Search Results (28)

Monitoring soil moisture (SM) using permanently installed gamma radiation (GR) detectors is a promising non-invasive method based on the inverse relationship between SM and soil-emitted GR. In a previous study, we successfully estimated SM from environmental gamma radiation (EGR) measured by a low-cost counter-tube detector. Since this detector type provides a bulk GR response across a wide energy range, EGR signals are influenced by several confounding factors, e.g., soil radon emanation, biomass. To what extent these confounding factors deteriorate the accuracy of SM estimates obtained from EGR is not fully understood. Therefore, the aim of this study was to compare the accuracy of SM estimates from EGR with those from reference ⁴⁰K GR (1460 keV) measurements which are much less influenced by these factors. For this, a Geiger–Mueller counter (G–M), which is commonly used for EGR monitoring, and a gamma spectrometer were installed side by side in an agricultural field equipped with in situ sensors to measure reference SM and a meteorological station. The EGR_G–M and spectrometry-based ⁴⁰K measurements were related to reference SM using a functional relationship derived from theory. We found that daily SM can be predicted with an RMSE of 3.39 vol. % from ⁴⁰K using the theoretical value of α = 1.11 obtained from the effective ratio of GR mass attenuation coefficients for the water and solid phase. A lower accuracy was achieved for the EGR_G–M measurements (RMSE = 6.90 vol. %). Wavelet coherence analysis revealed that the EGR_G–M measurements were influenced by radon-induced noise in winter. Additionally, biomass shielding had a stronger impact on EGR_G–M than on ⁴⁰K GR estimates of SM during summer. In summary, our study provides a better understanding on the lower prediction accuracy of EGR_G–M and suggests that correcting for biomass can improve SM estimation from the bulk EGR data of operational radioactivity monitoring networks. Full article

The interaction of the Almone River with groundwater in the Caffarella area (Rome, Italy) was investigated using a multi-method approach based on hydrogeological and radon analyses. Eleven measurement stations were established along the river at distances of approximately 270 m from one another. Stream discharge, water physicochemical properties, and radon levels were measured from June 2024 to March 2025. The contribution of two tributaries of the Almone was evaluated, but it was found to be negligible in terms of radon contribution. Except for an average increase of 40 L/s between stations 1A and 2A, the Almone’s discharge (corrected for the streams input) was constant (around 150 L/s) in June and slightly increasing from 6A to 11A in March due to heavier rainfalls. The increased discharge between stations 1A and 2A was interpreted as groundwater overflow from the volcanic aquifer into the alluvial body and in turn into the river due to a change in geometry and volume of the volcanic aquifer. In that part of the river, radon concentration increased only in March, due to the fast transition of the groundwater from a high to a lower radon emanation unit. Radon decreased along the valley due to atmospheric evasion, as confirmed by pH growth due to CO₂ degassing. Full article

The successful prospecting of kimberlite pipes is dependent upon a comprehensive understanding of the deep structures of the pipes and the host geological formation. This is a challenging task, given the complex nature of diamond deposits, the small size of pipes in the plan, the absence of stable features in potential fields, etc. As a consequence, the allocation of control structures is practically not used in exploration work. In this regard, the Arkhangelsk diamond province (NW Russia) is distinguished by the considerable overburden thickness, which presents a significant challenge for the application of geophysical methods. It is thus imperative to devise novel methodologies for conducting investigations. In order to achieve this, a set of methods was employed, including microseismic sounding, passive seismic interferometry, and radon emanation mapping. This set of methods has previously been tested only on a few pipes and has not previously been employed in the Griba deposit. The Volchya pipe was selected as the test object due to its proximity to the Griba pipe. The findings revealed that the pipe displayed a more complex configuration than was previously postulated. The controlling faults were found to be oriented in a southwesterly to northwesterly direction and to exhibit a contrasting narrow vertical structure at depths greater than 400 m. Further identification of control structures by the proposed set of methods can increase the efficiency of diamond prospecting. Full article

