, mathematically robust test of the cyclicity of supercontinents. Moreover, our statistical approach inherently provides a sensitivity parameter the tuning of which allows to probe changepoints at various temporal resolution. The constructed Bayesian framework is thus of significant potential to detect other types of trend swings in Earth’s history, such as shift of geodynamic regimes, moving beyond cyclicity detection which limits the application of conventional Fourier/Wavelet analysis.

How to cite: Qian, H., Tian, M., and Zhang, N.: Unveiling Geological Patterns: Bayesian Exploration of Zircon-Derived Time Series Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5268, https://doi.org/10.5194/egusphere-egu24-5268, 2024.

Semi-enclosed freshwater and brackish ecosystems, characterised by restricted water outflow and prolonged residence times, often accumulate nutrients, influencing their productivity and ecological dynamics. These ecosystems exhibit significant variations in bio-physical-chemical attributes, ecological importance, and susceptibility to human impacts. Untangling the complexities of their interactions remains challenging, necessitating a deeper understanding of effective management strategies adapted to their vulnerabilities. This research focuses on the bio-physical aspects, investigating the differential effects of spring and summer light on phytoplankton communities in semi-enclosed freshwater and brackish aquatic ecosystems.

Through extensive field sampling and comprehensive environmental parameter analysis, we explore how phytoplankton respond to varying light conditions in these distinct environments. Sampling campaigns were conducted at Müggelsee, a freshwater lake on Berlin's eastern edge, and Barther Bodden, a coastal lagoon northeast of Rostock on the German Baltic Sea coast, during the springs and summers of 2022 and 2023, respectively. Our analysis integrates environmental factors such as surface light intensity, diffuse attenuation coefficients, nutrient availability, water column dynamics, meteorological data, Chlorophyll-a concentration, and phytoplankton communities. Sampling encompassed multiple depths at continuous intervals lasting three days.

Preliminary findings underscore significant differences in seasonal light availability, with summer exhibiting extended periods of substantial light penetration. These variations seem to impact phytoplankton abundance and diversity uniquely in each ecosystem. While ongoing analyses are underway, early indications suggest distinct phytoplankton responses in terms of species composition and community structure, influenced by the changing light levels. In 2022 the clear water phase during spring indicated that bloom events have occurred under ice cover much earlier than spring, while in the summer there were weak and short-lived blooms of cyanobacteria. The relationship between nutrient availability and phytoplankton dynamics, however, remains uncertain according to our data.

This ongoing study contributes to understanding the role of light as a primary driver shaping phytoplankton community structures and dynamics in these environments.  Our research findings offer insights for refining predictive models, aiding in ecosystem-specific eutrophication management strategies, and supporting monitoring efforts of Harmful Algal Blooms.

How to cite: Kaharuddin, A. and Kaligatla, R.: Comparative Study of Spring and Summer Light Effects on Phytoplankton Communities in Semi-Enclosed Fresh- and Brackish Aquatic Ecosystems., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5733, https://doi.org/10.5194/egusphere-egu24-5733, 2024.

EGU24-6065 | ECS | Orals | NP4.1

Magnetospheric time history:  How much do we need for forecasting? 

Kendra R. Gilmore, Sarah N. Bentley, and Andy W. Smith

Forecasting the aurora and its location accurately is important to mitigate any potential harm to vital infrastructure like communications and electricity grid networks. Current auroral prediction models rely on our understanding of the interaction between the magnetosphere and the solar wind or geomagnetic indices. Both approaches do well in predicting but have limitations concerning forecasting (geomagnetic indices-based model) or because of the underlying assumptions driving the model (due to a simplification of the complex interaction). By applying machine learning algorithms to this problem, gaps in our understanding can be identified, investigated, and closed. Finding the important time scales for driving empirical models provides the necessary basis for our long-term goal of predicting the aurora using machine learning.

Periodicities of the Earth’s magnetic field have been extensively studied on a global scale or in regional case studies. Using a suite of different time series analysis techniques including frequency analysis and investigation of long-scale changes of the median/ mean, we examine the dominant periodicities of ground magnetic field measurements at selected locations. A selected number of stations from the SuperMAG network (Gjerloev, 2012), which is a global network of magnetometer stations across the world, are the focus of this investigation.

The periodicities retrieved from the different magnetic field components are compared to each other as well as to other locations. In the context of auroral predictions, an analysis of the dominating periodicities in the auroral boundary data derived from the IMAGE satellite (Chisham et al., 2022) provides a counterpart to the magnetic field periodicities.

Ultimately, we can constrain the length of time history sensible for forecasting.

How to cite: Gilmore, K. R., Bentley, S. N., and Smith, A. W.: Magnetospheric time history:  How much do we need for forecasting?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6065, https://doi.org/10.5194/egusphere-egu24-6065, 2024.

EGU24-6151 | Posters on site | NP4.1

Using information-theory metrics to detect regime changes in dynamical systems 

Javier Amezcua and Nachiketa Chakraborty

Dynamical systems can display a range of dynamical regimes (e.g. attraction to, fixed points, limit cycles, intermittency, chaotic behaviour) depending on the values of parameters in the system. In this work we demonstrate how non-parametric entropy estimation codes (in particular NPEET) based on the Kraskov method can be applied to find regime transitions in a 3D chaotic model (the Lorenz 1963 system) when varying the values of the parameters. These infromation-theory-based methods are simpler and cheaper to apply than more traditional metrics from dynamical systems (e.g. computation of Lyapunov exponents). The non-parametric nature of the method allows for handling long time series without a prohibitive computational burden. 

How to cite: Amezcua, J. and Chakraborty, N.: Using information-theory metrics to detect regime changes in dynamical systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6151, https://doi.org/10.5194/egusphere-egu24-6151, 2024.

EGU24-9367 | ECS | Orals | NP4.1

Fractal complexity evaluation of meteorological droughts over three Indian subdivisions using visibility Graphs 

Susan Mariam Rajesh, Muraleekrishnan Bahuleyan, Arathy Nair GR, and Adarsh Sankaran

Evaluation of scaling properties and fractal formalisms is one of the potential approaches for modelling complex series. Understanding the complexity and fractal characterization of drought index time series is essential for better preparedness against drought disasters. This study presents a novel visibility graph-based evaluation of fractal characterization of droughts of three meteorological subdivisions of India. In this method, the horizontal visibility graph (HVG) and Upside-down visibility graph (UDVG) are used for evaluating the network properties for different standardized precipitation index (SPI) series of 3, 6 and 12 month time scales representing short, medium and long term droughts. The relative magnitude of fractal estimates is controlled by the drought characteristics of wet-dry transitions. The estimates of degree distribution clearly deciphered the self-similar properties of droughts of all the subdivisions. For an insightful depiction of drought dynamics, the fractal exponents and spectrum are evaluated by the concurrent application of Sand Box Method (SBM) and Chhabra and Jenson Method (CJM). The analysis was performed for overall series along with the pre- and post-1976-77 Global climate shift scenarios. The complexity is more evident in short term drought series and UDVG formulations implied higher fractal exponents for different moment orders irrespective of drought type and locations considered in this study. Useful insights on the relationship between complex network and fractality are evolved from the study, which may help in improved drought forecasting. The visibility graph based fractality estimation evaluation is efficient in capturing drought and it has vast potential in the drought predictions in a changing environment.

Keywords:  Drought, Fractal, SPI, Visibility Graph

How to cite: Rajesh, S. M., Bahuleyan, M., Nair GR, A., and Sankaran, A.: Fractal complexity evaluation of meteorological droughts over three Indian subdivisions using visibility Graphs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9367, https://doi.org/10.5194/egusphere-egu24-9367, 2024.

EGU24-9537 | Posters on site | NP4.1

Wavelet-Induced Mode Extraction procedure: Application to climatic data 

Elise Faulx, Xavier Fettweis, Georges Mabille, and Samuel Nicolay

The Wavelet-Induced Mode Extraction procedure (WIME) [2] was developed drawing inspiration from Empirical Mode Decomposition. The concept involves decomposing the signal into modes, each presenting a characteristic frequency, using continuous wavelet transform. This method has yielded intriguing results in climatology [3,4]. However, the initial algorithm did not account for the potential existence of slight frequency fluctuations within a mode, which could impact the reconstruction of the original signal [4]. The new version (https://atoms.scilab.org/toolboxes/toolbox_WIME/0.1.0) now allows for the evolution of a mode in the space-frequency half-plane, thus considering the frequency evolution of a mode [2]. A natural application of this tool is in the analysis of Milankovitch cycles, where subtle changes have been observed throughout history. The method also refines the study of solar activity, highlighting the role of the "Solar Flip-Flop." Additionally, the examination of temperature time series confirms the existence of cycles around 2.5 years. It is now possible to attempt to correlate solar activity with this observed temperature cycle, as seen in speleothem records [1].

[1] Allan, M., Deliège, A., Verheyden, S., Nicolay S. and Fagel, N. Evidence for solar influence in a Holocene speleothem record, Quaternary Science Reviews, 2018.
[2] Deliège, A. and Nicolay, S., Extracting oscillating components from nonstationary time series: A wavelet-induced method, Physical Review. E, 2017.
[3] Nicolay, S., Mabille, G., Fettweis, X. and Erpicum, M., A statistical validation for the cycles found in air temperature data using a Morlet wavelet-based method, Nonlinear Processes in Geophysics, 2010.
[4] Nicolay, S., Mabille, G., Fettweis, X. and Erpicum, M., 30 and 43 months period cycles found in air temperature time series using the Morlet wavelet, Climate Dynamics, 2009.

How to cite: Faulx, E., Fettweis, X., Mabille, G., and Nicolay, S.: Wavelet-Induced Mode Extraction procedure: Application to climatic data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9537, https://doi.org/10.5194/egusphere-egu24-9537, 2024.

EGU24-10258 | Orals | NP4.1

New concepts on quantifying event data 

Norbert Marwan and Tobias Braun

A wide range of geoprocesses manifest as observable events in a variety of contexts, including shifts in palaeoclimate regimes, evolutionary milestones, tectonic activities, and more. Many prominent research questions, such as synchronisation analysis or power spectrum estimation of discrete data, pose considerable challenges to linear tools. We present recent advances using a specific similarity measure for discrete data and the method of recurrence plots for different applications in the field of highly discrete event data. We illustrate their potential for palaeoclimate studies, particularly in detecting synchronisation between signals of discrete extreme events and continuous signals, estimating power spectra of spiky signals, and analysing data with irregular sampling.

How to cite: Marwan, N. and Braun, T.: New concepts on quantifying event data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10258, https://doi.org/10.5194/egusphere-egu24-10258, 2024.

EGU24-10415 | ECS | Orals | NP4.1

Application of Transfer Learning techniques in one day ahead PV production prediction 

Marek Lóderer, Michal Sandanus, Peter Pavlík, and Viera Rozinajová

Nowadays photovoltaic panels are becoming more affordable, efficient, and popular due to their low carbon footprint. PV panels can be installed in many places providing green energy to the local grid reducing energy cost and transmission losses. Since the PV production is highly dependent on the weather conditions, it is extremely important to estimate expected output in advance in order to maintain energy balance in the grid and provide enough time to schedule load distribution. The PV production output can be calculated by various statistical and machine learning prediction methods. In general, the more data available, the more precise predictions can be produced. This poses a problem for recently installed PV panels for which not enough data has been collected or the collected data are incomplete. 

A possible solution to the problem can be the application of an approach called Transfer Learning which has the inherent ability to effectively deal with missing or insufficient amounts of data. Basically, Transfer Learning is a machine learning approach which offers the capability of transferring knowledge acquired from the source domain (in our case a PV panel with a large amount of historical data) to different target domains (PV panels with very little collected historical data) to resolve related problems (provide reliable PV production predictions). 

In our study, we investigate the application, benefits and drawbacks of Transfer Learning for one day ahead PV production prediction. The model used in the study is based on complex neural network architecture, feature engineering and data selection. Moreover, we focus on the exploration of multiple approaches of adjusting weights in the target model retraining process which affect the minimum amount of training data required, final prediction accuracy and model’s overall robustness. Our models use historical meteorological forecasts from Deutscher Wetterdienst (DWD) and photovoltaic measurements from the project PVOutput which collects data from installed solar systems across the globe. Evaluation is performed on more than 100 installed PV panels in Central Europe.

How to cite: Lóderer, M., Sandanus, M., Pavlík, P., and Rozinajová, V.: Application of Transfer Learning techniques in one day ahead PV production prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10415, https://doi.org/10.5194/egusphere-egu24-10415, 2024.

EGU24-11897 | Posters on site | NP4.1

Results of joint processing of magnetic observatory data of international Intermagnet network in a unified coordinate system 

Beibit Zhumabayev, Ivan Vassilyev, Zhasulan Mendakulov, Inna Fedulina, and Vitaliy Kapytin

In each magnetic observatory, the magnetic field is registered in local Cartesian coordinate systems associated with the geographic coordinates of the locations of these observatories. To observe extraterrestrial magnetic field sources, such as the interplanetary magnetic field or magnetic clouds, a method of joint processing of data from magnetic observatories of the international Intermagnet network was implemented. In this method, the constant component is removed from the observation results of individual observatories, their measurement data is converted into the ecliptic coordinate system, and the results obtained from all observatories are averaged after the coordinate transformation.

The first data on joint processing of measurement results from the international network of Intermagnet magnetic observatories in the period before the onset of magnetic storms of various types, during these storms and after their end are presented. There is a significant improvement in the signal-to-noise ratio after combining the measurement results from all observatories, which makes it possible to isolate weaker external magnetic fields. A change in the shape of magnetic field variations is shown, which can provide new knowledge about the mechanism of development of magnetic storms.

How to cite: Zhumabayev, B., Vassilyev, I., Mendakulov, Z., Fedulina, I., and Kapytin, V.: Results of joint processing of magnetic observatory data of international Intermagnet network in a unified coordinate system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11897, https://doi.org/10.5194/egusphere-egu24-11897, 2024.

We introduce the CLEAN algorithm to identify narrowband Ultra Low Frequency (ULF) Pc5 plasma waves in Earth’s magnetosphere. The CLEAN method was first used for constructing 2D images in astronomical radio interferometry but has since been applied to a huge range of areas including adaptation for time series analysis. The algorithm performs a nonlinear deconvolution in the frequency domain (equivalent to a least-squares in the time domain) allowing for identification of multiple individual wave spectral peaks within the same power spectral density. The CLEAN method also produces real amplitudes instead of model fits to the peaks and retains phase information. We applied the method to GOES magnetometer data spanning 30 years to study the distribution of narrowband Pc5 ULF waves at geosynchronous orbit. We found close to 30,0000 wave events in each of the vector magnetic field components in field-aligned coordinates. We discuss wave occurrence and amplitudes distributed in local time and frequency. The distribution of the waves under different solar wind conditions are also presented. With some precautions, which are applicable to other event identification methods, the CLEAN technique can be utilized to detect wave events and its harmonics in the magnetosphere and beyond. We also discuss limitations of the method mainly the detection of unrealistic peaks due to aliasing and Gibbs phenomena.

How to cite: Inceoglu, F. and Loto'aniu, P.: Using the CLEAN Algorithm to Determine the Distribution of Ultra Low Frequency Waves at Geostationary Orbit, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12928, https://doi.org/10.5194/egusphere-egu24-12928, 2024.

EGU24-12938 | Posters on site | NP4.1

Applying Multifractal Theory and Statistical Techniques for High Energy Volcanic Explosion Detection and Seismic Activity Monitoring in Volcanic Time Series 

Marisol Monterrubio-Velasco, Xavier Lana, Raúl Arámbula-Mendoza, and Ramón Zúñiga

Understanding volcanic activity through time series data analysis is crucial for uncovering the fundamental physical mechanisms governing this natural phenomenon.

In this study, we show the application of multifractal and fractal methodologies, along with statistical analysis, to investigate time series associated with volcanic activity. We aim to make use of these approaches to identify significant variations within the physical processes related to changes in volcanic activity. These methodologies offer the potential to identify pertinent changes preceding a high-energy explosion or a significant volcanic eruption.

In particular, we apply it to analyze two study cases. First, the evolution of the multifractal structure of volcanic emissions of low, moderate, and high energy explosions applied to Volcán de Colima (México years 2013-2015). The results contribute to obtaining quite evident signs of the immediacy of possible dangerous emissions of high energy, close to 8.0x10^8 J. Additionally, the evolution of the adapted Gutenberg-Richter seismic law to volcanic energy emissions contributes to confirm the results obtained using multifractal analysis. Secondly, we also studied the time series of the Gutenberg-Richter b-parameter of seismic activities associated with volcanic emissions in Iceland, Hawaii, and the Canary Islands, through the concept of Disparity (degree of irregularity), the fractal Hurst exponent, H, and several multifractal parameters. The results obtained should facilitate a better knowledge of the relationships between the activity of volcanic emissions and the corresponding related seismic activities.  

How to cite: Monterrubio-Velasco, M., Lana, X., Arámbula-Mendoza, R., and Zúñiga, R.: Applying Multifractal Theory and Statistical Techniques for High Energy Volcanic Explosion Detection and Seismic Activity Monitoring in Volcanic Time Series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12938, https://doi.org/10.5194/egusphere-egu24-12938, 2024.

EGU24-13593 | ECS | Posters on site | NP4.1

Characterizing Uncertainty in Spatially Interpolated Time Series of Near-Surface Air Temperature 

Conor Doherty and Weile Wang

Spatially interpolated meteorological data products are widely used in the geosciences as well as disciplines like epidemiology, economics, and others. Recent work has examined methods for quantifying uncertainty in gridded estimates of near-surface air temperature that produce distributions rather than simply point estimates at each location. However, meteorological variables are correlated not only in space but in time, and sampling without accounting for temporal autocorrelation produces unrealistic time series and potentially underestimates cumulative errors. This work first examines how uncertainty in air temperature estimates varies in time, both seasonally and at shorter timescales. It then uses data-driven, spectral, and statistical methods to better characterize uncertainty in time series of estimated air temperature values. Methods for sampling that reproduce spatial and temporal autocorrelation are presented and evaluated. The results of this work are particularly relevant to domains like agricultural and ecology. Physical processes including evapotranspiration and primary production are sensitive to variables like near-surface air temperature, and errors in these important meteorological inputs accumulate in model outputs over time.

How to cite: Doherty, C. and Wang, W.: Characterizing Uncertainty in Spatially Interpolated Time Series of Near-Surface Air Temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13593, https://doi.org/10.5194/egusphere-egu24-13593, 2024.

EGU24-13879 | ECS | Posters on site | NP4.1

Understanding the role of vegetation responses to drought in regulating autumn senescence 

Eunhye Choi and Josh Gray

Vegetation phenology is the recurring of plant growth, including the cessation and resumption of growth, and plays a significant role in shaping terrestrial water, nutrient, and carbon cycles. Changes in temperature and precipitation have already induced phenological changes around the globe, and these trends are likely to continue or even accelerate. While warming has advanced spring arrival in many places, the effects on autumn phenology are less clear-cut, with evidence for earlier, delayed, or even unchanged end of the growing season (EOS). Meteorological droughts are intensifying in duration and frequency because of climate change. Droughts intricately impact changes in vegetation, contingent upon whether the ecosystem is limited by water or energy. These droughts have the potential to influence EOS changes. Despite this, the influence of drought on EOS remains largely unexplored. This study examined moisture’s role in controlling EOS by understanding the relationship between precipitation anomalies, vegetation’s sensitivity to precipitation (SPPT), and EOS. We also assess regional variations in responses to the impact of SPPT on EOS.

The study utilized multiple vegetation and water satellite products to examine the patterns of SPPT in drought and its impact on EOS across aridity gradients and vegetation types. By collectively evaluating diverse SPPTs from various satellite datasets, this work offers a comprehensive understanding and critical basis for assessing the impact of drought on EOS. We focused on the Northern Hemisphere from 2000 to 2020, employing robust statistical methods. This work found that, in many places, there was a stronger relationship between EOS and drought in areas with higher SPPT. Additionally, a non-linear negative relationship was identified between EOS and SPPT in drier regions, contracting with a non-linear positive relationship observed in wetter regions. These findings were consistent across a range of satellite-derived vegetation products. Our findings provide valuable insights into the effects of SPPT on EOS during drought, enhancing our understanding of vegetation responses to drought and its consequences on EOS and aiding in identifying drought-vulnerable areas.

