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Abstract A detailed geochemical study on radon related to local geology was carried out in the municipality of Celleno, a little settlement located in the eastern border of the Quaternary Vulsini volcanic district (central Italy). This study included soil-gas and terrestrial gamma dose rate survey, laboratory analyses of natural radionuclides (238U, 226Ra, 232Th, 40K) activity in rocks and soil samples, and indoor radon measurements carried out in selected private and public dwellings. Soil-gas radon and carbon dioxide concentrations range from 6 to 253 kBq/m3 and from 0.3 to11% v/v, respectively. Samples collected from outcropping volcanic and sedimentary rocks highlight: significant concentrations of 238U, 226Ra and 40K for lavas (151, 150 and 1587 Bq/kg, respectively), low concentrations for tuffs (126, 123 and 987 Bq/kg, respectively), and relatively low for sedimentary rocks (108, 109 and 662 Bq/kg, respectively). Terrestrial gamma dose rate values range between 0.130 and 0.417 μSv/h, being in good accordance with the different bedrock types. Indoor radon activity ranges from 162 to 1044 Bq/m3; the calculated values of the annual effective dose varied from 4.08 and 26.31 mSv/y. Empirical Bayesian Kriging Regression (EBKR) was used to develop the Geogenic Radon Potential (GRP) map. EBKR provided accurate predictions of data on a local scale developing a spatial regression model in which soil-gas radon concentrations were considered as the response variable; several proxy variables, derived from geological, topographic and geochemical data, were used as predictors. Risk prediction map for indoor radon was tentatively produced using the Gaussian Geostatistical Simulation and a soil-indoor transfer factor was defined for a 'standard' dwelling (i.e., a dwelling with well-defined construction properties). This approach could be successfully used in the case of homogeneous building characteristics and territory with uniform geological characteristics. Graphical abstract Unlabelled Image Highlights • A detailed geochemical study on radon was carried out in a volcanic area of central Italy. • Geogenic Radon Potential map was developed using Empirical Bayesian Kriging Regression. • A soil-indoor transfer factor was defined for a 'standard' dwelling. • Indoor Rn partly depends on housing characteristics (e.g., tuff used as building material) [ABSTRACT FROM AUTHOR]

Abstract The objective of this paper is to evaluate the possible migration of coal-bed methane and carbon dioxide to the earth's surface in a selected areas from the southern part of the Upper Silesian Coal Basin (USCB) and resulted hazards produced by near-surface gas migration, referred to the geological setting and the origin of these gases. The surface geochemical survey was run over the areas of both the operating and the abandoned bituminous coal mines, including the remediated shafts and the regional tectonic dislocations: the Bzie-Czechowice and the Jawiszowice fault zones. The survey included a total of 453 soil gas samples collected at a depth of about 1.2 m and along 7 horizontal profiles as well as in the vicinities of remediated shafts. All collected gas samples were chromatographically analysed for methane and carbon dioxide concentrations. Selected samples showing increased concentrations of methane and/or carbon dioxide were analysed also for stable carbon isotopes of these gases. Additionally, gas emission was measured at 5 sites selected due to the increased concentrations of the gases. The maximum detected concentrations of methane and carbon dioxide in soil gas samples were 52.8 and 17.4 vol%, respectively. The closure of high methane-emitting bituminous coal mines in the USCB, including the termination of mine ventilation, caused the increase of average methane concentrations in the near-surface zone. Vast anomalies of both gases can be the effects of migration from secondary accumulations of "free" methane present in the elevated parts of Carboniferous formation capped by Miocene claystones and mudstones. Methane originated from primary accumulations located beneath the degassing zone and migrated along fault zones. However, carbon dioxide migrated from both the primary and the secondary accumulations, and, sometimes, it originated also from secondary oxidation of methane. The methane recovery captured with degassing wells run in the area of the abandoned "Morcinek" Mine disturbed the naturaly, vertically migrating methane towards the earth's surface and caused the local decrease of average methane concentrations in soil gas collected along the D-D' sampling line. It was additionally confirmed by relatively high methane concentrations (over 50 vol%) detected in samples collected from the wells degassing the shafts I, II and III of the closed "Morcinek" Mine. The methane is of microbial origin and migrated from secondary accumulation located within the Carboniferous (Pennsylvanian) coal-bearing strata. In the regional tectonic zone of the Bzie-Czechowice Fault, over 4 times higher average carbon dioxide concentrations were detected, in comparison with those analysed in the Jawiszowice Fault Zone. Carbon dioxide was of microbial origin, migrating from a secondary accumulation. Relatively low values of both the methane and carbon dioxide emissions were noticed at sampling sites, where elevated concentrations of both gases were encountered previously in the near-surface zone. This suggests that gases may accumulate in the near-surface zone as a result of long-term, and relatively slow migration from the depth. Hence, and in this case the potential gas hazard caused by uncontrolled and fast inflow of methane and carbon dioxide to a basements of buildings is insignificant. Highlights • The closure of coal mines caused the increase of methane concentrations in soil gas. • Methane recovery with wells disturb vertical migration of gases towards the surface. • Thermogenic and microbial CH 4 and CO 2 migrate from Pennsylvanian coal-bearing strata. • Low values of CH 4 and CO 2 emission shows insignificant gas hazard at the surface. [ABSTRACT FROM AUTHOR]

