Soil Radon Research Articles

Major factors affecting soil radon emanation

Major factors affecting soil radon emanation

Preliminary studies on soil radon activity at geothermal hotspot of Bakreswar-Tantloi

Bakreswar-Tantloi region of India, besides being a geothermally active region, also harbours a high amount of Radon in soil-gas and groundwater of the region. Measurement of Radon-content across the region is an active area of research aimed to properly understand the geothermal potential of the region, the study of local geology and to determine the risks of Radon exposure in the area. In an aim to evaluate the Radon potential of this important geothermal hub, we have done a pilot study on the region by doing spot measurements of Soil-Radon activity in 41 specific geographic locations spread out across the region of interest which will act as groundwork for further in-depth analysis. The measurements showed that Radon activity varies widely in the region with the Radon activity ranging from 1 to 52 across the measured locations. Mean Radon activity across the measured locations was found to be 16 with standard deviation of the sample set of 14 Seven locations recorded Radon activity to be greater than standard deviation from average while four locations recorded Radon activity greater than twice the standard deviation from average.

Radon Risk Assessment and Correlation Study of Indoor Radon, Radium-226, and Radon in Soil at the Cobalt–Nickel Bearing Area of Lomié, Eastern Cameroon

Radon Risk Assessment and Correlation Study of Indoor Radon, Radium-226, and Radon in Soil at the Cobalt–Nickel Bearing Area of Lomié, Eastern Cameroon

Evaluation of Natural Radioactivity and Risk Assessment of Radon in Surface Soils from Gold Mining Areas

Evaluation of Natural Radioactivity and Risk Assessment of Radon in Surface Soils from Gold Mining Areas

Determination of terrestrial γ-radiation dose rate and soil radon concentration in a river region of Southern China

Determination of terrestrial γ-radiation dose rate and soil radon concentration in a river region of Southern China

Уточнение модели связей летучих газов почвенного воздуха, радона и атмосферного электрического поля

The task of the research is to clarify the relationship between volatile gases, soil radon and atmospheric radon, taking into account the results of experiments. A physical explanation is presented for the presence and absence of correlations between carbon dioxide and soil radon, anomalous release of soil radon and atmospheric radon during a pre-thunderstorm drop in atmospheric pressure. It is noted that the complex of bonds between hydrogen, methane, soil radon and atmospheric radon, taking into account the observation conditions and atmospheric pressure drop, has never been considered. The conditions for sampling soil air and the participation of carbon dioxide in the transfer of radon in the near-surface soil layers are considered.

Application of Optically Stimulated Luminescence Technique in Exploring a Concealed Sandstone‐type Uranium Deposit

AbstractIdentifying ore‐induced geochemical anomalies at the surface that indicate concealed deposits in buried areas remains a significant challenge in geochemical exploration. In this study, in order to trace the source of the geochemical anomalies, systematic luminescence intensity analyses were conducted on quartz grains from the Quaternary regolith at the Hadatu sandstone‐type uranium deposit in the Erenhot Basin. The optically stimulated luminescence (OSL) ages were much older than the depositional ages of the Quaternary regolith. Moreover, quartz OSL ages were closely related to both borehole grades and sampling depths. Thus, the abnormal mineral OSL ages from near‐surface sediments were ultimately controlled by the sandstone‐type uranium deposits. This is identical to the rapid changes of quartz OSL ages (0.063 ka/cm) and equivalent doses (0.19 Gy/cm) with depths in a given sampling site. The instantaneous soil radon concentration was positively correlated with the quartz OSL apparent age, indicating their ore‐induced origin and, as a result, their effectiveness in the exploration of concealed uranium deposits. Other parameters, including mobile‐state uranium and 210Po contents, were poorly correlated with quartz OSL ages and therefore should only be used with caution for geochemical exploration. This is the first time an attempt has been made to discriminate the ore‐induced sources for different surface anomaly parameters, including instantaneous soil radon, mobile‐state uranium and 210Po contents for concealed sandstone‐type uranium deposits.

Assessment of the tectonic effects on soil radon activity along the margin of the Arabian plate boundary in northwestern Syria

The main purpose of the present study is to assess the role of active tectonics in influencing the emanation level of soil radon across two tectonically active structures of the Northern Dead Sea Fault (NDSF) in northwestern Syria: namely, the Qastoon and Al-Harif fault segments. The radon measurements were basically directed by the results drawn from earlier studies of archaeoseismic and paleoseismic investigation in Al-Harif, besides integrated geophysical and morphotectonic survey at the Qastoon site. In view of that, a total of 80 soil gas radon points were measured in this work with sampling depth of 75 cm, using AlphaGUARD PQ 2000Pro radon detector. The background range of normal radon emission from local soil was determined in area located away from the influence of the tectonic disturbances. The obtained radon data were statistically analyzed and the mean values have been standardized in terms of probability of magnitude which enhances the comparison process and so facilitating the separation of normal radon variations from other anomalous or geotectonic related values. The overall results revealed remarkable occurrences of fault-associated radon anomalies with maximum peak values of ~6 to 7 times above the background, trending in accordance with the predicted traces of the fault ruptures at the Qastoon and Al-Harif, respectively.

