The process of transforming point cloud data into high-quality meshes or CAD objects is, in general, not a trivial task. Many problems, such as holes, enclosed pockets, or small tunnels, can occur during the surface reconstruction process, even if the point cloud is of excellent quality. These issues are often difficult to resolve automatically and may require detailed manual adjustments. Nevertheless, in this work, we present a semi-automatic pipeline that requires minimal user-provided input and still allows for high-quality surface reconstruction. Moreover, the presented pipeline can be successfully used by non-specialists and only relies commonly available tools.

Our pipeline consists of the following main steps: First, a normal field over the point cloud is estimated, and Screened Poisson Surface Reconstruction is applied to obtain the initial mesh. At this stage, the reconstructed mesh usually contains holes, small tunnels, and excess parts – i.e., surface parts that do not correspond to the point cloud geometry. In the next step, we apply morphological and geometrical filtering in order to resolve the problems mentioned before. Some fine details are also removed during the filtration process; however, we show how these can be restored – without reintroducing the problems – using a distance guided projection. In the last step, the filtered mesh is re-meshed to obtain a high-quality triangular mesh, which – if needed – can be converted to a CAD object represented by a small number of quadrangular NURBS patches.

Our workflow is designed for a point cloud recorded by a laser scanner inside one of seven artificially carved caves resembling chapels with several niches and passages to the outside of a sandstone hill slope in Georgia. We note that we have not tested the approach for other data. Nevertheless, we believe that a similar pipeline can be applied for other types of point cloud data, – e.g., natural caves or mining shafts, geotechnical constructions, rock cliffs, geo-archeological sites, etc. This workflow was created independently, it is not part of a funded project and does not advertise particular software. The case study's point cloud data was used by courtesy of the Dipartimento di Scienze dell'Ambiente e della Terra of the Università degli Studi di Milano–Bicocca.

How to cite: Pluta, K. and Domej, G.: From Point Clouds to Surfaces: Overview on a Case Study, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1523, https://doi.org/10.5194/egusphere-egu21-1523, 2021.

On-the-go field measurements of soil and plant characteristics, including yield, are commonplace in current Precision Agriculture applications. Yet, such measurements can be affected by positional inaccuracies that result from equipment configuration or operation characteristics (e.g. GPS antenna position with respect to sensor position) and delays in the data transmission, reception or logging. The resulting time and position lags cause a misfit between the measurements and their attributed GPS position.

In order to compensate for this effect a simple coordinate translation along the measurement direction is proposed, depending on the local velocity and a field- and measurement configuration-specific time lag, which is estimated by minimizing the average absolute difference between the nearest neighbors. The correction procedure is demonstrated using electromagnetic induction data with different spatial configurations and by comparing
variograms for corrected and non-corrected data.

Best results are obtained when overlapping measurements are available, obtained in opposite driving directions, while the worst results are found when no overlapping measurements exist or only those corresponding to headland turns. Further improvements in the nearest neighbor search algorithm, e.g. by imposing the search in adjacent measurement swaths are discussed. The results are valid beyond motorized soil sensing applications.

Acknowledgement
This work is funded by the Spanish State Agency for Research through grant PID2019-104136RR-C21 and by IFAPA/FEDER through grant AVA2019.018.

How to cite: Gonzalez Jimenez, A., Pachepsky, Y., Gómez Flores, J. L., Ramos Rodríguez, M., and Vanderlinden, K.: Correcting position of delayed on-the-go field measurements by optimizing nearest neighbor statistics, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2510, https://doi.org/10.5194/egusphere-egu21-2510, 2021.

The validity of any glaciological paleo proxy used to interpret climate records is based on the level of understanding of their transfer from the atmosphere into the ice sheet and their recording in the snowpack. Large spatial noise in snow properties is observed, as the wind constantly redistributes the deposited snow at the surface routed by the local topography. To increase the signal-to-noise ratio and getting a representative estimate of snow properties with respect to the high spatial variability, a large number of snow profiles is needed. However, the classical way of obtaining profiles via snow-pits is time and energy-consuming, and thus unfavourable for large surface sampling programs. In response, we present a dual-tube technique to sample the upper metre of the snowpack at a variable depth resolution with high efficiency. The developed device is robust and avoids contact with the samples by exhibiting two tubes attached alongside each other in order to (1) contain the snow core sample and (2) to access the bottom of the sample, respectively. We demonstrate the performance of the technique through two case studies in East Antarctica where we analysed the variability of water isotopes at a 100 m and 5 km spatial scales.

How to cite: Dallmayr, R., Freitag, J., Hörhold, M., Laepple, T., Lemburg, J., Della Lunga, D., and Wilhelms, F.: A dual-tube sampling technique for snowpack studies, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4112, https://doi.org/10.5194/egusphere-egu21-4112, 2021.

One of the main goals of the GCOS Reference Upper Air Network (GRUAN) is to perform reference observations of profiles of atmospheric temperature, humidity and wind for monitoring climate change. Two essential criteria for establishing a reference observation are measurement-traceability and the availability of measurement uncertainties. Radiosoundings have proven valuable in providing in-situ profiles of temperature, humidity, pressure and wind at unmatched vertical resolution. Data products from commercial radiosondes often rely on black-box or proprietary algorithms, which are not disclosed to the scientific user. Furthermore, long-term time-series from these products are frequently hampered by changes in the hardware and/or the data processing.

The GRUAN data products (GDP’s) comply with the above-mentioned criteria for a reference product. Correction algorithms are open-source and well documented and the data include vertically resolved best estimates of the uncertainties. Another major advantage of a GRUAN data product is that it includes the radiosonde’s raw measurement data, which allows for reprocessing when new or improved corrections become available. Currently, GDP’s are available for the Vaisala RS92 and Meisei RS-11G radiosondes. Data products for additional radiosonde models, as well as for other measurement techniques are in the making. The GDP’s are used to determine trends, constrain and calibrate data from more spatially‐comprehensive observing systems (including satellites and current radiosonde networks), and provide appropriate data for studying atmospheric processes.

This presentation introduces the GRUAN processing of Vaisala RS41 radiosoundings, the correction algorithms that are applied, and the derivation of the vertically resolved uncertainty estimates. Well-known, dominant error sources for the RS41 profiles are related to solar radiation, causing a temperature error, and time-lag of the humidity sensor at low temperatures. The corrections for these error sources are based on dedicated experiments that were performed at Lindenberg observatory to measure the response of the RS41 temperature sensor to solar irradiance and to determine the time-lag of the humidity sensor at temperatures down to -70 °C. The RS41-GDP.1 is planned to become available in 2021. The majority of the 30, globally distributed, GRUAN sites employ the RS41, and its predecessor the RS92 before, establishing a continuous data record of more than 10 years of reference climate observations.

How to cite: Sommer, M., von Rohden, C., Simeonov, T., and Dirksen, R.: RS41 GRUAN Data Product Version 1 (RS41-GDP.1) - Reference Radiosonde Data for the Troposphere and Lower Stratosphere, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6055, https://doi.org/10.5194/egusphere-egu21-6055, 2021.

We present the results obtained using an original open-source low-cost sensor (LCS) system developed to measure tropospheric O₃ in a remote high altitude alpine site. We conducted our study at the Col Margherita Observatory (2543 m a.s.l.), a World Meteorological Organization Global Atmosphere Watch Regional Station (WIGOS Id: 0-380-0-MRG), located in the Italian Eastern Alps. The sensing system mounts three equivalent commercial low-cost sensors that have been calibrated using a laboratory standard (Thermo 49iPS), referenced to the Standard Reference Photometer #15 calibration scale by the WMO, before field deployment. Intra and inter-comparison between sensors and reference (Thermo 49c) have been conducted for six months from May to December 2018. The sensor’s dependence on the environmental meteorological variables has been considered and discussed. The evaluation of the analytical performances of this sensing system provides a limit of detection < 5 ppb, limit of quantitation < 17 ppb, linear dynamic range up to 250 ppb, intra-Pearson correlation coefficient (PCC) up to 0.96, inter-PCC > 0.8, bias > 3.5 ppb and ±8.5 at 95% of confidence. Thanks to the first implementation of an LCS System in an alpine site, we demonstrated how it is possible to obtain valuable data from a low-cost instrument in a remote harsh environment. This opens new perspectives for the adoption of a low-cost sensor network in atmospheric sciences. We further present our recent experience using LoRa to integrate the sensing system into a low-power wide-area network (LPWAN). We developed an end-node and a gateway, designing PCBs derived from the Arduino Mega, optimizing their power consumption and equipping them with batteries, a proper solar panel or wind turbine to ensure their autonomy while collecting environmental ozone and meteorological (T, RH, WS, WD) data. We drafted the communication software to send compressed data from end-nodes to gateways. The gateways are part of an openVPN with the main server located in Venice. The server also provides a postgreSQL database and a R-shiny web application for data visualization and manipulation. To enhance redundancy, the local data are also synchronized to a cloud database. In the next years, thanks to the Marie Skłodowska-Curie grant PIONEER, we will exploit our experiences to provide a comprehensive low-cost wireless sensor network to characterize transport of polluted air masses and provide long term climate data collection in support of the state-of-the-art instrumentation and established networks in remote alpine areas.

Bibliography

Dallo F. et al.: Calibration and assessment of electrochemical low-cost sensors in remote alpine harsh environments, Atmospheric Measurement Techniques, amt-2020-483. In review

Acknowledgements. This work was part of the Arctic Field Grant O3NET project, funded by the Research Council of Norway. The work received financial support by the National Project of Interest Next-Data (MIUR). The exploitation of the LoRa technology was performed with the ITIS "Max Planck" through the Remote Observatory SYstem (ROSY) "Alternanza scuola-lavoro" project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 844526

How to cite: Dallo, F., Zannoni, D., Gabrieli, J., Cristofanelli, P., Calzolari, F., de Blasi, F., Spolaor, A., Battistel, D., Lodi, R., Cairns, W. R. L., Fjæraa, A. M., Bonasoni, P., Bauman, F., and Barbante, C.: Low-cost sensor network in remote alpine environments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6646, https://doi.org/10.5194/egusphere-egu21-6646, 2021.

How to cite: Yan, Y. T., Chua, S., DeCarlo, T., Kempf, P., Morgan, K., and Switzer, A.: Core-CT:  A MATLAB application for the quantitative analysis of sediment and coral cores from X-ray computed tomography (CT) , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6960, https://doi.org/10.5194/egusphere-egu21-6960, 2021.

In order to enable investigations and further comprehensive understanding of dynamical processes, it is clear one has to identify all relevant parameters and aim to record them all under best conditions concerning e.g. resolution, coverage in space, and in many cases on a multitude of scales in time. Obviously, it is also difficult to satisfy all these constrains in full. Especially scientific long-term observations often suffer the lack of necessary lasting commitment; secure funding, continual high quality maintenance, protected environment, or sufficient planning stability. Fortunately, the Swiss Mont Terri rock laboratory, with its history of now 25 years of forefront scientific expertise, a long-standing fruitful cooperation formed by the partners of the consortium and in consequence thereof state-of-the-art results obtained through 100 completed individual experiments and 45 additional experiments actually ongoing, ensures the conditions listed above.

Based on this favorable prospect, a now growing tiltmeter array is established at the underground laboratory. The instruments are embedded in several multidisciplinary experiments, dedicated to numerous, different scientific questions. Starting in April 2019, the first two platform tiltmeters became operational. Less than two years later, ten biaxial instruments are quasi-continuously monitoring deformation at various locations within the galleries and niches at Mont Terri. The envisioned, increasing spatial coverage of the network will facilitate geodetic observations of the underground rock laboratory as a whole and of its subregions as well.

Already in September 2012, a 50 m long hydrostatic levelling system (HLS) was installed along a gallery in the underground laboratory to detect displacements across an active geological fault zone. The combination of both, i.e. the uniaxial, integral deformations data provided by HLS together with the array of biaxial, point measurements acquired by the tiltmeters offers a unique concerted opportunity to achieve detailed deformation data in a large underground rock laboratory and to survey the associated dynamical processes occurring on timeframes covering seconds to decades.

How to cite: Rebscher, D., Guglielmi, Y., Gutierrez, I., Meier, E., and Schefer, S.: Investigations based on biaxial tiltmeter array and uniaxial hydrostatic levelling system at the Mont Terri rock laboratory, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8624, https://doi.org/10.5194/egusphere-egu21-8624, 2021.

Decade-long series of tilt- and strain-meter observations in NE Italy allow monitoring the crustal deformation from short transient to long-term phenomena. These recordings, some of them started in 1960, are generated by sources spanning a wide spectrum of spatial scales, such as sudden underground flooding due to extreme rainfall [1, 2], years-long fluid diffusion transients due to fault behavior [3], the free oscillation arising from megathrust earthquakes (e.g. Chile 1960, Sumatra 2004, Tohoku 2011).
The instrumental sites lie on karst formations, in an area of continental collision and active seismicity, the northeastern portion of the Adria microplate, where the south-directed thrusts of the Alpine system merge with the NW-SE transpressive regime of the External Dinarides. Measurements include the ongoing interseismic strain accumulation processes, including the peculiar observation of episodic disturbances and southward tilting in the three years preceding the 1976 Mw6.4 Friuli earthquake [4].

The channel systems of Karst hydrology, which undergo complete flooding and overpressure buildup in extremely short time spans (e.g. near-simultaneous flooding over a distance of 30 km) result in observable surface deformation and a change in the gravity field. Tilt time series allow to extract and model this type of hydrology-forced uplift and associated deformation [2,5].

Tilt- and strain-meters allow for accuracy and precision in measuring crustal deformation, to a level which space-borne geodesy cannot provide. The main drawback, however, is that only point measurements are provided, in locations where stations could be set up.
On the other hand, the thousands of points on the surface that DInSAR can provide are affected by coarser accuracy and influenced by atmospheric effects - resulting in LoS displacements uncorrelated to the actual surface deformations. We aim at enabling the transfer of knowledge from tilt- and strain-meters observations to DInSAR-derived data, thus allowing a first assessment of ground-truth constrained displacement models.