How to cite: Choi, E. and Gray, J.: Understanding the role of vegetation responses to drought in regulating autumn senescence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13879, https://doi.org/10.5194/egusphere-egu24-13879, 2024.

EGU24-16981 | ECS | Orals | NP4.1

A machine-learning-based approach for predicting the geomagnetic secular variation 

Sho Sato and Hiroaki Toh

We present a machine-learning-based approach for predicting the geomagnetic main field changes, known as secular variation (SV), in a 5-year range for use for the 14th generation of International Geomagnetic Reference Field (IGRF-14). The training and test datasets of the machine learning (ML) models are geomagnetic field snapshots derived from magnetic observatory hourly means, and CHAMP and Swarm-A satellite data (MCM Model; Ropp et al., 2020). The geomagnetic field data are not used as-is in the original time series but were differenced twice before training. Because SV is strongly influenced by the geodynamo process occurring in the Earth's outer core, challenges still persist despite efforts to model and forecast the realistic nonlinear behaviors (such as the geomagnetic jerks) of the geodynamo through data assimilation. We compare three physics-uninformed ML models, namely, the Autoregressive (AR) model, Vector Autoregressive (VAR) model, and Recurrent Neural Network (RNN) model, to represent the short-term temporal evolution of the geomagnetic main field on the Earth’s surface. The quality of 5-year predictions is tested by the hindcast results for the learning window from 2004.50 to 2014.25. These tests show that the forecast performance of our ML model is comparable with that of candidate models of IGRF-13 in terms of data misfits after the release epoch (Year 2014.75). It is found that all three ML models give 5-year prediction errors of less than 100nT, among which the RNN model shows a slightly better accuracy. They also suggest that Overfitting to the training data used is an undesirable machine learning behavior that occurs when the RNN model gives accurate reproduction of training data but not for forecasting targets.

How to cite: Sato, S. and Toh, H.: A machine-learning-based approach for predicting the geomagnetic secular variation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16981, https://doi.org/10.5194/egusphere-egu24-16981, 2024.

EGU24-17344 | Posters on site | NP4.1

Introducing a new statistical theory to quantify the Gaussianity of the continuous seismic signal 

Éric Beucler, Mickaël Bonnin, and Arthur Cuvier

The quality of the seismic signal recorded at permanent and temporary stations is sometimes degraded, either abruptly or over time. The most likely cause is a high level of humidity, leading to corrosion of the connectors but environmental changes can also alter recording conditions in various frequency ranges and not necessarily for all three components in the same way. Assuming that the continuous seismic signal can be described by a normal distribution, we present a new approach to quantify the seismogram quality and to point out any time sample that deviates from this Gaussian assumption. To this end the notion of background Gaussian signal (BGS) to statistically describe a set of samples that follows a normal distribution. The discrete function obtained by sorting the samples in ascending order of amplitudes is compared to a modified probit function to retrieve the elements composing the BGS, and its statistical properties, mostly the Gaussian standard deviation, which can then differ from the classical standard deviation. Hence the ratio of both standard deviations directly quantifies the dominant gaussianity of the continuous signal and any variation reflects a statistical modification of the signal quality. We present examples showing daily variations in this ratio for stations known to have been affected by humidity, resulting in signal degradation. The theory developed can be used to detect subtle variations in the Gaussianity of the signal, but also to point out any samples that don't match the Gaussianity assumption, which can then be used for other seismological purposes, such as coda determination.

How to cite: Beucler, É., Bonnin, M., and Cuvier, A.: Introducing a new statistical theory to quantify the Gaussianity of the continuous seismic signal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17344, https://doi.org/10.5194/egusphere-egu24-17344, 2024.

EGU24-17566 | ECS | Posters on site | NP4.1

Unveiling Climate-Induced Ocean Wave Activities Using Seismic Array Data in the North Sea Region 

Yichen Zhong, Chen Gu, Michael Fehler, German Prieto, Peng Wu, Zhi Yuan, Zhuoyu Chen, and Borui Kang

Climate events may induce abnormal ocean wave activities, that can be detected by seismic array on nearby coastlines. We collected long-term continuous array seismic data in the Groningen area and the coastal areas of the North Sea, conducted a comprehensive analysis to extract valuable climate information hidden within the ambient noise. Through long-term spectral analysis, we identified the frequency band ranging from approximately 0.2Hz, which appears to be associated with swell waves within the region, exhibiting a strong correlation with the significant wave height (SWH). Additionally, the wind waves with a frequency of approximately 0.4 Hz and gravity waves with periods exceeding 100 seconds were detected from the seismic ambient noise. We performed a correlation analysis between the ambient noise and various climatic indexes across different frequency bands. The results revealed a significant correlation between the North Atlantic Oscillation (NAO) Index and the ambient noise around 0.17Hz.

Subsequently, we extracted the annual variation curves of SWH frequency from ambient noise at each station around the North Sea and assembled them into a sparse spatial grid time series (SGTS). An empirical orthogonal function (EOF) analysis was conducted, and the Principal Component (PC) time series derived from the EOF analysis were subjected to a correlation analysis with the WAVEWATCH III (WW3) model simulation data, thereby confirming the wave patterns. Moreover, we conducted the spatial distribution study of SGTS. The spatial features revealed that the southern regions of the North Sea exhibit higher wind-wave energy components influenced by the Icelandic Low pressure system and topography, which explains the correlation between ambient noise in the region and the NAO index. Furthermore, spatial features disclosed a correlation between the first EOF mode of the North Sea ocean waves and the third mode of sea surface temperature anomalies. This research shows the potential of utilizing existing off-shore seismic monitoring systems to study global climate variation and physical oceanography.

How to cite: Zhong, Y., Gu, C., Fehler, M., Prieto, G., Wu, P., Yuan, Z., Chen, Z., and Kang, B.: Unveiling Climate-Induced Ocean Wave Activities Using Seismic Array Data in the North Sea Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17566, https://doi.org/10.5194/egusphere-egu24-17566, 2024.

EGU24-18061 | ECS | Orals | NP4.1

A new methodology for time-series reconstruction of global scale historical Earth observation data 

Davide Consoli, Leandro Parente, and Martijn Witjes

Several machine learning algorithms and analytical techniques do not allow gaps or non-values in input data. Unfortunately, earth observation (EO) datasets, such as satellite images, are gravely affected by cloud contamination and sensor artifacts that create gaps in the time series of collected images. This limits the usage of several powerful techniques for modeling and analysis. To overcome these limitations, several works in literature propose different imputation methods to reconstruct the gappy time series of images, providing complete time-space datasets and enabling their usage as input for many techniques.

However, among the time-series reconstruction methods available in literature, only a few of them are publicly available (open source code), applicable without any external source of data, and suitable for application to petabyte (PB) sized dataset like the full Landsat archive. The few methods that match all these characteristics are usually quite trivial (e.g. linear interpolation) and, as a consequence, they often show poor performance in reconstructing the images. 

For this reason, we propose a new methodology for time series reconstruction designed to match all these requirements. Like some other methods in literature, the new method, named seasonally weighted average generalization (SWAG), works purely on the time dimension, reconstructing the images working on each time series of each pixel separately. In particular, the method uses a weighted average of the samples available in the original time series to reconstruct the missing values. Enforcing the annual seasonality of each band as a prior, for the reconstruction of each missing sample in the time series a higher weight is given to images that are collected exactly on integer multiples of a year. To avoid propagation of land cover changes in future or past images, higher weights are given to more recent images. Finally, to have a method that respects causality, only images from the past of each sample in the time series are used.

To have computational performance suitable for PB sized datasets the method has been implemented in C++ using a sequence of fast convolution methods and Hadamard products and divisions. The method has been applied to a bimonthly aggregated version of the global GLAD Landsat ARD-2 collection from 1997 to 2022, producing a 400 terabyte output dataset. The produced dataset will be used to generate maps for several biophysical parameters, such as Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), normalized difference water index (NDWI) and bare soil fraction (BSF). The code is available as open source, and the result is fully reproducible.

References:

Potapov, Hansen, Kommareddy, Kommareddy, Turubanova, Pickens, ... & Ying  (2020). Landsat analysis ready data for global land cover and land cover change mapping. Remote Sensing, 12(3), 426.

Julien, & Sobrino (2019). Optimizing and comparing gap-filling techniques using simulated NDVI time series from remotely sensed global data. International Journal of Applied Earth Observation and Geoinformation, 76, 93-111.

Radeloff, Roy, Wulder, Anderson, Cook, Crawford, ... & Zhu (2024). Need and vision for global medium-resolution Landsat and Sentinel-2 data products. Remote Sensing of Environment, 300, 113918.

How to cite: Consoli, D., Parente, L., and Witjes, M.: A new methodology for time-series reconstruction of global scale historical Earth observation data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18061, https://doi.org/10.5194/egusphere-egu24-18061, 2024.

EGU24-18197 | ECS | Orals | NP4.1 | Highlight

The regularity of climate-related extreme events under global warming 

Karim Zantout, Katja Frieler, and Jacob Schewe and the ISIMIP team

Climate variability gives rise to many different kinds of extreme impact events, including heat waves, crop failures, or wildfires. The frequency and magnitude of such events are changing under global warming. However, it is less known to what extent such events occur with some regularity, and whether this regularity is also changing as a result of climate change. Here, we present a novel method to systematically study the time-autocorrelation of these extreme impact events, that is, whether they occur with a certain regularity. In studies of climate change impacts, different types of events are often studied in isolation, but in reality they interact. We use ensembles of global biophysical impact simulations from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) driven with climate models to assess current conditions and projections. The time series analysis is based on a discrete Fourier transformation that accounts for the stochastic fluctuations from the climate model. Our results show that some climate impacts, such as crop failure, indeed exhibit a dominant frequency of recurrence; and also, that these regularity patterns change over time due to anthropogenic climate forcing.

How to cite: Zantout, K., Frieler, K., and Schewe, J. and the ISIMIP team: The regularity of climate-related extreme events under global warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18197, https://doi.org/10.5194/egusphere-egu24-18197, 2024.

EGU24-18210 | ECS | Posters on site | NP4.1

Long-term vegetation development in context of morphodynamic processes since mid-19th century 

Katharina Ramskogler, Moritz Altmann, Sebastian Mikolka-Flöry, and Erich Tasser

The availability of comprehensive aerial photography is limited to the mid-20th century, posing a challenge for quantitatively analyzing long-term surface changes in proglacial areas. This creates a gap of approximately 100 years, spanning the end of the Little Ice Age (LIA). Employing digital monoplotting and historical terrestrial images, our study reveals quantitative surface changes in a LIA lateral moraine section dating back to the second half of the 19th century, encompassing a total study period of 130 years (1890 to 2020). With the long-term analysis at the steep lateral moraines of Gepatschferner (Kauner Valley, Tyrol, Austria) we aimed to identify changes in vegetation development in context with morphodynamic processes and the changing climate.

In 1953, there was an expansion in the area covered by vegetation, notably encompassing scree communities, alpine grassland, and dwarf shrubs. However, the destabilization of the system after 1980, triggered by rising temperatures and the resulting thawing of permafrost, led to a decline in vegetation cover by 2020. Notably, our observations indicated that, in addition to morphodynamic processes, the overarching trends in temperature and precipitation exerted a substantial influence on vegetation development. Furthermore, areas with robust vegetation cover, once stabilised, were reactivated and subjected to erosion, possibly attributed to rising temperatures post-1980.

This study demonstrates the capability of historical terrestrial images to enhance the reconstruction of vegetation development in context with morphodynamics in high alpine environments within the context of climate change. However, it is important to note that long-term mapping of vegetation development through digital monoplotting has limitations, contingent on the accessibility and quality of historical terrestrial images, as well as the challenges posed by shadows in high alpine regions. Despite these limitations, this long-term approach offers fundamental data on vegetation development for future modelling efforts.

How to cite: Ramskogler, K., Altmann, M., Mikolka-Flöry, S., and Tasser, E.: Long-term vegetation development in context of morphodynamic processes since mid-19th century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18210, https://doi.org/10.5194/egusphere-egu24-18210, 2024.

EGU24-19601 | ECS | Posters on site | NP4.1

Discrimination of  geomagnetic quasi-periodic signals by using SSA Transform 

Palangio Paolo Giovanni and Santarelli Lucia

Discrimination of  geomagnetic quasi-periodic signals by using SSA Transform

  • Palangio1, L. Santarelli 1

1Istituto Nazionale di Geofisica e Vulcanologia L’Aquila

3Istituto Nazionale di Geofisica e Vulcanologia Roma

 

Correspondence to:  lucia.santarelli@ingv.it

 

Abstract

In this paper we present an application of  the SSA Transform to the detection and reconstruction of  very weak geomagnetic signals hidden in noise. In the SSA Transform  multiple subspaces are used for representing and reconstructing   signals and noise.  This analysis allows us to reconstruct, in the time domain, the different harmonic components contained in the original signal by using  ortogonal functions. The objective is to identificate the dominant  subspaces that can be attributed to the  signals and the subspaces that can be attributed to the noise,  assuming that all these  subspaces are orthogonal to each other, which implies that the  signals and noise  are independent of one another. The subspace of the signals is mapped simultaneously on several spaces with a lower dimension, favoring the dimensions that best discriminate the patterns. Each subspace of the signal space is used to encode different subsets of functions having common characteristics, such as  the same periodicities. The subspaces  identification was performed by using singular value decomposition (SVD) techniques,  known as  SVD-based identification methods  classified in a subspace-oriented scheme.The  quasi-periodic variations of geomagnetic field  has been investigated in the range of scale which span from 22 years to 8.9 days such as the  Sun’s polarity reversal cycle (22 years), sun-spot cycle (11 years), equinoctial effect (6 months), synodic rotation of the Sun (27 days) and its harmonics. The strength of these signals vary from fractions of a nT to tens of nT. Phase and frequency variability of these cycles has been evaluated from the range of variations in the geomagnetic field recorded at middle latitude place (covering roughly 4.5 sunspot cycles). Magnetic data recorded at L'Aquila Geomagnetic observatory (geographic coordinates: 42° 23’ N, 13° 19’E, geomagnetic coordinates: 36.3° N,87°.2 E, L-shell=1.6) are used from 1960 to 2009.

 

 

How to cite: Paolo Giovanni, P. and Lucia, S.: Discrimination of  geomagnetic quasi-periodic signals by using SSA Transform, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19601, https://doi.org/10.5194/egusphere-egu24-19601, 2024.

EGU24-22262 | ECS | Posters on site | NP4.1

Temporal Interpolation of Sentinel-2 Multispectral Time Series in Context of Land Cover Classification with Machine Learning Algorithms 

Mate Simon, Mátyás Richter-Cserey, Vivien Pacskó, and Dániel Kristóf

Over the past decades, especially since 2014, large quantities of Earth Observation (EO) data became available in high spatial and temporal resolution, thanks to ever-developing constellations (e.g.: Sentinel, Landsat) and open data policy. However, in the case of optical images, affected by cloud coverage and the spatially changing overlap of relative satellite orbits, creating temporally generalized and dense time series by using only measured data is challenging, especially when studying larger areas.

Several papers investigate the question of spatio-temporal gap filling and show different interpolation methods to calculate missing values corresponding to the measurements. In the past years more products and technologies have been constructed and published in this field, for example Copernicus HR-VPP Seasonal Trajectories (ST) product.  These generalized data structures are essential to the comparative analysis of different time periods or areas and improve the reliability of data analyzing methods such as Fourier transform or correlation. Temporally harmonized input data is also necessary in order to improve the results of Machine Learning classification algorithms such as Random Forest or Convolutional Neural Networks (CNN). These are among the most efficient methods to separate land cover categories like arable lands, forests, grasslands and built-up areas, or crop types within the arable category.

This study analyzes the efficiency of different interpolation methods on Sentinel-2 multispectral time series in the context of land cover classification with Machine Learning. We compare several types of interpolation e.g. linear, cubic and cubic-spline and also examine and optimize more advanced methods like Inverse Distance Weighted (IDW) and Radial Basis Function (RBF). We quantify the accuracy of each method by calculating mean square error between measured and interpolated data points. The role of interpolation of the input dataset in Deep Learning (CNN) is investigated by comparing Overall, Kappa and categorical accuracies of land cover maps created from only measured and interpolated time series. First results show that interpolation has a relevant positive effect on accuracy statistics. This method is also essential in taking a step towards constructing robust pretrained Deep Learning models, transferable between different time intervals and agro-ecological regions.

The research has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2021 funding scheme.

 

Keywords: time series analysis, Machine Learning, interpolation, Sentinel

How to cite: Simon, M., Richter-Cserey, M., Pacskó, V., and Kristóf, D.: Temporal Interpolation of Sentinel-2 Multispectral Time Series in Context of Land Cover Classification with Machine Learning Algorithms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22262, https://doi.org/10.5194/egusphere-egu24-22262, 2024.

BG3 – Terrestrial Biogeosciences

EGU24-441 | ECS | PICO | BG3.1

Comparison of Polish and Hungarian floodplain soils’ reaction to the climate change  

Dániel Szász, András Bidló, Pál Balázs, Piotr Hulisz, Péter Végh, and Adrienn Horváth

We made our investigation in the Gemenc forest, which is situated beside the Danube river near to the southern border of Hungary. Mainly in the last decades, watercourse management played a significant role in landscape evolution. Most of the area is on the saved side today, so it doesn’t get flooded. The Danube usually brings CaCO3 to this area with its sediment. The flooded areas are built from fine sediment materials. Meadow soils rich in CaCO3 are characteristic, and the forests of this land grow healthy here (assuming that are high-quality forest types). Farther away from the river, higher plains have sand with humus soils and Chernozem soils. On our Polish investigation we took samples from the northern floodplains of Vistula, in 2 different areas, which located on the saved side. Overall the samples were very similar to the Hungarian ones.

Forest ecosystems of this area are probably one of the most important members of the continental vegetation that store carbon. Because of their size, they take a huge part of the global carbon cycle. During our examinations, we visited six Quercus petraea and Robinia pseudoacacia forests and took samples from the soil profiles of those forest soil besides the determination of water holding capacity. The humus content of the examined soil samples varied between 0.7 and 6.9 %. Since the study areas are no longer or rarely affected by flooding, the highest organic matter content was found in the topsoil layer for each sample. SOM content gradually decreased with depth. The effect of flooding is clearly shown by the fact that we found organic matter in the samples even in the layer below 100 cm, and in several cases, we found buried humus levels. Accordingly, the organic carbon stock of these soils may be higher than average. However, the decreasing number of floods endangers the vitality of forest stands. With less flooding, decreasing groundwater level and an increase in the temperature at night, dew formation becomes more limited, and evaporation increases. These changes also affect the decomposition processes taking place in the soil, the circulation of nutrients, and soil respiration. Increasing temperature, the speed of decomposition, and the intensity of soil respiration increase, which can further increase the decrease in the soil's C pool.

In the Polish samples, the SOM varied between 0,4 and 20,9 %, with an extremety of a soil with peaty features. The ph varied between 2,0 and 8,0, with the former also being the „extremety”, otherwise the avarage value being 7,7. If we compare the two study areas, we can conclude that the soils themselves are less vulnerable to the effects of the climate change, due to the differences in the microclimate, the precipitation and the evaporation

This article was made in frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.

 

How to cite: Szász, D., Bidló, A., Balázs, P., Hulisz, P., Végh, P., and Horváth, A.: Comparison of Polish and Hungarian floodplain soils’ reaction to the climate change , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-441, https://doi.org/10.5194/egusphere-egu24-441, 2024.

EGU24-1047 | ECS | PICO | BG3.1 | Highlight

Water retention of soils with coarse texture under forest stands using classical method and PTFs 

Máté Katona, Péter Végh, Pál Balázs, András Bidló, and Adrienn Horváth

A changing climate brings more extreme weather and uneven distribution of rainfall events. These effects are already being observed, and although the average of the many annual rainfall totals is not changing significantly, the length and frequency of periods without rainfall and droughts have increased significantly. These changes are also felt by forest stands and their sensitivity to drought is a crucial factor in their growth and health. Our research team has been collecting data on the organic matter content and water-holding capacity of Hungarian soils for many years and has now also produced pF measurements. The sub-region of the Transdanubian Mountains region has provided a comprehensive picture of coarse-textured soil on which forest soil-forming processes take place. Soil samples were taken up to the limit of the occurrence of soil-forming processes, but at least up to 100 cm. Acidic Arenosols developed on the sand parent material. On these, mixed stands of beech and turkey oak-sessile oak associations developed. The pH, CaCO3 content, organic matter content, texture, and bulk density of the soils were determined under laboratory conditions in 10 cm layers. The majority of the soil samples had an acidic pH between 4.4-6.4, with fine sand and sandy loam physical texture and free of calcium carbonate, with low humus content (0.9% in the upper 40 cm) compared to forest soils. From the pF measurements and using pedotransfer functions, we determined the potential water availability for plants, and using local climate data and measured soil data, we constructed a Thornthwaite-type water balance model for the area and used it to estimate the drought sensitivity of the area. These models improve and speed up the methods and therefore its accuracy and applicability to forest soils is a primary concern of this research.

