Radon (222Rn) is a radioactive gas with well-documented harmful effects; the World Health Organization has confirmed it as a cancerogenic for humans. These detrimental effects have prompted Europe to establish national reference levels to protect the exposed population. This is reflected in European directive 59/2013/EURATOM, which has been transposed into the national regulations of EU Member States. Specifically, the directive requires the identification of Radon Priority Areas to facilitate remediation in regions with high Rn levels. The regulation also includes measures for radiation protection, aiming to safeguard the population collectively and individuals from Rn exposure. These two requirements can be conceptualised and translated into two complementary concepts: collective and individual risk. This work addresses the lack of a standardised methodology at the European level for defining radon (Rn) risk across regions. It provides the first approach to transitioning from collective to individual risk areas (CRAs to IRAs), offering clear insights into the application of European Rn protection regulations. Key challenges have been addressed, including geo-hazard mapping without a response variable, evaluating the performance of Spatial Multi-Criteria Decision Analysis, and assessing the use and representativeness of available indoor Rn data to support individual risk assessment. The study also explores the optimal scale for delineating Radon Priority Areas. The effectiveness of this novel approach, which incorporates both collective and individual risk factors in accordance with European regulations, has been tested in a case study in the Bolzano province (north-eastern Italy).
Consumer-grade economical radon monitors are becoming increasingly popular in private and institutional use, in the contexts of both Citizen Science and traditional research. Although originally designed for screening indoor radon levels in view of radon regulation and decisions about mitigation or remediation—motivated by the health hazard posed by high radon concentrations—researchers are increasingly exploring their potential in some environmental studies. For long time, radon has been used as a tracer for investigating atmospheric transport processes. This paper focuses on RadonEye, currently the most sensitive among low-cost monitors available on the market, and specifically, its potential use for monitoring very low radon concentrations. It has two objectives: firstly, discussing issues of statistics of low count rates, and secondly, analyzing radon concentration time series acquired with RadonEyes outdoors and in low-radon indoor spaces. Regarding the first objective, among other things, the inference radon concentration reported to expected true is discussed. The second objective includes the application of autoregressive methods and fractal statistics to time series analysis. The overall result is that radon dynamics can be well captured using this “low-tech” approach. Statistical results are plausible; however, few results are available in the literature for comparison, particularly concerning fractal methods. The paper may therefore be seen as an incentive for further research in this direction.
Abstract This work highlights the importance of the Geogenic Radon Potential (GRP) component originated by degassing processes in fault zones. This Tectonically Enhanced Radon (TER) can increase radon concentration in soil gas and the inflow of radon in the buildings (Indoor Radon Concentrations, IRC). Although tectonically related radon enhancement is known in areas characterised by active faults, few studies have investigated radon migration processes in non-active fault zones. The Pusteria Valley (Bolzano, north-eastern Italy) represents an ideal geological setting to study the role of a non-seismic fault system in enhancing the geogenic radon. Here, most of the municipalities are characterised by high IRC. We performed soil gas surveys in three of these municipalities located along a wide section of the non-seismic Pusteria fault system characterised by a dense network of faults and fractures. Results highlight the presence of high Rn concentrations (up to 800 kBq·m −3 ) with anisotropic spatial patterns oriented along the main strike of the fault system. We calculated a Radon Activity Index (RAI) along north–south profiles across the Pusteria fault system and found that TER is linked to high fault geochemical activities. This evidence confirms that TER constitutes a significant component of GRP also along non-seismic faults.
Summary In the Baveno “Seula” quarry, in North-West of Italy, the mining in the area has three aspects: 1) quarrying the pink granite for the production of ornamental stone blocks; 2) recycling of the debris and of the production scraps from previous mining for the production of cliff’s boulder and smashed inert material; 3) mining the k-feldspar mineral from the mining landfill. In this context, the aim of the geophysical survey was to map the bedrock topography and evaluate the volume of the debris (overburden), which would be used for the processing of feldspar mineral. Secondly, we want roughly to characterize the debris (granulometry) and the quality of the underlying stone. We used the ERT methodology, since we expect a significant resistivity contrast between debris (more conductive due to the presence of water in voids and at the interface with the bedrock) and the compact stone (more resistive). The geophysical survey allowed the identification of different layers, and the top of the granite to be mapped. The excavation operations in some portions of the investigated area reached the bedrock: the electrical resistivity sections clearly show the coincidence between the estimated bedrock location from the ERT results and the real position.