[1] Braitenberg C. (2018). The deforming and rotating Earth - A review of the 18th International Symposium on Geodynamics and Earth Tide, Trieste 2016 , Geodesy and Geodynamics, 187-196, doi::10.1016/j.geog.2018.03.003

[2] Braitenberg C., Pivetta T., Barbolla D. F., Gabrovsek F., Devoti R., Nagy I. (2019). Terrain uplift due to natural hydrologic overpressure in karstic conduits. Scientific Reports, 9:3934, 1-10, doi.:10.1038/s41598-019-38814-1

[3] Rossi, G., Fabris, P. & Zuliani, D. Overpressure and Fluid Diffusion Causing Non-hydrological Transient GNSS Displacements. Pure Appl. Geophys. 175, 1869–1888 (2018). https://doi.org/10.1007/s00024-017-1712-x

[4] Dragoni M., Bonafede M., and Boschi E. (1985). On the interpretation of slow ground deformation precursory to the 1976 Friuli earthquake. Pure and Applied Geophysics 122, 781–792. doi:10.1007/978-3-0348-6245-5_3

[5] Grillo B., Braitenberg C., Nagy I., Devoti R., Zuliani D., Fabris P. (2018). Cansiglio Karst-Plateau: 10 years of geodetic-hydrological observations in seismically active northeast Italy. Pure and Applied Geophysics, 175, 5, 1765-1781, doi:10.1007/s00024-018-1860-7.

How to cite: Braitenberg, C., Pastorutti, A., Grillo, B., and Bartola, M.: The tilt and strainmeter network of NE Italy: multi-decadal observations of crustal deformation as ground truth for DinSAR., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9848, https://doi.org/10.5194/egusphere-egu21-9848, 2021.

The remote location of the Geodynamic Observatory Moxa of Friedrich-Schiller University Jena, about 30 km south of Jena in the Thuringian slate mountains, results in very low ambient noise and thus very good conditions for long-term geophysical observations, which are further improved, as many sensors are installed in the subsurface in galleries or in boreholes.

So far, the focus of Moxa observatory has been on observing transients signals of deformation and fluid movements in the subsurface. This is accomplished by sensors like a superconducting gravimeter CD-034, three laser strain meters measuring nano-strain along three galleries in north-south, east-west and NW-SE directions, or borehole tiltmeters. Further, information on fluid flow is gained from downhole temperature measurements employing an optical fiber. These sensors are complemented by a climate station and two shallow drill-holes, one of which has been fully cored, which in addition to the temperature times series provide information on water level and rock physical properties. Near surface geophysical profiling using e.g. electrical resistivity tomography has led to a good knowledge of the structurally complex subsurface of the observatory.

Recently, a node for the Global Network of Optical Magnetometers for Exotic physics (GNOME) has been installed in the temperature-stabilized room at Moxa observatory close to the superconducting gravimeter. The GNOME is a world-spanning collaboration employing optically pumped magneto­meters (OPM) to search for space-time correlated transient signatures heralding exotic physics beyond the Standard Model. GNOME is sensitive to prominent classes of dark-matter scenarios, e.g., axion or axion-like particles forming macroscopic structures in the Universe. The installation in close vicinity to the superconducting gravimeter ensures well-controlled and -monitored ambient conditions such as temperature, air pressure and especially vibrations, allowing improved vetoing of false-positive detection events in the Moxa GNOME node.

Here, we focus on introducing Moxa Observatory’s sensor systems with an emphasis of actual sensor configurations and further on highlighting how various information on fluid flow coming from the specific sensors lead to an improved understanding of the direction and magnitude of subsurface fluid flow.

How to cite: Kukowski, N., Stolz, R., Scholtes, T., Schwarze, C., and Goepel, A.: Long-term recordings at the FSU Jena Geodynamic Observatory Moxa (Thuringia, central Germany), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12850, https://doi.org/10.5194/egusphere-egu21-12850, 2021.

Surface fractures at the filament of X-ray tube increase more with metal fatique or wrong cooling  and heating processes. Fractured filament continue to work as repeating open circuit positions in random times with  turning fully conductive state in short time. We are explaining how open circuit flashes at the filament providing wrong measurement results. Their low voltage electric circuit conductive problems  repeat in milliseconds periods. At  the results, it gives the impression of healthy measurement values. Because that the measured sample absorbs photonic energy and direct it to neighbouring elements in continuous element  electron scattering  circulations , by the way that delayed secondary electron energy scatters hide all electron supply extinctions on the semi broken flament wire and indirect counts  continue by the detector from coming reflection energy. ( real counts are not from exact beam  target of sample surface during energy deprivations , and it is impossible to understand that the measurement is inaccurate because it causes similarity as discrete element counts in sedimentation layers ).  Filament voltage arcs do not warn machine with error reporting systems until to whole ruptured filament touch to anode walls or their far displaced edges of 2 broken filament positioning. Erroneous records take their place in the world of science if the lithology was not followed. We collected faulty measurement data from our experiences for indicate when and  how possible to facing such as events.

For eliminate  explained reasons at above , the tubes must be gently heated and  cooled. Excessive cooling or heating of the tubes or oxid placement and leakeage  at gasget contacts reduces the surface contact areas of the insilators with the corrosion by  condensing water around the rubber insulation gasgets , it causes cooling liquid leakage or increasing humidity at the tube housing block via following serial failures of HV unit such as increasing amounts of the broken tube events. During the replacement of insulating gasgets, enough care should be taken for gasket contact points as oiling  them with  silicone grease as a form of the thin film. High responsibility must be with continuous  result control  and reference correlations on the scientific sample. With this way we can eliminate possible  negative results by malfunctions on measurements.

How to cite: Acar, D., Çagatay, N., Genç, Ş. C., Eriş, K. K., Biltekin, D., and Yakupoğlu, N.: Experiences on production - usage reasoned malfunctions & development of  X-ray tubes used in science and their effects on sediment measurements, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13341, https://doi.org/10.5194/egusphere-egu21-13341, 2021.

The detailed spatial and temporal information of surface deformation detected during volcanic unrest by InSAR images suggests a degree of complexity of volcanic systems (e.g., source geometries and distribution of material properties) that cannot be correctly represented by simple models of a pressure source embedded in an elastic, homogeneous, isotropic half-space.

The inversion of deformation data, performed for the characterization of the source of deformation, is based on the model we choose to represent the volcanic system. Therefore the quality of the chosen model influences the source size and its temporal changes estimated through the inversion, and thus their interpretation. In fact, our assumptions about geometries and/or magma and rock properties affect the estimations of changes in magma volumes and reservoir pressure. To obtain a more reliable interpretation of surface signals, it is thus paramount to have more realistic models, where the distribution of material properties is constrained by multiple data sets, with greater flexibility in the definition of sources in space and time.

Assuming we could invert InSAR data with models that can deal with a complex and arbitrarily shaped deformation source, how unique could this solution be? How much could we say about the evolution of the deformation source over time? Furthermore, how much information about the spatial complexity of the source and its evolution in space and time would be missed?

To answer these questions, we characterize the deformation source from the inversion of InSAR data based on a finite element method (FEM) forward model without an a-priori source geometry. The deformation source is bound by estimating the strength of an amorphous cluster of deformation sources distributed over a grid. This uses the principle of superposition already applied to point or cuboid volume elements, embedded in a homogeneous half-space. Also, the numerical model integrates the cluster-source with a heterogeneous distribution of material properties and the topography.

In our study, we quantify the ambiguity in the estimation of arbitrary geometries of sources of deformation composed by clusters of Finite Element Method unit sources distributed over a grid. The regularized least-squares solutions of the steady-state PDEs inverse model are obtained using a COMSOL Multiphysics-based routine. Through the inversion of the InSAR time series of the unrest at Uturuncu volcano (Bolivia), we quantify the ability of the employed cluster-source approach to identify the changes of deformation sources in time. 

This research is financed by an individual fellowship of the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 793811.

How to cite: Ronchin, E., Castaldo, R., Pepe, S., Tizzani, P., Solaro, G., and Battaglia, M.: Non-uniqueness in the inversion of volcano deformation data: change of volume or change of position?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9881, https://doi.org/10.5194/egusphere-egu21-9881, 2021.

There are two partially linked risks to the Kyiv city associated with the Dnieper river: (A) risk of the inundation of the urban coastal areas during the extremely high floods or due to the break of the Hydropower Plant dam located upstream Kyiv, and, (B) risk of the secondary radioactive contamination of the Dnieper waters due to the intensification of the dynamics of "Chornobyl" radionuclides during high floods and man-made impacts -  dredging in Kyiv Reservoirs for navigation routes and other purposes.

The Chornobyl Nuclear Power Plant has located 130 km from Kyiv at the bank of Pripyat river, which is 20 km downstream from ChNPP inflows into the Kyiv reservoir of the Dnieper River. After the Chornobyl accident, about 5.4×10¹³ Bq of ¹³⁷Cs and 10¹³ Bq of ⁹⁰Sr were deposited in the bottom sediments of the Kyiv Reservoir. Nowadays, 35 years after the Chornobyl accident, the population of Kyiv still is very sensitive to the risks of secondary environmental contaminations by the “Chornobyl radionuclides”. Therefore even low levels of such risks should be carefully assessed by well-grounded methods.

The main goals of our multidisciplinary study are:

• to develop a model/data based Decision Support System (DSS) for the assessment of both kind of the described above risks A) and B),
• to analyze the influence of the natural hazard – extremely high river floods on the resuspension of contaminated sediments and environmental risks due to the man-made impacts – dredging, dam breaks, and others.

The components of these research and development activities are following:

• field and laboratory studies of the contemporary contamination of the bottom sediments and biota in the Kyiv reservoir to receive the input data for the model calibration and improvement of the model structure;
• customization for the Kyiv Reservoir and the Dnieper river at Kyiv of the 2D COASTOX model which the hydrodynamic module is based on the nonlinear shallow water equations, and the sediment/radionuclide transport model using the advection-diffusion equations with specific sink/source terms for radionuclides;
• customization for the Kyiv Reservoir of the hydro-ecological POSEIDON model that simulates the influence of resuspension of radioactive sediments on the contamination of fishes and other hydrobionts;
• improvement of methods for the numerical solution of model equations and algorithms based on finite volume methods for their parallelization using multiprocessor systems and graphics cards to speed up computations;
• to create high-performance DSS with a user-friendly interface that can use GPUs to quickly predict the radiation status of surface waters and inundation of river banks in emergencies.

The DSS is installed in the Department of Hydrological Forecasting of the Ukrainian Hydrometeorological Center and is used for the quantification of the risk scenarios and analyses of the links of both risks. Due to the high computational performance, the DSS can be used for the real-time numerical predictions with the zoning of the flood risks in a case of emergency.

How to cite: Kivva, S., Zheleznyak, M., Bezhenar, R., Pylypenko, O., Sorokin, M., Demydenko, A., Kanivets, V., Laptev, G., Votsekhovich, O., Boyko, V., and Gudkov, D.: Modeling of major environmental risks for the Kyiv city,  Ukraine from the Dnieper river waters  -  inundation of coastal areas and contamination by the radionuclides deposited in bottom sediments after the Chornobyl accident, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13038, https://doi.org/10.5194/egusphere-egu21-13038, 2021.

Mixed forests are still little understood ecosystems. Their structure and composition are not well known and not clearly classified. In times of climate change, monitoring of forests is becoming increasingly important. Forest stands were usually researched by field work, which requires high costs and man-power. Field surveys are further only conducted in small patches of the forests, which does often not represent the whole forest. For mixed forests, usually only a dominate species is mentioned but the forests are not classified further. The greater need of better methods with high accuracies to detect and classify tree species in the forest encouraged this study.

UAVs have been proven to be an efficient tool to conduct automatic field surveys in forestry applications. These easy-to-use and cheap tools are able to gather images with a high resolution. Image processing with image analysis and deep learning techniques is an emerging part in forestry investigations. Therefore, we combined manual field surveys, image analysis and automatic classifications in our study.

The forests, we were investigating, are riparian forests in Shonai area, Japan, which are classified as mixed forests. 7 sites were chosen and field surveys were conducted. Most of the sites are located in flat areas, but 3 sites are located on slopes, where the access is difficult and field work barely possible. We imaged all sites in different seasons with UAVs and performed image analysis with computer vision and ArcGIS methods. Trees were detected and classified manually and automatically. A comparison of all applied methods was drawn, evaluated and will be provided.

Our first results are promising to characterize forests in a new dimension. We will provide detailed information about tree species composition, tree locations and forest structures. Mixed forests can be deeper analysed by maps of dominate and subdominant tree species. Area calculations for tree canopies will be highlighted for the main tree species. We will provide winter images for tree counting in heavy snowfall regions and classification accuracies of deep learning techniques.  

How to cite: Kentsch, S., Lopez Caceres, M. L., and Diez, Y.: Automatic tree species classification by using field data, image analysis and deep learning techniques in riparian forests, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1698, https://doi.org/10.5194/egusphere-egu21-1698, 2021.

Apatite fission track dating and T,t-modelling are now a well-established thermochronological instruments for investigating geological problems (Malusà and Fitzgerald, 2019). In the course of their development, complicating factors that affect the track counts and confined track lengths in geological samples were corrected for, foremost among them the crystallographic orientation of the confined track and the chemical composition of the apatite (Green et al., 1986, and subsequent papers). Methods have also been proposed to improve the confined track statistics, using ²⁵²Cf irradiation, ion irradiation, fracturing, and re-etching (Yamada et al., 1998). However, there is to date no adequate correction for the protocol used to reveal the tracks, which differs from lab to lab although all are based on nitric acid.