The present publication was supported by the National Research Development and Innovation Fund of the Ministry of Innovation and Technology (successor: Ministry of Culture and Innovation) under the project TKP2021-NKTA-43, funded by the TKP2021-NKTA grant programme, and by the New National Excellence Programme of the Ministry of Culture and Innovation, code number ÚNKP-23-3-I-SOE-172, funded by the National Research, Development, and Innovation Fund. The field and laboratory tests were also carried out using equipment purchased with the support of the project "GINOP-2.3.3-15-2016-00039 - Investigation of the conditions for growing woody biomass".

How to cite: Katona, M., Végh, P., Balázs, P., Bidló, A., and Horváth, A.: Water retention of soils with coarse texture under forest stands using classical method and PTFs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1047, https://doi.org/10.5194/egusphere-egu24-1047, 2024.

EGU24-1784 | ECS | PICO | BG3.1 | Highlight

Benchmarking simulations of forest regrowth across Europe 

Thi Lan Anh Dinh, Daniel Goll, Philippe Ciais, Nuno Carvalhais, and Ronny Lauerwald

Dynamic global vegetation models (DGVMs) are essential for quantification of the response of land carbon storage to changes in atmospheric chemistry, climate, and land cover. While DGVMs are often evaluated concerning carbon responses to changes in CO2 and climate, local responses to changes in land cover have received less attention. This is of concern as DGVMs are needed to project the long-term consequence of afforestation or deforestation on the land carbon balance under climate. Here, we present an assessment of the Organizing Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE) model, one of the state-of-the-art DGVMs, aiming to evaluate the simulated growth in forest biomass carbon stocks across the European Union against comprehensive observational data.

We conduct a model-data comparison of biomass growth using databases that contain paired observations of above-ground biomass (AGB) and plant age, categorized across various age groups spanning from very young (0-19 years) to old (>99 years) forests for boreal and temperate forests. The biomass dataset encompasses a harmonized collection from multiple open forest inventory databases, comprising 603 sites across Europe for six plant functional types (PFTs). On average, the stands are approximately 58 years old, with a mean AGB of 6.4 kgC.m-2. The findings indicate that simulations replicate the observed trend: AGB increases rapidly in young stands (<60 years old) and moderately saturates in later ages (>60 years old). However, the observed AGBs exhibit broader ranges and have more extremes than the simulated values. This is expected as observations refer to individual species, while our simulations are on the level of PFTs, which are an assemblage of species. Moreover, the comparisons reveal that the model underestimates AGB for temperate needleleaf evergreen forests, with a median deviation of approximately 60% from observed values. We propose a recalibration of the maximal rate of carboxylation and gross primary production fraction lost as growth respiration to reduce this deviation to less than 10%.

Our study highlights the potential of using observational biomass data to assess and calibrate DGVMs. This approach significantly enhances the ability of DGVMs to accurately reproduce the short-term land carbon sink response to reforestation. We provide a protocol that can easily be adapted to evaluate and recalibrate other DGVMs for the same purpose.

How to cite: Dinh, T. L. A., Goll, D., Ciais, P., Carvalhais, N., and Lauerwald, R.: Benchmarking simulations of forest regrowth across Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1784, https://doi.org/10.5194/egusphere-egu24-1784, 2024.

EGU24-2330 | ECS | PICO | BG3.1

Unusal equilibrium behavior of forest ecosystems in the Loess Plateau 

Ning Chen, Li Ma, and Liping Yang

Ecosystems may exhibit various equilibrium behaviors (e.g., linear and threshold), which will dramatically affect how we understand and regulate ecosystem dynamics under different environmental conditions, thus reshaping ecosystems’ sustainable development. Studying equilibrium behaviors is particularly crucial for the Loess Plateau because hundreds of billions of Chinese Yuan have been paid to alter ecosystem structure and thereby to reduce soil erosion. Resultant increasing vegetation, however, exhausts soil water, which heavily threatens the sustainability of ecosystem function and services therein. It has been a widespread and long-lasting controversy over whether and where to afforest. However, one of the most fascinating equilibrium behaviors of alternative stable states, which permits more than one states under the similar conditions, has largely ignored in the framework. By integrating remote sensing products, a minimal model, and environmental data, this study explored alternative tree-cover states and its effects on functions and services of forest ecosystems in the Loess Plateau. The equilibrium behavior along annual precipitation gradient appeared to a threshold-type (uni-stability) combined with a fold bifurcation. That is, tree cover showed a threshold-type uni-stability when annual precipitation was lower than 400 mm, beyond which alternative stable states of high tree cover (forest, >35% tree cover), and medium tree cover (open woodland, 7%~35% tree cover) co-existed. Increasing spatial heterogeneity, and especially vegetation-precipitation positive feedback would advance the thresholds of transitions between alternative states towards to higher annual precipitation. Furthermore, regime shift from forest to open woodland states increased carbon stock, while reduced water yield, i.e., carbon and water formed a trade-off. This unusual balancing behavior not only enriches our understanding theoretically but also substantially benefit afforestation planning in the Loess Plateau practically, thereby promote forest ecosystem functions and services of forest ecosystems.

How to cite: Chen, N., Ma, L., and Yang, L.: Unusal equilibrium behavior of forest ecosystems in the Loess Plateau, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2330, https://doi.org/10.5194/egusphere-egu24-2330, 2024.

Attaining a “land degradation neutral world” by 2030, as envisaged by the United Nations (UN) 2030 agenda for sustainable development, sustainable development goal (SDG) number 15, requires accurate information for the implementation of targeted interventions. The Trends.Earth historical data set to support monitoring and reporting, and to track the impact of sustainable land management is only available up to the year 2021. However, combining the predictive ability of Cellular-Automata-Markov (CA-Markov) model(s) in Idris Selva and the Trends.Earth model could provide an insight into potential future land cover degradation. Therefore, this study assesses the status of the land cover degradation in the Upper Zambezi River Basin (UZB) in southern Africa using the CA-Markov model and the Trends.Earth model. The UZB includes the headwaters of the Zambezi River and is susceptible to land cover degradation with potential negative effects on water resources. High resolution multispectral Landsat data are used in the Land Change Modeler (LCM) and the CA-Markov chain model in Idris Selva 17.0 to assess historical changes and predict future changes in land use and land cover (LULC) for the period 1993-2033. The LULC change maps produced with the LCM and CA-Markov models in Idris Selva are used to assess the land cover degradation status for the period 1993-2033 in the UZB using the Trends.Earth model in QGIS 3.34. Results show that land cover degradation maps produced, at local level, from high spatial resolution multispectral data provides more detail of land cover degradation compared to the Trends.Earth global data set. In terms of land cover degradation, the UZB is largely stable. However, of concern are areas, including wetlands and the headwaters of the Zambezi River, which shows land cover degradation as a result of loss of forest cover to expansions in human settlements and cropland. On the contrary, some areas show improvements in forest cover due to conversion of grassland and cropland into forest cover. For the period 2023 – 2033 the forest cover in the UZB is predicted to have a net reduction of 236258 hectares at a net annual rate of -0.14%. The spatial extent of land cover degradation is projected to build-up on the historical spatial extent. Predicting land cover degradation, as demonstrated in this study, makes available information for instituting targeted interventions which may help in the monitoring and management of water resources, as well as contribute towards a land degradation neutral world. 

How to cite: Zimba, H., Kawawa, B., Mbewe, S., and Imasiku, N.: Predicting future land cover degradation through the integrated use of the Cellular-Automata-Markov chain model and the Trends.Earth model: An application in the Upper Zambezi River Basin in southern Africa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3115, https://doi.org/10.5194/egusphere-egu24-3115, 2024.

EGU24-4841 | ECS | PICO | BG3.1

How accurately does L band vegetation optical depth predict aboveground biomass? 

Yuan Zhang, Philippe Ciais, Jean-Pierre Wigneron, Jérôme Chave, Nan Cong, Xiaojun Li, Yan Yang, and Sassan Saatchi

L band vegetation optical depth (L-VOD) is a widely used remote sensing variable for investigating the spatiotemporal variation in aboveground biomass (AGB). A key step of this method is to fit L-VOD against AGB, then use a space-for-time assumption to infer AGB change from fitted L-LOD change. In this study, we evaluated the performance of different fitting equations and explored their implications in predicting AGB. We used the SMOS-ICV2 L-VOD dataset and four AGB reference datasets. Specifically, we examined the implications of the space-for-time assumption in predicting the AGB interannual variations. We find that all the statistical fitting methods can capture the AGB spatial variation, yet introducing tree cover as a predictor significantly improves the AGB prediction, especially in regions with small and medium L-VOD values. However, these methods all fail to capture AGB spatial variation in dense forests. The AGB reference data also show large discrepancies in these regions. Our results also show that the spatial AGB sensitivities to L-VOD are much larger than the temporal AGB sensitivities to L-VOD, implying considerable uncertainties in temporal AGB changes predicted with spatially built models. By providing a comprehensive evaluation of fitting methods, our results offer a cautionary tale to the use of L-VOD data to infer AGB dynamics and the necessity of developing long-term field-based biomass change datasets for further constraining and evaluating AGB predictions from remote sensing observations.

How to cite: Zhang, Y., Ciais, P., Wigneron, J.-P., Chave, J., Cong, N., Li, X., Yang, Y., and Saatchi, S.: How accurately does L band vegetation optical depth predict aboveground biomass?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4841, https://doi.org/10.5194/egusphere-egu24-4841, 2024.

EGU24-5353 | PICO | BG3.1 | Highlight

Changing groundwater ecosystems and recharge – neither temperature nor nutrients or carbon are the main drivers 

Susanne I. Schmidt, Miroslava Svátková, Vít Kodeš, and Tanja Shabarova

Waterbodies across the world undergo changes. This influences the communities in the ecosystems. Groundwater is no exception. However, few studies focused so far on how the combined effects from environment, groundwater recharge, and a changing climate, impact the organisms living in the groundwater. In 2019-2021 in southwestern Czech Republic, we sampled fauna and microorganisms in 37 wells that had been monitored by CHMI for up to 40 years and that varied in the trends in chemical and physical characteristics. The wells tapped the shallow quaternary and deeper aquifers of seven major hydrogeological zones. Some of the wells represented recharge zones, others tapped artesian aquifers. Trends in temperature over the past decades were ambiguous. Carbon and nutrients did not show clear patterns, neither over time, nor predicting fauna and microorganisms. Fauna was, however, significantly more abundant in wells representing recharge zones. Most unexpected were the observations that silica increased significantly in all but one well, and that faunal numbers were lowest in the wells with the highest silica values, although there is no reason for fauna being harmed by silica, - on the contrary. The correlation is thus believed to show indirect effects, with the increase in silica probably being the (by)product from either climate change or land use change, or the combination of the two, and groundwater fauna being impacted by the underlying developments. This may have implications for ecosystem functions, and ultimately, the use of groundwater for drinking water production.

How to cite: Schmidt, S. I., Svátková, M., Kodeš, V., and Shabarova, T.: Changing groundwater ecosystems and recharge – neither temperature nor nutrients or carbon are the main drivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5353, https://doi.org/10.5194/egusphere-egu24-5353, 2024.

EGU24-5802 | ECS | PICO | BG3.1

Optimizing Irrigation Strategies for Mitigating Drought Stress in Reforestation Areas: Lessons from a Drought Stress Experiment 

Leonie Hahn, Markus Schmidt, Carsten Lorz, Andreas Rothe, Anja Rammig, and Christian Zang

The increasing frequency of drought events in recent years has become a major hurdle for reforesting forests after natural disturbances in many areas globally, including parts of Central Europe. As an example, reforestation projects after bark beetle disturbances have faced notable failures and losses due to prolonged drought conditions in Northern Bavaria (Germany). Irrigation is a potential measure increasing reforestation success and is currently funded by the regional government. However, historically irrigation was not a common technique in this area and there is a lack of both practical and scientific knowledge concerning irrigation strategies. The optimal timing for the irrigation of the saplings as well as the water amount applied are crucial aspects in this context.

This study addresses this knowledge gap by conducting a drought stress experiment within a greenhouse environment, focusing on four commonly planted tree species prevalent in our study region in northern Bavaria. Various approaches were explored to reliably detect drought stress and identify the irrigation demand both concerning timing and amount of water applied: the experimental design integrates environmental data with ecophysiological measurements and employs drought stress indices derived from close-range remote sensing. The most promising methodology for detecting the irrigation demand, identified through rigorous experimentation, will be further explored on forest sites post-planting. Implementing such optimized irrigation strategies holds promise for safeguarding reforestation endeavors, particularly in regions prone to drought, and contributes to the sustainable management of forest ecosystems and water usage.

How to cite: Hahn, L., Schmidt, M., Lorz, C., Rothe, A., Rammig, A., and Zang, C.: Optimizing Irrigation Strategies for Mitigating Drought Stress in Reforestation Areas: Lessons from a Drought Stress Experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5802, https://doi.org/10.5194/egusphere-egu24-5802, 2024.

The drought is becoming more frequent and severe with changing precipitation pattern in the future. How the water use efficiency responds to drought in different periods during the growing season has become a key scientific issue to explore the response mechanism of carbon and water cycle coupling process to drought in alpine meadow ecosystem. This project focused on the response mechanism of alpine meadow ecosystem productivity to drought and the relationship between productivity, evapotranspiration (or rainfall) and water use efficiency under simulated drought events in the early and middle growth seasons, and discuss the response mechanism of water use efficiency of alpine meadow ecosystem to drought. The result showed that (1) the delayed green-up under early growing season drought and advanced withered date under middle growing season drought occurred in graminoids, weeds and plant community, which indicated ‘escape strategy’ to drought. (2) the effect of advanced withered date was divergent among graminoid and weeds on the aboveground net primary production, which may lead to a stronger resistance of community productivity to middle growing season drought. (3) besides soil water deficit, the limited accumulation of aboveground biomass inhibited the physiological process of carbon exchange in alpine meadow community either. However, the carbon exchange process presented an over compensation mechanism, and the material distribution strategy may vary after rainfall restoration. (4) early growing season drought had no significant effect on water use efficiency of alpine meadow community (p > 0.05), while water use efficiency increased significantly under middle growing season drought (p < 0.05). The main reason is that the plant community is more sensitive to early growing season drought, which depressed the aboveground biomass, while aboveground productivity of alpine meadow plant community has stronger resistance to middle growing season drought. This project studied the response mechanism of alpine meadow ecosystem to extreme drought events in different periods, which has great scientific significance to the study of ecosystem response to extreme climate events, and provides a scientific basis for predicting and simulating the response of alpine meadow ecosystem in Northern Tibet to climate change in the future, especially the change of precipitation pattern.

How to cite: Hu, G.: Water use efficiency response of plant communities to drought in different growing periods in alpine meadow, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7326, https://doi.org/10.5194/egusphere-egu24-7326, 2024.

EGU24-8047 | PICO | BG3.1

Different strategies of the catchment division in the process of multi-objective calibrating the conceptual rainfall-runoff model 

Milica Aleksić, Martin Kubáň, Ján Szolgay, and Juraj Párajka

While the familiar path of experimenting with multi-objective calibrating a conceptual rainfall-runoff model involves the whole catchment area, this study examines and compares various spatial divisions of the catchment during the calibration process. The input data that is used includes runoff values (Q), precipitation (P), air temperature (T), and potential evapotranspiration (PET). Additionally, values of soil moisture obtained by the sensors of the remote sensing source (advanced scatterometer (ASCAT) remote sensing product-ASCAT SWI) were also incorporated into the analysis within a selected catchment in Slovakia. This study provides insights into the best practices for integrating satellite soil moisture data into multi-objective calibration. Moreover, including satellite soil moisture data is particularly significant, offering a novel perspective on moisture dynamics within the catchment. One of the objectives of this research is to identify the optimal spatial division of the catchment, explicitly evaluating the effectiveness of elevation-based division versus land cover-based division. These different catchment subdivisions should point to the impact on the accuracy and reliability of the rainfall-runoff model. The calibration strategy chosen for this study is divided into the period from 2007 to 2014 for the calibration run and for the validation run chosen period from 2015 to 2019. First results show improvement of soil moisture correlation results in land cover-based division contrary to elevation zone subdivision, in the whole period of calibration (2007-2014), as well as in only summer months period (June, July, August and September). Different established calibration strategies should offer a robust framework for calibrating the rainfall-runoff model in future.

Acknowledgement

This study was supportedby the VEGA Grant Agency No. VEGA 1/0577/23.

How to cite: Aleksić, M., Kubáň, M., Szolgay, J., and Párajka, J.: Different strategies of the catchment division in the process of multi-objective calibrating the conceptual rainfall-runoff model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8047, https://doi.org/10.5194/egusphere-egu24-8047, 2024.

EGU24-8056 | ECS | PICO | BG3.1 | Highlight

Spatial-temporal changes of the long-term average monthly runoff in Slovakia 

Zuzana Sabová, Silvia Kohnová, and Anna Liová

This study aims to analyse the changes in the long-term average monthly runoff regime on the territory of Slovakia. For the analysis, the average monthly discharges from 57 gauging stations of the whole territory of Slovakia, which the Slovak Hydrometeorological Institute provided for the period 1961-2020, were used. The selected basin areas range from approximately 10 km2 to 1000 km2. The monthly discharge data available were divided into two periods: the old one, 1961-2000, and the new reference period, according to the World Meteorological Organization (WMO), from 1991 to 2020.  The appropriate number of clusters was determined according to the statistical analysis using the average Silhouette Width and the Elbow method. Subsequently, the PCA method and K-means clustering were performed to pool the catchments into groups. The results present the outputs of the particular runoff regime in the selected gauging stations divided into five clusters. South-central Slovakia and central Slovakia characterise Cluster No. 1; Cluster No. 2 by the northwest and northeast of the country; Cluster No. 3 for the centre of northern Slovakia; Cluster No. 4 for central Slovakia, and Cluster No. 5 for the east, south and west part of Slovakia. When comparing the changes in the regime of both periods, we can state that the best, 89% agreement was in Custer No.2, representing the High Tatras region, and 86 % agreement was in Cluster No.5 for the western part of Slovakia, with is 44% in Custer No.4, where the highest long-term average monthly flows remain in April, but the lowest normalized long-term average monthly flows shift from January to February. In Custer No.3, with 40 % agreement of catchment forming the clusters, we find a similar shift of peak long-term average monthly flows from April (1961-2000) to March (1991-2020). The most significant changes in the long-term average monthly runoff regime were found for the catchment in Cluster No.1.

Finally, the most important characteristic features of the individual clusters of gauging stations created were also analysed, which could help incorporate other catchments into appropriate regional types in the future. The methodological procedure developed could also be used in further studies to predict future flow regime changes on the territory of Slovakia.

Acknowledgements

This study was supported by the Slovak Research and Development Agency under Contract No. APVV-20-0374 and VEGA Grant Agency No 1/0782/21. The authors thank the agencies for their research support.

How to cite: Sabová, Z., Kohnová, S., and Liová, A.: Spatial-temporal changes of the long-term average monthly runoff in Slovakia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8056, https://doi.org/10.5194/egusphere-egu24-8056, 2024.

EGU24-8142 | PICO | BG3.1

The experiment of the effects of rainfall intensity and substrate depth of an extensive vegetated roof 

Jana Grečnárová, Michaela Danáčová, and Matúš Tomaščík

Nowadays, extreme precipitation events are becoming more and more prevalent, which, in some
situations, can cause serious problems and damage. To avoid the impacts of extreme rainfall events,
blue-green infrastructure elements are used to retain and slow down stormwater runoff. Examples are
vegetated (green) roofs, widely considered a promising nature-based solution for urban stormwater
management.
This experiment is focused on studying the influence of the retention capacity and the depth of the
selected commercial substrate of extensive vegetated roofs. The rainfall intensity testing aims to
demonstrate and explore new insights into vegetated roofs during severe extreme precipitation. The
actual experimental process was performed under laboratory conditions, where extreme rainfall
intensities (2 - 4 mm/min) with a duration of 15 minutes were subsequently simulated using a rainfall
simulator. The main identifier of the quality and capability of the substrate used on the vegetated roof
is the amount of runoff captured from the simulated rainfall intensity. The measured outputs will be
used as inputs to predictions reducing stormwater runoff. The knowledge gained and the different
variations of the simulations can significantly help in constructing and designing vegetated roofs and
effective urban stormwater management.