Observations on the stress related variations of soil radon concentration in the Gulf of Corinth, Greece

Our observations indicate a characteristic pattern in the long-term variation of soil radon concentrations, which seems to be consistent with the expected variation of regional stress in relation to seismicity. However, it seems that the major changes in radon level begin before the rock rapture, i.e. before the earthquake occurs. These conclusions have emerged after long-term observations with continuous and thorough real-time gamma-radiation monitoring in the seismically active area of the Gulf of Corinth, Greece. The recordings acquired close to a hot spring were of very high quality, implying that the deep hydraulic flow can possibly play a key role in the pre-earthquake variation of radon level. We were able to observe outstanding examples of radon level variations before significant seismic events in the Gulf of Corinth that cannot be attributed to other external factors such as atmospheric phenomena.

A preliminary study on soil radon anomaly and its formation mechanism in karst area of southwest China

A preliminary study on soil radon anomaly and its formation mechanism in karst area of southwest China

Annual monitoring of soil radon behavior and entry into building

A simple experimental scheme is proposed to study the concentration behavior and mechanism of soil radon transport from beneath a building foundation. In addition to the results of the annual monitoring of soil radon concentration and environmental factors, the calculated results of the annual continuous monitoring of the soil radon entry rate into experimental room with high levels of indoor radon are presented. This room is located in the basement of one of the buildings in Haifa, Israel. The correlation between radon behavior and environmental factors is discussed. It is found that the soil radon concentration beneath the building is maximum in the winter season due to very heavy rains. There is an absence of soil radon entry by only convection mechanism into the experimental room for the summer and autumn seasons; however, the indoor radon concentration remains high (about 500 Bq m-3) due to diffusion of soil radon. A regular soil radon entry into the experimental room by convection is observed in the winter and spring seasons with a maximum, approximately at the beginning of the spring season, and therefore, the indoor radon concentration is twice as high as in the summer and autumn seasons. The obtained results indicate that not only convective process but also diffusion of soil radon plays a significant role in the formation of indoor radon.

Estimation of 238U and 232Th in soil and water of prominent fault region of Mizoram

The study investigates radon and thoron concentrations in soil and water at one of the most prominent faults in Mizoram state, India. The obtained isotope pair data were consequently used for estimating the uranium and thorium content of the region. An indigenously developed and calibrated ZnS(Ag) alpha based scintillation counter (Model: SMARTRnDuo, BARC, India) was deployed for assessing radon and thoron data. Thoron concentration was found to be higher than radon concentration in both soil and water. The isotope pair and their parent nuclei concentration in water were found to be higher than in soil. The uranium and thorium content in soil were estimated to be 17.5 and 22.6 Bqkg-1 respectively, but in water, they were estimated to be 41.6 and 124.8 Bqkg-1 respectively. Comparisons with global averages were also presented in detail and no radiological risk has been observed for the region. A continuous radon data was generated at Mizoram University, Aizawl, Mizoram (India) for cross-analysis with data at Mat fault. It was observed that radon data of the two locations behave similarly during geophysical phenomena, indicating that the region was seismically active. No geophysical properties of thoron were observed.

Spatial Variability and Behavior of Background Radon Concentrations in Ambient Air in the San Mateo Basin of the Grants Mineral Belt.

A modeling study and analysis of measurement data was conducted in the San Mateo basin near the former Homestake Mining Company of California's mill site located north of Milan, NM, to understand the spatial variability of background radon and identify a suitable background station. Recent guidance from the US Nuclear Regulatory commission clarifies the requirement that dose assessments of existing facilities be based on environmental measurements at the facility's unrestricted boundary instead of predictive modeling. Background is important because it is subtracted from radon measured at the boundary for dose calculations. The current background station lies on the slopes above the wash floor. The mill site contains two tailing piles with a total area of 1.03 km2 that in 2019 emitted 1,750 mBq m-2 s-1 from the larger of the piles and 320 mBq m-2 s-1 from the smaller pile. Atmospheric transport modeling was conducted to facilitate understanding of the movement of radon in the San Mateo wash bottom and surrounding hillsides. The model was validated using emission and measurement data from the nearby Ambrosia Lake mining region. The modeling, in combination with current measurements and previous studies, indicated the wash floor has characteristically higher radon concentrations than the slopes above the wash. This phenomenon was attributed to (1) higher radon soil flux in the alluvial sediments that make up the wash floor, (2) nocturnal drainage flow that results in a pooling of radon on the wash floor, and (3) inversion conditions that trap radon in a shallow air mass on the wash floor during late evening and early morning hours. Using a regression of predicted and observed radon concentrations, a background concentration of 25.7 Bq m-3 was derived that was close to that measured at background stations about 4 km north of the tailings pile and on the San Mateo wash floor.