The study of the influence of geological structure (e.g., faults) on radon emanations is usually applicable provided that there are conditionally background (control) territories with which radon indicators will be compared. In the presented study, we selected an area where pre-Cenozoic faults that could potentially be associated with the radon hazard of the Kuznetsk coal basin were not identified. The cover deposits in the study area are represented by loamy and clayey strata overlying the Paleozoic sedimentary cycles. The radon field was estimated based on the radon flux density (RFD) and radon activity concentration (RAC) in the soil gas. The RAC was measured in two ways—by the sorption method on activated carbon and by the method of active sampling of soil gas from a borehole. At the same time, the role of meteorological conditions and the physical properties of the soil in the radon field was assessed. Our study shows that local variations in the physical properties of the soil are insignificant and do not have a significant effect on the RAC in the soil gas of the Kuznetsk coal basin, with the exception of soil moisture. High values of RAC in the territory considered as conditionally background, in the absence of pre-Cenozoic faults, suggest other causes (the presence of the latest Neogene–Quaternary faults, high concentrations of ²²⁶Ra, or other insufficiently studied causes). Due to the absence of faults, it is possible to assume a diffusion type of radon transfer in the geological environment, which indicates a shallow source of radon in such high concentrations. Our results indicate that studies of the ²²⁶Ra content and additional studies of the radon hazard of similar areas should also be carried out. Full article

Laboratory-scale experiments were conducted on Carboniferous Limestone gravels from the Mendip Hills area, England; sandstones from the Pirambóia and Botucatu formations, Paraná sedimentary basin, Brazil; samples of schist and quartzite from Caldas Novas Hydrothermal Complex, Brazil; and the minerals tantalite, cassiterite, and columbite from mining areas at Rio Grande do Norte State, Brazil, with the purpose of evaluating the release of ²²²Rn to the water phase. The specific surface area of the samples corresponded to 1.69–81.36 cm²g⁻¹, which provided values of 0.001–1.68 dpm/g and 3.18 × 10⁻⁶ to 0.59 for the radon released and radon emanation coefficient, respectively. These results allowed us to calculate the radon flux with respect to the radon leakage, which corresponded to values of 0.00016–0.00158 Bq/m²/d for the denser materials and 0.018–0.43 Bq/m²/d for limestones and sandstones. They also permitted us to find an inverse, significant relationship between the radon generated by the minerals/rocks and the radon flux into the water phase, which was tested for sediments in coastal and inland Brazilian areas, demonstrating utility for evaluating the diffusive radon flux from the sediments, which is an important parameter to monitor submarine groundwater discharge (SGD) by means of radon as a natural tracer. Full article

The purpose of this paper is, first of all, to review the previous works on the seismic (or earthquake (EQ)-related) direct current (DC) (or quasi-stationary) electric fields in the lower atmosphere, which is likely to be generated by the conductivity current flowing in the closed atmosphere–ionosphere electric circuit during the preparation phase of an EQ. The current source is electromotive force (EMF) caused by upward convective transport and the gravitational sedimentation of radon and charged aerosols injected into the atmosphere by soil gasses during the course of the intensification of seismic processes. The theoretical calculations predict that pre-EQ DC electric field enhancement in the atmosphere can reach the breakdown value at the altitudes 2–6 km, suggesting the generation of a peculiar seismic-related thundercloud. Then, we propose to apply this theoretical inference to the observational results of seismogenic VHF (very high frequency) and VLF/LF (very low frequency/low frequency) natural radio emissions. The formation of such a peculiar layer initiates numerous chaotic electrical discharges within this region, leading to the generation of VHF electromagnetic radiation. Earlier works on VHF seismogenic radiation performed in Greece have been compared with the theoretical estimates, and showed a good agreement in the frequency range and intensity. The same idea can also be applied, for the first time, to seismogenic VLF/LF lightning discharges, which is completely the same mechanism with conventional cloud-to-ground lightning discharges. In fact, such seismogenic VLF/LF lightning discharges have been observed to appear before an EQ. So, we conclude in this review that both seismogenic VHF radiation and VLF/LF lightning discharges are regarded as indirect evidence of the generation of anomalous electric fields in the lowest atmosphere due to the emanation of radioactive radon and charged aerosols during the preparation phase of EQs. Finally, we have addressed the most fundamental issue of whether VHF and VLF/LF radiation reported in earlier works is either of atmospheric origin (as proposed in this paper) or of lithospheric origin as the result of microfracturing in the EQ fault region, which has long been hypothesized. This paper will raise a question regarding this hypothesis of lithospheric origin by proposing an alternative atmospheric origin outlined in this review. Also, the data on seismogenic electromagnetic radiation and its inference on perturbations in the lower atmosphere will be suggested to be extensively integrated in future lithosphere–atmosphere–ionosphere coupling (LAIC) studies. Full article