Keywords: precipitation, retention capacity, vegetated roof, runoff,

How to cite: Grečnárová, J., Danáčová, M., and Tomaščík, M.: The experiment of the effects of rainfall intensity and substrate depth of an extensive vegetated roof, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8142, https://doi.org/10.5194/egusphere-egu24-8142, 2024.

EGU24-8187 | ECS | PICO | BG3.1

Estimation of the Peak Runoff Coefficient on Small Catchments in Slovakia 

Lynda Paulíková, Silvia Kohnová, and Roman Výleta

Runoff is one of the essential indicators for designing measures that retain or safely divert water in the country. However, in the 21st century, rural basins face changes caused by climate or land use. These alters force society to think about the transformation that time brings and to change the view on some parameters of the country's functioning within the outflow processes. The presented contribution deals with runoff changes over the last decades, in which the difference in the values ​​of peak runoff coefficients in small watersheds is analysed using direct and indirect estimation methods.

The first part of the study deals with the indirect approximate calculation of the peak runoff coefficient in 128 small catchments up to an area of 150 km2 (approx. 58 mi2 ) located on the territory of the Slovak Republic. Input data consisted of estimated concentration times according to Nash and Kirpich formulae, estimated design values for maximum floods and IDF curves for all available rain gauge stations in each analysed basin. The results were compared to previous studies.

In the second part, for two selected basins (Parná – Horné Orešany and Belá – Liptovský Hrádok), we estimated the peak runoff coefficient using the direct method. The chosen watersheds represent different landscape structures, where the first is a lowland type, and the second a high-mountain type of landscape. The analysis was based on direct measurements of hourly peak flows from 1989 to 2021. The flood wave parameters for calculating the peak runoff coefficients were obtained by substituting the causative precipitation. These data were subsequently statistically analysed using the Johnson probability distribution. The peak runoff coefficient for a 100-year return period was separately modelled for the summer and winter periods in both basins and compared to the indirect estimation results.

The study's results are intended to highlight the differences in the methods used to estimate peak runoff coefficients in small watersheds.

 

Acknowledgements

This study was supported by the Slovak Research and Development Agency under Contract VEGA Grant Agency No 1/0782/21. The authors thank the agencies for their research support.

How to cite: Paulíková, L., Kohnová, S., and Výleta, R.: Estimation of the Peak Runoff Coefficient on Small Catchments in Slovakia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8187, https://doi.org/10.5194/egusphere-egu24-8187, 2024.

EGU24-8216 | PICO | BG3.1

Investigating the applicability of long short-term memory model for streamflow prediction  

Mitra Tanhapour, Kamila Hlavcova, Silvia Kohnova, Hadi Shakibian, Jaber Soltani, and Bahram Malekmohammadi

Streamflow prediction, especially extreme events, poses a significant challenge due to the intricate and unpredictable nature of the rainfall-runoff process. Recently, promising results have been observed in time series problems by applying deep learning methods, including Long Short Memory (LSTM) and sequential modelling. This study investigates the application of the LSTM network to predict daily streamflow in the Dez River basin, Iran, during 2012–2019. Accordingly, observed precipitation, temperature, empirical evapotranspiration, and runoff were utilized as predictor variables. The performance of the LSTM model was compared with an established process-based approach, the Hron rainfall-runoff model, which served as a benchmark to evaluate the effectiveness of this innovative model. The models were evaluated using Kling-Gupta efficiency (KGE), Nash-Sutcliff efficiency coefficient (NSE), normalized root mean square error (NRMSE), and mean absolute percentage error (MAPE). Through evaluation and analysis, the NSE and MAPE indices were, respectively, 0.95 and 15.6% for the LSTM model in the validation stage. The results demonstrated that the LSTM model performed better than the Hron model in predicting daily streamflow. The superior performance of the LSTM network represents its efficiency in capturing and utilizing inherent temporal dependencies in hydrological data. This finding highlights the potential of the proposed model for improving the accuracy and reliability of real-time hydrological forecasts.

How to cite: Tanhapour, M., Hlavcova, K., Kohnova, S., Shakibian, H., Soltani, J., and Malekmohammadi, B.: Investigating the applicability of long short-term memory model for streamflow prediction , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8216, https://doi.org/10.5194/egusphere-egu24-8216, 2024.

EGU24-8738 | PICO | BG3.1 | Highlight

Historical drought occurrence on Slovak rivers during the period 1931–2020 

Pavol Miklanek, Pavla Pekárová, Veronika Bačová Mitková, Zbyněk Bajtek, Dana Halmova, and Ján Pekár

In the last decade (2011-2020), Slovakia has experienced a significant decrease in flows in most river basins. The aim of this study is to statistically analyse the changes in the hydrological regime of selected Slovak streams based on observations over a 90-year period (1931-2020), using measured average daily discharges. Several regions in Europe, particularly in the Mediterranean area, including Spain, Italy, and Greece, have been affected by significantly dry years. The occurrence of dry years is not unusual, as extreme droughts have also occurred in the Danube River basin in the past, such as in 1863, 1921, 1947, 1992-93, and 2003. Our goal is to analyse changes in the low flow regime of rivers in Slovakia, which have long observation records. Understanding the low flow regime is one of the inputs for determining hydro-ecological limits, which is essential for maintaining and achieving good ecological status of surface waters. Several flow and non-flow characteristics were evaluated when assessing hydrological drought. Flow characteristics include: minimum average daily flows (in monthly or annual steps, over the entire period), M-day flows (the exceedance curve of average daily flows), minimum monthly and annual flows, and T-year minimum flows. Non-flow characteristics evaluated include changes in the timing of dry periods (date of occurrence), the number of low flow days, the longest drought episode, and the deficit volumes. Individual flow characteristics were calculated from the series of average daily flows. The trend analysis showed that in the given sub-catchments there is a decrease in the T-year minimum flows, as well as a decrease in the basic runoff. The comparison of the 100-year minimum specific runoff with the values of the specific base runoff shows that the 100-year minimum runoff can be up to ca. 4 times lower than the estimated specific base runoff in an extremely dry year.

 

Acknowledgement

This work was supported by the project VEGA No. 2/0015/23 “Comprehensive analysis of the quantity and quality of water regime development in streams and their mutual dependence in selected Slovak basins”, and by the project APVV No. 20-0374 “Regional detection, attribution and projection of impacts of climate variability and climate change on runoff regimes in Slovakia”

How to cite: Miklanek, P., Pekárová, P., Bačová Mitková, V., Bajtek, Z., Halmova, D., and Pekár, J.: Historical drought occurrence on Slovak rivers during the period 1931–2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8738, https://doi.org/10.5194/egusphere-egu24-8738, 2024.

EGU24-9482 | ECS | PICO | BG3.1

Comparison of soil carbon stock of afforested and treeless sites 

Mátyás Csorba, András Bidló, Pál Balázs, Péter Végh, and Adrienn Horváth

Numerous research based on long-term weather data sets proves a drier and warmer climate in Hungary. Research related to climate change and carbon sequestration is developing dynamically, so it is notable to show how climate change affects the quality and quantity of organic matter content in soils. The importance of changes in soil organic carbon stocks follows from its effects on ecosystems on a global level. In the last decades, afforestation programs were also started in Hungary to promote carbon sequestration. However, there have been several criticisms of afforestation efforts by experts and researchers dealing with agriculture, according to which agricultural areas, particularly grasslands, can sequestrate more organic carbon than forest stands. It is also not suggested to plant forest stands in dry, sandy areas, as it has a drying effect on the soil due to its high water demand compared to the fields, thereby reducing the net carbon sequestration. This research aim was to examine the above proposition at 5 locations where wooded and treeless, different land-used areas were managed next to each other. Based on our scientific investigation, it cannot be clearly stated that the soil of the forests we examined has a richer carbon stock than the neighboring arable land or pasture, but together with the amount of carbon stored in the O horizon, the forests surplus prevailed upon every examined point. Due to the slow process of carbon sequestration and organic matter entering the soil, we also plan to conduct long-term tests.

This article was made in the frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.

 

How to cite: Csorba, M., Bidló, A., Balázs, P., Végh, P., and Horváth, A.: Comparison of soil carbon stock of afforested and treeless sites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9482, https://doi.org/10.5194/egusphere-egu24-9482, 2024.

EGU24-10271 | ECS | PICO | BG3.1

Tree Mortality in a Relict Scots pine forest due to climate change 

Adrienn Horváth, Ferenc Lakatos, Péter Szűcs, Zoltán Patocskai, Péter Végh, Dániel Winkler, András Bidló, and Borbála Gálos

An investigated old-growth Scots pine (Pinus sylvestris L.) forest is located in a protected area. Climate, soil, and local hydrological conditions highly influence the health conditions of this relict forest stand. Drought symptoms are already visible thus complex analyses assessing of these site factors were investigated. Site conditions always influence vegetation. Conversely, vegetation always affects site conditions. Therefore, the relationship between forest stand vitality and stand growth becomes more complicated in the case of damage chain appearance in an elderly, resistant forest stand. Our research aimed to answer the following questions:

  • How have site conditions changed in the research area in recent decades?
  • Which are the most significant site-limiting factors in this case?
  • Can a relict and protected ecosystem adapt to the changed conditions?

To identify the complex causes of tree mortality, climatic and soil conditions were analyzed and completed with bryological and biotic (pests) surveys. Altogether unfavorable soil conditions (coarse sand) and increasing aridity have led to a decline in tree vitality. Bark beetles have a high population density in the stand, so the beetles contributed to tree mortality. New spreading invasive moss species have appeared in the recently formed gaps, where crone projection is low. The disappearance of this relict forest stresses the urgent need for Hungarian forest management to prepare strategies for adaptive tree species selection.

This article was made in the frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.

How to cite: Horváth, A., Lakatos, F., Szűcs, P., Patocskai, Z., Végh, P., Winkler, D., Bidló, A., and Gálos, B.: Tree Mortality in a Relict Scots pine forest due to climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10271, https://doi.org/10.5194/egusphere-egu24-10271, 2024.

EGU24-11660 | ECS | PICO | BG3.1

Data integration and simple water balance analysis of the Sopron Botanical Garden’s hydrometeorological station data 

Lili Muraközy, Péter Kalicz, Márton Kiss, and Zoltán Gribovszki

Analyzing the water balance of long-lived plant communities, like forests, requires centuries long monitoring of hydrometeorological processes. Long-term measurements, however, are essential for assessing the effects of climate change as well. In Sopron, meteorological records—one of the first systematic analyses in Hungary—started in 1711. From 1925.06.01 to 1974.04.24, the Botanical Garden's meteorological station at the University of Sopron was the city's official station. In 1974, the official station was relocated to Kuruc Hill Observatory. The remaining instruments in the Botanical Garden were still functional. The presentation goes over the basic data processing for hydrometeorological purposes, error analysis, the integration of the station's data, simple water balance estimation and FAI (forest aridity index) analysis.

The following joint projects (143972SNN project and the TKP2021-NKTA-43 project) supported the preparation of this paper. TKP2021-NKTA-43 has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.

Supported by the ÚNKP-23-2-III-SOE-176 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund.

How to cite: Muraközy, L., Kalicz, P., Kiss, M., and Gribovszki, Z.: Data integration and simple water balance analysis of the Sopron Botanical Garden’s hydrometeorological station data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11660, https://doi.org/10.5194/egusphere-egu24-11660, 2024.

EGU24-11762 | ECS | PICO | BG3.1

Black pine-grass paired plot water balance experiment in the botanic garden of Sopron UNI 

Kamilla Orosz, András Herceg, Péter Kalicz, Katalin Anita Zagyvai-Kiss, Klaudija Lebar, Katarina Zabret, Nejc Bezak, Gábor Keve, Dániel Koch, and Zoltán Gribovszki

Hydrological measurements, particularly those conducted on paired plots, provide valuable tools for comparing the water balance of different surface covers. Hydro-meteorological measurements have been carried out in the University of Sopron Botanical Garden since 1925. Conducting long-term measurements provides a good opportunity for studying the water balance in forested areas. The proximity of educational facilities allows for frequent measurements, regular equipment checks, and student participation. A hydrological paired-plot experiment site was established in the botanical garden as part of an international Slovenian-Hungarian project. We set up the research plot under black pine trees. For comparative purposes, we designated an open-air plot as a control site, positioned approximately 100 meters away from the pine trees. The focus of the experiment was to better understand the complex water dynamics within the research site under the black pine tree canopy. The first set of experiments is suitable for analysing rainfall distribution in a forest (canopy and litter interception), and comparing the soil moisture and groundwater dynamics of grass and forest plots. In the experimental area, automated equipment installation is presently underway. The experiment serves educational and demonstration purposes in addition to its primary research function.

The following joint projects (143972SNN, N2-0313 projects and the TKP2021-NKTA-43 project) supported the preparation of this paper. TKP2021-NKTA-43 has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme. This contribution is also part of ongoing research entitled “Microscale influence on runoff” supported by the Slovenian Research and Innovation Agency (N2-0313).

How to cite: Orosz, K., Herceg, A., Kalicz, P., Zagyvai-Kiss, K. A., Lebar, K., Zabret, K., Bezak, N., Keve, G., Koch, D., and Gribovszki, Z.: Black pine-grass paired plot water balance experiment in the botanic garden of Sopron UNI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11762, https://doi.org/10.5194/egusphere-egu24-11762, 2024.

EGU24-12022 | PICO | BG3.1

Examination of the organic carbon stock of the soil of Hungarian beech stands and the determining factors 

András Bidló, Pál Balázs, Máté Katona, Péter Végh, and Adrienn Horváth

The beech stands ratio of Hungarian forests barely reaches 6%. However, beech is a native tree species with high production capacity; therefore, its importance in nature conservation and economy is significant. Due to global climate change, the focus is on the ability of carbon fixing and storage capacity in beech forest ecosystems. While we can estimate the amount of biomass above ground with relative precision, we have little data about organic carbon in soils.

The primary goal of our work was to collect as much data as possible on the amount of organic carbon stored in the soil of these native forest stands. Furthermore, the most significant factors were determined that influenced the sequestration.

During the research, undisturbed and disturbed soil samples were collected from every 10 cm layer in 40 beech stands. The depth depended on the bedrock. On loessy or sandy bedrock, the depth was 110 cm. In the case of rocky structure, samples were taken from 0-40 cm depth. Moreover, litter samples were taken and analyzed. The properties of the stands were also recorded on the sampling sites (tree species, diameter, etc.).

The soil pH was 5.17 on average, while the minimum value was 3.87 and the maximum was 8.4. The humus content varied between 0.16 and 15.65% because it decreased with depth. The average organic carbon stock was 6.39 C t/ha (Cminimum  1.46 C t/ha, Cmaximum 34.03 C t/ha). Moisture determines the organic carbon stock of the soil most of all.

This article was made in the frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme. Some of the tools used during the research were acquired within the framework of the "Investigation of the conditions for the cultivation of wood biomass - GINOP-2.3.3-15-2016-00039" project.

How to cite: Bidló, A., Balázs, P., Katona, M., Végh, P., and Horváth, A.: Examination of the organic carbon stock of the soil of Hungarian beech stands and the determining factors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12022, https://doi.org/10.5194/egusphere-egu24-12022, 2024.

EGU24-12680 | ECS | PICO | BG3.1

Evaluation of the Sentinel-3A Gross Dry Matter Productivity (GDMP) product for evergreen forests 

Wafa Chebbi, Eva Rubio, Francisco Antonio García-Morote, Manuela Andrés-Abellán, Marta Isabel Picazo-Córdoba, Rocío Arquero-Escañuela, and Francisco Ramón López-Serrano

The recent consolidation of global carbon monitoring systems has been coupled with notable advances in methods for estimating the carbon cycle components in terrestrial ecosystems. These developments include a comprehensive assessment of the uncertainty and biases associated with these estimations. Gross primary productivity (GPP) is the most significant component of the terrestrial carbon cycle. Accurate estimation of GPP and its fluctuations over space and time is crucial not only for assessing ecosystem functioning and carbon balance but also for evaluating the resilience of ecosystems to adapt, survive and thrive in response to climate changes. Unfortunately, direct measurement of GPP through remote sensing (RS) signals is not feasible. Several RS signals associated with vegetation pigments and canopy structures can indeed function as proxies for GPP. These signals can be effectively integrated with various modelling approaches, considering different types and levels of complexity, to generate an estimation of global GPP at high spatio-temporal resolution.

This study aims to explore how Sentinel satellites can improve the remote global GPP estimation. Specifically, we evaluated the quality of the 10-daily GDMP product of Sentinel-3, ensuring its reliability and credibility, with a specific focus on evergreen forests, particularly Aleppo pine stands. The outcomes of this study are expected to contribute to refining and calibrating GDMP algorithms for improved accuracy.

The first aspect of our methodology involves the selection of several Aleppo pine forests across South-East Spain, where eddy covariance towers were installed, to study inter-site variability including soil characteristics, vegetation dynamics and forest management. Then, direct cross-comparisons between eddy covariance measurements and satellite observations were conducted for 4 independent study sites covering different periods (i.e., 2015-2018 and 2019-2023) to quantify uncertainties and biases in the GDMP product.

The results revealed that the GDMP product exhibits improved performance during wet periods, ranging across sites from the highest R2 of 0.83 to the lowest R2 of 0.71, but it encounters challenges in accurately simulating Gross GPP under drought conditions. This funding was expected because some potentially important factors such as drought stress among others were omitted in the current computation model of Copernicus Global Land Service. Therefore, it is suggested that the product could be more accurately labelled as a potential GDMP. Similarly, our analysis showed that Aleppo pine demonstrates high plasticity in response to local conditions that is not adequately captured by this GDMP model.

To address the challenges encountered in accurately simulating the GDMP product, we are working on developing a potential solution. This involves incorporating drought stress factors to enhance the model by integrating relevant physiological and environmental variables that influence specific responses of Aleppo pine to water shortage.

How to cite: Chebbi, W., Rubio, E., García-Morote, F. A., Andrés-Abellán, M., Picazo-Córdoba, M. I., Arquero-Escañuela, R., and López-Serrano, F. R.: Evaluation of the Sentinel-3A Gross Dry Matter Productivity (GDMP) product for evergreen forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12680, https://doi.org/10.5194/egusphere-egu24-12680, 2024.

EGU24-13016 | ECS | PICO | BG3.1 | Highlight

Examining the groundwater turnover in a lowland salt steppic oak forest 

Zsombor Kele, Péter Kalicz, and Zoltán Gribovszki

Over the past centuries, many changes have occurred in addition to climate change, from human encroachment to deforestation and drainage, and much more. Research has shown that lowland forests use a significant amount of groundwater, without which it is much harder to imagine their existence, even as a dominant source of water. It is therefore crucial to understand how much and how forests can be maintained under the expected conditions, because groundwater levels are sinking year by year in large parts of the Hungarian lowlands.

From a conservation perspective, it is also crucial to investigate the activities taking place in the Ohat oak forest, which is a remnant area along the Tisza. Two groundwater wells were drilled in the region in 2021, and automated measuring equipment was put in each of them to track the daily variations in groundwater levels. In order to estimate the groundwater abstraction from the forest, we will utilize the White method to compute the groundwater recharge during times when there is no precipitation.

Additionally, we will look at how the local conditions have changed in relation to the region's long-term meteorological data series. We will be able to compare the soil water recharge in various years thanks to the multi-year data series, and search for connections between the recharging and the monthly and yearly weather conditions. We will also compare the summer and winter periods of the recharging.

This three years are very good for the examination, because there was also drought and wet years, the groundwater level was deeply subslided, and after that, in 2023, it was recharged a lot, because of the rainy weather. These conditions caused a big difference between every year’s recharging, which is instructive for the ecosystem functioning.

The following joint projects (143972SNN project and the TKP2021-NKTA-43 project) supported the preparation of this paper. TKP2021-NKTA-43 has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.