Warming global climate threatens the stability of the polar regions and may result in cascading broad impacts. Studies conducted on permafrost in the Arctic regions indicate that these areas may store almost twice the carbon currently present in the atmosphere. Therefore, permafrost thawing has the potential to magnify the warming effect by doubling the more direct anthropogenic impact from burning of fossil fuels, agriculture and changes in land use. Permafrost thawing may also intensify the Rn transport due to the increase of fluid saturation and permeability of the soil. A detailed study of 222Rn and 220Rn activity levels in polar soils constitutes a starting point to investigate gas migration processes as a function of the thawing permafrost. Although several studies have been carried out in the Arctic regions, there is little data available from the Southern Hemisphere. The Italian – New Zealand “SENECA” project aims to fill this gap and to provide the first evaluations of gas concentrations and emissions from permafrost and/or thawed shallow strata of the Taylor Valley, Antarctica. Taylor Valley is one of the few Antarctic regions that are not covered by ice and therefore is an ideal target for permafrost investigations. Results from our field measurements highlight very low values for 222Rn and higher values for 220Rn, suggesting a shallow source. Usually the measured 222Rn activity values are controlled by the radionuclide content in the soil, the temperature of the soil, the porosity of the soil, and the water content. We applied the Akerblom formula to calculate the radon at equilibrium with the activity concentration of the 226Ra on the collected soil samples, and the presence of 222Rn amounts higher than those naturally produced by the outcropping sediments is detected. These results demonstrate the presence of preferential gas pathways through the permafrost from a deep source. It is the first time that this type of study has been performed in Antarctica and can make a significant contribution to understanding the melting permafrost processes and its implications for the environment. This dataset also represents an important benchmark for future measurements to track the melt progress of Antarctic permafrost.
Numerous field and laboratory studies have been conducted to investigate the relationship between radon variation and seismic events, as well as the complex link between radon emission and rock deformation mechanisms. However, a clear understanding of this correspondence and systematic observations of these phenomena are still lacking, and recent experimental studies have yet to yield conclusive results. In this study, we investigate the possible relationships between radon migration dynamics and rock deformation at the micro-scale through laboratory experiments using the SHIVA apparatus under shear stress-controlled conditions and simultaneous high-resolution radon measurements. We studied the behaviour of three different lithologies to show that radon emission varies in response to rock deformation and this variation is highly dependent on the mineralogy and microstructure. This study represents the first attempt to define radon gas as an indicator of transient and rapid rock deformation at the micro-scale.
Due to its potential use as a carbon-free energy resource with minimal environmental and climate impacts, natural hydrogen (H2) produced by subsurface geochemical processes is today the target of intensive research. In H2 exploration practices, bacteria are thought to swiftly consume H2 and, therefore, small near-surface concentrations of H2, even orders of 102 ppmv in soils, are considered a signal of active migration of geological gas, potentially revealing underground resources. Here, we document an extraordinary case of a widespread occurrence of H2 (up to 1 vol%), together with elevated concentrations of CH4 and CO2 (up to 51 and 27 vol%, respectively), in aerated meadow soils along Italian Alps valleys. Based on current literature, this finding would be classified as a discovery of pervasive and massive geological H2 seepage. Nevertheless, an ensemble of gas geochemical and soil microbiological analyses, including bulk and clumped CH4 isotopes, radiocarbon of CH4 and CO2, and DNA and mcrA gene quantitative polymerase chain reaction analyses, revealed that H2 was only coupled to modern microbial gas. The H2-CO2-CH4-H2S association, wet soil proximity, and the absence of other geogenic gases in soils and springs suggest that H2 derives from near-surface fermentation, rather than geological degassing. H2 concentrations up to 1 vol% in soils are not conclusive evidence of deep gas seepage. This study provides a new reference for the potential of microbial H2, CH4 and CO2 in soils, to be considered in H2 exploration guidelines and soil carbon and greenhouse-gas cycle research.
Radon is a radioactive gas and a major source of ionizing radiation exposure for humans. Consequently, it can pose serious health threats when it accumulates in confined environments. In Europe, recent legislation has been adopted to address radon exposure in dwellings; this law established national reference levels and guidelines for defining Radon Priority Areas (RPAs). This study focuses on mapping the Geogenic Radon Potential (GRP) as a foundation for identifying RPAs and, consequently, assessing radon risk in indoor environments. Here, GRP is proposed as a hazard indicator, indicating the potential for radon to enter buildings from geological sources. Various approaches, including multivariate geospatial analysis and the application of artificial intelligence algorithms, have been utilised to generate continuous spatial maps of GRP based on point measurements. In this study, we employed a robust multivariate machine learning algorithm (Random Forest) to create the GRP map of the central sector of the Pusteria Valley, incorporating other variables from census tracts such as land use as a vulnerability factor, and population as an exposure factor to create the risk map. The Pusteria Valley in northern Italy was chosen as the pilot site due to its well-known geological, structural, and geochemical features. The results indicate that high Rn risk areas are associated with high GRP values, as well as residential areas and high population density. Starting with the GRP map (e.g., Rn hazard), a new geological-based definition of the RPAs is proposed as fundamental tool for mapping Collective Radon Risk Areas in line with the main objective of European regulations, which is to differentiate them from Individual Risk Areas.
