Mud volcanoes (MV), classified as "sedimentary volcanism", represent the surface expression of underground processes characterized by movements of large masses of fluids (water and gas) and sediments. Some MVs can represent a serious source of geohazards, mainly related to paroxysmal events with flooding of huge amounts of mud that can damage structures and seriously injure people in their vicinity. Although MVs constitute a source of geohazard, albeit limited to their proximity, monitoring protocols for their surveillance have never been employed. Gas released from mud volcanoes consists mainly of CH₄ and minor components N₂, O₂, CO₂ and light hydrocarbons, but radon emission rate has been poorly studied. With the aim of filling this knowledge gap, the present work proposes a multidisciplinary approach to the study of MVs, with the final goal of identifying reliable indicators of their state of activity that could be used as precursors of paroxysmal events and their dangerousness for the population. The multidisciplinary monitoring method used to study the Salse di Nirano MVs is based on radioactivity and greenhouse gas emissions, stratigraphy and magnetism of the rocks in order to develop a model of the space-time evolution of their activity and identify any variations. To estimate the amount of gas released, some surveys of flux measurements (CO₂, CH₄) and gas content (CO₂, CH₄, ²²²Rn, ²²⁰Rn) were conducted.

Furthermore, with the aim of identifying a correlation between methane emissions and radon activity, a series of laboratory tests were performed in a controlled system.

Salse di Nirano are within a natural reserve, visited by many people every year, so the definition of the natural gas hazard estimation is essential for the protection of the population and extremely useful for the local authorities. Our objective is to acquire a better understanding of the processes happening in the eruption conduit, the activity (speed and intensity of gas migration) of the seepage system connected to the feeding reservoir, and the interaction between faults and deep and/or shallow reservoirs. The results can also be exported to other areas characterized by the presence of sedimentary volcanism.

How to cite: Sciarra, A., Falanga, M., Mancini, S., Guida, M., Grassa, F., Misiti, V., Pinzi, S., Galli, G., Venuti, A., and Cascella, A.: A multidisciplinary monitoring approach involving radioactivity, greenhouse gas emissions, stratigraphy and rock magnetism, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1184, https://doi.org/10.5194/egusphere-egu25-1184, 2025.

Atmospheric nuclear tests until 1980 and in particular the Chernobyl nuclear accident in April 1986 left considerable amounts of caesium in the environment of Eastern, Northern, and Central Europe. Regional information on the current distribution of caesium is very limited. Airborne gamma-ray spectrometry or radiometry is routinely used to investigate the regional distribution of the naturally occurring radio-elements K-40, U-238 and Th-232 in the rocks and soils of the earth’s surface and to derive compositional and geological information. Due to the large source-receiver distance and the low activity sources, large-volume scintillation detectors are used for this purpose. The spectral resolution of these instruments is low compared to laboratory setups. Therefore, the identification of photo peaks of artificial isotopes in airborne gamma-ray spectra is not straight forward and attempts to routinely determine Cs-137 signals are rare.

In this study, helicopter radiometry data that was originally collected for soil science applications in northern Germany was examined with regard to its Cs-137 information content. The spectra were acquired with a 4x4 litre NaI, 1024 channel instrument (Radiation Solutions). The overlap of the Cs-137 photo peak at 662 keV with Tl-208 and Bi-214 photo peaks from the uranium and thorium decay chains led to the development of a spectral unfolding method. In the spectra corrected in this way the intensity of the Cs-137 signal could be determined. These Cs-137 intensity values were then compared with measurements on the ground, so that a calibration of the airborne system for absolute ground activities of Cs-137 was possible. Applied to large airborne data sets covering areas in the order of 100 km² resulted in activity maps that give interesting insights into the present day Cs-137 levels in the environment of Northern Germany.

How to cite: Ibs-von Seht, M.: Determination of environmental Cs-137 levels from standard airborne gamma-ray spectrometry data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1777, https://doi.org/10.5194/egusphere-egu25-1777, 2025.

Semi-arid regions, characterized by low and erratic rainfall, need significant efforts in managing their water resources. Groundwater, a vital resource in these areas, is often overexploited, leading to depletion and degradation. The lack of suitable data and methods to quantify regional hydrological processes often requires a comprehensive understanding of groundwater systems, including their recharge rates, flow patterns, and water quality and the adaptation to climate change.

To date, groundwater management is primarily based on hydrogeological modeling and key parameters such as recharge rate and groundwater dynamics.

The use of radioisotopes makes it possible to date groundwater resources and evaluate its recharge times. By using a combination of residence time indicators (3H, 14C, 36Cl) and stable water isotopes (2H and 18O), it is possible to provide a greater constraint on the residence time of water in groundwater aquifers.