How to cite: Kele, Z., Kalicz, P., and Gribovszki, Z.: Examining the groundwater turnover in a lowland salt steppic oak forest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13016, https://doi.org/10.5194/egusphere-egu24-13016, 2024.

EGU24-15021 | PICO | BG3.1 | Highlight

How rainfall interception influences soil erosion in agricultural, urban and forest catchments 

Juraj Parajka, Borbála Széles, Dušan Marjanovic, Katarina Zabret, Klaudija Lebar, Urša Vilhar, Nejc Bezak, and Mojca Šraj

Rainfall intercepted by vegetation is, in many regions, an important part of the hydrological water cycle. Part of the intercepted rainfall evaporates into the atmosphere, and throughfall and stemflow contribute to runoff generation, control soil moisture and runoff connectivity patterns and affect soil erosion. The question of how changing climate and land cover conditions impact rainfall interception, raindrop microstructure, and their erosive power still needs to be better understood.

This presentation introduces the main aims of a bilateral research project between TU Wien, University of Ljubljana and the Slovenian Forestry Institute that focuses on the understanding of the effect of meteorological and vegetation characteristics on changes in raindrop microstructure and, therefore, on the erosive power of rainfall. The main idea of the research cooperation is to analyse and understand the main mechanisms of the rainfall interception process in different climate conditions and vegetation settings. The high-resolution disdrometer measurements from the experimental urban and forest plots in Slovenia and a small agricultural basin in Austria are used to determine and compare raindrop distributions and their changes. The high-resolution observations of discharge, sediment concentrations and isotope analyses contribute to the understanding of the erosion processes and sediment transport in the streams.

 

Acknowledgment: This contribution is part of the ongoing research project entitled “Evaluation of the impact of rainfall interception on soil erosion” supported by the Slovenian Research and Innovation Agency (J2-4489) and it was funded in part by the Austrian Science Fund (FWF) I 6254-N.

How to cite: Parajka, J., Széles, B., Marjanovic, D., Zabret, K., Lebar, K., Vilhar, U., Bezak, N., and Šraj, M.: How rainfall interception influences soil erosion in agricultural, urban and forest catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15021, https://doi.org/10.5194/egusphere-egu24-15021, 2024.

EGU24-15203 | ECS | PICO | BG3.1

Legacy of former land use and its effect on carbon content of soil in present forests 

Pál Balázs, András Bidló, Adrienn Horváth, Máté Katona, and Péter Végh

Increasing carbon presence in the atmosphere prompts scientists to understand carbon sequestration processes better. Forest is one of the most promising ecosystems where this sequestration can take place with higher efficiency. In this research, we analysed long-term land use change processes and carbon content of soils in present Hungarian forests, searching for the answer: is there any relationship between the former land use and the carbon content of soils?
We selected 183 forest stands scattered across the country, where the age of the trees were approximately 60-70 years old. Soil samplings were carried out in the depth of 40-110 cm (in 10 cm layers). In order to derive long-term land use change information, we used historical map series dating back to the 18th century.
Results will contribute to the understanding of the carbon sequestration processes of terrestrial ecosystems.
This article was made in frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.

How to cite: Balázs, P., Bidló, A., Horváth, A., Katona, M., and Végh, P.: Legacy of former land use and its effect on carbon content of soil in present forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15203, https://doi.org/10.5194/egusphere-egu24-15203, 2024.

EGU24-16602 | PICO | BG3.1

The role of soil organic matter content in the composition and abundance of Collembola communities in a forest-open landscape mosaic 

Dániel Winkler, Mátyás Csorba, András Bidló, Pál Balázs, Péter Végh, and Adrienn Horváth

The presence of soil fauna is essential for healthy soil life. As part of the soil mesofauna, Collembola are significant contributors to humus formation and the spread of mycorrhizal fungi, which are of major importance for plants, and they also help to decompose organic matter and mineralise the soil. Among the soil parameters, organic matter content is one of the most significant determinants of the abundance and diversity of Collembola. Our study aimed to explore these relationships in a forest-open landscape mosaic in a dry, sandy area in the Danube-Tisza Mid-Region of Hungary. Soil samplings were carried out in different forest types and nearby open areas (grassland and abandoned cultivated habitats). Five non-destructive soil samples of 100 cm3 were taken at each site using a soil corer with a 3.6 cm diameter and a 10 cm depth for the soil fauna survey. In total, 2,018 specimens from 13 families, and 49 species were sampled and identified. We used a multivariate ordination method (CCA) to investigate the relationship of individual species and life forms to specific soil parameters. It was found that mainly hemiedaphic species (such as Appendisotoma franzi, A. juliannae, Lepidocyrtus nigrescens) showed the strongest connection to soil organic matter. In contrast, euedaphic species (e.g., Doutnacia xerophila, Mesaphorura krausbaueri, Protaphorura cancellata) showed a weaker binding. The epedaphic, soil surface-dwelling species (e.g., Entomobrya multifasciata, Orchesella cincta) did not show a strong preference for soil organic matter content or other soil parameters. Based on similarity analyses (cluster analysis, Bray-Curtis distance), open habitats showed a distinct separation according to the Collembola species composition and abundance.

This article was made in frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.

How to cite: Winkler, D., Csorba, M., Bidló, A., Balázs, P., Végh, P., and Horváth, A.: The role of soil organic matter content in the composition and abundance of Collembola communities in a forest-open landscape mosaic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16602, https://doi.org/10.5194/egusphere-egu24-16602, 2024.

EGU24-18551 | ECS | PICO | BG3.1

Exploring Regional-Scale Covariation: Atmospheric CO2 Anomalies Distribution Patterns, Vegetation Spread, and Climate Variables 

Buddola Jagadish, Prabir Kumar Patra, and Mukunda Dev Behera

The role of the terrestrial biosphere in regulating the global carbon cycle is critical, and it is crucial to comprehend the regional-scale source-sink dynamics and the underlying mechanisms for developing effective mitigation strategies. The present study investigated the dynamic relationship between atmospheric CO2 levels and environmental factors in South Asia (SA), Southeast Asia (SEA) and West Asia (WA); these regions are home to diverse ecosystems, including tropical rainforests, mangroves, and coral reefs. Understanding carbon dynamics in these ecosystems is crucial as they play a significant role in sequestering and storing carbon. Utilizing data from 2015 to 2021 from the OCO-2 satellite, we analyzed the column-averaged dry air mole fraction of atmospheric CO2 (XCO2) along with variables such as precipitation, temperature, and Leaf Area Index (LAI), which distinguishes between high and low vegetation types. These environmental factors were synchronized with the spatial and temporal attributes of bias-corrected Lite (V11) level-2 daily files obtained from OCO-2. The majority of the zones in the area showed a positive relationship between their temperature anomalies and XCO2 anomalies, albeit with varying lag periods (ranging from 0 to 4 months). This suggests that these zones could potentially act as sources of CO2 during warmer periods. This trend was not observed in some regions, including the western plateau and hills, eastern coastal planes and hills, Pakistan, and Nepal, where the relationship between temperature and CO2 exhibited varying lag effects. The correlations were examined between the inter-annual variability (IAV) of detrended and depersonalized monthly-resampled anomalies of XCO2 datasets and various environmental factors (anomalies) across diverse agroclimatic zones. In tropical savannah and humid subtropical climates, observed a positive correlation, between XCO2 anomalies and precipitation whereas arid and semi-arid areas displayed negative correlations. These patterns indicate that increased rainfall in certain regions might enhance vegetation productivity, thereby reducing atmospheric CO2 levels. Furthermore, in areas dominated by tropical aseasonal forests, a dense LAI correlated negatively with XCO2, suggesting that more dense vegetation leads to increased CO2 absorption through photosynthesis. In contrast, tropical seasonal forests showed a positive correlation between LAI and XCO2, each with a unique lag period. Our analysis demonstrates the complex patterns of CO2 anomalies distribution in SA, WA and SEA influenced by climatic factors (precipitation and temperature) and vegetation density (LAI). These insights are crucial for understanding regional CO2 source-sink dynamics and formulating effective climate change mitigation strategies.

How to cite: Jagadish, B., Patra, P. K., and Behera, M. D.: Exploring Regional-Scale Covariation: Atmospheric CO2 Anomalies Distribution Patterns, Vegetation Spread, and Climate Variables, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18551, https://doi.org/10.5194/egusphere-egu24-18551, 2024.

Understanding the intricate relationships between climate and vegetation remains a fundamental challenge in contemporary ecology. The ability to anticipate the specific climatic factors affecting different tree species and understand how they respond is crucial for mitigating the impacts of climate change on forested ecosystems. Additionally, quantitatively assessing habitat loss resulting from anthropogenic activities is essential for informed conservation efforts.
Our objective is to evaluate the potential distribution of pitch pine (Pinus rigida) in North America and assess the associated habitat loss. To achieve this, we employ a stepwise multidimensional climate envelope modeling approach, comparing two data-intensive models—the Variable Interaction Model (VIM) and the Variable Non-Interaction Model (VNM). These models discern the influence of diverse combinations of climatic characteristics on the distribution of the species. Both VNM and VIM employ Shapley values for factor ranking during construction. VNM assumes independent effects, resulting in a hyperrectangle-shaped climate envelope, while VIM considers interactions, yielding a complex, data-driven multidimensional envelope. Data integration involves mining the US Forest Inventories and climatic data  encompassing 19 parameters.  The results unequivocally highlight the VIM superior predictive accuracy compared to the Variable Non-Interaction Model VNM. Our findings reveal a habitat loss of approximately 91 %, primarily attributed to anthropogenic activities. This underscores the critical importance of comprehending the interplay between climatic factors in the development of climate envelope models for species ranges. The modeling approach developed in this study has the potential to enhance species distribution models for various tree species in the context of evolving climatic conditions.

How to cite: Strigul, N. and Rumyantseva, O.: Multidimensional climate envelop modeling of pitch pine (Pinus rigida) distribution in North America, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20540, https://doi.org/10.5194/egusphere-egu24-20540, 2024.

EGU24-22121 | PICO | BG3.1 | Highlight

Effect of irrigation on tree vitality in a temperate forest in Germany 

Michael Köhler, Nataliya Bilyera, Heiko Gerdes, and Henning Meesenburg

Over the past decades, extensive groundwater extraction has disturbed the water balance in the Hessian Ried region of Germany, resulting in a deepening of the groundwater table. Consequently, the forests in this area, which were initially reliant on groundwater, are now solely dependent on precipitation. The increasing frequency of summer droughts further jeopardizes the vitality of these forestsTo address these issues, above-ground irrigation as an alternative to restoring the groundwater table could be pivotal. Implementing irrigation strategies may allow to revitalize trees and/or reduce mortality rates.

To assess the impact of irrigation on tree vitality, an experiment is conducted since 2021 in the municipal forest of Gernsheim, located in the Hessian Ried region, Germany, a region, where large forest areas are suffering from groundwater abstraction. The experiment involved designated control and irrigation plots, each in threefold replication covering 2500 m2 per plot. Perforated pipes were installed at the irrigation plots on the ground, delivering water based on real-time field measurements of soil water content, matric potential, and precipitation regime. The irrigation plots received 186 mm, 505 mm, and 332 mm of additional water in 2021, 2022, and 2023, respectively.

Phenological observations indicated that irrigation prevented premature senescence of the foliage compared to control plots following a drought in 2022. Even in the following year, non-irrigated plots showed 10% less canopy cover. Additionally, leaf area index was significantly higher in 2022 and 2023 at the irrigated compared to the control plots, despite starting lower there in 2021. The negative impact of drought on tree growth was also significantly reduced by irrigation: the diameter increment of trees at irrigated plots during the drought year 2022 was similar to previous moist years for oak trees, while the increment was even higher for hornbeam trees. Tree mortality rates remained consistent at 3-5% in 2022 regardless of irrigation. However, tree mortality decreased to 0% in 2023 under the irrigation scheme, while it remained high at 10% in the control plots.

To concludeforest irrigation effectively reduced premature senescence of tree foliage during the severe drought of 2022, and thus prolonged the growing period. Irrigation significantly contributed to preserving tree vitality and reducing tree mortality in the subsequent year. Given that trees might endure the adverse effects of drought for several years, long-term studies are necessary to determine to what extent forest condition can be revitalized over time with irrigation.

How to cite: Köhler, M., Bilyera, N., Gerdes, H., and Meesenburg, H.: Effect of irrigation on tree vitality in a temperate forest in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22121, https://doi.org/10.5194/egusphere-egu24-22121, 2024.

Oaks (Quercus sp.) are common tree species growing under subtropical to (hemi-)boreal climates and are expected to become more widespread due to climate change and related adaptation management decisions. Due to their high wood density, valuable timber, resistance towards drought and long-life expectations, oaks can be promising candidates for future tree species for maintaining in-situ carbon storage in European forests as well as provisioning long-lived wood products. Forest structure is important for forest growth and forest value and is the legacy of historic forest management (or its absence), site conditions and tree species presence. Mechanistic modelling tools, such as the hybrid patch model PICUS, allow exploring possible trajectories of forest development and quantifying the effects of climate, stand density and management.Here we report on a case study in the project “OptFor-EU” in Oak-Hornbeam forests in Austria, that are already subject to water-limitations. We tested state-of-the-art stand establishment methods against naturally regenerated stands and found that large-dimension timber can be produced within less than 100 years, with appropriate intensive management routines. We demonstrate, by comparing simulations with observations, that intensified management will likely lead to reduced carbon storage and increased carbon uptake, indicating trade-offs between timber production and carbon storage. We expect that adaptive forest management alternatives can help balance forest ecosystem services and support knowledge-based decision support.

References

F. Irauschek, W. Rammer, M.J. Lexer, Evaluating multifunctionality and adaptive capacity of mountain forest management alternatives under climate change in the Eastern Alps, Eur. J. For. Res. 136 (2017) 1051–1069. https://doi.org/10.1007/s10342-017-1051-6.

M. Neumann, H. Hasenauer, Thinning Response and Potential Basal Area — A Case Study in a Mixed Sub‐Humid Low‐Elevation Oak‐Hornbeam Forest, Forests. 12 (2021). https://doi.org/10.3390/f12101354.

How to cite: Neumann, M., Pichler, J., and Lexer, M. J.: Contrasting carbon storage with timber production in managed and unmanaged Oak forests in Austria based on simulations and observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1560, https://doi.org/10.5194/egusphere-egu24-1560, 2024.

When the EU Commission launched the plan of planting additional “three billion trees” within the Green Deals` strategy, it did not foresee the outcry amongst environmentalist groups and forestry sector groups alike. For both types of stakeholders, the measure is not effective, albeit for opposite reasons: Whilst environmentalists criticise that it halters the increase of biodiversity, the forestry sector interest groups denote the strategy as not understanding the practices of tree planting in forest management. Indeed, the policy so far is reported as one of European failure, at least according to the forest reporting and monitoring systems (Forest Information System for Europe, 2022). The paper sets out to investigate the current policy responses which mirror the manyfold demands around forests for both climate mitigation and adaptation measures (Ludvig et al. 2021). Forests are often depicted as best solutions to carbon storage and the building of carbon stocks (Law et al. 2011). However, foresight studies on grounds of forest inventories have shown that forests cannot respond to many of these demands (Ledermann et al 2022)

By way of policy document analysis and expert interviews with different decision takers and interest groups at EU level (forestry, environment and climate), my research firstly asks “How is restoration for reaching climate goals perceived?” and secondly “how do the current policies relate climate-goals with restoration in the forest and land use sector?”.

The paper will contribute to disentangle the principal debates about principal trade-offs and accompanying policy mixes in the field of contested natural resources and eco-system services. Across the different documents, the understanding of “restoration” differs; likewise so along the range of stakeholder opinions. Not surprisingly, all interviewed stakeholders see the tackling of climate change as a priority. But the grounds of (scientific) understanding and argumentation are diverse. The paper disentangles those differences with outlining a classification of the principal grounds of understanding/perceptions in order to conclude with a proposal for synergetic effects of the key policy strategies involved.

How to cite: Ludvig, A.: How to tackle climate-related restoration in the forest-based sector? A focus on policy trade-offs , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1568, https://doi.org/10.5194/egusphere-egu24-1568, 2024.

EGU24-1727 | ECS | PICO | BG3.5

Multi-Functional Forestry in Europe: Balancing Climate Change Mitigation, Timber Production, and Ecosystem Services 

Konstantin Gregor, Andreas Krause, Christopher Reyer, Thomas Knoke, Susanne Suvanto, Thomas Nagel, and Anja Rammig

Forests play a crucial role in climate change mitigation strategies. They store carbon in biomass, soils, and wood products, and substituting carbon-intensive products with wood products further avoids greenhouse gas emissions. However, substantial uncertainties surround the quantification of their actual mitigation potentials.

Using dynamic vegetation modeling, we quantify the impact of various factors on the mitigation potential of forests, namely climate change and nitrogen deposition, disturbances, forest age, forest type, harvesting and wood usage practices, and the decarbonization pace of non-wood products. Our results indicate that reducing sustainable harvest levels is not reasonable within the next decades as wood products will continue to provide substantial substitution effects, even in scenarios with rapid decarbonization. However, increased material usage should be prioritized over using wood as fuel.

Climate change, disturbances, and decarbonization introduce critical uncertainties that require novel methods and data to address these uncertainties. Moreover, forests offer many more ecosystem services than climate change mitigation. Their provision needs to be considered in forward-looking, climate-smart management strategies, alongside their adaptation potential to a rapidly changing climate. To this end, we propose a robust multi-criteria optimization approach for developing strategies for multi-functional forestry that are viable across a broad range of climate scenarios and adhere to demands on timber production and EU strategies. Our methodology indicates that all these demands and aims exert strong pressure on European forests. Alleviating this pressure will be necessary to ensure healthy forests that can provide climate change mitigation and other ecosystem services.

How to cite: Gregor, K., Krause, A., Reyer, C., Knoke, T., Suvanto, S., Nagel, T., and Rammig, A.: Multi-Functional Forestry in Europe: Balancing Climate Change Mitigation, Timber Production, and Ecosystem Services, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1727, https://doi.org/10.5194/egusphere-egu24-1727, 2024.

EGU24-3090 | PICO | BG3.5

Enhanced precipitation events and forests stability: a case study in Emilia-Romagna and Tuscany (Italy). 

Teodoro Georgiadis, Letizia Cremonini, Giorgio Matteucci, Federica Rossi, Francesca Giannetti, Ilaria Zorzi, Alessio Collalti, Ettore D'andrea, and Simone Cardoni

Climate change is endangering natural and anthropogenic ecosystems, as pointed out by the recent IPCC Reports and the COPs' statements. The impacts of climate change on natural ecosystems can affect their production capacity, particularly in those systems characterized by a high quality of yields, especially in densely populated and industrialized countries. We analyze two recent intense rainfall events that hit the Emilia-Romagna and Tuscany (Italy) regions and the damage caused to the agricultural ecosystems downstream of forests and woodlands. Although the scientific debate on these events' climatic or purely meteorological origin is still open, these occurrences provide a potential direct example of the harm climate change may bring. The topic of forest management for risk reduction is also analyzed on the forest itself and anthropized systems and related economies. The study was conducted within the European OptFor-EU Project.

 

How to cite: Georgiadis, T., Cremonini, L., Matteucci, G., Rossi, F., Giannetti, F., Zorzi, I., Collalti, A., D'andrea, E., and Cardoni, S.: Enhanced precipitation events and forests stability: a case study in Emilia-Romagna and Tuscany (Italy)., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3090, https://doi.org/10.5194/egusphere-egu24-3090, 2024.

Forests are expected to provide several ecosystem services, such as wood production, clean water and carbon sequestration and storage, simultaneously. The basic aerial unit of forest management is gradually changing from stand to catchment scale. Catchment scale management of forest nutrient balance is an important part of modern forestry. A leap towards holistic management of ecosystem services through customised forest management strategies has become possible when high resolution forest, terrain, and soil data can be combined with detailed process-based ecosystem models. We have developed catchment level, spatially distributed nutrient balance and hydrology models, which calculate location-specific forest growth, carbon and nutrient dynamics, and the nutrient export to water courses. Model applications have shown that the nutrient export is very unevenly distributed throughout catchments: 5 % of the catchment area can produce 25% of the nitrogen export. This identification of nutrient export hotspots facilitates knowledge-based planning of forest operations and cost-efficient locating of water protection. We have found that catchments may also contain locations where the stand growth is nutrient limited. This opens the possibility for precision fertilization in which the quality, dose and timing of the fertilization can be adjusted so that the site-specific nutrient supply meets the nutrient demand. Our simulations indicate that especially in peatland forests, fertilization together with water and forest management can effectively improve wood production, decrease carbon emissions and control nutrient export to watercourses.  Furthermore, these models can be used to compare different harvesting methods and forest management strategies with respect to multiple ecosystem services. Process-based ecosystem models including nutrient balance and geospatial high-resolution data are particularly useful in forecasting the effects of climate change allowing development of pro-active adaptation schemes in a specific catchment.