Radon in soil poses a significant health risk when it accumulates inside dwellings. The estimation of radon potential is a difficult task due to the complex dynamics of radon within soil and its relations with the weather. This research focuses on the variability of radon activity, driven by environmental changes, assessed in two loam soils (loamy sand–granite soil and silty clay loam-calcareous soil) with different radium contents. We conducted an experiment with teow soil columns in a semi-controlled outdoor laboratory, in a warm semi-arid climate. We also examined the consequences of abundant rainfall on radon activity through artificial soil water content (SWC) experiment conditions. Statistical analyses reveal that SWC is the most significant parameter influencing radon activity in these experiments. Radon is proportional to SWC and inversely proportional to temperature, evapotranspiration, and pressure in both soils, while wind is negatively related only in the loamy sand soil. Based on our findings, we modelled radon potential considering different soils and climatic contexts. SWC influences radon potential by changing radon emanation, activity, and permeability, depending on the local soil texture and radium concentration. Full article

Building materials, such as brick and concrete, are known indoor radon (²²²Rn) and thoron (²²⁰Rn) sources. Most radon and thoron exhalation studies are based on the laboratory testing of pieces and blocks of such materials. To discuss if laboratory findings can be applied to a real-world environment, we conducted intensive in situ exhalation tests on two solid concrete interior walls of an apartment in Japan for over a year. Exhalation rates of radon (J_Rn) and thoron (J_Tn) were measured using an accumulation chamber and dedicated monitors, alongside monitoring indoor air temperature (T) and absolute humidity (AH_in). There were weak correlations between J_Rn or J_Tn and T or AH_in at one tested wall, and moderate correlations of J_Rn and strong correlations of J_Tn with T or AH_in at the other wall, meaning more or less seasonal variations. The findings aligned with previous laboratory experiments on J_Rn but lacked corresponding data for J_Tn. Additionally, a moderate or strong correlation between J_Rn and J_Tn was observed for both tested walls. Comparison with theoretical calculations revealed a new issue regarding the impact of each process of emanation and migration within concrete pores on radon and thoron exhalation. Overall, this study provides insight into parameterizing radon and thoron source inputs in modeling the spatiotemporal dynamics of indoor radon and thoron. Full article

Radon, a radioactive inert gas that comes from the decay of naturally occurring radioactive species, poses a substantial health risk due to its involvement in lung cancer carcinogenesis. This work proposes a metrological approach for determining radon exhalation rates from diverse building materials. This methodology employs an electrostatic collection chamber for alpha spectrometry of radon isotopic decay products. Experimental evaluations were conducted particularly focusing on volcanic gray tuff from Sant’Agata de’ Goti (Campania region, Italy), a material commonly utilized in construction, to assess radon exhalation rates. The study aligns with Legislative Decree 101/2020, a transposition of European Directive 59/2013/Euratom, highlighting the need to identify materials with a high risk of radon exhalation. Moreover, this work supports the goals of the Italian National Radon Action Plan related to the aforementioned decree, aiming to develop methodologies for estimating radon exhalation rates from building materials and improving radioprotection practices. Full article

The paper considers a dispersive geological medium (seismically turbid medium, as defined by A.V. Nikolaev), which is in a stress–strain state. Results of studies on the joint monitoring of seismic effects and radon emanation in various geological environments are presented. It is concluded that the turbidity of the medium, as a statistical characteristic, can be generalized in terms of other media parameters, such as permeability. A stable connection between radon emanation and dynamic processes occurring in a geological environment and caused by external influences has been established. The concentration of radon can also reflect the degree of enrichment of the environment by underground fractures. Consequently, saturation of the environment with radon provides information about the presence of disturbances in a geological environment in the form of cracks and a stress–strain state of the medium before and after seismic loadings. Radon observations make it possible to assess a continuity of the environment and the possibility of leaching in natural conditions. Therefore, it could be efficiently used for underground leaching efficiency assessment. Full article

Physical and chemical agents in workplace environments can be hazardous for employees. Much of the exposure to ionizing radiation can occur due to the presence of radon in the workplace. Mining environments are more susceptible to containing radon gas because it emanates from soil or rocks. Radon is known to be associated with lung cancer as it is a gaseous chemical agent under normal conditions and is also radioactive. Since there is little knowledge about radon in Brazilian mining workplaces, this study aims to measure occupational exposure to radon in mining environments through a proposed methodology and to verify its compliance with international standards to confirm the potential risk of exposure for employees. Radon concentration in open-pit mining work environments was measured and used as a basis for comparison to assess the proposed new evaluation method, which will consist of laboratory evaluations of samples taken from the same workplaces. The radon concentration data in the work environments were compared to laboratory tests for statistical correlation. The results, compared to reference values, tolerance limits, and action levels, showed that radon, in outdoor mining workplaces, can be considered a low risk to employees’ health. The application of the methodology also indicated that the laboratory tests and the field evaluations presented a statistical correlation with each other, being an indication that the laboratory tests can be used to estimate the risks in a preliminary way. Another important point is the fact that it was observed that measurements in the laboratory were more practical and faster to perform when compared to field evaluations. These facts can bring future gains in the number of tests performed and workplace evaluated in mining environments. Full article