Thanks to the advancement analytical techniques on the use of 36Cl, present in the environment following nuclear tests, is a promising method for estimating water transit times and recharge rates of aquifers on a basin scale and for distinguishing water and chloride cycles.

Studies have already been carried out in the Chari-Logone aquifer of the emblematic Lake Chad basin, located in the central Sahel, where the analysis of 36Cl in the central areas shows the presence of very old groundwater (<2 Ma), suggesting that the aquifers in the Sahel host a significant amount of renewable water, which could therefore be used as a strategic freshwater resource.

Continued investment in developing reliable and less time-consuming analytical techniques is crucial to manage groundwater resources sustainably in semi-arid regions.

How to cite: Telloli, C., Borgognoni, F., and Rizzo, A.: Addressing water security using 36Cl, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2764, https://doi.org/10.5194/egusphere-egu25-2764, 2025.

RockyRAD represents an evolution of the traditional Geiger counter, transforming it into a complete and innovative educational tool. This compact and portable device is part of a kit containing rock samples, selected for their varying levels of natural radioactivity. These samples allow students to investigate the radioactivity of rocks, understanding how it is influenced by internal factors such as chemical composition, rather than external characteristics such as color or texture.

Students can compare the radiation levels of igneous and sedimentary rocks, assess the effectiveness of shielding materials, or conduct long-term background radiation measurements. This hands-on approach provides a deeper understanding of the radioactivity originating from natural radioisotopes (e.g., U-238) and their decay products as well as the interactions between radiation and matter.

Through an Android app, users can share results, export data for analysis, and plan extended experiments, making it suitable for citizen science. Students can evaluate reliability, calculate uncertainties, and observe how these change with measurement time, linking experimental observations to theoretical principles. The device provides both counts per minute (CPM) and equivalent dose rate (nSv/h), facilitating the understanding of absorbed dose concepts.

Teachers can design experiments tailored to school curricula, fostering an interdisciplinary approach that integrates physics, Earth science, and statistics.

In today’s energy landscape, where nuclear power is regaining attention, RockyRAD promotes scientific inquiry and awareness. By studying rock radioactivity, students develop a deeper understanding of environmental radiation, supporting informed perspectives on nuclear energy and other energy choices.

How to cite: Albéri, M., Annunziata, M., Barba, P., Barbagli, A., Chiarelli, E., Colonna, T., Cortopassi, A., Elek, N. I., Gallorini, F., Givoletti, J., Guastaldi, E., Mantovani, F., Mattone, C., Morichi, M., Petrone, D., Pierini, S., Raffo, C., Raptis, K. G. C., Strati, V., and Vivaldi, F.: RockyRAD: a hands-on kit for exploring rock radioactivity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8454, https://doi.org/10.5194/egusphere-egu25-8454, 2025.

In Germany, radionuclide exposure is calculated for various scenarios according to derived international standards (AVV-Tätigkeiten 2020). The radiation protection law and the relevant administrative regulations (StrlSchG, StrlSchV) define exposure limits and the implementation of the calculations. These administrative regulations are used in authorisation procedures and in the prospective determination of the expected exposure of individuals in the population. These regulatory measures are intended to ensure the protection of the population from additional radioactive radiation within the framework of the 10 µSv criterion of the IAEA (IAEA 1988 Safety Guides No. 89). Understanding the underlying mechanisms of radionuclide transport in defined ecosystems is pivotal to achieve the best-estimated scenarios.

Contamination of the soil can occur through air or water discharge. Discharge via air can result in dry or wet deposition. In the case of discharge via water, contamination can occur through artificial irrigation, sediment deposition from irrigated fields or contamination of soils in floodplains. All these pathways are considered relevant for assessing radionuclide fate and transport through soil.

In the current project, the transport processes of these contamination pathways on cropland and pasture are analysed in more detail aiming to identify the driving parameters and review all processes that have not yet been included in the equations in the calculation bases. Soil properties and hydrogeological characteristics play an essential role in water-bound transport in the soil. Soils are divided into different soil horizons (O, A, B, C and R horizons) with different properties, which are subject to seasonal changes as well as changes caused by cropland use and pasture. For dissolved substances, chemical processes such as speciation and complex formation, solubility and solution kinetics, retention by sorption and redox reactions play an important role, often strongly dependent on pH values. In addition to chemical processes, physical processes such as advection, diffusion, dispersion, and capillary rise are also relevant. At the root-soil interface, biological processes such as root exudation, mycorrhizal symbiosis (fungal activity), root-hair interactions and plant-controlled water movements within the plant are increasingly important. In terms of plant species, a distinction is made between leafy vegetables, root vegetables and grains.