Recent step-etch experiments with the most used etchants show that both the duration of the etch and the temperature and concentration of the solution have non-negligible effects on the measured lengths (Sobel and Seward, 2010; Jonckheere et al., 2017 and references therein; Tamer et al., 2019). Earlier attempt to overcome these problems investigated etching for such a time that the track openings conform to a pre-determined size (Ravenhurst et al., 2003) or measuring confined tracks of a given minimum width (Yamada et al., 1993). The first method has the drawback that the widths of the host tracks and confined tracks are not directly related, whereas the second fails to consider the anisotropic width of confined tracks.

In our geological investigation of the German Naab area, we adopt a step-etch approach, measuring the c-axis angle, length, width and dip of each individual confined track after 20s and 30s immersion in 5.5 M HNO₃. From the width increase we calculate the rate of widening of the track (apatite etch rate; Aslanian et al., 2021), and from that the effective etch time t_E, i.e., the true duration that the confined track has been etched, equal to the immersion time minus the time needed for the etchant to reach the specific confined track. Our results show that the confined track lengths are correlated with their effective etch times. This information is used to account for etch-protocol-related differences between the induced and fossil track lengths entered in the T,t-modelling software. We envisage this will improve the accurateness and resolution of the resulting T,t-paths. We will check this against the excellent independent geological constraints that exist for the Naab region.

The research was funded by the EU/MEYS (CZ.02.2.69/0.0/0.0/19_074/0014756).

References

Aslanian et al., 2021. American Mineralogist. In press.

Green et al., 1986. Chemical Geology 59, 237-253.

Jonckheere et al., 2017. American Mineralogist 102, 987-996.

Malusà and Fitzgerald, 2019.  Fission-Track Thermochronology and its Application to Geology. Pp 393.

Ravenhurst et al., 2003. Canadian Journal of Earth Sciences 40, 995-1007.

Sobel and Seward, 2010. Chemical Geology 271, 59-69.

Tamer et al., 2019. American Mineralogist 104(10), 1421-1435.

Yamada et al., 1993. Chemical Geology 122, 249-258

Yamada et al., 1998. Chemical Geology 149, 99–107.

How to cite: Novakova, L., Jonckheere, R., Wauschkuhn, B., and Ratschbacher, L.: Contribution to the discussion on processing and measurement methodology of apatite fission-track analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10436, https://doi.org/10.5194/egusphere-egu21-10436, 2021.

Nanometrics' Pegasus digitizer is the basis for a scientific grade node and is the latest development in many years of designing and building reliable seismic instruments for the scientific and monitoring community. Coupled in a grab-and-go quick deploy package with a variety of sensors enables responses to many types of events and environmental measurements. These types of systems are not only for hazards, such as earthquakes and volcanoes, but can form the basis of better tools used for critical structure and microzonation studies using ambient noise.  Pegasus takes advantage of a complete ecosystem of software, making planning, deploying and data harvesting very simple and straightforward as well as providing a dataset that includes automatically generated metadata in the form of StationXML and standard miniSEED data files.  Pegasus design criteria was based on optimal SWaP (Size, Weight and Power) and makes it unique in short to long duration deployments without swapping of units in the field, while its broad sensor compatibility enables many types of measurements and is completely compatible with the advantages of Nanometrics smart sensors.

How to cite: Hamilton, V. and Moores, A.: A Multi-Use Case Scientific Sensor Node, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13772, https://doi.org/10.5194/egusphere-egu21-13772, 2021.

ML has been successfully applied to solve many NDT-CE tasks. This is usually demonstrated with performance metrics that evaluate the model as a whole based on a given set of data. However, since in most cases the creation of reference data is extremely expensive, the data used is generally much sparser than in other areas, such as e-commerce. As a result, performance indicators often do not reflect the practical applicability of the ML model. Estimates that quantify transferability from one case to another are necessary to meet this challenge and pave the way for real world applications.

In this contribution we invetigate the uncertainty of ML in new NDT-CE scenarios. For this purpose, we have extended an existing training data set for the classification of corrosion damage by a new case study. Our data set includes half-cell potential mapping and ground-penetrating radar measurements. The measurements were performed on large-area concrete samples with built-in chloride-induced corrosion of reinforcement. The experiment simulated the entire life cycle of chloride induced exposed concrete components in the laboratory. The unique ability to monitor deterioration and initiate targeted corrosion initiation allowed the data to be labelled - which is crucial to ML. To investigate transferability, we extend our data by including new design features of the test specimen and environmental conditions. This allows to express the change of these features in new scenarios as uncertainties using statistical methods. We compare different sampling and statistical distribution-based approaches and show how these methods can be used to close knowledge gaps of ML models in NDT.

How to cite: Völker, C., Kruschwitz, S., and Benner, P.: Uncertainty quantification for a sparse machine learning (ML) data set in non-destructive testing in civil engineering (NDT-CE) , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8798, https://doi.org/10.5194/egusphere-egu21-8798, 2021.

Increasing agricultural production challenges, such as climate change, environmental concerns, energy demands, and growing expectations from consumers triggered the necessity for innovation using data-driven approaches such as visual analytics. Although the visual analytics concept was introduced more than a decade ago, the latest developments in the data mining capacities made it possible to fully exploit the potential of this approach and gain insights into high complexity datasets (multi-source, multi-scale, and different stages). The current study focuses on developing prototypical visual analytics for an apple variety testing program in South Tyrol, Italy. Thus, the work aims (1) to establish a visual analytics interface enabled to integrate and harmonize information about apple variety testing and its interaction with climate by designing a semantic model; and (2) to create a single visual analytics user interface that can turn the data into knowledge for domain experts. 

This study extends the visual analytics approach with a structural way of data organization (ontologies), data mining, and visualization techniques to retrieve knowledge from an extensive collection of apple variety testing program and environmental data. The prototype stands on three main components: ontology, data analysis, and data visualization. Ontologies provide a representation of expert knowledge and create standard concepts for data integration, opening the possibility to share the knowledge using a unified terminology and allowing for inference. Building upon relevant semantic models (e.g., agri-food experiment ontology, plant trait ontology, GeoSPARQL), we propose to extend them based on the apple variety testing and climate data. Data integration and harmonization through developing an ontology-based model provides a framework for integrating relevant concepts and relationships between them, data sources from different repositories, and defining a precise specification for the knowledge retrieval. Besides, as the variety testing is performed on different locations, the geospatial component can enrich the analysis with spatial properties. Furthermore, the visual narratives designed within this study will give a better-integrated view of data entities' relations and the meaningful patterns and clustering based on semantic concepts.

Therefore, the proposed approach is designed to improve decision-making about variety management through an interactive visual analytics system that can answer "what" and "why" about fruit-growing activities. Thus, the prototype has the potential to go beyond the traditional ways of organizing data by creating an advanced information system enabled to manage heterogeneous data sources and to provide a framework for more collaborative scientific data analysis. This study unites various interdisciplinary aspects and, in particular: Big Data analytics in the agricultural sector and visual methods; thus, the findings will contribute to the EU priority program in digital transformation in the European agricultural sector.

This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 894215.

How to cite: Chuprikova, E., Mejia Aguilar, A., and Monsorno, R.: An Ontology-based Visual Analytics for Apple Variety Testing, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15804, https://doi.org/10.5194/egusphere-egu21-15804, 2021.

The increase of the metropolises stresses the urban areas and intensive planning works is necessary. Therefore, the development of new technologies and methodologies able to explore the subsoil and manage its resources in urban areas becomes an important source in terms of saving time and money. In the last decade, a new subdiscipline in the Applied Geophysics started: Urban Geophysics (Lapenna, 2017). Urban Geophysics analyzes the contribute, in terms of limits and potentialities, that geophysical methodologies can give for providing useful information about the subsoil, environment, buildings and civil infrastructures and supporting the public administrations in planning interventions in urban scenarios.

This work introduces a laboratory test, that was performed at the Hydrogeosite CNR-IMAA laboratory of Marsico Nuovo (Basilicata region, Italy). The test consisted in a multisensor geophysical application on an analogue engineering model. Thanks to the possibility to work in laboratory conditions, a detailed knowledge of the structure was available, providing great advantages for assess the capability of the geophysical methodologies for analyze engineering issues, regarding the characterization of the infrastructural critical zone placed at the interface soil-structure. For this purpose, geoelectrical and electromagnetic methodologies, including Cross hole Electrical Resistivity Tomography and Ground Penetrating Radar, were used to characterize the geometry of the foundation structures and the disposition of the rebar for the reinforced concrete frame. Finally, new geophysical approaches were applied in order to define the corrosion rate of reinforcement.

How to cite: Fornasari, G., Capozzoli, L., De Martino, G., Giampaolo, V., and Rizzo, E.: Geophysical characterization of an engineering infrastructure: laboratory tests., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4508, https://doi.org/10.5194/egusphere-egu21-4508, 2021.

Nowadays, non-invasive sensing technologies working at different spatial scales represent a recognized tool to support archaeological researches, because their deployment and cooperative use allow detection and localization of buried ruins before performing excavation. Therefore, they get significant advantages in planning the stratigraphic assays, while reducing costs and times, and support holistic approaches where cultural heritage management, protection and fruition aspects are considered under a unified context.

As a further example among those available in literature, this communication summarizes a successful case study carried out at the Archaeological site of Paestum, sited in the southern Italy [1].

Based on the analysis of aerial imagery and several unexpected archaeological findings, terrestrial measurement campaigns, involving magnetometer (MGA) [2] and ground penetrating radar (GPR) [3] methodologies, were carried out in the northwest quarter of the ancient city near the fortification wall and few meters away from the gate of Porta Marina. As detailed in [4], the MGA was exploited to investigate a large subsurface area in a relatively short time and allowed the identification of the most significant archaeological anomalies, by accounting for the variations of the earth magnetic field due to the different magnetic susceptibilities of construction materials and the magnetic characteristics of the shallow subsoil. The georeferenced MGA image was exploited to select the area requiring a further and more detailed survey, which was performed by means of GPR. Then, GPR data were processed by means of a microwave tomography based approach [4], which allowed a high resolution three dimensional reconstruction of buried targets starting from the electromagnetic field that they backscatter when illuminated by a known incident field. By doing so, detailed information about depth, shape, and orientation of the buried targets were retrieved and an impressive visualization of the the basement of the structure was achieved.

The area is currently under excavation and the initial discovered ruins fully confirm the hypotheses formulated on the basis of the elements found on the surface, the photo interpretations and geophysical investigations. The proposed reconstructive hypothesis of the building as a whole is a stylobate of 10.83 m x 6.80 on which 4 x 7 columns were arranged, with a significantly increased intercolumniation on the short sides (2.02 m) compared to the long sides (1.68 m).

[1] https://www.museopaestum.beniculturali.it/?lang=en

[2] A. Aspinall, C. Gaffney, A. Schmidt, A Magnetometry for archaeologists. Geophysical methods for archaeology, Altamira Press, Lanham, (2008).

[3] D. J. Daniels, Ground penetrating radar, IET, (2004).

[4] Capozzoli, L.; Catapano, I.; De Martino, G.; Gennarelli, G.; Ludeno, G.; Rizzo, E.; Soldovieri, F.; Uliano Scelza, F.; Zuchtriegel, G. The Discovery of a Buried Temple in Paestum: The Advantages of the Geophysical Multi-Sensor Application. Remote Sens. 2020, 12, 2711.

How to cite: Catapano, I., Capozzoli, L., Ludeno, G., Gennarelli, G., De Martino, G., Rizzo, E., Scelza, F. U., Zuchtriegel, G., and Soldovieri, F.: Multi-sensing geophysical surveys at the Archaeological Park of Paestum: the discovery of a small Doric temple, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13191, https://doi.org/10.5194/egusphere-egu21-13191, 2021.

Ground Penetrating Radar has widely proven to be an effective tool for archaeological purposes [1, 2]. Our contribution concerns a geophysical experimental activity carried out in the Complex of Villa dei Sette Bassi, an archaeological site located in Rome, Italy.

In particular, the area was hypothesized to be interested by the track of the ancient via Latina [3, 4], which was the main internal route that connected Rome with the ancient Region of Campania; it ran parallel to the Via Appia, but it was built way before it.

The historical evolution of this landscape has seen great changes since the Middle Ages with a new economy that designed new parcels, new land uses and the stripping of building material from ancient remains: activities that have profoundly altered the territory in its appearance and functioning but also its road network. The uncontrolled building development, has over time hidden the ancient road network, today witnessed only by decontextualized monuments immersed in modern urbanization. Accordingly, great portion of the ancient via Latina remains still buried.

This works reports on the outcomes of the geophysical tests conducted within the area of Villa dei Sette Bassi, with the specific goal of locating the buried track of the via Latina. The survey has been carried out by using multi-frequency ground penetrating radar (GPR) systems with different central frequencies. In detail, a preliminary low frequency analysis was conducted over the entire area that was indicated to be interested by the hidden remains by literary sources, to the intent of detecting the position of the buried road with higher accuracy. Based on the this, a second survey with higher resolution was conducted over a regularly spaced grid.

As a result, GPR tests have returned a coherent reflection pattern that is reasonably representative of a road subgrade/embankment. According to the preliminary archaeological interpretations, these results are most likely related to the historical track of via Latina, even though inspection pits are required in order to verify these assumptions.

In conclusion, GPR demonstrated a great applicability to archaeological purposes, i.e. to detect buried remains and to interpret the function of buried structures, despite the reliability and productivity of the data interpretation are strongly influenced by the expertise of both the geophysicists and the archaeologists involved.

References

[1] Bianchini Ciampoli, L., Santarelli, R., Loreti, E.M., Ten, A., Benedetto, A. {2020} “Structural detailing of buried Roman baths through GPR inspection”, Archaeological Prospections, In Press.