Highlights • Multi-tracer approach used to definitively assess soil gas migration issues. • CO 2 injection reservoir leak alleged due to CO 2 concentrations in soils. • δ13C CO2 and δ18O CO2 values provided limited insight. • 14C CO2 indicated 'modern carbon' supporting a microbial source for soil gases. Abstract Stable (13C) and radiogenic (14C) carbon isotope tracers are recognized approaches to identify gas sources using soil gas monitoring techniques; however, definitive characterization from a subsurface injection/storage reservoir can be complicated by processes that produce and consume CO 2. Few studies assess the combined use of compositional (fixed gases, hydrocarbons, and sulphurous compounds) and isotopic (13C, 18O and 14C) indicators from soil gases as tools to evaluate CO 2 storage reservoir leaks. Compositional and isotopic indicators from soil gases were compared at an investigation site (IS) alleged to be impacted by CO 2 leaking from an underlying injection reservoir with a baseline control site (BCS) outside of the injection area. Soil gas δ 13C CO2 values collected from the IS (−23.4‰to −22.6‰) were comparable with the range observed at the BCS (−22.8‰ and −23.3‰), falling within the range anticipated for both biogenic and injected CO 2. 14C values were also comparable between IS (98.0 pMC to 107.0 pMC) and BCS (102.8 pMC to 105.3 pMC) sites, representing a modern carbon source that was distinct from the CO 2 injection gas (0.34 pMC). The results provide several lines of evidence that CO 2 fluxes in soil gases at the IS were related to naturally occurring processes and were not caused by a gas migration issue from a geological CO 2 storage reservoir. [ABSTRACT FROM AUTHOR]

Soils provide many functions as they represent a habitat for flora and fauna, supply water, nutrient, and anchorage for plant growth and more. They can also be considered as large bioreactors in which many processes occur that involve the consumption and production of different gas species. Soils can be a source and sink for greenhouse gases. During the last decades this topic attracted special attention. Most studies on soil-atmosphere gas fluxes used chamber methods or micro-meteorological methods. Soil gas fluxes can also be calculated from vertical soil gas profiles which can provide additional insights into the underlying processes. We present a design for sampling and measuring soil gas concentration profiles that was developed to facilitate long term monitoring. Long term monitoring requires minimization of the impact of repeated measurements on the plot and also minimization of the routine workload while the quality of the measurement needs to be maintained continuously high. We used permanently installed gas wells that allowed passive gas sampling at different depths. Soil gas monitoring set ups were installed on 13 plots at 6 forest sites in South West Germany between 1998 and 2010. Until now, soil gas was sampled monthly and analysed for CO2, N2O, CH4, O2, N2, Ar, and C2H4 using gas chromatography. We present typical time series and profiles of soil gas concentrations and fluxes of a selected site as an example. We discuss the effect of different calculation approaches and conclude that flux estimates of O2, CO2 and CH4 can be considered as highly reliable, whereas N2O flux estimates include a higher uncertainty. We point out the potential of the data and suggest ideas for future research questions for which soil gas monitoring would provide the ideal data basis. Combining and linking the soil gas data with additional environmental data promises new insights and understanding of soil processes.