The aim of the work is to take an interdisciplinary and holistic look at possible contamination pathways in soils by means of a system analysis. The BIOMASS process involving the definition of a FEP (Features, Events and Processes) list and visualizing it in an interaction matrix for the analysis. This conceptual model will be used to implement the appropriate mathematical models for each interaction between compartments. The concentration in the soil will then be calculated using a compartment model or numerical groundwater models. Different methods and models will be analysed and applied in individual cases. The key challenges are the different scales of the area to be analysed, the heterogeneity of the soil and the general uncertainty in the data.

How to cite: Johnen, M., Brennan, Dr. K., Gülez, S., Filby, Dr. A., Tzivaki, Dr. M., and Artmann, Dr. A.: Radionuclides on the Move: Insights into Water-Bound Soil Transport Processes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8873, https://doi.org/10.5194/egusphere-egu25-8873, 2025.

This research focuses on the Maccalube di Aragona Nature Reserve (Agrigento, Italy), studying environmental radioactivity and plant activity in the context of mud volcano dynamics. The Reserve contains several gryphons and pools emitting methane, hydrocarbons, and highly saline water. Occasionally, these volcanoes experience explosive events, such as a fatal explosion in 2014. The research is part of the Promud project- INGV (https://progetti.ingv.it/it/promud), which aims to assess the Reserve’s geophysical, seismological, geodetic, and biodiversity characteristics for civil protection purposes.

Two field surveys were conducted to measure environmental radioactivity, focusing on ²²²Rn and ²²⁰Rn emissions from soil gas by means of specific accessorized equipment (RAD7). The main aim was to acquire more data to support the identification of the source location in a compact clay layer. Results showed a high concentration of ²²²Rn only in correspondence with the active emitting centers, whereas concentrations below the instrumentation sensitivity were revealed elsewhere. Moreover, the radioactive contents were determined in muds, soils, and parts of the plants (especially leaves) taken in the surroundings. Particularly, ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs were measured by using gamma spectrometry. Very homogeneous concentrations of previous radionuclides were found, except for ⁴⁰K measured in the dried plants suggesting a possible link between that radionuclide and the plant’s activity.

Studying plants that thrive in extreme environments could provide valuable insights into the relationship between soil properties and reservoirs. For this study, the halophytic species Suaeda vera, collected from the Maccalube Reserve, was used as a model. Samples were also collected from a mountainous habitat to compare its metabolism under stressed and stress-free conditions. An untargeted metabolomic analysis of hydroalcoholic extracts of aerial parts of S. vera, performed using HR-LC-MS, revealed a diverse and rich phytochemical profile. This analysis identified a wide range of specialized metabolites. Plants from the Maccalube region have an interesting phytochemical profile, producing sulphated metabolites, particularly flavonoids, which are rare and often associated with survival in harsh environments. This secondary metabolism suggests a local biochemical adaptation of the Maccalube population. It may be influenced by the harsh environmental conditions of the region.

How to cite: Falanga, M., Alizadesh, Z., Rosa, E., De Tommasi, N., Mancini, S., Aközcan Pehlivanoğlu, S., and Cusano, P.: Environmental Radioactivity and Plants Adaptations in the Maccalube Nature Reserve (Ag): Insights and Implications for the sedimentary volcanic source, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9446, https://doi.org/10.5194/egusphere-egu25-9446, 2025.

The trend towards increasing circular economy calls for re-use of all types of waste, including recycling from industrial residues such as NORM (Naturally Occurring Radioactive Materials). These secondary raw materials are currently being considered and partly used in construction materials, for critical element extraction, in medicine, and in carbon sequestration. In the geothermal, oil and gas industry mineral deposits (scales) form during deep fluid production due to changes in thermodynamic conditions and may incorporate significant amounts of natural radionuclides. Currently these residues are discarded although the scales may contain valuable metals.

Scale samples were collected from the well and aboveground geothermal facilities and analysed via XRD, XRF and ICP-MS. Their main mineralogical constituents range from Sr-rich barite, laurionite, native copper, sulphide minerals to magnetite. Some scales contain economically viable elements, such as Cu, Ba, As and Zn. Rare earth elements also occur in minor amounts (∑ ~ 50 ppm). Radionuclide activities on bulk samples were measured via gamma-spectrometry and vary from below 1 Bq/g up to 130 Bq/g, 57 Bq/g, 63 Bq/g and 40 Bq/g for Ra-226, Pb-210, Ra-228 and Th-228, respectively. Thus, for some samples the measured activities fall within the category of surveillance.

The association between mineralogy and radionuclides is investigated following partial leaching and sequential extraction. Kind and activity concentrations of radionuclides depend on the extraction method, which is determined by the mineral phase of the targeted element. The extraction process will require dose measurements followed by a calculation of the exposure to ionizing radiation. This evaluation represents a preliminary study towards the usability of the scales and demonstrates the need for further research on recycling of the residues, with due consideration given to radiation protection aspects. 