[2] Milligan, R., & M., Atkin, {1993}. The use of ground-probing radar within a digital environment on archaeological sites, in Andresen, J., Madsen, T. and Scollar, I., eds., Computing the Past: Computer Application and Quantitative methods in Archaeology: Aarhus, Denmark, Aarhus University Press, pp. 285–291.

[3] Monti, P.G. {1995} “Via Latina”, Istituto Poligrafico e Zecca dello Stato. Libreria dello Stato Roma.

[4] Rea, R., Montella, F., Egidi, R.. Alteri, R., Diamanti, F., Mongetta, M., {2005} “Via Latina”, in Lexicon Topographicum Urbis Romae, III, pp. 133-202, Quasar ed., Roma.

How to cite: Bianchini Ciampoli, L., Benedetto, A., Ten, A., Amici, C. M., and Santarelli, R.: Retrieving signs of buried historical roads by GPR: preliminary results from Villa dei Sette Bassi in Rome, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16316, https://doi.org/10.5194/egusphere-egu21-16316, 2021.

The estimation of the bulk permittivity of heterogeneous mixtures is of great interest for many Ground Penetrating Radar (GPR) and electromagnetic sensing applications [1], [2]. The most used method for estimating the bulk permittivity is the Complex Refractive Index Model (CRIM). The simplicity of this method is one its advantages however, the accuracy of the permittivity estimation has not been tested. Here, the CRIM model’s shape factor is examined and optimised in order to achieve a more accurate concrete bulk permittivity estimation. The concrete components are aggregate particles, cement particles, air-voids and moisture content; and they are randomly distributed with different volume percentages to produce various combinations. These combinations are modelled using the Finite-Difference Time-Domain (FDTD) method as it is an accurate and computationally efficient method [3]. The numerical modelling is then used to predict the bulk permittivity allowing to fine-tune CRIM model’s shape factor. The models are modelled in 3D and a GSSI-like antenna structure is used as the transmitting source [4]. The permittivity estimation uses an accurate time-zero method, which increases the accuracy of the estimated bulk permittivity hence, the shape factor [5], [6]. The results have shown that the optimised CRIM model over-performs the original CRIM model shape factor therefore, a better and more accurate bulk permittivity estimation is achieved for concrete mixtures.

References

[1] Daniels, D. J., (2004), Ground Penetrating Radar, 2nd ed. London, U.K., Institution of Engineering and Technology.

[2] Annan, A. P., (2005), Ground Penetrating Radar,  in Investigations in Geophysics, Society of Exploration Geophysicists, pp. 357-438.

[3] Taflove, A., Hagness, S. C., (2005), Computational electromagnetic: The Finite-Difference Time-Domain Method, Artech House, Norwood.

[4] Warren, C., & Giannopoulos, A., (2011), Creating Finite-Difference Time-Domain Models of Commercial Ground Penetrating Radar Antenna Using Taguchi’s Optimization Method, Geophysics, 76(2), G37-G47.

[5] Zadhoush, H., Giannopoulos, A., Giannakis, I., (2020), Optimising GPR time-zero adjustment and two-way travel time wavelet measurement using a realistic 3D numerical model, Near Surface Geophysics, Under review (Minor revisions).

[6] Zadhoush, H., (2020), Numerical Modelling of Ground Penetrating Radar for Optimization of the Time-zero Adjustment and Complex Refractive Index Model, PhD Thesis Submitted at The University of Edinburgh.

How to cite: Zadhoush, H., Giannopoulos, A., and Giannakis, I.: A Revised Complex Refractive Index Model for Inferring the Permittivity of Heterogeneous Concrete Models, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16517, https://doi.org/10.5194/egusphere-egu21-16517, 2021.

Ground penetrating radar (GPR) is a high-resolution geophysical non-destructive detection method, which is widely used in near surface target detection, and has been successfully applied in urban construction and geotechnical engineering. In urban life, underground pipelines undertake important missions such as energy transmission and information transmission. As the basic data of smart city, the acquisition of spatial location information of underground pipelines depends on geophysical detection data such as GPR. The traditional recognition and interpretation of  GPR underground pipeline image mainly depends on and is seriously limited by the professional experience of the staff, which is very disadvantageous to the development of large-scale urban underground pipeline survey. To address this problem, according to the GPR reflection image characteristics of isolated targets such as underground pipelines, this paper proposes an intelligent recognition concept of isolated targets in GPR profile based on CBIR (Content-based image retrieval) According to Hash algorithm and improved vector K-means clustering analysis, the intelligent detection, automatic image sorting and recognition of underground pipeline target in GPR profile are realized. Finally, the pipeline material is judged by extracting the image brightness function of the middle trace in the recognition area. The application results of numerical simulation experiments and measured data show that this algorithm can effectively identify the hyperbolic characteristics of the pipeline in the GPR profile, and the identified area can accurately reflect the spatial location of the underground pipeline.

How to cite: Li, B. and Zhao, Y.: Intelligent recognition of underground pipeline From GPR image based on Hash algorithm, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11199, https://doi.org/10.5194/egusphere-egu21-11199, 2021.

Shallow-seismic surface wave and ground penetrating radar (GPR) are employed in a wide range of engineering and geosciences applications. Full-waveform inversion (FWI) of either seismic or multi-offset GPR data are able to provide high-resolution subsurface characterization and have received particular attention in the past decade. Those two geophysical methods are involved in the increasing requirements of comprehensive site and material investigations. However, it is still challenging to provide an effective integration between seismic data and electromagnetic data. In this paper, we investigated the joint petrophysical inversion (JPI) of shallow-seismic and multi-offset GPR data for more consistent imaging of near surface. As a bridge between the seismic parameters (P-wave velocity, S-wave velocity, and density) and GPR parameters (relative dielectric permittivity and electric conductivity), the petrophysical relationships with the parameters namely porosity and saturation are employed to link two data sets. We first did a sensitivity analysis of the petrophysical parameters to the seismic and GPR parameters and then determined an efficient integration of using shallow-seismic FWI to update porosity and GPR FWI to update saturation, respectively. A comparison of several parameterisation combinations shows that the seismic velocity parameterisation in shallow-seismic FWI and a modified logarithm parameterisation in GPR FWI works well in reconstructing reliable S-wave velocity and relative dielectric permittivity models, respectively. With the help from the petrophysical links, we realized JPI by transforming those well recovered parameters to the petrophysical parameters and then to other seismic and GPR parameters. A synthetic test indicates that, compared with the individual petrophysical inversion and individual FWI, JPI outperforms in simultaneously reconstructing all seismic, GPR, and petrophysical parameters with higher resolution and improved details. It is proved that JPI would be a potential data integration approach for the shallow subsurface investigation.

How to cite: Qin, T., Bohlen, T., and Pan, Y.: Joint petrophysical full-waveform inversion of the shallow-seismic and multi-offset GPR data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14803, https://doi.org/10.5194/egusphere-egu21-14803, 2021.

In 2019, 3.1 billion Euro of damage was caused by piped water, accounting for the largest share (53%) of building insurance claims in Germany. In the event of damage, the accurate determination and localization of water ingress is essential to plan for and perform efficient renovations. Neutron probes are already applied successfully on building floors to localize the source of damage and other affected areas. However, additional information about the depth of moisture penetration can only be obtained by the destructive extraction of drilling cores, which is a time- and cost-intensive procedure. With its high sensitivity to water and fast measurement procedure, Ground Penetrating Radar (GPR) can serve as a suitable extension to the neutron probe, enabling more precise characterization of common forms of moisture damage.

In this research project, we study the influence of common types of moisture damage in differing floor constructions using GPR and a neutron probe. A measurement setup with interchangeable layers is used to vary the screed material (cement or anhydrite) and insulation material (Styrofoam, Styrodur, glass wool, perlite), as well as the respective layer thickness. Every configuration is measured for the following main cases: 1) dry state; 2) with a damaged insulation layer and 3) a damaged screed layer.

The evaluation is focused on the extraction of distinctive signal features for GPR, which can be used to classify the underlying case of damage. Furthermore, possible combinations of these features are investigated using multivariate data analysis and machine learning in order to evaluate the influence of different floor constructions.

To validate the developed methods, practical measurements on real damage cases in Germany are carried out and compared to reference data obtained from drilling cores.

How to cite: Klewe, T., Strangfeld, C., Ritzer, T., and Kruschwitz, S.: Classification of moisture damage in layered building floors with GPR and neutron probe, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7437, https://doi.org/10.5194/egusphere-egu21-7437, 2021.

Abstract—Metro traffic in subsurface tunnels is under a rapid development in many cities in the recent decades. However, the voids and other concealed defects inside and/or behind the tunnel lining pose critical threat to the safety of the operating metro tunnels. Ground penetrating radar (GPR) is a non-destructive geophysical technique by transmitting electromagnetic (EM) waves and receiving the reflected signals. GPR has proved its capability in the detection of the existence of tunnel structural defects and anomalies. However, the voids are still hard to be recognized in a GPR image due to the strong scattering clutter caused by the dense steel bars reinforced inside the concrete lining [1]. In this paper, we analyze the propagations of EM waves through reinforce concrete segments of shield tunnels by finite difference time domain (FDTD) simulations and model test.  Firstly, a series of simulations results we have done, indicates that the center frequency of GPR ranges from 400 MHz to 600 MHz has a good penetration through the densely reinforced concrete lining. And the distance between the antennas and the surface of shield tunnel segments should be less than 0.2 m to ensure a good coupling of incident electromagnetic energy into the concrete structure. Then, to image the geometric features of the void behind the segment, reverse-time migration method is applied to the simulated GPR B-scan profile, which presents higher resolution results than the results by using the traditional diffraction stack migration (Figure 1) [2]. Finally, the field experiment results prove that a commercial GPR system operating at a center frequency of 600 MHz do detect a void behind the shield tunnel (Figure 2). The reflection from the void, which starts from the back interface of the segments and lasts over 20 ns, are significantly different from the reflections from the rebars (Figure 3). In summary, GPR has potential in the detection of voids behind the shield tunnel segment. More simulations and field experiments will be performed in the future.

Keywords—ground penetrating radar (GPR); shield tunnel; voids; reverse time migration (RTM)

Acknowledgement—this work was supported by Shenzhen Science and Technology program (grant number:KQTD20180412181337494).

Fig. 1 Numerical simulation of two segments of 2D shield tunnel. (a) numerical model, (b) simulated GPR B-scan profile, (c) migrated profile by using diffraction stack migration and (d) migrated profile by using reverse-time migration.

Fig. 2 One photo of the field experiment.

Fig. 3 GPR reflections from a void behind the segment of a subway tunnel

References

[1]     H. Liu, H. Lu, J. Lin, F. Han, C. Liu, J. Cui, B. F. Spencer, “Penetration Properties of Ground Penetrating Radar Waves through Rebar Grids” , IEEE Geoscience and Remote Sensing Letters ( DOI: 10.1109/LGRS.2020.2995670)

[2]          H. Liu, Z. Long, F. Han, G. Fang, Q. H. Liu, “Frequency-Domain Reverse-Time Migration of Ground Penetrating Radar Based on Layered Medium Green's Functions”, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 11, no. 08, pp. 2957-2965, 2018.

How to cite: Liu, H., Lin, J., Meng, X., and Du, Y.: Detection of voids behind segments in the shield tunnels by using Ground Penetrating Radar, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14103, https://doi.org/10.5194/egusphere-egu21-14103, 2021.

Urban Resilience represents the capability of an urban system to preserve its features (in terms of public and private qualities and services) when shock events occur [1]. This topic is receiving an increasing interest for the climate change emergency which require innovative strategies for preserving the natural and anthropic resources present in the subsoil. In this framework, the Urban Geophysics could give a strong contribution to improving the knowledge of the critical issues affecting urban area [2].

One of the most interesting challenges is represented by the detection of ground collapse phenomena that can hardly reduce the safety and reliability of civil structures and infrastructures, as clearly demonstrated by the ground occurred in the Ospedale del Mare car park (Naples, Italy) [3] during the COVID-19 emergency that has brought the light on the weakness of the planning processes of the public authorities when fast decisions are required. Indeed, decision making in urban planning can be effectively supported by rational and reasoned use of the geophysical technologies able to reduce the risks imputable to the activities and decision required by the emergency planning in urban contexts.

This work focuses its attention on the capability of geophysical methodologies to detect, characterize and monitoring the presence of buried sinkholes, collapses, voids within the subsoil able to cause severe structural stability problems with rapid and non-invasive applications based on the use of Ground Penetrating Radar and Electrical Resistivity Tomographies. The studied cases showed how the cooperative use of the geoelectrical and electromagnetic methods can identify and monitor potential risks of collapses highlighting the pros and cons of the two techniques in terms of resolution and depth of study.

REFERENCES

[1] Lapenna V. (2016) Resilient and sustainable cities of tomorrow: the role of applied geophysics. Bollettino di Geofisica Teorica ed Applicata 58(4):237–251. https ://doi.org/10.4430/bgta0204

[2] Capozzoli L., De Martino G., Polemio M. et E. Rizzo, Surveys in Geophysics 2019, Geophysicaltechniquesfor monitoring settlement phenomena occurring in reinforced concrete buildings, Surveys in Geophysics, DOI: 10.1007/s10712-019-09554-8;

[3] Borghese L.,  Mortensen A. and R. Picheta, https://edition.cnn.com/2021/01/08/europe/italy-hospital-sinkhole-scli-intl/index.html (latest access 01/20/2021, January 9, 2021

How to cite: Capozzoli, L., De Martino, G., Fornasari, G., Giampaolo, V., and Rizzo, E.: ERT and GPR surveys for the detection of incipient collapse areas in urban environment, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15100, https://doi.org/10.5194/egusphere-egu21-15100, 2021.