The analysis of the relationship between radon and seismicity was previously carried out in the seismic zone of Vrancea (Romania), positioning the measuring stations on tectonic faults. This article analyzed the evolution of radon under conditions of deep and surface seismicity and the presence of mud volcanoes, as well as fires caused by gasses emanating from the ground. The monitoring area was extended to the Black Sea and the area of the Făgăraș-Câmpulung fault, where a special radon detection system was established and proposed for patenting. The case study was the impact of the earthquakes in Turkey (7.8 R and 7.5 R on 6 February 2023) on the seismically active areas in Romania in terms of gas emissions (radon, CO₂). The main analysis methods for radon (we also included CO₂) were applied to integrated time series and the use of anomaly detection algorithms. Data analysis showed that the effects of global warming led to variations in seasonal gas emissions compared to previous years. This made it difficult to analyze the data and correlate it with seismicity. Several of the cases presented require more in-depth analysis to determine the cause of the unusually high radon levels. The primary purpose of establishing the monitoring network is to use the gas emissions as seismic precursors, but the measurements are affected by the conditions under which the monitoring is conducted. In some cases, we are dealing with the effects of pollution, and in other cases, more extensive studies are required. One solution we plan to use is to expand the measurement points to locate the source of the anomalies and use weather data to determine the impact of global warming on the measurements. The main conclusions related to the development of a radon monitoring network and, in general, to the emission of gasses in earthquake-prone areas relate to the importance of the choice of equipment, monitoring location, and installation method. Full article

The noise-like behavior of the geomagnetic anomalies observed in Tlamacas station (volcano Popocatepetl, Mexico), linked to the ionization produced by intensive radon release, are presented in the experimental part of this study. The magnetic field perturbations produced by charge spreading currents within the fair-weather electric field are considered in the theoretical model based on the electrode. The electric charges are generated by the air ionization due to radon emanation. The simulations demonstrated that the ionization of the air leads to magnetic field perturbations of about 0.001–0.1 nT in the ULF (ultra low frequency) range 10⁻³–10⁻¹ Hz. Magnetic field perturbations can be higher when the radon emanation occurs in a region with terrain irregularities. Full article

Soil radon gas concentrations ranging from the detection limit up to 15 kBq/m³ were measured for the first time at the Kilbourne Hole maar in two selected regions: the first region was located on the western volcanic field, and the second was located inside the crater, near the southern border. Radioactive anomalies were found in association with the pyroclastic deposit, and the corresponding heat map provided information on the radon diffusion direction by the C_Rn gradient. It was observed for the first time that the anomalies found at the southern border are associated with a known geological fault, in opposition to what was found on the western border. The results provided by a radon activity concentration gradient of above (8 kBq/m³)/15 m suggest the existence of a fault that has not been detected yet. The observation that high levels near a dormant fault are related to tectonically enhanced radon was confirmed. The activity concentrations of Rn-gas were contrasted to existing gravimetric and magnetic data to provide measuring information on radon emanation, suggesting the existence of a high, naturally occurring radioactivity in the soil in the first place or an increased porosity of the locally defined lithology. The results indicated a higher correlation of 85% with magnetic anomalies. This is in opposition to the gravimetric data, which was only 30%. This study is a contribution to the characterization maar of volcanic geology by the soil radon activity index, which was designated as “low” in this case. Full article

Radon is an increasingly common concern, mainly when it is found indoors exposing the users of the space to radiation. As a gas, radon is an element produced due to uranium decay; it emanates naturally from soil and is considered by the World Health Organization as the second most common cause of lung cancer. Several methodologies are available for mitigating the indoor radon concentration, with distinct improvements and efficiencies that need to be proved with on-site testing. The case study here presented analyzes the effect of applying a barrier membrane, covering the pavement of a ground floor room located in a historic building with a high occupancy rate, on an abnormal radon concentration evidenced by experimental data. After the barrier membrane installation, a new long-term monitoring campaign (3 months) was carried out to assess indoor radon concentration. The obtained results showed that the barrier membrane lowered the indoor radon concentration by 90%. However, the radon exposure level remained higher than the recommended level to enable safe occupation and the regular use of space. Nevertheless, as the reduction in the radon concentration was very significant by the adoption of a barrier membrane, the combination of this technical solution with other mitigation methodologies, namely including the adoption of mechanical ventilation procedures, can become a very efficient solution for radon remediation, reducing the number of air changes per hour (ACH) from 30–60 to 4–6. Full article