The application of the 222Radon (Rn) deficit technique using subsurface soil gas probes for the identification and quantification of light non-aqueous phase liquids (LNAPL) has provided positive outcomes in recent years. This study presents an alternative method for applying this technique in the headspace of groundwater monitoring wells. The developed protocol, designed for groundwater monitoring wells with a portion of their screen in the vadose zone, is based on the use of portable equipment that allows rapid measurement of the Rn soil gas activity in the vadose zone close to the water table (i.e., smear zone) where LNAPL is typically expected. The paper first describes the step-by-step procedure to be followed for the application of this method. Then, a preliminary assessment of the potential of the method was carried out at two Italian sites characterized by accidental gasoline and diesel spills into the subsurface from underground storage tanks. Although the number of tests conducted does not allow for definitive conclusions, the results obtained suggest that, from a qualitative point of view, Rn monitoring in the headspace of monitoring wells is a promising, fast, and minimally invasive screening method that could also potentially reduce the costs associated with field data acquisition. This method proves to be suitable for detecting the presence of LNAPL in both the mobile and residual phases with results consistent with the other lines of evidence available at the sites, such as groundwater and soil gas monitoring. Future efforts should be directed toward evaluating the accuracy of this method for a quantitative assessment of residual LNAPL saturations. [Display omitted] • An alternative soil gas Rn deficit technique for LNAPL evaluation is presented. • The method is based on Rn measurements in the headspace of monitoring wells. • The application in two Italian sites demonstrated the effectiveness of the method. • Compared to traditional techniques, time, costs and invasiveness can be reduced. [ABSTRACT FROM AUTHOR]

Radon (222Rn) and thoron (220Rn) from soil gas are very significant factors that can affect the indoor radon level in the first floor or in the basement. China is one of the countries with the highest thorium content in the world. Therefore, it is very significant to study 222Rn/220Rn concentration in the soil in Shenzhen City (SC). A 222Rn/220Rn survey was performed using a portable radon monitor (model RAD7) at 69 sites, covered a total area of 1800 km2 in 2013 to get the original data for radon risk estimation in SC. The average values of 222Rn and 220Rn concentration of soil gas of the total 69 locations are 86 ± 72 kBq·m−3 and 118 ± 85 kBq·m−3, respectively. 222Rn/220Rn concentrations are related to geological lithology. 222Rn concentrations vary from 40 to 370 kBq·m−3 and from 15 to 118 kBq·m−3 in weathered granite products and sediments, respectively, while 220Rn concentrations are from 103 to 435 kBq·m−3 and 2.2 to 96 kBq·m−3. The higher 220Rn values were mainly observed at the sites covered by the weathered granite products. Comparing with the areas of high 222Rn concentration, the areas of high 220Rn values are larger. The distribution of 222Rn concentration in the vertical direction displays an exponential distribution mode, but there is no rule of 220Rn concentration. The investigation suggests that people should pay attention to 220Rn contribution in the radon mapping of SC, as well as in the indoor radon survey.

In the present investigation, analysis of radon concentration in 20 water and soil samples collected from different locations of Bikaner and Jhunjhunu districts of Rajasthan, India has been carried out by using RAD7 an electronic Radon detector. The measured radon concentration in water samples lies in the range from 0.50 to 22 Bq l−1 with the mean value of 4.42 Bq l−1, which lies within the safe limit from 4 to 40 Bq l−1 recommended by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2008). The total annual effective dose estimated due to radon concentration in water ranges from 1.37 to 60.06 μSV y−1 with the mean value of 12.08 μSV y−1, which is lower than the safe limit 0.1 mSv y−1 as set by World Health Organization (WHO, 2004) and European Council (EU, 1998). Radon measurement in soil samples varies from 941 to 10,050 Bq m−3 with the mean value of 4561 Bq m−3, which lies within the range reported by other investigators. It was observed that the soil and water of Bikaner and Jhunjhunu districts are suitable for drinking and construction purpose without posing any health hazard.