How to cite: Palviainen, M. and Laurén, A.: Nutrient balance as a tool in multi-objective forest management aiming at climate change mitigation and other ecosystem services, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3102, https://doi.org/10.5194/egusphere-egu24-3102, 2024.

EGU24-3418 | ECS | PICO | BG3.5 | Highlight

European Forest Type Map 

Francesca Giannetti, Ilaria Zorzi, Stefanie Linser, Mathias Neumann, Sorin Cheval, Alessio Collalti, Elia Vangi, Elisa Grieco, Davide Travaglini, Gherardo Chirici, and Anna Barbati

Forest types are key factors to consider when monitoring forests, particularly in consideration of  the increasing need to assess how climate change is affecting different forests in Europe and beyond. A comprehensive classification system is indeed essential for understanding the diverse forest ecosystems, tracking their changes over time and across various spatial and geographical scales. Moreover, it provides valuable insights on the baseline conditions and current states of forest ecosystems, aiding in decision-making for conservation and resource management. 

A "forest type classification scheme" aims to break down extensive forested areas, like stocked forest land, into smaller, more similar units. This breakdown helps streamline the analysis, interpretation, and communication of forest-related data. In Europe, the European Forest Types (EFT) classification system has demonstrated its effectiveness and user-friendliness in facilitating the comprehension, interpretation, and dissemination of data regarding indicators that depict the conditions and changes within European forests, as well as forest management practices. The EFT, could support a standardised reporting of several forest area related indicators. This includes assessments of biodiversity, organised into ecologically similar groups across the entire European region. However, until now, there was no EFTs map available for Europe.  To produce the map, a comprehensive analysis of relevant spatial datasets available at the European scale, essential for mapping, was first carried out.  Based on the variety of the datasets available, the JRC dataset featuring a comprehensive 39 forest tree species "relative probability of presence (RPP) maps”, was used along with eight different forest masks developed to identify environmental diversity, to accurately identify the different EFT categories. The RPP maps and the forest masks were used as inputs in a rule-based expert system algorithm to identify the 14 EFT categories and provide a thorough explanation for the classification of the EFT categories. The raster map created at a scale of 100 metres enabled the production of the first consistent EFTs maps across Europe and marked a significant advancement, providing a systematic means of classifying forest areas into EFTs, filling a critical gap in the spatial monitoring and reporting of forest indicators in the context of international frameworks. Moreover, existing EFTs maps can effectively be used as a basis for forest monitoring and support for decision-making, including forest-based adaptation and mitigation needs.

This study was funded by the Horizon Europe Project OptFor-EU (Grant agreement n°101060554).

How to cite: Giannetti, F., Zorzi, I., Linser, S., Neumann, M., Cheval, S., Collalti, A., Vangi, E., Grieco, E., Travaglini, D., Chirici, G., and Barbati, A.: European Forest Type Map, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3418, https://doi.org/10.5194/egusphere-egu24-3418, 2024.

EGU24-10675 | ECS | PICO | BG3.5

Assessing the effects of heat and droughts on forest-climate interactions in Europe using a regional climate model with an interactively coupled vegetation module  

Christina Asmus, Lars Buntemeyer, Florian Knutzen, Joni-Pekka Pietikäinen, and Diana Rechid

Forests play a pivotal role in the climate system by exchanging energy, water, and gases with the atmosphere.  Through biogeochemical processes such as photosynthesis, respiration, and transpiration, forests heavily influence the carbon and water cycles. In particular, their capacity to sequester carbon through photosynthesis demonstrates their role as carbon sinks. Further, through biogeophysical processes forests influence the local and regional climate by determining local temperature and humidity distributions. 

However, forests not only influence the climate - they are also affected by it. Their vulnerability to climate extremes, particularly to heat and droughts, raises substantial challenges. Droughts induce water stress, affecting both biogeochemical and biogeophysical processes, at the soil-forest-atmosphere interface. Within the EU Horizon project OptFor-EU and in collaboration with the Euro-CORDEX Flagship Pilot Study LUCAS, we employ numerical models to assess the climate-forest interactions and to evaluate forest resilience in a changing climate. 

In this study, we examine the effects of heat and droughts on European forests and their climatic feedbacks in simulations using the regional climate model REMO2020 coupled with its interactive, mosaic-based vegetation module iMOVE. The coupling enables the exchange of crucial parameters on model timestep level, and therefore, captures the complex interactions between climate, soil, and vegetation. We focus on biophysiological forest parameters such as the leaf area index (LAI), as well as on biophysical processes such as evapotranspiration, and on their feedbacks with the regional climate. Our simulations cover the European continent and have a horizontal resolution of 0.11°, forced with reanalysis data from ERA5.1 at the lateral boundaries. Starting from 1981 until 2020, they cover the hot and dry years of the last decades, such as 2003 and 2018-2020.  Our findings reveal insights into the vulnerability and resilience of European forests to heat and drought events, as well as into their role in climate extremes mitigation.   

Acknowledgments

This research received funds from the project “OPTimising FORest management decisions for a low-carbon, climate resilient future in Europe (OptFor-EU)” funded by the European Union Horizon Europe programme, under Grant agreement n°101060554. 

How to cite: Asmus, C., Buntemeyer, L., Knutzen, F., Pietikäinen, J.-P., and Rechid, D.: Assessing the effects of heat and droughts on forest-climate interactions in Europe using a regional climate model with an interactively coupled vegetation module , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10675, https://doi.org/10.5194/egusphere-egu24-10675, 2024.

Removal of CO2 from the atmosphere (CDR) will most likely be required to reach the goal of the Paris Agreement to limit global warming to well-below 2°C above pre-industrial temperature, in addition to rapid reduction of greenhouse gas emissions. Re-/afforestation (A/R) is among the most prominently discussed CDR methods, as it can be realized at low cost and is already implemented in many places today. However, forests are vulnerable to various disturbances caused by climate change, such as wildfires, droughts, and heat stress, which can lead to a decreased CO2 uptake or even a release of previously stored carbon back to the atmosphere. There is still a high uncertainty on the effects of climate change on the CDR potential of A/R. Here, we show spatially explicit how climate change affects the potential of A/R to sequester and store carbon under severe climate change (SSP3-7.0) and moderate climate change (SSP1-2.6), as simulated by the dynamic global vegetation model LPJmL5. Utilizing a highly stylized global afforestation scenario, we explore changes in net primary productivity, soil respiration and CO2 emissions from fires and identify the region-specific underlying causes (such as soil moisture changes or heat stress). We also demonstrate to what extent CO2 fertilization could counteract detrimental effects of climate change and highlight the possibility to underestimate climate impacts by overestimating the CO2 fertilization effect. By revealing and explaining spatial patterns of simulated future climate impacts on the CDR potential of A/R, our study contributes to a more profound understanding of the role A/R might be able to play in removing CO2 from the atmosphere.

How to cite: Mathesius, S. and Gerten, D.: Spatially differentiated impacts of climate change on the carbon sequestration potential of afforestation and reforestation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10702, https://doi.org/10.5194/egusphere-egu24-10702, 2024.

The global forest cover is undergoing significant changes which affect climate through biophysical and biogeochemical processes. Using potential biophysical effects and carbon flux datasets, we quantify the biophysical and biogeochemical impacts of forest cover changes over the past two decades. The net loss of global forest cover from 2001 to 2020 resulted in global average warming of 0.0042°C, with biophysical and biogeochemical contributions of 0.0020°C and 0.0022°C, respectively. The biophysical impacts dominated most regions of the world (68%), and the biogeochemical impacts were mainly concentrated in Europe and the tropics. The tradeoff between biophysical and biogeochemical impacts was found for 58% of forest cover change areas, mainly in boreal regions, while synergy was distributed in the southeastern United States and tropical regions. The study highlights the urgent need to protect and manage forest cover to reverse the warming.

How to cite: Li, Y. and Chen, H.: The biophysical and biogeochemical impacts of global forest cover changes on land surface temperature from 2001 to 2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13869, https://doi.org/10.5194/egusphere-egu24-13869, 2024.

EGU24-14662 | ECS | PICO | BG3.5

The critical role of optimal forest management in China for meeting its wood demand and climate target 

Haotian Zhang, Hao Zhao, Pekka Lauri, Nicklas Forsell, Petr Havlik, and Jinfeng Chang

China’s demand for wood and forest products continues to grow with the booming papermaking industry and residence use, leading to a dramatic increase in imports of wood products. Meanwhile, woody biomass for bioenergy with carbon capture and storage (BECCS) has been projected as a pivotal negative emission strategy in meeting climate goals in the future. However, the imposition of natural forest ban and the pursuit of future climate targets may create additional gaps in the availability of forestry products. Here, we use the GLOBIOM-China model to assess the impacts of diverse woody biomass demands, national programs for afforestation and forest plantation, and management measures in China under climate targets. The results indicate an increase in domestic roundwood consumption by 20.3~50.3 million m3 in 2050 under 1.5℃ scenario compared to that under the baseline scenario (BAU) without BECCS demand, with increased proportion for wood fuel uses and less for pulp and sawn wood consumption. Domestic production fails to meet the energy and material demands for woody products by 2060, necessitating an additional import of 63~144 million m3 of roundwood compared with the BAU, approximately accounting for 29~46% of domestic production. Enhancing logging potential can help prevent the continued transformation of natural forests into managed forests and forest plantations on cropland, as well as reduce roundwood imports by 55-89 million m3, when compared to the management of forests under normal increments. Moreover, such productivity enhancement could contribute to an additional sequestration in forestry of 0.1-1.26 Gt CO2 by 2060. This study underscores the imperative for enhanced forestry system management in China to effectively meet its ambitious climate commitments.

How to cite: Zhang, H., Zhao, H., Lauri, P., Forsell, N., Havlik, P., and Chang, J.: The critical role of optimal forest management in China for meeting its wood demand and climate target, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14662, https://doi.org/10.5194/egusphere-egu24-14662, 2024.

EGU24-14753 | PICO | BG3.5

Changes in climate extremes over the European Forest Types (1991-2050) 

Sorin Cheval, Francesca Gianetti, Alessio Collalti, Alexandru Dumitrescu, Mathias Neumann, and Nicu Constantin Tudose

A forest type (FT) generally describes a category of forest defined by its composition, and/or site-specific factors, and used in a system suitable to the situation at country level. The FTs are recognised to be a flexible approach to support the collection of data and organise forest indicators in a given area at different spatial scales, from country up to continental level.

The ongoing climate change is associated with increased intensity, duration and spatial extent of climate extremes, which may exacerbate the impacts on many ecological systems and socio-economic sectors, including  forest ecosystems and forest management.

This study explores the observed variability (1991-2020) and estimated changes (2021-2050) in the climate extremes that may occur over the European Forest Types (EFT), to provide a continental-scale perspective of the potential impact on forest ecosystems and provide decision support for forest management. Both temperature and precipitation CLIMPACT extremes indices relevant for forestry described and proposed by the Expert Team on Sector-Specific Climate Indices were computed using CERRA sub-daily regional reanalysis data for Europe. We use model outputs of climate change projections based on two Representative Concentration Pathways (i.e., RCP4.5, and RCP8.5). The climate information was analysed in combination with the 100 m resolution gridded EFT dataset produced within the Horizon Europe project OptFor-EU, ensuring consistency with similar studies at the European level. The results are detailed for case study areas situated in eight European countries (Norway, Lithuania, United Kingdom, Germany, Austria, Romania, Spain, and Italy).

While all EFTs are subject to increasing temperatures extremes and precipitation intensities, we found clear regional differences. The continental coverage and the level of details provided by these results support both the development of EU adaptation and mitigation strategies and plans, as well as the local forest management practices within the climate change context.

Acknowledgements

This research received funds from the project “OPTimising FORest management decisions for a low-carbon, climate resilient future in Europe (OptFor-EU)” funded by the European Union Horizon Europe programme, under Grant agreement n°101060554.

How to cite: Cheval, S., Gianetti, F., Collalti, A., Dumitrescu, A., Neumann, M., and Tudose, N. C.: Changes in climate extremes over the European Forest Types (1991-2050), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14753, https://doi.org/10.5194/egusphere-egu24-14753, 2024.

EGU24-16389 | PICO | BG3.5

Co-developing a Decision Support System for climate adaptation and mitigation of European forests: lessons learnt from the stakeholder engagement 

Nicu Constantin Tudose, Christina Asmus, Sorin Cheval, Teodoro Georgiadis, Hermine Mitter, Miguel Inácio, Marius Rohde Johannessen, Jasdeep Anand, Florian Knutzen, Stefanie Linser, Mirabela Marin, Giorgio Matteucci, Mathias Neumann, Paulo Pereira, Raul Gheorghe Radu, Mar Riera Spiegelhalder, and Cezar Ungurean

Climate change stands as a primary stressor, exerting various adverse effects on forests that are particularly susceptible to swift alterations in climatic parameters. At the same time, forests provide a range of ecosystem services beneficial for society. Therefore, a proper management and planning of forests is essential to mitigate the effects of climate change and provide valuable services. Forest management and planning is a complex process due to numerous socio-economic, administrative or environmental aspects that should be considered at different spatial scales. To this end, Decision Support Systems (DSSs) proved to be valuable tools that guide forest managers in enhancing forest resilience and its capacities to mitigate climate change. Engaging stakeholders from the very beginning of the DSSs development process is seen as a prerequisite for the project’s success, adding value and delivering more serviceable outputs. 

Here, we summarize the most important outputs stemming from a stakeholder engagement process that occurred between July−December 2023, in order to raise awareness about the role of forests in achieving climate ambitions, identify relevant stakeholders and build relationships. These aspects serve as a basis for achieving the following research objectives: provide an improved characterisation of the forest services to mitigate climate change related risks, utilise end-user focused process modelling, empower forest end-users to make informed decisions to enhance forest resilience and forest mitigation, provide a novel decision support tool, bridging different European Union strategic priorities, robust science, and stakeholders in the forest and forest-based sectors. In addition, a novel set of Essential Forest Mitigation Indicators (EFMI) will be proposed to assess the climate change impact and its relation to forest management. Their relevance will be validated through stakeholder consultation.

The stakeholder engagement was performed through on-site workshops, and online, phone and email consultations, in eight European countries (Norway, Lithuania, United Kingdom, Germany, Austria, Romania, Spain, and Italy). Common issues that arose through the engagement of stakeholders are related to the challenges of handling different variables (e.g. scale of the study area, public/private forest ownership) between countries and differences in forest management across case studies. The most important lessons learned after the stakeholders workshops are: the importance of trusted relationships with local partners for an effective stakeholder engagement, the significance of including the stakeholders needs and expectations for a successful, long-term partnership, avoiding language barriers by using a non-technical language, as well as long-term policies and funding sources for planning security. A unique feature of the conducted workshops is the interest of stakeholders to be involved and contribute to the development of the Forest DSS, as a user-friendly and tailored tool to their needs.

Acknowledgements

This research received funds from the project “OPTimising FORest management decisions for a low-carbon, climate resilient future in Europe (OptFor-EU)” funded by the European Union Horizon Europe programme, under Grant agreement n°101060554

How to cite: Tudose, N. C., Asmus, C., Cheval, S., Georgiadis, T., Mitter, H., Inácio, M., Johannessen, M. R., Anand, J., Knutzen, F., Linser, S., Marin, M., Matteucci, G., Neumann, M., Pereira, P., Radu, R. G., Spiegelhalder, M. R., and Ungurean, C.: Co-developing a Decision Support System for climate adaptation and mitigation of European forests: lessons learnt from the stakeholder engagement, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16389, https://doi.org/10.5194/egusphere-egu24-16389, 2024.

EGU24-16649 | PICO | BG3.5

Assessing the Forest Management Impact on Forest Carbon Dynamics in Romanian Forests 

Raul Gheorghe Radu, Mathias Neumann, Nicu Constantin Tudose, Mirabela Marin, Cezar Ungurean, and Sorin Cheval

Forests play a crucial role in the EU's strategy for decarbonisation and in achieving neutrality targets, primarily through their capacity for carbon sequestration (carbon stock change) and storage (carbon stock) in above-ground biomass, dead organic matter, and soil organic matter. Alongside reforestation, sustainable forest management practices can further enhance the role of forests in decarbonisation. Our focus is on the Argeș-Vedea basin in Romania, a region stretching from the Carpathian Mountains to the Danube River. We analyse systematic sample plots across an area covering 300,000 hectares of forest.

We studied the relationship between stand attributes (basal area, diameter at breast height, age, species) and carbon stock changes in various carbon pools, evaluated also under different forest management practices context. Correlation analysis reveals a negative correlation between basal area and carbon stock changes in living trees and litter, which suggests that an increased basal area leads to reduced carbon stock changes (r= -0.15). Older stands tend to have lower net living tree carbon changes due to reduced growth and increased disturbance. Similarly, we found that soil carbon stock generally increases with the age of stands and decreases following disturbance, such as the harvesting of older stands (i.e., on average, by 10%).

The effects of various forest management practices (no intervention, clear-cuts, shelterwood, thinning, and stands affected by natural disturbance) on different carbon pools are distinct. While all interventions generally decrease carbon stock in above-ground biomass, thinning operations result in a minor increase, especially in the lower-density stands, but still five times less than non-intervention stands (+13 tC/ha) with a decrease in deadwood carbon, indicating the role of selective removal in forest health maintenance. In contrast, in no intervention management increases living tree carbon, underscoring the benefits of natural forest dynamics. Stands in the initial development stage exhibit the highest carbon sequestration capacity (+11 tC/ha), while stands in the understory initialization stage show a decrease in tree biomass (-11 tC/ha) due to the harvesting operations. Natural disturbances significantly impact the deadwood pool, tripling the carbon stock change compared to shelterwood-managed stands. Stands, where thinning is performed, are the only ones showing decreased deadwood carbon stock change. Similarly, the litter pool decreases in stands undergoing thinning and clear-cutting. Regarding the regeneration pool, stands affected by clear-cuts and natural disturbance (in a five-year period) showed the highest decrease in carbon stock change (-0.03 tC/ha).

This research reveals key insights into the variations in carbon stock caused by different management practices and the age progression of forest stands. This information is crucial for accurately modelling the carbon dynamics within forest ecosystems.

How to cite: Radu, R. G., Neumann, M., Tudose, N. C., Marin, M., Ungurean, C., and Cheval, S.: Assessing the Forest Management Impact on Forest Carbon Dynamics in Romanian Forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16649, https://doi.org/10.5194/egusphere-egu24-16649, 2024.

EGU24-16822 | ECS | PICO | BG3.5

Navigating Climate Change: Exploring Plenter Forest Potential in Styria, Austria 

Mathias Leiter, Christoph Pucher, Ferdinand Hönigsberger, Michael Kessler, Manfred J. Lexer, Harald Vacik, and Hubert Hasenauer

Forests stand at the forefront of climate change adaptation strategies, with their ability to sequester and store carbon, sustain bioeconomies, foster biodiversity, and provide a whole range of other ecosystem services. There is an increasing trend of promoting this multipurpose functionality of forests, resulting in a shift towards silvicultural practices that differ heavily from the now dominant even-aged, clear-cut forestry. One of these alternative management practices to promote multipurpose functionality is plenter forest management, a type of uneven-aged selection cutting system. Only little is known about the applicability of this management system on a regional or national scale. Therefore, this study assesses the potential expansion of plenter forest management, crucial for climate change mitigation. Focusing on tree species suitability, harvesting constraints, and road accessibility, we analysed factors impacting plenter management for the Austrian province of Styria for current and future climate conditions. Our findings reveal that while current forestry predominantly features even-aged Norway spruce, approximately 14% of the forest area could be managed as mixed-species plenter forests under current conditions. This research contributes to understanding potential in transforming forest practices for enhanced biodiversity, ecosystem services, and climate resilience on a regional scale.