Highway pavements serve the need for safe transportation of human being and freights, so their condition deserves continuous monitoring and assessment. However, pavements are most often monitored in terms of their surface performance evaluation. Either with or without surface distresses, excessive pavement unevenness and/or texture loss may lead to a reduced road users’ satisfaction. Most often, the pavement surface condition is sensed through laser profilers that operate at traffic speeds. Once detected through the stand-alone use of laser profilers, pavement roughness along a pavement surface may be of major concern for the related agencies, since the root causes of roughness issues are in most cases unknown.

Excessive unevenness might sometimes be interrelated with structural issues within one or more pavement layers or even issues within the pavement foundation support. Traditionally, coring and boreholes are considered suitable to detect the condition of pavement surface layers and pavement substructure respectively. However, these processes are destructive and time-consuming. On the contrary, Non-Destructive Testing

(NDT) can be alternatively used to rapidly evaluate potential structural problems at areas with roughness issues and identify areas for further investigation. A popular method to assess the pavement structural integrity is the use of nondestructive deflectometric tests, including the Falling Weight Deflectometer (FWD). This kind of testing outperforms the traditional approach; thus it is both desirable and practical.

On these grounds, related research is pursued towards integrating pavement profile and deflectometric data in order to further evaluate indications of increased pavement roughness. In particular, Long Term Pavement Performance (LTPP) data including deflectometric and pavement profile data is used. Additional sensing data through geophysical inspections with the Ground Penetrating Radar (GRP) is used to assist the overall pavement assessment. The study demonstrates the power of pavement sensing data in order to provide the related agencies with cost-effective and reliable evaluation methods and approaches.

How to cite: Plati, C., Gkyrtis, K., and Loizos, A.: Nondestructive data analysis for pavement profile evaluation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7920, https://doi.org/10.5194/egusphere-egu21-7920, 2021.

As an array antenna ground penetrating radar (GPR) system electronically switches any antenna combinations sequentially in milliseconds, multi-offset gather data, such as common mid-point (CMP) data, can be acquired almost seamlessly. However, due to the inflexibility of changing the antenna offset, only a limited number of scans can be obtained. The array GPR system has been used to collect time-lapse GPR data, including CMP data during the field infiltration experiment (Iwasaki et al., 2016). CMP data obtained by the array GPR are, however, too sparse to obtain reliable velocity using a standard velocity analysis, such as semblance analysis. We attempted to interpolate the sparse CMP data based on projection onto convex sets (POCS) algorithm (Yi et al., 2016) coupled with NMO correction to automatically determine optimum EM wave velocity. Our previous numerical study showed that the proposed method allows us to determine the EM wave velocity during the infiltration experiment.

The main objective of this study was to evaluate the performance of the proposed method to interpolate sparse array antenna GPR CMP data collected during the in-situ infiltration experiment at Tottori sand dunes. The interpolated CMP data were then used in the semblance analysis to determine the EM wave velocity, which was further used to compute the infiltration front depth. The estimated infiltration depths agreed well with independently obtained depths. This study demonstrated the possibility of developing an automatic velocity analysis based on POCS interpolation coupled with NMO correction for sparse CMP collected with array antenna GPR.

How to cite: Oikawa, K., Saito, H., Kuroda, S., and Takahashi, K.: Determining optimum wave velocity from sparse CMP automatically by coupling POCS interpolation and NMO correction: application to array antenna GPR data collected during in-situ infiltration test, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9074, https://doi.org/10.5194/egusphere-egu21-9074, 2021.

The radioactive cesium (¹³⁴Cs and ¹³⁷Cs), which originated from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, has remained in the soil and on plants as water-insoluble microparticles (termed as CsMPs) to some extent, and maintained relatively high radioactivity levels in the district. However, it has been reported that the radioactive Cs has been absorbed by plants. To interpret this phenomenon, the authors investigated CsMPs to determine if they become soluble during filtration and dialysis experiments. Moreover, other physical properties, such as mechanical properties and thermal stability, were observed during the course of the relevant experiments. These properties can be obtained by using carbonized charcoal litter with CsMPs. And simple and economic decontamination trials of the soil were performed by sieving after drying and roughly crushing.

How to cite: Tanaka, I., Yamaguchi, A., Kikuchi, K., Niimura, N., Saeki, Y., and Sugihara, M.: Dissolution, Mechanical Properties, and Thermal Stability of Microparticles Containing Radioactive Cesium on Plant Litter Derived from the Fukushima Daiichi Nuclear Power Plant Accident,  and Soil Decontamination Trials , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2976, https://doi.org/10.5194/egusphere-egu21-2976, 2021.

The Fukushima Dai-Ichi Nuclear Power Plant (FDNPP) accident that occurred in March 2011 released significant quantities of radionuclides into the environment. Ten years after the accident, questions still remain, particularly about the processes that led to the partial core meltdown of reactors 1 and 3. So far, some answers have been provided by the investigation of particles containing caesium (Martin et al., 2020) and sometimes uranium (Ochiai et al., 2018). Indeed, the composition of particles, which were produced and spread at the time of the reactor explosion, reflect the conditions that prevailed in the reactor. Accordingly, the objective of the current research is to develop a method for specifically locating actinide-bearing particles in sediment samples collected in the vicinity of FDNPP. To identify and locate such particles, three already existing methods have been upgraded, including 1) the method of fission tracks already used in the field of non-proliferation studies, 2) the autoradiography through the use of imaging plates that are currently employed in the context of the localization of particles containing radio-caesium and the dismantling of nuclear facilities (Haudebourg and Fichet, 2016), and 3) a real time autoradiography method through the use of the BeaQuant® instrument which has been developed for detecting radioactive particles in biology and geosciences.

In this study, a sediment sample collected nearby FDNPP, which may contain particles containing both radio-caesium and actinides, was selected. This sample was dried and sieved to 63 µm before being processed according to the different analysis protocols.  A quality control sample containing only uranium oxide particles was also analysed, as these particles are devoid of gamma-emitters.

The first results of this comparison of autoradiography methods for the detection of actinide-bearing particles in Fukushima samples will be presented. The method of fission tracks was particularly efficient for detecting both natural and anthropogenic uranium.

The next steps of this study will be to implement this method identified as optimal to isolate and characterise a larger number of particles released by FDNPP. The full characterization of these particles (size, morphology, elemental and isotopic compositions) will provide novel insights to determine their origin and to improve our understanding of their formation processes within the reactors and anticipate their fate in the environment.

References:

Haudebourg, R., Fichet, P., 2016. A non-destructive and on-site digital autoradiography-based tool to identify contaminating radionuclide in nuclear wastes and facilities to be dismantled. J. Radioanal. Nucl. Chem. 309, 551–561. https://doi.org/10.1007/s10967-015-4610-7

Martin, P.G., Jones, C.P., Cipiccia, S., Batey, D.J., Hallam, K.R., Satou, Y., Griffiths, I., Rau, C., Richards, D.A., Sueki, K., Ishii, T., Scott, T.B., 2020. Compositional and structural analysis of Fukushima-derived particulates using high-resolution x-ray imaging and synchrotron characterisation techniques. Sci. Rep. 10, 1636. https://doi.org/10.1038/s41598-020-58545-y

Ochiai, A., Imoto, J., Suetake, M., Komiya, T., Furuki, G., Ikehara, R., Yamasaki, S., Law, G.T.W., Ohnuki, T., Grambow, B., Ewing, R.C., Utsunomiya, S., 2018. Uranium Dioxides and Debris Fragments Released to the Environment with Cesium-Rich Microparticles from the Fukushima Daiichi Nuclear Power Plant. Environ. Sci. Technol. 52, 2586–2594. https://doi.org/10.1021/acs.est.7b06309

How to cite: Diacre, A., Fichet, P., Sardini, P., Donnard, J., Fauré, A.-L., Marie, O., Shozugawa, K., Susset, M., Hori, M., Pointurier, F., and Evrard, O.: Localization of actinide-bearing particles in sediment samples from the Fukushima restriction zone, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3320, https://doi.org/10.5194/egusphere-egu21-3320, 2021.

The 3rd model intercomparison project (MIP) of atmospheric dispersion model targeting on ¹³⁷Cs emitted from the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 was conducted (Sato et al. 2020). Nine models participated in the 3rd MIP. All participated models used the identical source term of Katata et al. (2015) and the identical meteorological data (Sekiyama and Kajino, 2020) as in the previous MIP (i.e., 2nd MIP Sato et al. 2018), but finer horizontal grid resolution (1 km) than that of 2nd MIP (3 km) was used for understanding the behavior of atmospheric ¹³⁷Cs measured in the vicinity of FDNPP. Results of the models elucidated that, as in the 2nd MIP, most of the observed high atmospheric ¹³⁷Cs concentrations (plumes) were reasonably well simulated by the models, and the good performance of some models cancelled a bad performance of some models when used as an ensemble, which highlights the advantage of the multimodel ensemble. The analyses also indicated that the use of the finer grid resolution (1 km) improved the meteorological field in the vicinity of FNDPP. As a consequence, the atmospheric ¹³⁷Cs measured near FDNPP was more reasonably reproduced in 3rd MIP than 2nd MIP.

As well as the evaluation of the performance of the model, we examined the usefulness of the results of atmospheric dispersion simulation in an emergency base on the results of 2nd and 3rd MIPs. For the analyses we defined the worst situation as that plume is observed but the model does not simulate it. The analyses reported that the worst situation happened in only 3% of the total calculation period by using the multimodel ensemble, even if the absolute value of the simulated ¹³⁷Cs in each model was different in the range of factor 3-6. The analyses also indicated that from six to eight models are required for making most of the advantages of the multimodel ensemble.

How to cite: Yamazawa, H., Sato, Y., Sekiyama, T., Kajino, M., Fang, S., Quérel, A., Quélo, D., Kondo, H., Terada, H., Kadowaki, M., Takigawa, M., Morino, Y., Uchida, J., Goto, D., Nakamura, M., and Kiriyama, Y.: 3rd model intercomparison projects of atmospheric dispersion model for 137Cs emitted from Fukushima Daiichi Nuclear Power Plant, and application of MIPs' results for usage in an emergency, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14377, https://doi.org/10.5194/egusphere-egu21-14377, 2021.

In April 2020, the largest forest fire occurred in the Chernobyl Exclusion Zone (ChEZ) in its history. The results of modeling the atmospheric transport of radioactive aerosols released into the atmosphere as a result of wildland fires in the ChEZ and around it are presented. The atmospheric transport model LEDI, developed at the Institute for Safety Problems of NPPs, and the Atmospheric Dispersion Module of the real -time online decision support system for offsite nuclear emergency RODOS, which development was funded by the EU, were used. The ¹³⁷Cs activity concentration in the surface air is calculated on a regional scale (in Ukraine) and a local scale (within the ChEZ). The ¹³⁷Cs activity in the surface air of Kyiv (115 km from the ChEZ borders) is found to have reached 2–4 mBq m⁻³ during the period April 3–20. The modeling results are generally consistent with measured data pertaining to radioactive contamination in Kyiv, within the ChEZ, and areas around four operating nuclear power plants in Ukraine.

A method for estimating the radionuclide activity emissions during wildland fires in radioactively contaminated areas is proposed. This method is based on satellite data of the fire radiative power (FRP), the radionuclide inventory in the fire area, and an emission factor for radioactive particles. A method was applied for forest fires in the ChEZ in April 2020. Preliminary estimations of an emission factor are made using FRP values obtained from NASA's MODIS and VIIRS active fire products.

On April 16, 2020, a strong dust storm was observed in the ChEZ, which coincided with the period of intense wildland fires. The additional ¹³⁷Cs activity raised by the dust storm from burned areas in the meadow biocenoses was estimated to be about 162 GBq, i.e. up to 20% of the total activity emitted into the air during the entire period of forest fires on April 3-20, 2020. According to the modeling results, during April 16-17, the input of resuspension of radioactive particles due to a dust storm was up to 80-95% of the total ¹³⁷Cs activity in the surface air near the Chernobyl NPP. In Kyiv, this value decreased to only about 4%.

The total effective dose to the population of Kyiv during the fire period is estimated to be 5.7 nSv from external exposure and the inhalation of ¹³⁷Cs and ⁹⁰Sr, rising to 30 nSv by the end of 2020. This is about 0.003% of the annual permissible level of exposure of the population. A committed effective dose up to 200-500 nSv is estimated for the personnel of the Chernobyl NPP from the radioactive aerosol inhalation during the 2020 forest fires, which is not more than 0.05% of the established control levels of internal exposure for them.

How to cite: Talerko, M., Lev, T., Kovalets, I., Zheleznyak, M., Igarashi, Y., Paskevych, S., Kashpur, V., and Kireev, S.: Modeling study of the atmospheric transport of radioactivity after wildland fires and a dust storm in the Chernobyl Exclusion Zone in April 2020, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5134, https://doi.org/10.5194/egusphere-egu21-5134, 2021.

The atmospheric release of radionuclides is a crucial potential hazard to public health. Its release rate is vital in assessing the international environmental risk of atmospheric radionuclide leaks and conducting nuclear emergency preparedness. However, according to the radionuclide leaks such as the Fukushima Daiichi accident and the recent iodine-131 and ruthenium-106 releases in 2017, the release rate cannot be directly measured or derived in a forward way, but can only be inversely estimated by comparing the environmental measurements with a model-predicted plume, a technique often referred to as source inversion. However, such inversion is vulnerable to the inevitable plume biases, including the plume range (i.e. the area of positive model predictions) and transport pattern in radionuclide transport modeling, leading to inaccurate source estimates and risk assessment.