Studies of scintillations and TEC variations with GPS satellite links together with soil radon anomalies preceding Nepal earthquakes of April–May 2015

Studies of scintillations and TEC variations with GPS satellite links together with soil radon anomalies preceding Nepal earthquakes of April–May 2015

Correlation of in-situ online 222Rn data at Mat fault with geophysical process

This study aims to correlate radon concentration anomalies with geophysical phenomena along the Indo-Burman subduction region. The soil radon production rate and exhalation rate of four different sampling depths were generated at Mat fault, Mizoram (India) between May 2018 and October 2018 and correlated. The nature of the obtained correlation coefficient was then further correlated with geophysical phenomena of the region. A ZnS(Ag) based scintillation counter named SMARTRnDuo (Model: SMARTRnDuo, BARC, India) was deployed for all 222Rn measurements. To categorize the 222Rn data into the anomaly and non-anomaly period data a meteorologically free radon data whose peaks being attributed only by geophysical phenomena was simultaneously generated at Mizoram University, Aizawl, Mizoram (India). A strong correlation coefficient was observed during the non-anomaly period between the radon production rate and exhalation rate while a weak or insignificant correlation coefficient during the anomaly period. The adopted method seems to be significant for premonitory of radon anomaly due to geophysical of the region.

Assessment of Seasonal Radon Concentration in Dwellings and Soils in Selected Areas in Ga East, Greater Accra Region of Ghana.

Seasonal radon levels have been studied in dwellings and soils in selected areas in Ga East, Greater Accra Region of Ghana using LR-115-type II (SSNTDs). This study was conducted to determine the seasonal correlation between soil and dwelling radon concentrations. Detectors were exposed from January to March and April to June, for dry and wet seasons, respectively. Overall, indoor radon was 133.4 ± 6.7 Bqm−3 and 72.1 ± 3.6 Bqm −3 for wet and dry seasons. The estimated annual effective dose to the lung received by the occupants at Paraku Estate, Dome, and Kwabenya was 6.9 ± 0.4, 7.2 ± 0.5, and 9.8 ± 0.8 mSvy−1 for the wet season and 3.8 ± 0.2, 4.3 ± 0.2, and 4.6 ± 0.3 mSvy−1 for the dry season. On average, the soil radon concentration was found to be 0.96 ± 0.07 kBqm−3 and 2.24 ± 0.01 kBqm−3 for wet and dry seasons. To determine the correlation between soil and dwelling radon, a positive Pearson correlation coefficient value R = (0.74) and R = (0.66) was obtained representing the dry and wet seasons. To test the statistical significance between soil and dwelling radon, P < 0.05 was obtained, indicating a statically significant relationship between the two.

Anomalies Prediction in Radon Time Series for Earthquake Likelihood Using Machine Learning-Based Ensemble Model

The ability to predict the radioactive soil radon gas concentration is important for human beings because it serves as a precursor to earthquakes. Several studies have been conducted across the globe to confirm the correlation of radon emission dynamics and earthquakes, and concluded that the soil radon gas is the witness of anomalous behaviour before the occurrences of several earthquakes. This anomalous behavior can help to construct a better prediction model for earthquake forecasting. This paper aims at employing different ensemble and individual machine learning methods on real time radon time series data with different scenarios to predict anomalies in data caused by the seismic activities.The ensemble methods include boosted tree, bagged cart and boosted linear model while standalone machine learning methods include support vector machine with linear and radial kernels and k-nearest neighbors ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}$ </tex-math></inline-formula> -NN). We tested the methods on a dataset recorded on the fault line located in Muzaffarabad. Time series data was collected over a period ranging from March 1, 2017 to May 11, 2018 including nine(09) earthquakes. The methods are tested in four different settings with 10 times 10 folds cross validation procedure over the time window of 1 to 4. The repeated 10 fold cross validation is performed to reduce the noise in the model performance estimation by replicating the 10 fold cross validation procedure 10 times. Statistical performance evaluation measures viz. root mean square error (RMSE), root mean squared log error (RMSLE), mean absolute percentage error (MAPE), percentage bias (PB), and mean squared error (MSE) have been calculated for the assessment of performance. In setting 1, the support vector machine with radial kernel performs better with the minimum RMSE score of 1381.023 when compared to other prediction models. In setting 3, it can be observed through different performance metrics such as RMSE, the value in the range [1262.864, 1409.616] which is minimum when other prediction models for predicting soil radon gas concentration dataset. For setting 4, the boosted tree model yielded the minimum RMSE and MAPE scores of 1573.174 and 0.056 respectively. Findings of the study shows that boosted tree and support vector machine with radial kernel proved to be better regression models for the prediction of anomalies in soil radon gas concentration during seismic activities. An important finding of this study suggests that by employing boosted tree ensemble method make us able to accurately predict soil radon gas concentration automatically from environmental parameters.