How to cite: Leiter, M., Pucher, C., Hönigsberger, F., Kessler, M., Lexer, M. J., Vacik, H., and Hasenauer, H.: Navigating Climate Change: Exploring Plenter Forest Potential in Styria, Austria, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16822, https://doi.org/10.5194/egusphere-egu24-16822, 2024.

EGU24-21572 | PICO | BG3.5

Carbon stock projection for four major forest plantation species in Japan 

Tomohiro Egusa, Ryo Nakahata, Mathias Neumann, and Tomo'omi Kumagai

Carbon sequestration via afforestation and forest growth is effective for mitigating global warming. Accurate and robust information on forest growth characteristics by tree species, region, and large-scale land-use change is vital and future prediction of forest carbon stocks based on this information is of great significance. We presented the forest age–carbon density functions of four major forest plantation species in Japan: Cryptomeria japonica, Chamaecyparis obtusa, Pinus spp., and Larix kaempferi. We then investigated the differences in the carbon sequestration potential of forests, including wood production, between five forestry practice scenarios with varying harvesting and afforestation rates, until 2061. For all four forest types, the estimates of growth rates and past forest carbon stocks were higher than those considered thus far. The predicted carbon sequestration from 2011 to 2061, assuming that 100% of harvested carbon is retained for a long time, twice the rate of harvesting compared to the current rate, and a 100% afforestation rate in harvested area, was three to four times higher than that in a scenario with no harvesting or replanting. Our results suggest that planted Japanese forests can exhibit high carbon sequestration potential under the premise of active forest management with technology development.

How to cite: Egusa, T., Nakahata, R., Neumann, M., and Kumagai, T.: Carbon stock projection for four major forest plantation species in Japan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21572, https://doi.org/10.5194/egusphere-egu24-21572, 2024.

EGU24-341 | ECS | Posters on site | BG3.6

Integrated Assessment of Climate Change and Forest Management Impacts on Carbon Fluxes and Biomass in a Southern Boreal Forest  

Md Rafikul Islam, Anna Maria Jönsson, John Bergkvist, Fredrik Lagergren, Mats Lindeskog, Meelis Mölder, Marko Scholze, and Natascha Kljun

Boreal forests play a crucial role in global carbon sequestration and storage, yet their vulnerability to climate change remains a significant concern. We present results from simulations with the process-based dynamic global vegetation model LPJ-GUESS of the combined effects of climate change and forest management on the carbon sink capacity of a boreal forest in southern Sweden. We compared two future climate change scenarios (RCP 4.5 and RCP 8.5) along with four forest management options against a baseline scenario without management interventions. Our findings indicate that projected temperature increases (+2 to +4°C) in the late 21st century will diminish the net carbon sink strength, particularly in old-growth forests. Clear-cut and subsequent reforestation resulted in a substantial decline (57-67%) in vegetation carbon during 2022-2100. The carbon compensation point (CCP) was reached 12-16 years after the clear-cut, indicating a period of carbon debt before the ecosystems resumed acting as a net carbon sink. Specific reforestation strategies, such as pine plantations, enhanced the overall net carbon sink by 7-20% relative to the baseline during 2022-2100. The carbon parity point, without considering harvested carbon, was reached 56-73 years after the clear-cut, highlighting the extended period required for the reforestation to achieve a carbon stock equivalent to the uncut baseline. These findings highlight the substantial influence of forest management on the net carbon budget, surpassing that of climate change alone. The adoption of relevant reforestation strategies could enhance carbon uptake, simultaneously improving forest productivity and ensuring the forest's vital role in carbon sequestration and storage amid a changing climate.

How to cite: Islam, M. R., Jönsson, A. M., Bergkvist, J., Lagergren, F., Lindeskog, M., Mölder, M., Scholze, M., and Kljun, N.: Integrated Assessment of Climate Change and Forest Management Impacts on Carbon Fluxes and Biomass in a Southern Boreal Forest , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-341, https://doi.org/10.5194/egusphere-egu24-341, 2024.

EGU24-1159 | ECS | Posters on site | BG3.6

Impact of climate and agricultural management practices on carbon fluxes using a CLM5 land surface model 

K Narender Reddy and Somnath Baidya Roy

Carbon exchange from agroecosystems contributes to the fluctuations of the carbon cycle. The present research employs the Community Land Model version 5 (CLM5) to examine the effects of climate and agricultural management methods, such as fertilization and irrigation, on carbon fluxes in the primary agroecosystems of India. In this study, CLM5 is calibrated and validated against the crop phenology dataset of spring wheat and rice. The crop phenology data is an unprecedented dataset that we have compiled by gathering information from many agricultural institutes around India. The crop dataset covers the period from 1970 to 2020. We have comprehensively tested and validated the CLM5 crop module in the Indian region. Subsequently, regional-scale simulations were conducted. The findings indicated that there are large variations in fluxes among different climatic regions of India, primarily due to disparities in growing circumstances. Throughout the study period, all fluxes exhibited statistically significant upward trends (p<0.1). Further numerical experiments are performed to examine the potential impact of natural factors, such as variations in temperature and levels of carbon dioxide (CO2), as well as agricultural techniques like nitrogen fertilizer and water availability, on the previously observed upward trends. The tests demonstrated that elevated levels of carbon dioxide (CO2), nitrogen fertilization, and irrigation water resulted in heightened carbon fluxes, with nitrogen fertilization exerting the most pronounced impact.

How to cite: Reddy, K. N. and Baidya Roy, S.: Impact of climate and agricultural management practices on carbon fluxes using a CLM5 land surface model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1159, https://doi.org/10.5194/egusphere-egu24-1159, 2024.

EGU24-2469 | ECS | Posters on site | BG3.6

Greening fails to translate into an increase in Net Primary Productivity due to warming constraints in India 

Ripan Das, Rajiv Kumar Chaturvedi, Adrija Roy, Subhankar Karmakar, and Subimal Ghosh

India has made the second-largest contribution to global greening in the last two decades. However, it is not clear whether this greening has led to an overall increase in net primary productivity and hence carbon uptake potential, given the impact of climate change on vegetation. In this study, using MODIS satellite data for the period 2001–2019, we attempt to find out the extent to which increased greening in India has led to an overall increase in primary productivity in recent decades. Despite a statistically significant increase in the Leaf Area Index (LAI), we found a slightly decreasing trend (not statistically significant) in Net Primary Productivity (NPP) and stable Gross Primary Productivity (GPP) during the 21st century. Our analysis also shows that the NPP of temporally consistent Indian forests shows a significant decreasing trend despite the increase in LAI. Notably, there are spatial differences in the NPP trend, with the regions contributing the most to NPP in India showing a stronger decreasing trend. The regions with a significantly decreasing NPP trend also experienced the strongest warming during the study period. We also used the nonlinear kernel regression method to investigate the temperature response of vegetation productivity in these regions. We observed that photosynthesis in these regions decreased above a certain temperature and respiration became stable, leading to a decrease in NPP. Our analysis shows that climate change, especially the rise in temperature, has already begun to affect vegetation productivity and carbon uptake in Indian forests. The study also conveys the clear scientific message that increased greening does not necessarily lead to increased carbon uptake, especially in a country like India where agriculture is intensifying. This analysis also has significant implications for the scientific analysis of planning to achieve India's net zero emissions pledge by 2070.

How to cite: Das, R., Chaturvedi, R. K., Roy, A., Karmakar, S., and Ghosh, S.: Greening fails to translate into an increase in Net Primary Productivity due to warming constraints in India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2469, https://doi.org/10.5194/egusphere-egu24-2469, 2024.

EGU24-2558 | Orals | BG3.6 | Highlight

The Database of European Forest Insect and Disease Disturbances: DEFID2 

Giovanni Forzieri and the DEFID2 team

Insect and disease outbreaks in forests are biotic disturbances that can profoundly alter ecosystem dynamics. In many parts of the world, these disturbance regimes are intensifying as the climate changes and shifts the distribution of species and biomes. As a result, key forest ecosystem services, such as carbon sequestration, regulation of water flows, wood production, protection of soils, and the conservation of biodiversity could be increasingly compromised. Despite the relevance of these detrimental effects, there are currently no spatially detailed databases that record insect and disease disturbances on forests at the pan-European scale. Here, we present the new Database of European Forest Insect and Disease Disturbances (DEFID2). It comprises over 650,000 harmonized georeferenced records, mapped as polygons or points, of insects and disease disturbances that occurred between 1963 and 2021 in European forests. The records currently span eight different countries and were acquired through diverse methods (e.g., ground surveys, remote sensing techniques). The records in DEFID2 are described by a set of qualitative attributes, including severity and patterns of damage symptoms, agents, host tree species, climate-driven trigger factors, silvicultural practices, and eventual sanitary interventions. They are further complemented with a satellite-based quantitative characterization of the affected forest areas based on Landsat Normalized Burn Ratio time series, and damage metrics derived from them using the LandTrendr spectral-temporal segmentation algorithm (including onset, duration, magnitude, and rate of the disturbance), and possible interactions with windthrow and wildfire events. The DEFID2 database is a novel resource for many large-scale applications dealing with biotic disturbances. It offers a unique contribution to design networks of experiments, improve our understanding of ecological processes underlying biotic forest disturbances, monitor their dynamics and enhance their representation in land-climate models. Further data sharing is encouraged to extend and improve the DEFID2 database continuously. The database is freely available at https://jeodpp.jrc.ec.europa.eu/ftp/jrc-opendata/FOREST/DISTURBANCES/DEFID2/.

How to cite: Forzieri, G. and the DEFID2 team: The Database of European Forest Insect and Disease Disturbances: DEFID2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2558, https://doi.org/10.5194/egusphere-egu24-2558, 2024.

EGU24-3354 | ECS | Posters on site | BG3.6

Assessing the climatological stability of the Congo basin rainforest 

Steven De Hertog, Félicien Meunier, and Hans Verbeeck

The Congo basin forests play a crucial role in the global carbon cycle, hosting a carbon sink of more than 10% of the global sink. This carbon potential also appears more stable than those of comparable other tropical forests. However, despite its importance for global climate, the Congo basin forest is receiving much less scientific attention. Yet, in recent years the body of data and knowledge is reaching a critical level which allows a study on the stability of the Congo basin forest under present and future climates. Here we applied an advanced vegetation model (ED2) over the Congo basin forests and explored their potential (in)stability under different climate forcings. The main objective was to explore the climate sensitivity of the Congo basin forests in terms of functional composition and carbon balance. This allows to asses the risk of the rain forest to shift into a savanna type vegetation. We addressed this question by integrating for the first time observational meteorological data available over the Congo basin in order to evaluate global reanalysis and climate modelling datasets. This led to unique simulations of the vegetation changes observed during past decades as well as for potential climate futures.

How to cite: De Hertog, S., Meunier, F., and Verbeeck, H.: Assessing the climatological stability of the Congo basin rainforest, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3354, https://doi.org/10.5194/egusphere-egu24-3354, 2024.

EGU24-3780 | ECS | Posters on site | BG3.6

Significant Impacts of El Niño-Southern Oscillation and Indian Ocean Dipole on China’s Gross Primary Production 

Ran Yan, Jun Wang, Weimin Ju, Xunmei Wang, and Jingye Tan

Gross primary production (GPP) stands as a crucial component in the terrestrial carbon cycle, greatly affected by large-scale circulation adjustments. This study investigates the influence of El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on China’s GPP, utilizing long-term GPP data simulated by the Boreal Ecosystem Productivity Simulator (BEPS). Partial correlation coefficients between GPP and ENSO reveal substantial negative associations in most parts of western and northern China during September-October-November (SON). These correlations shift to strongly positive over southern China in December-January-February (DJF), then weaken in March-April-May (MAM), eventually turning generally negative over southwestern and northeastern China in June-July-August (JJA). In contrast, the relationship between GPP and IOD basically exhibits opposite patterns. Composite analysis further confirms these seasonal GPP anomalous patterns. Mechanistically, we ascertain that, in general, these variations are predominantly controlled by soil moisture in SON and JJA, but temperature in DJF and MAM. Quantitatively, China's annual GPP demonstrates modest positive anomalies in La Niña and nIOD years, in contrast to minor negative anomalies in El Niño and pIOD years. This results from counterbalancing effects with significantly greater GPP anomalous magnitudes in DJF and JJA. Additionally, the relative changes in total GPP anomalies at the provincial scale display an east-west pattern in annual variation, while the influence of IOD events on GPP presents an opposing north-south pattern. We believe that this study can significantly contribute to our comprehension of how intricate atmospheric dynamics influence China’s GPP on an interannual scale.

How to cite: Yan, R., Wang, J., Ju, W., Wang, X., and Tan, J.: Significant Impacts of El Niño-Southern Oscillation and Indian Ocean Dipole on China’s Gross Primary Production, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3780, https://doi.org/10.5194/egusphere-egu24-3780, 2024.

EGU24-3888 | ECS | Orals | BG3.6

The covariation of forest age shifts and net carbon balance over the period 2010 to 2020 

Simon Besnard, Viola H.A Heinrich, Nuno Carvalhais, Martin Herold, Wouter Peters, Ingrid Luijkx, Maurizio Santoro, and Hui Yang

Understanding the relationship between forest age, an indicator of successional stages, and net carbon fluxes is crucial for effective forest management and climate mitigation. Using the satellite-based Global Age Mapping Integration (GAMI) v1.0 dataset, we analyzed forest age shifts from 2010 to 2020 and their correlation with net carbon dioxide (CO2) flux changes from independent atmospheric inversions. Globally, we do not report substantial forest age shifts during this period. The total area of young (1-20 years old), intermediate (21-60 years old), mature (61-150 years old), and old-growth (>150 years old) forests in 2020 compared to 2010 changed by approximately -0.07 (-7.7% compared to 2010), +0.03 (+6.0%), +0.03 (+2.1%), +0.01 (+1.1%) billion hectares, respectively. Despite these relatively stable global trends in forest age classes, we observe substantial changes at the regional scales. The Amazon, Congo basin, and Southeast Asia regionally experienced significant forest age decreases with local changes of up to 30% compared to 2010, attributed to deforestation and degradation. Siberian forests maintained their older age structure; however, large areas are transitioning to younger ages (0.09 billion hectares, 7.2% of Eurasia Boreal region), likely driven by increased fire frequency, logging activities, or climate-induced changes. Most European and North American forests trended toward older ages. However, those changes were heterogeneous at the sub-pixel level, revealing a complex mix of stand-replacement and aging dynamics across the different forest age spectrums. Stand-replaced forests, followed by regrowth, constitute a relatively minor fraction (6%) of the overall forested ecosystems, primarily dominated by aging forests (64%) and "stable" old-growth tropical forests (30%). Stand-replaced forests were prominent in young forests (0.1 billion hectares, 54.3% of total stand-replaced forests), while intermediate, mature, and old-growth forests accounted for 13.2%, 17.9%, and 14.6% of the total area of stand-replaced forests. Conversely, aging forests (excluding old-growth "stable" tropical forests) were primarily observed in the mature age classes, encompassing 1.2 billion hectares and constituting around 53% of the total aging forests. When coupling GAMI data with CO2 flux estimates, we observe a significant correlation between the spatial patterns of the stand-replaced forest fraction and net CO2 flux changes (R2 = 0.37, slope = 118.7 gC m-2 year-1 [a positive slope indicates increased carbon released], p-val = 0.05) across the eleven TRANSCOM-land regions. This correlation surpasses the correlation with aging forests (R2 = 0.02, slope = -3.7 gC m-2 year-1, p-val = 0.69). We attribute this significant correlation to the net above-ground biomass (AGB) losses in stand-replaced forests per unit area, substantially exceeding the magnitude of the net AGB gains observed in aging and old-growth "stable" tropical forests throughout 2010-2020. Our study highlights the importance of rapid forest turnover through stand-replacement, despite its limited spatial extent, on regional net carbon balance, especially when contrasted with the more gradual process of forest maturation.

How to cite: Besnard, S., Heinrich, V. H. A., Carvalhais, N., Herold, M., Peters, W., Luijkx, I., Santoro, M., and Yang, H.: The covariation of forest age shifts and net carbon balance over the period 2010 to 2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3888, https://doi.org/10.5194/egusphere-egu24-3888, 2024.

EGU24-4183 | Orals | BG3.6 | Highlight

Closing the data gap to develop Land Surface Models for Congo Basin forests 

Wannes Hubau and the DAMOCO, PILOTMAB & CANOPI consortium

Congo Basin forests are among the most diverse, carbon-rich and CO2-absorbing areas in the World (1,2) and play an increasingly important role in international climate policy (3). On the pivotal CoP26 in Glasgow, more than 100 World leaders promised to stop deforestation by 2030, including specific pledges to focus on protecting Congo Basin forests. However, there is a striking discrepancy between the Congo Basin’s paramount importance versus its poor scientific coverage (4). As a result of this data gap, Earth System Models are not capturing present-day tropical forest carbon dynamics (5). Therefore, our consortium is contributing to closing the Congo Basin forest data gap and improve Land Surface Models to capture its biodiversity and carbon dynamics. To reach this ambition, we are collecting field data on permanent forest inventory plots scattered across the Congo basin.

The data covers multiple time scales by combining different methodological approaches: (i) weakly monitoring of cambial and foliar phenology of selected trees in the plots provides seasonal- and annual-scale changes in carbon uptake, (ii) repeated tree diameter and height measurements of all trees in the plots reveal decadal-scale changes in the carbon balance and tree community composition, (iii) measuring whole-tree, wood and leaf traits on selected trees in the plots allow in-depth analysis of decadal-scale changes in taxonomic and functional composition, (iv) identification of radiocarbon dated soil charcoal sampled in the plots reveal century-scale and millennial-scale changes in biodiversity, (v) continuous monitoring of climate variables provides yearly and decadal-scale changes in temperature and water availability.

By themselves, those data shed light on the short- and long-term resilience of critical Congo Basin forest ecosystem functions. Here we present an overview of recently published and preliminary results showing how our consortium contributes to advance our understanding of the effects of environmental change on vegetation dynamics, tree mortality and carbon dynamics of Congo Basin forests. Combining all these collected field data will ultimately allow to parameterize and validate Land Surface Models specifically for the Congo Basin.

1.Hubau, W. et al. Nature 579, 80–87 (2020). 2. Jung, M. et al. Nat. Ecol. Evol. 5, 1499–1509 (2021). 3. Rockström, J. et al. PNAS 118, 1–5 (2021). 4. White, L. J. T. et al. Nature 598, 411–414 (2021). 5. Koch, A., Hubau, W. & Lewis, S. L. Earth’s Future. 9, 1–19 (2021).

How to cite: Hubau, W. and the DAMOCO, PILOTMAB & CANOPI consortium: Closing the data gap to develop Land Surface Models for Congo Basin forests, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4183, https://doi.org/10.5194/egusphere-egu24-4183, 2024.

EGU24-4893 | ECS | Posters on site | BG3.6

Projected decline of CO2 fertilization effects on vegetation carbon sequestration in India 

Vijaykumar Bejagam, Ashutosh Sharma, and Xiaohua Wei

The increase in vegetation productivity in India (net primary productivity; NPP) has been observed in recent decades; however, substantial uncertainty exists about the continued strength of these land carbon sinks under climate change. The enhanced NPP is driven by the strong positive carbon-concentration feedback (CO2 fertilization effect; CFE), but the temporal dynamics of this feedback are unclear. Using the carbon fluxes from the multiple Earth System Models (ESMs) of Coupled Model Inter-comparison Project (CMIP6), we showed an increasing trend in NPP would continue under climate change with projections of NPP to 2.00 ± 0.12 PgCyr-1 (25% increase) during 2021-2049, 2.36 ± 0.12 PgCyr-1 (18% increase) during 2050-2079, and 2.67 ± 0.07 PgCyr-1 (13% increase) during 2080-2099 in Indian tropic forests under SSP585 scenario. This suggests a significant decline in the growth rate of NPP in future periods. To understand the feedbacks that drive the NPP increase, we analyzed the relative effects of CFE and warming. We compared the simulations from the biogeochemical coupled model (BGC) from ESMs, which exclude the warming effects, with the fully coupled model, which includes both CFE and warming effects. The BGC model projected a 74.7% increase in NPP by the end of the century, significantly higher than the 55.9% increase projected by the fully coupled model. This shows that the consistent increase in the NPP was associated with the rise in atmospheric CO2. More importantly, results reveal that the decrease in the growth rate of NPP was due to the decline in the contribution of CFE across the different vegetations at a rate of -0.62% 100 ppm-1. Such a decline could be attributed to nutrient limitation, negative responses to high temperatures, droughts, heat waves, etc. Additionally, statistically significant shifts in the strength of carbon sinks (at a rate of -1.15% per decade) were identified in abating anthropogenic CO2 emissions. These shifts in land carbon sinks can potentially exacerbate global warming and impose additional challenges on our collective efforts to meet climate policy targets.