This paper describes an automated method that estimates the release rate while comprehensively correcting plume biases. By using the spatial correlation matrix, the predicted plume can spread over a broader area, thus covering the potential range of the true plume. Then, the difficult task of direct plume adjustment is simplified to tuning the predictions inside a correlation-adjusted plume. Based on this, the previous joint method can work efficiently to estimate the release rate while simultaneously refining the predictions inside the adjusted range, correcting both the plume range and the transport pattern. An ensemble-based algorithm is proposed to automatically calculate the spatial correlation in order to execute this method. With this algorithm, SERACT can accomplish realistic and robust source estimation without manual adjustment on any parameters.

The proposed method SERACT is validated with the two wind tunnel experiments based on a real Chinese nuclear power plant site, and the site features highly heterogeneous topography and dense buildings. In this paper, two radionuclide transport models with mild and severe plume biases respectively are used to assess the adjustment efficiency of SERACT, including source estimation and plume distribution. Its performance is compared with that of the standard approach and a recent state-of-the-art method. Its sensitivity to the number and quality of measurements, and the selection of autocorrelation scales is also investigated.

The results demonstrate that SERACT corrects the plume biases with high accuracy (Pearson’s Correlation Coefficient=1.0000, Normalized Mean Square Error≤1.03×10⁻³) and reduces the estimation error by nearly two orders of magnitude at best. In addition, SERACT exhibited stable performance in all the validation tests and gave the lowest error levels with various numbers and quality of measurements. With fully automated parameterization, its performance is close to that obtained with the optimal autocorrelation scale in all test cases. These results indicate that SERACT is robust in various inversion cases and is able to serve as a general remediation to the long-standing imperfect modeling issue in source inversion.

How to cite: Zhuang, S. and Fang, S.: Simultaneous release rate estimation and modeled plume bias correction for atmospheric radionuclide emissions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-114, https://doi.org/10.5194/egusphere-egu21-114, 2021.

To assess the levels of radioactivity, the soils of the Arctic region of Western Siberia were studied. The content of Cs-137 in the soils of the studied region ranges from 2 to 9 Bq/kg, with an average value of 4 Bq/kg.

The average contents of natural radionuclides (U, Th and K-40) in soils are determined by the radioactivity of the parent rocks. The radioanalytical results showed that the average Th content is 2.8 (0.3-6.7) ppm; U – 2.0 (0.5-6.6) ppm, K-40 – 233 (16-473) Bq/kg in the soils.

This work was supported by the Russian Science Foundation grant (project No 18-77-10039). Analytical studies were carried out at the Center for multi-elemental and isotope research SB RAS.

How to cite: Mezina, K., Melgunov, M., and Belyanin, D.: Natural and artificial radioactivity of soil of the Arctic part of Western Siberia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16193, https://doi.org/10.5194/egusphere-egu21-16193, 2021.

The ¹³⁷Cs (t_1/2 =30 years) is a principal radioisotope that was artificially introduced into the environment through the atmospheric bomb tests took place from the middle of the 1940s to the 1980s and from the major nuclear accidents (i.e., Chernobyl, 1986 and Fukushima, 2011). From the atmosphere, ¹³⁷Cs easily adsorbs to particles and it returns to lithosphere (pedosphere) by wet and dry deposition as a radioactive fallout component. Due to the Chernobyl nuclear accident, the released contaminated air mass, containing Cs-137, largely propagated, deposited, and distributed across several European countries in the ambient environment (Balonov et al., 1996). These particles also reached houses (e.g. through open windows, cracks, and vents) in an urban environment and deposited inside resulting in the exposition of the habitants to ¹³⁷Cs, especially in areas that are not accessible for a regular cleaning like attics. Following the nuclear accidents, primary attention was drawn to agricultural areas and less attention was paid to urban environments. Accordingly, the goal of this study is to compare the ¹³⁷Cs activity in attic dust as undisturbed samples, and urban soils as disturbed environmental materials to determine the ¹³⁷Cs distribution in urban environment. 

Attic dust (AD) samples were collected from 14 houses, which were built between 1900 and 1990 14 urban soil (US) samples were collected nearby the houses at a depth of 0-15 cm in Salgótarján, a former industrial city. To obtain a representative local undisturbed soil sample, a forest soil sample was collected from the upwind direction (NW) of the city. To check the ¹³⁷Cs content of the local industrial waste material, we also collected fly-ash slag sample from a waste dump.   AD and US samples were analyzed by a well-type HPGe and with an n-type coaxial HPGe detector in a low background iron chamber, respectively.

Cs-137 activity in the studied AD ranges from 5.51±0.9 to 165.9±3.6 Bq kg^-1, with a mean value of 75.4±2.5 Bq kg^-1 (decay corrected in 2016). In contrast, US samples show ¹³⁷Cs activity ranging between 2.3±0.4 and 13.6±0.6 Bq kg^-1.  The brown forest soil sample has elevated ¹³⁷Cs activity concentration (18.5±0.6 Bq kg^-1), compared to the urban soils. The fly-ash slags activity is below the detection limit (0.7±0.5 Bq kg^-1).

The average ¹³⁷Cs activity in AD is ~15 times higher than that of US. This result clearly indicates that attic area provides a protected (hardly or unchanged) environment, therefore physical condition of the dust remains constant in time, and there is a small chance for chemical reaction. Forest soil proves that US were highly disturbed by anthropogenic activity. This is supported by fly-ash slag activity results.  Whereas, ¹³⁷Cs activity concentration of the AD samples shows significantly higher than that of the studied soils in Hungary. This confirms again US cannot show the historical atmospheric ¹³⁷Cs pollution such as attic dust. A statistically significant relationship (p=0.003, r²=0.05) were found between the AD and US samples. Therefore, it can be considered that attic dust remained undisturbed for decades and preserve past record of components of atmospheric pollution.

How to cite: Tserendorj, D., Szabó, K. Z. S., Völgyesi, P. V., Abbaszade, G., Tan, D. L. T., Salazar, N., Zacháry, D., Nguyen, T. C., and Szabó, C.: Comparative study of Cs-137 activity concentration between attic dust and urban soil from Salgotarjan city, Hungary, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16233, https://doi.org/10.5194/egusphere-egu21-16233, 2021.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released the largest quantity of radiocaesium into the terrestrial environment since the Chernobyl nuclear accident. The surrounding land received 2.7 PBq of radiocaesium to forests, agricultural lands, grasslands, and urban areas, from which the radionuclides migrated through soil and waterways. In this presentation, the deposition and distribution of radionuclides, especially radiocaesium, in the terrestrial environment as a result of the FDNPP accident are discussed based on the past 10 years' intensive dataset. Anthropogenic activities such as rice and vegetable cultivation and residential activities in the upstream area have led to a rapid decline in the activity concertation of 137Cs of suspended sediment (SS) transport in the river network, and these declines directly control the dissolved 137Cs concentration in the river water. We outline the environmental and anthropogenic factors that influenced the subsequent transport and impacts of radionuclides through the environment. The environmental aftermath of the accident at Fukushima is compared to Chernobyl, and the relatively rapid remediation of the Fukushima region relative to the region surrounding Chernobyl will be explained.

How to cite: Onda, Y., Taniguchi, K., Yoshimura, K., and Wakiyama, Y.: The impact and fate of fallout radionuclides by Fukushima Daiichi Nuclear Power Plant Accident in hydrological systems and post-accident environmental recovery, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14671, https://doi.org/10.5194/egusphere-egu21-14671, 2021.

Radioiodine is one of the most important radionuclides released by the accidents of Fukushima Dai-ichi nuclear power plant (FDNPP). Iodine-131 elevated ambient radiation dose rate immediately after the accident, but it is extinguished due to its short half-life. The long-lived ¹²⁹I can be used as a tracer to retrospectively infer the level of ¹³¹I. Understanding of environmental behavior of ¹²⁹I is important for preparedness against nuclear disaster. This study presents sampling campaigns on the Abukuma River during two high flow events, and discusses riverine ¹²⁹I behavior based on comparisons with that of ¹³⁷Cs. The study site was the Kuroiwa site locating at midstream of the Abukuma river. Its catchment area was 2886 km² and mean ¹²⁹I inventory in the catchment was 0.041 Bq m^-2. Five and seven river water samples were taken during high-flow events in July 2018 (JUL18) and October 2018 (OCT18), respectively. Suspended sediment and filtrate samples were obtained by decantation and subsequent filtration with 0.45 μm-mash membrane filter, respectively. The suspended sediment and filtrate samples were measured for ¹³⁷Cs activity concentrations with HPGe detector and then measured for ¹²⁹I/¹²⁷I ratio with accelerator mass spectrometer and for ¹²⁷I concentration with ICP-QQQ-MS. Mean ¹²⁹I activity concentration in suspended sediment during JUL18 and OCT18 were 1.0 and 0.43 mBq kg^-1, respectively. In terms of temporal trends, ¹²⁹I activity concentration in suspended sediment lowered in the peak water discharge phase, contrastive to those of ¹³⁷Cs which were the highest at peak water discharge phase. Mean dissolved ¹²⁹I activity concentrations during JUL18 and OCT18 were 0.18 and 0.067 μBq L^-1, respectively. Both ¹²⁹I and ¹³⁷Cs activity concentrations in dissolved form tended to decrease with time during two high-flow events. Mean apparent distribution coefficient (Kd) during JUL18 and OCT18 were 4.3 ×10⁴ and 6.1 ×10³ L kg^-1, respectively. The Kd values of ¹²⁹I were lower than those of ¹³⁷Cs and it reveal relatively-high solubility of ¹²⁹I. Total exportation of ¹²⁹I from the catchment during JUL18 and OCT18 were estimated as 1.0 × 10⁴ and 2.3 × 10⁴ Bq, respectively. Exported ¹²⁹I in dissolved form accounted for 80 and 27% of total exportations, respectively. By contrast, more than 95% of ¹³⁷Cs was exported in particulate form in the events. These results indicated an importance of dissolved form for understanding environmental behavior of radioiodine.

How to cite: Wakiyama, Y., Matsumura, M., Matsunaka, T., Hirao, S., and Sasa, K.: Behavior of 129I in the Abukuma River water during two high-flow events in 2018, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14420, https://doi.org/10.5194/egusphere-egu21-14420, 2021.

In Fukushima Prefecture, radiocesium as the particulate and dissolved form has been discharging from the mountains and forests since the Fukushima Dai-ichi nuclear power plant (FDNPP) accident in 2011. In particular, in October 2019, the watershed around the FDNPP was subjected to extensive flooding due to Typhoon Hagibis, resulting in significant changes in the hydrological environment. In this study, we investigated the characteristics of changes in particulate/dissolved ¹³⁷Cs concentrations in the main 3 rivers in the north region of FDNPP 3–9 years after the nuclear accident and the impact of the typhoon on ¹³⁷Cs dynamics in river water.

Monthly observations of river waters in baseflow conditions showed a decrease in dissolved ¹³⁷Cs concentration with an environmental half-life of 2–10 years, and seasonal fluctuation such as increasing in summer and decreasing in winter. The annual amplitude of the dissolved ¹³⁷Cs concentration in water released from dams was smaller and the peak of the concentration was observed later than that in river sites where the influence of dams is small. The ¹³⁷Cs concentrations in the suspended solids did not show any significant seasonal variation, and the environmental half-life of 1–8 years was relatively faster than the dissolved forms observed at the same site. Immediately after Typhoon Hagibis in 2019, the dissolved ¹³⁷Cs concentration decreased significantly compared to the previous years, especially at two dam lake discharge sites. At the two sites, the dissolved ¹³⁷Cs concentration did not recover to the level predicted by the pre-typhoon data even one year after the typhoon event, but no significant decrease in ¹³⁷Cs concentration in suspended solids was observed. These differences in the environmental behavior of ¹³⁷Cs in different forms suggest that there are limitations in predicting particulate and dissolved ¹³⁷Cs concentrations with a fixed parameter such as partition coefficient.

How to cite: Tsuji, H., Ozaki, H., and Hayashi, S.: Mid-long term change of particulate/dissolved 137Cs concentration in river water and the impact of Typhoon Hagibis in 2019, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14063, https://doi.org/10.5194/egusphere-egu21-14063, 2021.

The impact of freeze-thaw processes and subsequent runoff affecting the ¹³⁷Cs flux and concentration in sediment discharge were revealed in bareland erosion plot following the Fukushima nuclear power plant accident by detailed monitoring and laser scanner measurement on the soil surface. We found that surface topographic changes due to the frost-heaving during the winter-spring period, and rill formation during the summer. We also found the evident seasonal changes in ¹³⁷Cs concentration; high during the early spring and gradually decreased thereafter, then surface runoff from the plot frequently occurred during spring and autumn when rainfall was high and reached a maximum in summer. From these results, the higher ¹³⁷Cs concentration in spring was caused by a mixture of unstable surface sediment following freeze-thaw processes and then transported in the early spring, but erosion amount is not significant because of the less rainfall event. The sediment with a lower ¹³⁷Cs concentration, which was supplied from the rill erosion and its expansion, was wash-offed during the summer, contributing most of the flux from erosion in bareland in Fukushima region. In case,  heavy rainfall occurs in the early spring, caution is required because high concentrations of cesium may flow down into the river.

How to cite: Igarashi, Y., Onda, Y., Wakiyama, Y., Yoshimura, K., Kato, H., Kozuka, S., and Manome, R.: Impacts of freeze-thaw processes and subsequent runoff on 137Cs washoff from bareland in Fukushima, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8553, https://doi.org/10.5194/egusphere-egu21-8553, 2021.

The Chornobyl accident in 1986 led to radioactive contamination of surface water bodies (SWB) in the Chornobyl Exclusion Zone (ChEZ), including lakes (Azbuchyn, Glyboke, Yanov crawl etc) and the Cooling Pond (CP). An abundance in fallout the dispersed fuel particles (FPs) was a specific feature of the accident, comprising the debris of irradiated nuclear fuel in different states of uranium oxidation mixed with construction materials.