Soil-based radon investigations are of value in correlating radon production and its transportation into buildings through the processes of convection and diffusion. Such studies can help in identifying land areas that pose special concerns. We present preliminary results of soil radon gas measurements at 60 different locations in an attempt to map out the geohazard zone of the city of Muzaffarabad. The seismic geohazard microzonation for the area includes five microzones based on different hazard parameters: a very high hazard zone, a high hazard zone, a moderate hazard zone, a low hazard zone, and a safe zone. Measurements were taken with an active radon monitoring system at the depths of 30, 40, 50, and 60 cm below the ground surface. The results obtained were explained by the lithology of the area. Average soil radon gas concentrations were correlated with the depth from the ground surface and indoor radon values for the study area. No significant correlation was found between soil radon gas and meteorological parameters, however soil radon gas increases as the depth from the surface of the ground grows. The results showed a linear relation between soil radon concentrations with depth from ground surface (R2 = 0.9577). The minimum soil radon concentration (68.5 Bq/m3) was found at a depth of 30 cm in the very high hazard zone, the maximum value (53.300 Bq/m3) at a depth of 60 cm in the seismically safe zone. Measured soil gas radon concentrations at depths of 30, 40, 50, and 60 cm were mapped for high, moderate, and low radon concentrations. Elevated soil radon gas concentrations were found in the safe zone, otherwise considered to be suitable for any type of construction.

Highlights • Near-surface soil gas and groundwater data can vary naturally and significantly. • Multiple approaches should be employed when assessing near-surface site data. • Air temperature modeling of soil gas data can assist in natural trend evaluation. • Identification of key groundwater parameters can assist in CO 2 exposure monitoring. • Modeling near-surface site data enhances monitoring efficiency and effectiveness. Abstract Near-surface soil gas and groundwater measurements can be helpful tools in assuaging concerns of potential out-of-zone migration of CO 2 from a geologic storage unit into the overlying near-surface environment. These data, therefore, help to build confidence with local stakeholders and regulators that stored CO 2 is not impacting surface/near-surface environments. Routine monitoring of soil gas concentrations in the vadose zone can be used to show a lack of change or effect. However, both air temperature modeling and the Romanak et al. (2012) process-based approach should be applied when soil gas data are evaluated, as increased CO 2 concentrations can occur naturally from changes in the soil environment. Laboratory testing of groundwater and formation rock (drill cuttings) samples, exposed to varying concentrations of CO 2 under in situ temperature and pressure conditions, yield valuable information with respect to water chemistry changes that could occur from a potential out-of-zone migration. Key field-measured groundwater monitoring parameters that change significantly in response to low levels of CO 2 are pH (rapid decrease), alkalinity (increase), and conductivity (increase). Empirical models that predict soil gas concentrations using routinely measured climatic data such as air temperature, as well as models that predict the magnitude and duration of potential CO 2 exposure in groundwater, should be employed as components of a broad surface and subsurface monitoring program. [ABSTRACT FROM AUTHOR]

In the present study, some mud volcanoes in Pingtung and Kaohsiung areas were selected. The selected mud volcanoes are located above the mud diaper system in southern Taiwan. Three different sampling techniques were used to collect samples in and around the said mud volcanoes. The results show that river water samples from different places fall on the meteoric line. Mud samples are found to be heavier in oxygen isotope while hydrogen isotope remains the same. Soil gas samples were also collected at the depth of 1 m and dissolved gases from the mud volcanic site (or nearby) were collected for gas chromatography analyses. Soil gas samples and dissolved gas from mud pool and groundwater were analyzed for radon concentration using RAD7 (solid-state nuclear track detector) bi-weekly. Long-term investigation will be needed to understand the relationship of mud volcanoes the eruption cycle with gas composition variations. It will also help to understand their relationship with tectonic activities in the region. [ABSTRACT FROM AUTHOR]