How to cite: Bejagam, V., Sharma, A., and Wei, X.: Projected decline of CO2 fertilization effects on vegetation carbon sequestration in India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4893, https://doi.org/10.5194/egusphere-egu24-4893, 2024.

EGU24-5483 | ECS | Orals | BG3.6

Comparing the efficiency of forest mitigation policies: Is sequestering more efficient than using wood? 

Cosmin Cosofret, Olivier Bouriaud, and Laura Bouriaud

Reducing the net CO2 emissions is a key target worldwide, as shown, for instance, by the commitment of the Paris Agreement, and in this context, forests are being scrutinized for their capacity to act as carbon sinks and store large amounts of carbon over long periods. Quantifying the substitution effect of wood remains very difficult as it depends on many factors difficult to measure, such as the distribution of wood products into types of products having different lifetimes and which can substitute for different materials.

In Romania, forests have a large overall biomass stock, even in managed forests, since the management is operating at an intensity much lower than in many other European countries. Increased regionality in the global change effects requires a more local investigation. Therefore, we used a dynamic forest landscape model (LandClim model) to compare the three opposed mitigation strategies of forests and quantify their potential for sequestration of carbon and substitution of carbon in the context of global changes.

Under the mild climate RCP26 the carbon stocks were kept at levels roughly similar to the current stocks. The Set Aside 100% (SA100) managed stands stored the highest quantity of carbon, showing a capping of growth at the end of the 200 simulated years. Under the extreme climate RCP85, stocks increased for three decades but then plummeted. The highest stocks were obtained by the Set Aside 0% (SA0) management.

The cumulative harvest showed two surges under the climate scenario RCP26, first at the beginning of the simulation (2020-2060) and then during the 2170-2210 period. Under mild climate change RCP26, the effect of substitution from wood procurement clearly exceeds the increase in storage that can be expected. Under the RCP85 climate, harvest occurred exclusively during 2020-2070, then practically stopped when all stocks and fluxes became a lot more similar among management scenarios, given the catastrophic drop of stocks past 2080.

Wind-related disturbances had relatively constant consequences under RCP26, albeit with more fluctuations and a much higher intensity in SA100. SA0 and SA30 had similar magnitudes until 2120, and then wind-induced losses increased more strongly for Set Aside 30% (SA30). By 2210 the amounts of wind-induced carbon losses were 50% larger for SA100 than for SA30. Under scenario RCP85, the management strategy did not influence these losses which were near zero after 2080, as a result of the very small stocks.

The literature suggests no management strategies for carbon storage in mild climates, but in extreme climates cannot be a solution. Therefore, under the cloud of increased disturbance and pressure of climate change, the substitution strategy is more effective and safer than sequestration.

 

How to cite: Cosofret, C., Bouriaud, O., and Bouriaud, L.: Comparing the efficiency of forest mitigation policies: Is sequestering more efficient than using wood?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5483, https://doi.org/10.5194/egusphere-egu24-5483, 2024.

EGU24-6377 | ECS | Posters on site | BG3.6

Global trends in forest fragmentation using multiple metrics 

Yibiao Zou, Thomas Crowther, Gabriel Smith, Haozhi Ma, Lidong Mo, Zhaofei Wu, Dominic Rebindaine, and Constantin Zohner

Deforestation has exacerbated the fragmentation of habitats into smaller, more isolated patches, driving global declines in biodiversity. Yet, a comprehensive global perspective of the trends in forest fragmentation, and its key drivers in relation to forest cover change remains elusive. To provide a comprehensive global overview of recent changes in forest fragmentation, we compare multiple fragmentation metrics, including those that are sensitive to forest cover and those that are not. Our analysis reveals that, according to cover-sensitive metrics that reflect the ecological implications of forest fragmentation, 52% of the world's forests have become more fragmented over the last two decades, a trend that is primarily attributed to increased deforestation in tropical zones. This value is twice as high than estimates from previous research, which estimated that forest fragmentation is declining across 75% of the global forest area. This discrepancy arises from a mathematical artifact, as previous cover-insensitive metrics equate declines in forest cover with decreased fragmentation. By adjusting for this and focusing on metrics that capture the ecologically relevant aspects of forest fragmentation, our study highlights a worrying trend: the ecological integrity of the global forest system has been significantly deteriorating in recent decades. This underscores the importance of using appropriate metrics to accurately assess the ecological impacts of forest fragmentation, especially in the context of global environmental change.

How to cite: Zou, Y., Crowther, T., Smith, G., Ma, H., Mo, L., Wu, Z., Rebindaine, D., and Zohner, C.: Global trends in forest fragmentation using multiple metrics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6377, https://doi.org/10.5194/egusphere-egu24-6377, 2024.

EGU24-6618 | ECS | Orals | BG3.6

Simulating CO2 seasonal cycle amplitude in northern high latitudes with an eco-evolutionary optimality model 

Wenjia Cai, Iain Colin Prentice, and Joram Hooghiem

Land-atmosphere carbon exchanges and feedbacks constitute one of the largest uncertainties in future climate projections. Seasonal variations in atmospheric CO2 content depend on uptake by photosynthesis and release by autotrophic and heterotrophic respiration, providing an atmospheric signal of land ecosystem activity. Large increases in the seasonal cycle amplitude (SCA) of CO2 have occurred since the 1950s, especially in northern high latitudes. However, land surface and dynamic vegetation models have produced a wide range of magnitudes for the SCA, and have generally underestimated its increase. We explored the controls of the SCA by using a parameter-sparse eco-evolutionary optimality (EEO) model, the ‘P model’, combined with generic representations of plant and decomposer respiration, to simulate seasonal cycles and decadal trends of net ecosystem exchange (NEE). Simulated NEE fields were used to model near-surface CO2 concentrations during the satellite era, with the help of the atmospheric chemistry-transport model TM5. The P model has previously been shown to reproduce trends of gross primary production (GPP) at flux sites with long records. Our model set-up also generated a realistic simulation of global net terrestrial carbon uptake, comparable with results produced by more complex dynamic vegetation models; and allowed us to attribute causes to observed SCA increases at high-latitude CO2 monitoring stations.

How to cite: Cai, W., Prentice, I. C., and Hooghiem, J.: Simulating CO2 seasonal cycle amplitude in northern high latitudes with an eco-evolutionary optimality model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6618, https://doi.org/10.5194/egusphere-egu24-6618, 2024.

EGU24-7557 | Orals | BG3.6

VODCA v2: Multi-sensor, multi-frequency vegetation optical depth data for long-term canopy dynamics and biomass monitoring  

Ruxandra-Maria Zotta, Leander Moesinger, Robin van der Schalie, Mariette Vreugdenhil, Wolfgang Preimesberger, Thomas Frederikse, Richard de Jeu, and Wouter Dorigo

Vegetation optical depth (VOD) is a model-based indicator derived from microwave Earth observations. It quantifies the attenuation of surface microwave emissions by the overlaying vegetation. VOD is an indicator of the total water content stored in the vegetation canopy and is related to vegetation density, its relative moisture content, and above-ground biomass (AGB). VOD has been used in various applications such as phenology analysis, drought,  biomass monitoring, and estimating the likelihood of fire occurrence, leaf moisture, and gross primary productivity. Most of these applications require consistent long-term measurements, which are not provided by single-sensor time series.  

The first version of the global, long-term Vegetation Optical Depth Climate Archive (VODCA v1)[1] enables long-term analysis by harmonising VOD retrievals from multiple passive microwave sensors, derived through the Land Parameter Retrieval Model (LPRM)[2]. VODCA v1 provides separate VOD products for different spectral bands, namely the Ku-band (period 1987–2017), X-band (1997–2018), and C-band (2002–2018).   

Here, we present a new version of the VODCA dataset. VODCA v2 comprises two new products: a multi-frequency product called VODCA CXKu (1987 – 2021), obtained by merging the C-, X- and Ku-band observations and an L-band product (2010 – 2021) based on LPRM-derived VOD from the SMOS (Soil Moisture and Ocean Salinity) and SMAP (Soil Moisture Active Passive) missions. Even though the single-frequency products of VODCA v1 have merits on their own, merging them into VODCA CXKu yields a dataset with lower random levels and improved temporal sampling. It provides similar spatiotemporal information to optical and microwave vegetation indicators, such as the Fraction of Absorbed Photosynthetically Active Radiation (fAPAR) from MODIS and the slope of the backscatter incidence angle relation of Metop ASCAT (ASCAT slope). VODCA CXKu agrees best with fAPAR in short vegetation (Spearman's R: 0.57) and broadleaf forests (Spearman's R: 0.49) and with ASCAT slope in grassland (Spearman's R: 0.48) and cropland (Spearman's R: 0.48). Additionally, VODCA CXKu shows temporal patterns similar to the Normalised Microwave Reflection Index (NMRI) from in situ L-band GNSS measurements of the Plate Boundary Observatory (PBO) and sapflow measurements from SAPFLUXNET. VODCA L shows strong spatial agreement (Spearman's R: 0.86) and plausible temporal patterns with yearly AGB maps from the Xu et al. (2021) dataset. 

We conclude that VODCA CXKu provides valuable information to study the vegetation canopy response to climate variability and anthropogenic impacts. We recommend using it in long-term vegetation monitoring studies focusing on short vegetation types and broadleaf forests. VODCA L provides valuable insight into AGB.

[1] Moesinger, L., Dorigo, W., de Jeu, R., van der Schalie, R., Scanlon, T., Teubner, I., and Forkel, M.: The global long-term microwave Vegetation Optical Depth Climate Archive (VODCA), Earth Syst. Sci. Data, 12, 177–196, https://doi.org/10.5194/essd-12-177-2020, 2020.  

[2] Van der Schalie, R., de Jeu, R.A., Kerr, Y.H., Wigneron, J.P., Rodríguez-Fernández, N.J., Al-Yaari, A., Parinussa, R.M., Mecklenburg, S. and Drusch, M., 2017. The merging of radiative transfer based surface soil moisture data from SMOS and AMSR-E. Remote Sensing of Environment189, pp.180-193. 

How to cite: Zotta, R.-M., Moesinger, L., van der Schalie, R., Vreugdenhil, M., Preimesberger, W., Frederikse, T., de Jeu, R., and Dorigo, W.: VODCA v2: Multi-sensor, multi-frequency vegetation optical depth data for long-term canopy dynamics and biomass monitoring , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7557, https://doi.org/10.5194/egusphere-egu24-7557, 2024.

EGU24-7624 | ECS | Posters on site | BG3.6

The potential carbon benefit in drylands of China 

Zimin Tan and Shuai Wang

China’s drylands cover a large area and provide important ecosystem services as carbon sink by storing large amounts through vegetation and soils, so that it can be the key component of China’s terrestrial ecosystems. Due to water limitation and severe carbon-water trade-offs, China’s drylands are highly dynamic, which has an important impact on the trend of carbon sequestration in ecosystems of China and the interannual variability. Many studies have focused on carbon storage in cropland, grassland and forest ecosystems, but few comprehensive analyses focused on carbon storage and potentials in China's drylands. Here, we train a model with multiple influence factors to simulate the carbon storage potential in drylands of China to predict the biomass carbon carrying capacity of China’s drylands. After comparing observed and predicted biomass carbon density of drylands of China, we find that the carbon storage in China’s drylands realised by nearly 70 percent. The carbon actual storage in the drylands of the east of Inner Mongolia, the Northeast China, the northern part of Xinjiang, and the Huang-huai-hai region are the highest, and the potential carbon benefits of these places are highest too. Following by the Qinghai-Tibet Plateau and Jin-Shaan-Gan areas, and the lowest carbon storage and potential carbon benefits were found in the central and western parts of Inner Mongolia. Divided by the aridity gradient, it was found that the semi-arid zone has highest potential for carbon storage. We also identified areas where vegetation has not yet reached its full potential, such as the eastern and southern parts of the Tibetan Plateau and the Xinjiang region. Although the potential carbon storage in these areas is low, the proportion of carbon storage realised is below 40 percent, which has higher potential and conservation priority, indicating that the conservation of carbon in drylands of China needs to pay attention to the proportion of carbon sequestration realised at the same time, in addition to the potential carbon benefits.

How to cite: Tan, Z. and Wang, S.: The potential carbon benefit in drylands of China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7624, https://doi.org/10.5194/egusphere-egu24-7624, 2024.

EGU24-8510 | ECS | Posters on site | BG3.6 | Highlight

 The GEO-TREES initiative: high-accuracy ground data for satellite-derived biomass mapping 

Iris Dion, Jerome Chave, Stuart Davies, Alvaro Duque, Oliver Phillips, Camille Piponiot-laroche, Beatriz Schwantes Marimon, Klaus Scipal, and Irie Casimir Zo Bi

Verifiable and consistent measurement of forest carbon stocks and fluxes are necessary and they require to know where the biomass carbon is whether the vital functions of forests are changing, and what their future holds. Space agencies have made enormous investments in Earth Observation missions to map forest biomass across continents to support climate science and carbon markets. But satellites alone cannot produce accurate carbon maps–all maps vitally rely on field data collected by people and instruments to train their models and validate their products. To ensure satellites are producing reliable maps, it is needed frequently-acquired, high-quality field data. Furthermore, the challenge of acquiring ground biomass measurements is also one of environmental and social justice. The forests for which reference data are most needed, and the people depending on these forests, already suffer the worst impacts of climate change. Those in-country partners with unique forest expertise are key players in the fight against climate chaos, yet they are among the most disadvantaged globally. It follows that they need sustained support not only to collect data but to grow, train, and develop their own group's capacities. The GEO-TREES initiative proposes to fill this critical gap by building the world's first ground-based, standardized, open-access, equitably developed, reference forest biomass validation system to ensure that satellite observations accurately represent real forest carbon stocks, today and in the future. GEO-TREES is an ambitious world-wide network. It aims to establish at least 100 high-intensity forest biomass reference sites, to represent the main environmental and anthropogenic dimensions over which forests occur globally, and achieve greater sampling intensity in the critical tropics with an additional 210 lower-cost highly-distributed sites. Standing at the nexus of ecology and remote sensing, GEO-TREES builds on four principles: 1. Partnerships & engagement: To generate high-quality ground measurements, GEO-TREES partners with ecological and botanical specialists around the world. Partners are fully engaged and involved in every step of building the reference system. Without strong representation and fair funding of partners, particularly from the Global South, science capacity cannot be advanced, and the long-term sustainability of the GEO-TREES system would not be possible. 2. Innovative technologies: Ground measurement involves four integrated sets of measurements: forest inventory plots, airborne laser scanning, terrestrial laser scanning, and climate monitoring. GEO-TREES is based on established recommendations of the Committee on Earth Observation Satellites for validating biomass observations (https://lpvs.gsfc.nasa.gov/AGB/AGB_home.html), and will improve them based on new advances when necessary. 3. Long-term commitment: Forests are alive. Forest carbon stores change, sometimes rapidly, through space and time. Maintaining current, accurate estimates of carbon and biomass stocks requires continued long-term measurements. Long-term measurements also ensure the continued engagement and participation of partners throughout the system. 4. Open-access data: GEO-TREES is committed to equitably produced and openly shared global forest biomass reference measurements. High-quality, high-resolution maps of the world’s forests developed through the Earth Observation missions in partnership with GEO-TREES will be made open to all.

How to cite: Dion, I., Chave, J., Davies, S., Duque, A., Phillips, O., Piponiot-laroche, C., Schwantes Marimon, B., Scipal, K., and Zo Bi, I. C.:  The GEO-TREES initiative: high-accuracy ground data for satellite-derived biomass mapping, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8510, https://doi.org/10.5194/egusphere-egu24-8510, 2024.

EGU24-9771 | Orals | BG3.6

Changes in global vegetation distribution and composition under idealized overshoot scenarios 

Lars Nieradzik, Hanna Lee, Paul Miller, Jörg Schwinger, and David Wårlind

Within the framework of the project IMPOSE (Emit now, mitigate later? IMPlications of temperature OverShoots for the Earth system) six idealized emission-overshoot simulations have been performed with the Earth System Model NorESM2-LM2 and used as forcing for the 2nd generation dynamic global vegetation model LPJ-GUESS to investigate the impact of different CO2 overshoots on global vegetation.

The simulations describe a set of scenarios with high, medium, and low cumulative CO2 emissions, each of which has a short (immediate) and a long (100 years) peak of cumulative CO2 emissions before declining towards a baseline simulation where a cumulative 1500 PgC is emitted within the first 100 years. The simulations have been performed in a “World without humans”, i.e. without land-use change, urban areas, fire-suppression, etc. to eliminate the somewhat arbitrary human factor.

The results clearly show that the height of the overshoot has a large impact on global vegetation distribution and composition while its duration does not seem to play a significant role. Overall, we can state that any overshoot scenario results in vegetation patterns that are different from (though converging towards) the non-overshoot baseline simulation. The higher the overshoot, the larger the initial deviation.

We have observed that there is less savannah after an overshoot and less so, the higher the overshoot, due to a reduced amount of tropical rain-green trees. As a result, there is also significantly less potential for fire. Further, there is more boreal vegetation, partly at the expense of temperate summer-green trees. A convergence towards the baseline simulation seems to be possible but isn’t reached by the end of the simulation window.

Furthermore, it can be observed that overshoots are asymmetrical when it comes to succession, i.e. while there are well-known succession patterns when global temperatures rise and vegetation is expanding into previously colder regions, patterns are different when the temperatures on the decline.

Finally, we like to state that dynamic vegetation is an important feature in Earth-system models w.r.t. vegetation carbon sequestration. Not only do the biogeophysical feedbacks matter, the total amount of carbon sequestered is about 16% higher than in simulations in which dynamic vegetation was supressed. These, and other feedbacks will be investigated in more detail in the ongoing Horizon Europe projects OptimESM and RESCUE.

How to cite: Nieradzik, L., Lee, H., Miller, P., Schwinger, J., and Wårlind, D.: Changes in global vegetation distribution and composition under idealized overshoot scenarios, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9771, https://doi.org/10.5194/egusphere-egu24-9771, 2024.

EGU24-10400 | ECS | Orals | BG3.6

Post-Disturbance Recovery Shifts in Boreal Evergreen Landscapes: Impacts on Carbon Dynamics and Land Surface Properties. 

Lucia S. Layritz, Konstantin Gregor, Andy Krause, Stefan Kruse, Ben Meyer, Tom A. M. Pugh, Carl Boettiger, and Anja Rammig

In the evergreen boreal forest, field studies show that vegetation does not always regenerate to its previous state after disturbance but instead transitions to systems dominated by deciduous trees or non-forest vegetation. Gaining a better understanding of drivers and impacts of post-disturbance recovery is thus crucial to accurately project future vegetation dynamics and associated impacts on the carbon, water, and energy balance of the region. We here perform simulations with the dynamic vegetation model LPJ-GUESS to investigate (1) if observations of post-disturbance recovery dynamics can be reproduced in the model, (2) which environmental factors control such shifts, and (3) how these in turn influence land surface properties such as albedo and evapotranspiration. We find that post-disturbance recovery trajectories can be clustered into distinct response patterns of recovery and shifts to alternative plant types. These shifts occur even in places where multiple plant types can in theory establish in the model and thus emerge due to shifts in competitive advantage mediated by warming and soil properties. We further find that shifts from forested to non-forested ecosystems have strong impacts on land-surface properties while shifts between different forest types are less impactful. We conclude that LPJ-GUESS is capable of reproducing observed disturbance-induced changes in vegetation dynamics following disturbances. Post-disturbance recovery is a key process driving accelerated vegetation change under climate change, further stressing the importance of accurately representing disturbance impact and recovery processes in land surface and coupled modeling.

How to cite: Layritz, L. S., Gregor, K., Krause, A., Kruse, S., Meyer, B., Pugh, T. A. M., Boettiger, C., and Rammig, A.: Post-Disturbance Recovery Shifts in Boreal Evergreen Landscapes: Impacts on Carbon Dynamics and Land Surface Properties., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10400, https://doi.org/10.5194/egusphere-egu24-10400, 2024.