Contamination of SWB by 90Sr and transuranic isotopes was mainly because of FPs. Experimental studies on the behaviour of FPs in soils and aquatic systems have shown that main factors controlling release of radionuclides outside FPs are: composition of the matrix, state of initial oxidation and oxidation properties of the environment.  

FPs behavior in SWB has not been sufficiently studied, though limited data suggest contrasting differences to terrestrial environments. Mainly is because of the different oxidation properties of soil and bottom sediment, creating better conservation conditions for FPs in sediment. In case when in SWB bed become dry and exposed, as is the case in the CP after decommissioning, an intensive processes of primary soil formation begin on exposed areas. This later forced dissolution of FPs, and hence radionuclides transition into more mobile forms followed by release to groundwater and surface runoff. 

We have developed convenient method for identifying Chornobyl FPs based on radiography, which comprises the exposure of X-ray film by spreading over a thin-layered dry solid sample. Processing X-ray films and image analysis makes it possible to estimate the size of FPs, as well as dispersion and distribution of radionuclide activity within the FPs of different size fractions. This also facilitates picking up single FPs to carry out extended individual analysis by EDXRF, SEMs etc. The radiography method was used to estimate the chemical resistance of FPs after sequential leaching to predict the behaviour of radionuclides in natural field conditions.

Overall, more than 120 samples were collected from bottom sediments cores taken from different SWB in ChEZ and analyzed by radiography. The results obtained show that from 70 to 90% of activity of radionuclides in sediments are associated with FPs. One gram of sediment contains several 10s to several 100s of individual FPs, while there is significant spatial heterogeneity of FPs density over the territory of ChEZ. The majority of FPs are less than 3 microns and their contribution to total activity was estimated as minor.

The main contribution to activity (>70%) comes from particles with a diameter of more than 10 microns and, accordingly, mobility of radionuclides will be determined by processes of destruction and leaching of radionuclides from particles of these size. Chemically resistant FPs are of 3-5 microns, and the highest concentration of fuel particles is typical for SWB located in close proximity to the ChNPP.

Up to 7% of the activity remains associated with FPs after being treated with strong 8M nitric acid indicating that 90Sr, transuranic and, partly, 137Cs are confined in chemically very stable particles and may not be mobilized under natural conditions for many decades. 

How to cite: Protsak, V., Laptev, G., Derkach, G., Korychenskyi, K., Prokopchuk, N., Nanba, K., Igarashi, Y., Konoplev, A., Kireev, S., and Smith, J.: Recent developments of the radiography method for characterisation of Fuel particles in Surface water bodies of Chornobyl Exclusion zone , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15221, https://doi.org/10.5194/egusphere-egu21-15221, 2021.

Since the 1986 Chornobyl accident transport of radionuclides by Pripyat River shares more than 90% of the annual total flux of radioactivity coming out the Chornobyl Exclusion Zone (ChEZ).  90Sr was the main contributor to this flux. In course of time destruction of the accidentally dispersed "fuel particles" leads to increase of mobile, e.g. water-soluble, forms of 90Sr  on territories affected by, while fixation of 137Cs in soil is reflected by significant reduction in 137Cs aquatic transport outside the ChEZ.

Heavily contaminated floodplain of the Pripyat River, located in vicinity of ChNPP upstream of Yaniv Bridge up to Ukrainian - Belorussian border, was considered as a “hotspot” with highest risks to the Pripyat and Dnipro water contamination due to recurrent flooding of these territories. This was evidently elucidated after the 1991 ice jam event when drastic increase of 90Sr in water was observed. The dikes splitting leftbank floodplain from the Pripyat river channel were constructed in 1992-1993. Yet, it is still important to quantify the amount of 90Sr that can be washed off the floodplain due to potential dike breakage caused by the extreme floods. 

Key parameters used to describe status of radionuclide in reaching equilibrium in soil-water system are the distribution coefficient (Kd) and kinetic rate that is reciprocal of typical time scale of desorption processes. These parameters subsequently were estimated in 1991 on the basis of batch experiment carried out with the soil monoliths sampled from the Pripyat floodplain ( Laptev and Voistekhovich, 1991). Results were used in the 2D model COASTOX for justification the construction of protecting dikes (Zheleznyak at al., 1992).

To analyze current ability of 90Sr to be washed off the floodplain, soils monoliths were collected in 2020. The experimental studies of the soil cores collected from same location as the monoliths allowed to estimate mobile speciation of 90S and calibrate mass-exchange parameters. Amount of the readily exchangeable forms of 90Sr in soils significantly increased from 10-30% in the first years after the accident up to 65-75% as to 2020. Results of field and laboratory  studies were used for simulation the scenarios of 90Sr washing off the floodplain during the dikes breaks on the basis of contemporary version of COASTOX model, that includes the parallel algorithms for numerical solution of the model equations on the unstructured computational grids for multi CPU and GPU systems. Approaches for the modelling of the secondary release of 90Sr due the rapid destruction of “fuel particles” are considered. Taking into account two concurrent processes - decrease of amount of 90Sr in uppermost soil layer due to decay and downward vertical migration (1), amid increased amount of exchangeable forms of 90Sr (2), one could project subsequent increasing of 90Sr  in Pripyat and Dnipro river waters downstream the source in case of the dike breakage scenarios. On the other hand, computer simulation suggests that the maximal values of the 90Sr concentrations expected to be not higher than the measured ones during the high floods events after the accident.

How to cite: Laptev, G., Voitsekhovych, O., Protsak, V., Zheleznyak, M., Nanba, K., Konoplev, A., Igarashi, Y., Wakiyama, Y., Bezhenar, R., Kivva, S., Pylypenko, O., Sorokin, M., Kireev, S., and Veremenko, D.: Temporal changes of mobile forms of 90Sr on Pripyat River floodplain in vicinity of Chornobyl NPP: measurements and risk assessments for river water contamination, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10934, https://doi.org/10.5194/egusphere-egu21-10934, 2021.

Cooling Pond (CP) of the Chornobyl Nuclear Power Plant (ChNPP) is one of the most radioactively contaminated large water bodies over the globe. During the active phase of the ChNPP accident, radionuclides got into the CP in result of atmospheric deposition, release of highly contaminated water from system of accidental cooling, and water used to extinguish the fire. In the years after the accident, the contamination was distributed in the CP due to currents. For this period, three types of hydrological conditions dominated in the CP. Initially, the currents were forced by the cooling system of the ChNPP, which caused a circular movement of water. After the decommissioning of the ChNPP, the natural circulation took place in the CP. Starting from the end of 2014, when pumps that continuously fed the CP with water from the Prypiat River were shutdown, a gradual decrease of water level began. Now the water level has dropped by about 6 m leading to the transformation of the whole reservoir into several small lakes and redistribution of radionuclides in them. The objectives of the study were to calibrate models, which were customized for the CP, using data for the whole post-accident period including data collected during the drawdown period by the joint efforts of Ukrainian and Japanese researchers, and then to provide model based predictions of the future radionuclide concentrations in new water bodies.

During field studies that were carried out in November 2020, the current state of radioactive contamination of the CP was investigated. Samples of water, suspended and bottom sediments and biota were taken in 9 closed or semi-closed water bodies formed after partial drying of the CP. Concentrations of Cs-137 and its distribution in dissolved and particulated forms were measured in the laboratory. For simulations, the modeling system that consists of the 3D model of thermohydrodynamics and radionuclide transfer THREETOX and the box model POSEIDON-R was created. The THREETOX model was used for the obtaining currents in the CP for each type of hydrological conditions. The POSEIDON-R model was applied for the long-term simulations of the changes of activity concentration in the water, bottom sediments and biota starting from the 1986. The system of boxes in the POSEIDON-R model includes shallow and deep-water boxes. It was built in such a way that after the water level in the CP fell, the calculations were performed only in deep-water boxes. Fluxes of water between boxes were calculated based on currents from the THREETOX model. Seasonal changes in distribution coefficient K_d describing the partition of Cs-137 concentration between water and sediments were also taken into account. Calculated concentrations of Cs-137 in water and bottom sediments agree well with measurements for all boxes and for entire modeling period. It has been shown that POSEIDON-R model is able to reproduce changes in the concentrations of Cs-137 in freshwater fish occupying different levels the food chain. Scenarios for the potential changes of Cs-137 concentrations were considered by the variation of basic parameters.

How to cite: Bezhenar, R., Zheleznyak, M., Gudkov, D., Kanivets, V., Laptev, G., Protsak, V., Sakaguchi, A., Nanba, K., Wada, T., Kanasashi, T., Kireev, S., Veremenko, D., Nasvit, O., and Uematsu, S.: Model & data based assessment of the impacts of drawdown of the Chornobyl NPP Cooling Pond on the Cs-137 concentrations in water, sediments and biota, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12329, https://doi.org/10.5194/egusphere-egu21-12329, 2021.

In Japan's forests, field data on the distribution and migration of radiocesium deposited by the Fukushima Daiichi Nuclear Power Plant accident, from the initial dynamics to the distribution in the forest over ten years, have been vigorously collected. The results have been published in an IAEA technical report (IAEA- TECDOC-1927, 2020) as a database of migration parameters to be compiled by an international project (MODARIA II: Modelling and Data for Radiological Impact Assessments) promoted by the International Atomic Energy Agency (IAEA). Radiocesium's transfer mechanisms in the forest by hydrological processes and the runoff through the water system were summarized based on investigations in experimental forests and watersheds in Fukushima Prefecture. Besides, we outlined the missing links that need to be clarified by re-analysis of existing data and additional experiments based on previous studies on Fukushima and Chernobyl. Finally, we discussed the direction of future monitoring surveys.

How to cite: Kato, H., Shinozuka, T., Akaiwa, S., Iida, H., Saidin, Z. H., and Onda, Y.: Transfer of the Fukushima accident-derived radiocesium by hydrological processes in Japanese forests, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14511, https://doi.org/10.5194/egusphere-egu21-14511, 2021.

The accident at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) in 2011 led to the uncontrolled release of a significant amount of radioactive materials into the marine environment. To prevent the further release of highly contaminated water, which was used for cooling the overheated nuclear reactor cores, and groundwater, which was continuously pumped out the reactor buildings, a large number of tanks was installed in the area around NPP to collect all this water. However, at the moment the capacity of tanks is almost exhausted. The contaminated water was processed to decrease the activity stored in the tanks, but any decontamination system cannot remove all radionuclides from the water. According to TEPCO (2020) data, about 1.2 million m³ of contaminated water were stored in tanks in March 2020 containing radionuclides with long and moderate half-life, among which 10 radioisotopes (H-3, C-14, Co-60, Sr-90, Tc-99, Ru-106, Sb-125, I-129, Cs-134, Cs-137) are dominant (Buesseler, 2020). Therefore, it is important to estimate the impact on human health of potential release of contaminated water from tanks to the ocean. This impact significantly depends on the ability of radionuclides to concentrate in the marine organisms, which are in the human diet, and the values of dose coefficient. The compartment model POSEIDON-R was applied for calculation the concentration of activity in the water, bottom sediments and biota at different distances from the FDNPP. The area of interest was covered by the system of compartments with specification around FDNPP. The exchanges of activity between compartments were governed by average currents in the region. The maximal concentrations and doses were conservatively estimated for coastal box 4x4 km around the FDNPP. Accumulation of activity in the organisms was calculated by dynamical model taking into account chemical properties of the element, its role in metabolic processes and the positions of organisms in the pelagic and benthic food webs. The potential individual doses of radiation were estimated using average consumption rates of marine products in Japan based only on domestic production. The conservative scenario, when a whole volume of contaminated water will be released into the marine environment at a constant rate during 10 years, was chosen. According to results of modelling for 50 years, the obtained dose even in the coastal box turned out to be significantly lower than the maximum annual effective dose commitment for the public equal to 1 mSv (IAEA, 2011). The main contribution into the dose is expected from I-129 and C-14. Although the activity of tritium (H-3) far exceeds activities of other radionuclides in tanks, its contribution to the total dose is only third due to low ability to concentrate in organisms and low dose coefficient. The dose factors and activity factors for 10 radionuclides at different distances from the FDNPP were obtained to be used for estimation of doses to human and concentration of activities in marine organisms for any long-lasting release scenario.

How to cite: Maderich, V. and Bezhenar, R.: Modelling study of the potential release of contaminated water from storage tanks at the Fukushima Dai-ichi NPP into marine environment, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10690, https://doi.org/10.5194/egusphere-egu21-10690, 2021.

This investigation uses the tracer information provided by the 2011 direct ocean release of radio-isotopes, (¹³⁷Cs, ~30-year half-life and ¹³⁴Cs, ~2-year half-life) from the Fukushima Dai-ichi nuclear power plant (FDNPP) together with hydrographic profiles to better understand the origins and pathways of mode waters in the North Pacific Ocean. While using information provided by radionuclide observations taken from across the basin, the main focus is on the eastern basin and results from analyses of two data sets 2015 (GO-SHIP) and 2018 (GEOTRACES) along the 152°W meridian. The study looks at how mode waters formed in the spring of 2011 have spread and mixed, and how they have not. Our radiocesium isotope samples tell a story of a surprisingly confined pathway for these waters and suggest that circulation to the north into the subpolar gyre occurs more quickly than circulation to the south into the subtropical gyre. They indicate that in spite of crossing 6000 km in their journey across the Pacific, the densest 2011 mode waters stayed together spreading by only a few hundred kilometers in the north/south direction, remained subsurface (below ~200 m) for most of the trip, and only saw the atmosphere again as they followed shoaling density surfaces into the boundary of the Alaska Gyre. The more recent data are sparse and do not allow direct measurement of the FDNPP specific ¹³⁴Cs, however they do provide some information on mode water evolution in the eastern North Pacific seven years after the accident. 