An Improved Imputation Method for Accurate Prediction of Imputed Dataset Based Radon Time Series

This article primarily focuses on the performance evaluation of a new methodology, imputation by feature importance (IBFI), to serve its imputed dataset in further regression scenarios when dealing with soil radon gas concentration (SRGC) time-series data. The time-series data have been collected spanning over fourteen(14) months period, which included four seismic events, and have been used for experimentation. The imputation by feature importance (IBFI) has been experimented and obtained results are found more efficient in the imputation of missing patterns in investigated time series when compared to traditionally used imputation methods viz. mean, median, mode, predictive mean matching (PMM), and hot-deck imputation.The IBFI methodology has been used in a variety of settings, such as data missing not at random (MNAR), missing completely at random (MCAR), and missing at random (MAR), with missingness percentages ranging from 10% to 30%. In this study, the imputed datasets, 9 for each imputation method, have been used further to predict the attribute of interest (radon concentration (RN)) keeping others as independent attributes such as thoron, temperature, relative humidity, and pressure time series. Support vector machine (SVM) with linear kernel has been used as a learning algorithm and its performance was evaluated based on the fact that how efficient and unbiased values were imputed. Statistical performance evaluation measures viz. root mean squared log error (RMSLE), root mean square error (RMSE), mean squared error (MSE),and mean absolute percentage error (MAPE) have been calculated for the assessment of performance. The findings of our study show that the IBFI imputed dataset has provided a better-fitted model. The model generation and predictions upon IBFI imputed time series result in more accurate predictions when compared to mean, median, mode, PMM, and hot-deck imputed time series. Furthermore, PMM and median imputed time series also perform closer to the IBFI imputed time series.

Soil radon exhalation rate measurement in Duhok city by two techniques

Radon exhalation rate is the rate of radioactive radon gas that escapes from the soil into the atmosphere. In this study exhalation rate of radon was measured for 33 samples of soil, in four districts of Duhok province, using two different techniques: one using radon concentration and other using radium content, by both alpha and gamma spectroscopy. For the radon measurement, alpha-sensitive RAD7 detector was used. While in the second method, radon exhalation rate was expressed as a function of radium concentration, measured by well type NaI (Tl) detector and other soil parameters. Analysis, shows that the average of radon exhalation rate, by the first technique, varies from 14.6 ? 3.2 to 55.7 ? 1.6 Bqm-2h-1, while by the second technique, it varies from 13.3 ? 2.4 to 50.6 ? 4.1 Bqm-2h-1. Overall, the measured values, for both methods at all the sample points, present a good correlation and less than global mean average recommendation.

Mitigation Techniques for Interior Radon in Refurbishment Work in High Radiation Areas of Galicia: An Experimental Model to Test Building Solutions

Abstract Radon is a naturally occurring radioactive gas, which tends to accumulate inside built structures. It is therefore necessary to include techniques to mitigate radon concentration during refurbishing work. The aim of this study is to assess the effectiveness of a number of mitigation techniques, under real conditions, to determine which is most suitable, in each case, for use in rebuilding solutions. The methodology consisted in performing four experimental tests on mitigation strategies recommended by the Código Técnico de la Edificación (Technical Building Code) (CTE-DB-HS6) and by the Government of the Autonomous Community of Galicia, (Xunta de Galicia, 2018). The concentration was measured with three different systems: radon in soil at 80 cm, passive detectors to confirm mean concentration, and continuous monitoring by devices calibrated at the LaRUC Laboratory of the University of Cantabria, in order to compare the results of the tests. The experiments were carried out in premises located in a high radiation area in Arteixo (La Coruña, Spain). Four experimental models were designed, corresponding to each of the building solutions under study, and tested over a period of 16 days in two repeated series of trials. The results obtained show that, of the different strategies tested, pressurising the living space achieves an efficient reduction of the radon concentration with a significant simplicity of construction. This solution, compatible with the minimal intervention and reversibility principles stablished in the charters of Venice, Krakovia and Nara, is shown to be especially useful when work is carried out on structures considered to be part of protected heritage.