How to cite: Goldberg, T., Klasen, N., Regenspurg, S., and Frings, P.: Radiation protection aspects in conjunction with re-use of residues from the geoenergy industry, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4205, https://doi.org/10.5194/egusphere-egu25-4205, 2025.

The health impacts of the radioactive Radon are well-documented by the World Health Organization (WHO) and numerous studies. Geogenic Radon Potential (GRP) refers to the natural production of Radon by the Earth, independent of anthropogenic influences. GRP has been a focal point of research aimed at understanding the factors influencing radon variability and its spatial distribution. However, the limited availability of systematic soil-gas radon concentration measurements, along with other constraints, often leads to coarse-resolution modeling of GRP. With the availability of adequate and quality data, regional studies can be promising in investigating these influencing factors, and modelling of GRP hazards at finer spatial scales.

This study uses GRP survey data provided by the Hessian Agency for Nature Conservation, Environment and Geology (HLNUG) to develop machine learning models for predicting the spatial distribution of GRP in the state of Hessen, Germany, and to produce a high-resolution GRP hazard map. The models employed include Random Forest Regressor (RF), Support Vector Regressor (SVR), Gradient Boosting Regressor (GBR), and Multi-Layer Perceptron Regressor (MLPR). The dataset comprises 1,509 GRP sampling points for an area of about 21.000 km², and 37 potential predictors related to geology, soil characteristics, and climatic variables—key factors known to influence radon levels. Sequential Feature Selection (SFS) and a 5-fold spatial cross-validation strategy were employed to mitigate autocorrelation effects and enhance model generalization. Model performance was evaluated using multiple metrics and compared against ground-truth values and local geology.

Results revealed that the RF and GBR models outperformed others, achieving R² scores of 0.69 and 0.65 on the validation dataset, respectively, while the SVR and MLPR models underperformed. Predicted GRP values ranged from 8.9 to 178.2 for RF and 1.7 to 268.4 for GBR. Geological and soil properties emerged as the dominant predictors of GRP variability in Hessen, with predicted maps highlighting a strong dependence on local geological features. High-risk areas were effectively identified by the RF model. The study also highlights the need for additional measurements in data-scarce regions and the exploration of hybrid physics-based models that integrate domain-specific knowledge into spatial predictions.

How to cite: Gbondo, A. M., Lehne, R., Petermann, E., and Henk, A.: Identifying Radon hazard areas: Machine learning-driven Geogenic Radon Potential mapping in Hessen, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8682, https://doi.org/10.5194/egusphere-egu25-8682, 2025.

Radon (²²Rn) is a naturally occurring radioactive gas that occurs in rocks and soils, and its migration pathways are influenced by geological faults. These processes can significantly increase radon leakage into buildings, posing a significant health risk. Classified as a carcinogen by the World Health Organisation, exposure to radon has required the establishment of national reference levels across Europe under Directive 2013/59/EURATOM and the identification of Radon Priority Areas (RPAs) to guide remediation initiatives. This legislation emphasises the need for both collective and individual risk management, using advanced radon risk assessment tools.

In this study, we present an innovative approach to construct a geogenic radon hazard index (GRHI) map for Italy using a robust bottom-up methodology. Our approach integrates several geological proxies related to radon source (e.g. geology, radionuclide content) and migration pathways (e.g. faults) using supervised auto-machine learning (Autogluon). A dataset of approximately 30,000 soil radon measurements was divided into training and test datasets. A conceptual model with ten predictors was developed to estimate soil radon concentrations at unsampled locations on a 1x1 km grid. The LightGBMLarge algorithm resulted in the best model (R²_test = 0.524) which was validated by a combination of statistical metrics. The SHAP analysis highlighted the relative importance of the predictors in the model.

The GRHI map was further combined with census section data (ISTAT database) and population density to produce a risk map from Collective Risk Areas (CRA) to Individual Risk Areas (IRA). This final map serves as a valuable tool for national and regional administrations to identify IRAs in accordance with Directive 2013/59/EURATOM (Article 103).

This research addresses the lack of a standardised European methodology for radon risk assessment. It provides a comprehensive framework to bridge the gap between collective and individual risk. Through the integration of geological knowledge with machine learning and demographic data, this work provides useful information for the improvement of radiation protection and public health strategies.

How to cite: Ciotoli, G., Benà, E., Mori, F., Ruggiero, L., Beaubien, S. E., Sciarra, A., Procesi, M., Mazzoli, C., Sassi, R., and Bigi, S.: The Italian radon risk map, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11146, https://doi.org/10.5194/egusphere-egu25-11146, 2025.