How to cite: Macdonald, A., Yoshida, S., and Rypina, I.: A 2011-2018 Fukushima Perspective on North Pacific Mode Water Pathways, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10397, https://doi.org/10.5194/egusphere-egu21-10397, 2021.

Artificial radionuclide ¹³⁷Cs has been supplied into the ocean by global fallout due to atmospheric nuclear weapons tests since 1945, releases from reprocessing plants since 1952, and most recently by fallout and discharge due to the Fukushima Dai-ichi Nuclear Power Plant (1F NPP) accident since 2011.¹³⁷Cs activities measured for scientific purposes as well as environmental health and safety monitoring have been summarized in a historical database by IAEA. The spatio-temporal density of the observations varies widely, therefore simulation by an ocean general circulation model (OGCM) can be helpful in the interpretation of these observations. We used the Parallel Ocean Program version 2 (POP2) of the Community Earth System Model version 2 (CESM2). The horizontal resolution is 1.125 degrees in longitude and 0.28 to 0.54 degrees in latitude. The simulation period was from 1945 to 2030, and the atmospheric conditions were forced to cycle through repeating normal years. The purposes of this study are to investigate the effect of the release from the reprocessing plants on the distribution of ¹³⁷Cs activity by global fallout in the Atlantic Ocean, and the effect of the release derived from the 1F NPP accident on the one by global fallout in the Pacific Ocean.

The simulated ¹³⁷Cs activities were in good agreement with the observed data in the database in the Atlantic Ocean and the Pacific Ocean. The simulated ¹³⁷Cs activity immediately after each release event in the North Pacific were inconsistent with the observed one because of the inadequate reproduction of the Kuroshio Current in this quasi-resolution ocean model. However, the influence of the dilution effect is expected to become smaller as the time after the release increases. The influence of the ¹³⁷Cs activity by release from the reprocessing plant on the one by global fallout in the Atlantic Ocean is limited to the northeast coast of the European continent and the Marginal Seas. It was also suggested that ¹³⁷Cs activity by global fallout has made detection difficult since the 1990s.The influence of the ¹³⁷Cs activity by the 1F NPP on the one by global fallout was found to be broadened by the Kuroshio extension area and extended to the California coast. This distribution was similar to that of the one by global fallout. However, there are few observed data off the California coast after 2011. It was also suggested that ¹³⁷Cs activity by global fallout has made detection difficult since the 2020 in the Pacific Ocean.

Even after 2020, it is still possible to detect ¹³⁷Cs activity by global fallout in the global ocean. The difference in the vertical distribution between the Pacific and Atlantic oceans reflects the ocean circulation, which is useful for the validation of ocean general circulation models. There is still room for improvement in setting the input conditions to the ocean for each event.

How to cite: Tsumune, D., Bryan, F., Lindsay, K., Misumi, K., Tsubono, T., Tateda, Y., Inomata, Y., and Aoyama, M.: Estimation of 137Cs inventories by a global ocean general circulation model for the global database interpolation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14483, https://doi.org/10.5194/egusphere-egu21-14483, 2021.

A process of the removal of dissolved elements in the ocean by adsorption onto sinking particulate matters (scavenging) is studied analytically and using Lagrangian and Eulerian numerical methods. The generalized model of scavenging in a multicomponent reactive medium with first-order kinetics consisting of water and multi-fraction suspended particular matter has developed. Two novel numerical schemes were used to solve advection-diffusion-reaction equations for advection-dominated flows. The particle tracking algorithm based on the method of moments was developed. It is free on time step limitation necessary for an application of a standard method to the equations with reaction kinetics. The modified flux-corrected transport method for the Eulerian equations is a flux-limiter method based on a convex combination of low-order and high-order schemes. The similarity solutions of the model equations for an idealized case of instantaneous release of reactive radionuclide on the ocean surface were obtained. It was found that the dispersion of reactive contamination caused by reversible phase transition can be much greater than caused by diffusion. The solutions using both numerical methods are consistent with the analytical similarity solution even at zero diffusivity. The scavenging of the ^239,240Pu that was introduced to the ocean surface due to the fallout from past nuclear weapon testing was simulated. The results of the simulation agreed with observation data in the north-western Pacific Ocean. The importance of the scavenging by both the large fast-sinking particles and small particles slowly sinking and dissolving with depth due to the biochemical processes was shown.

How to cite: Brovchenko, I., Maderich, V., Kivva, S., Kim, K. O., Kim, H., and Kovalets, K.: Scavenging of radionuclides in multicomponent medium with first-order reaction kinetics: Lagrangian and Eulerian modeling, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8664, https://doi.org/10.5194/egusphere-egu21-8664, 2021.

Radiocesium-bearing microparticles (CsMPs), which are insoluble, Cs-bearing, silicate glass particles, have been found in terrestrial and freshwater environments after the TEPCO's Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in Japan. Few studies have investigated the distribution of CsMPs in freshwater ecosystems and their uptake by aquatic organisms. In this study, we determined the uptake of CsMPs by aquatic insects in the Ota River in Fukushima. Although aquatic insects are usually measured for radioactivity in bulk samples of several tens of insects, we investigated the variability of ¹³⁷Cs concentration in individual aquatic insects, and the influence of CsMPs on them. Measurement of ¹³⁷Cs concentrations in detritivorous caddisfly (Stenopsyche marmorata) larvae and carnivorous dragonfly larvae showed that 3 of 47 caddisfly larvae had considerably higher radioactivity, whereas no such outliers were observed in dragonfly larvae. These caddisfly larvae were confirmed to contain the CsMPs emitted from Unit 2 of the FDNPP, using a scanning electron microscope and radioactivity measurements after isolation of the CsMPs. CsMPs were also found in potential food sources of caddisfly larvae, such as periphyton and drifting particulate organic matter, indicating that larvae may ingest CsMPs along with food particles of similar size. Our study demonstrated that CsMPs could be taken up by aquatic insects and possibly by the fish consuming them. The existence of CsMPs can result in sporadic, extremely high ¹³⁷Cs concentrations, and large variations in samples, and consequently obscure the actual transfer and temporal trends of ¹³⁷Cs in freshwater ecosystems.

How to cite: Ishii, Y., Miura, H., Jo, J., Tsuji, H., Saito, R., Koarai, K., and Hayashi, S.: Radiocesium-bearing microparticles cause a large variation in 137Cs concentration in the aquatic insect, Stenopsyche marmorata, in the Ota River, Fukushima, Japan, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13886, https://doi.org/10.5194/egusphere-egu21-13886, 2021.

Elimination of the powerful radiation accidents consequences (i.e. Chernobyl and Fukushima accidents) has undoubtedly provided mankind with great experience in implementing both practical and fundamental knowledge about the radiation safety of society and the environment. In general, the practical application of scientific knowledge accumulated in the pre-accident period has led to significant positive successes of post emergency measures. The advantage of practical needs in scientific studies has narrowed the scope of fundamental work to the impact of radiation on biological objects in the affected area at the Chernobyl NPP, so the progress in this direction is modest so far.

To date, there is no unambiguous answer to the problem of the small radiation doses impact on biota, namely under such conditions people live today in areas contaminated with artificial radionuclides after Chernobyl and Fukushima accidents. Despite the accumulated experience in the elimination of radiation accidents, it is premature to consider the problem of environmental radionuclide pollution solved. This calls us to expand basic research question at identifying patterns in the state of cellulose-destroying soil microflora on contaminated areas in Ukrainian Polissya and assess their soil-forming activity.  

The study of the microbiota state on territories contaminated with radionuclides (including high level of contamination) is at an early stage, despite the intensive development of such studies after the radiation accident in Fukushima, Japan by a team of researchers from the University of Tokyo led by Professor T. Takahashi.

The aim of our work was to study the cellulose-destroying activity of the soil microflora of Ukrainian Polissya under conditions of elevated radionuclides contamination. We selected two locations - one outside the exclusion zone and the second in the exclusion zone. Both locations were characterized by a significant gradient of radionuclide contamination. At the first location, three points with soil ¹³⁷Cs activity of 0.6±0.045, 2.9±0.08, 4.6±0.11 kBq×kg^-1 soil and ⁹⁰Sr activity of 0.033±0.004, 0.18±0.015, 0.27±0.012 kBq×kg^-1 soil were selected. At the location in the exclusion zone, the ¹³⁷Cs activity at the sampling points 25±2, 170±1.5, 490±1 kBq×kg^-1 soil were selected. Since the experimental sites are located in a relatively small area, the physico-chemical soil properties between the points at each location do not have a significant difference.

To determine the rate of organic matter decomposition by soil microorganisms at all micro-sites, the standardized Tea Bag Index (TBI) method was applied. We used two types of tea bags TM Lipton - green tea (EAN8722700055525 or EAN8714100770542) and rooibos (EAN8722700188438) as a standardized plant material. Therefore, the obtained results can be compared between the microsites with different contamination level, as well as with similar data obtained by researchers for all ecosystems and many soil types from more than 2000 places around the world.

We acknowledge the National Research Foundation of Ukraine for the financial support of this research (Project №2020.01/0489).

How to cite: Klepko, A., Illienko, V., Lazarev, M., and Bilyera, N.: Study of cellulose-destroying activity of soil microflora on the radionuclide contaminated territories of Ukraine, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15011, https://doi.org/10.5194/egusphere-egu21-15011, 2021.

Sludge and slurry uranium repositories of ore processing wastes built in the middle of the 20th century lost their waterproofing properties over time, which leads to the upper aquifers pollution with uranium, heavy metals, sludge macrocomponents: anions of nitrates, sulfates, carbonates, calcium and iron. It is known that the uranium behavior in the environment depends on its oxidation-reduction potential, which determines its oxidation state and solubility. High nitrate content in aquatic systems leads to the uranium migration in the highly oxidized form and minimizes its sorption on the rocks minerals. 

Biogenic elements solution in waters can lead to the microbiota activity stimulation and biogeochemical uranium immobilization. Nitrate consumption leads to the redox potential decreasing and uranium reduction to insoluble forms. It is known that the most stable form of microorganisms in the environment is microbial biofilms. Their development on rock surface changes its physicochemical characteristics and sorption properties. This paper focused on changing the physicochemical and mineralogical parameters of rocks after microbial growth and its effect on the uranium immobilization. It should be noted that in situ bioremediation is one of the promising and inexpensive methods of groundwater remediation. Therefore, an assessment of the role of microbial biofilms in the immobilization of uranium will provide important information for predicting the effectiveness of the bioremediation.  

Angarsk Electrochemical Combine AECC (Irkutsk Region, Russia) is engaged in the processing of uranium ores and concentrates; has sludge storage facilities on the territory, which for a long time have contaminated the upper aquifers with nitrate ions, ammonium, uranium and other components. The main minerals of upper aquatic horizons weathered sandstone are: quartz, plagioclase, K-feldspar, kaolinite, smectite, specular stone, illite-smectite, vermiculite, chlorite, amphibole and apatite in trace amounts. The clay component is more than 20% with a kaolinite predomination. 

In laboratory experiments, the modeling of the growth of microbial biofilms on rocks from contaminated and uncontaminated areas of the formation was carried out by adding organic substrates. Samples were dominated by representatives of the family Pseudomonadaceae, known for their ability to form biofilms and wide range of metabolic capabilities. An uneven distribution of biofilm on the sand was established, presumably in areas containing an increase in the amount of biogenic elements - Ca, Fe, etc., as well as organic carbon. On average, after 15 days, the coverage area of the polysaccharide matrix was 20-30%. The appearance of a polysaccharide matrix can lead to a change in the sorption capacity of rocks and to formation of local zones of uranium accumulation in organic matter. 

As a result of microbial action, the dissolution of carbonate minerals and a number of changes in the composition of clay sandstones is noted. The microbial effect on rocks leads to a multidirectional change in their sorption capacity in relation to uranium. The formation of an exopolysaccharide matrix increases the sorption capacity of rocks due to the appearance of new functional groups. Moreover, with strong microbial fouling, it can lead to a decrease in uranium sorption.

This work was supported by a grant from RFBR 20-05-00602 A.

How to cite: Popova, N., Alexey, S., Grigoriy, A., and Anatoly, B.: Uranium immobilization at microbial biofilms on upper water horizons loams nearby sludge repository, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13193, https://doi.org/10.5194/egusphere-egu21-13193, 2021.

MEDA HS is the relative humidity sensor on the Mars 2020 Perseverance rover provided by the Finnish Meteorological Institute (FMI). The sensor is a part of Mars Environmental Dynamic Analyzer (MEDA), a suite of environmental sensors provided by Centro de Astrobiología in Madrid, Spain. MEDA HS, along with METEO-H in ExoMars 2022 surface platform, is a successor of REMS-H on board Curiosity.

Calibration of relative humidity (RH) instruments for Mars missions is challenging due to the range of RH (from 0 to close to 100%) and temperature conditions (from about -90 ºC to + 22 ºC) that need to be simulated in the lab. Thermal gradients in different parts of the system need to be well known and controlled to ensure reliable reference RH readings. For MEDA HS the calibration tests have been performed for different models of MEDA HS in three Martian humidity simulator laboratories: FMI laboratory, Michigan Mars Environmental Chamber (MMEC) and DLR PASLAB (Planetary Analog Simulation Laboratory).

MEDA HS flight model was tested at FMI together with flight spare and ground reference models in low pressure dry CO₂ gas from +22ºC to -70ºC and in saturation conditions from -40ºC down to -70ºC. Further, the MEDA HS flight model final calibration is complemented by calibration data transferred from an identical ground reference model which has gone through rigorous testing also after the flight model delivery. During the test campaign at DLR PASLAB that started in Autumn 2020, MEDA HS has been calibrated over the full relative humidity scale between -70 to -40ºC in CO₂ in the pressure ranges from 5.5 to 9.5 hPa, representative of Martian surface atmospheric pressure. The results can be extrapolated to higher and lower temperatures.