The search for hydrocarbon deposits in the Carpathian Foredeep is dominate by seismic methods. However, chances for additional discoveries of oil and gas will be increased by the integration of geochemical methods with non-seismic methods. The authors document mutual relationships between data obtained from surface geochemical survey and surface geoelectric survey. The geoelectric and geochemical surveys were run along 8 linear profiles positioned over the Rudka gas deposit discovered in Miocene sediments. This deposit is located over the margin of the Ryszkowa Wola Horst (Carpathian Foredeep). The Rudka deposit accumulates microbial gas generated under strictly defined conditions (microbial reduction of carbon dioxide). Soil gas samples were collected from a depth of 1.2 m at 177 sites and analyzed for methane, alkanes, alkenes, and non-hydrocarbon components. Maximum concentrations of CH 4 , total alkanes C 2 -C 5 and total alkenes C 2 -C 4 are 1200.0 ppm, 16.49 ppm and 0.289 ppm, respectively. The high concentrations of methane correlated with high values of C 1 /∑(C 2 -C 4 ) ratio indicate the presence of recent (microbial) methane whereas higher alkanes detected in soil gases originated from deep hydrocarbon accumulations. Two methodological variants of magnetotelluric survey were applied: natural field magnetotelluric soundings and controlled-source audiomagnetotelluric profiling. The interpreted resistivity values of Miocene sediments change from 0.6 to 20 Ωm but higher resistivities, locally exceeding 100 Ωm also occur in the near-surface zone. The lateral decreases of resistivity observed in the cross-sections may be linked to tectonic discontinuities. Changes of resistivity values identified in the magnetotelluric profiles and interpreted as the signs of “gas chimneys” correlate well with anomalous concentrations of total alkanes C 2 -C 5 . The multistage analysis of the results of surface geochemical and geoelectric surveys demonstrated that gas-saturated zones may extend beyond the known contour of the Rudka gas deposit. These results demonstrate that geoelectric and geochemical data collected in the near-surface zone are valuable complements of conventional hydrocarbon exploration methods. [ABSTRACT FROM AUTHOR]

Carbon Capture and Storage (CCS) is playing a greater role in reducing CO 2 emissions. The Aquistore project at Estevan, Saskatchewan, Canada is an operational CCS demonstration and research site. Surface soil gas geochemistry is one method of Measurement, Monitoring, and Verification (MMV) techniques used for detection of leakage at CO 2 injection sites. We have been operating the surface soil gas MMV program for several years, which has involved measuring gas concentrations of CO 2 , O 2 , N 2 , CH 4 , the stable isotope of CO 2 ( δ 13 C), and radiocarbon isotope Δ 14 CO 2 as tracers for storage containment analysis. Soil CO 2 surface flux measurements were also conducted during the baseline monitoring program. At Aquistore, CO 2 concentration is typically elevated relative to the mean for the location, but such values are characteristic in this area. Ratio-based tracer analyses, such as O 2 vs. CO 2 , CO 2 vs. N 2 , and CO 2 vs. N 2 /O 2 , all indicated that storage is secure. The Δ 14 CO 2 values observed in soil gas were interesting in the parts of the site which had a more depleted baseline than expected. To date, there have been no changes in the soil gas indicators since the injections started. These observations will help to inform new research aimed at improving the effectiveness and efficiency of soil gas MMV at Aquistore and similar projects worldwide. [ABSTRACT FROM AUTHOR]

One of the goals of the French national campaign called “Etablissements Sensibles (Sensitive Establishments)” is to evaluate indoor air degradation in schools because of vapor intrusion of volatile compounds from soil gases towards the indoor air, related to the presence of former industrial sites on or near the establishment. During this campaign, as recommended by the United States of Environmental Protection Agency (US EPA), indoor air quality was evaluated from soil gas concentrations using generic attenuation factors, and extra investigations into soil gases and indoor air were performed when the estimated values exceeded target indoor air concentrations. This study exploits matched data on subsurface soil gases and indoor air that came from the “Sensitive Establishments” campaign. It aims to consolidate and refine the use of attenuation factors as a function of environmental variables acquired routinely during environmental assessments. We have been able to select the measured environmental variables that have the most influence on vapor intrusion using Principal Components Analysis and hypotheses tests. Since the collected data are mainly related to weak sources (only 15% schools required risk management measures related to vapor intrusion), halogenated volatile organic compounds (HVOC) were selected as tracer compounds for vapor intrusion for this study. This choice enables the exclusion or minimization of background sources contributions. From the results we have calculated the descriptive statistics of the attenuation factors distribution for the subslab-to-indoor air pathway and refined the attenuation factors for this pathway through an easily obtained parameter, building age. Qualitative comparison of attenuation factors according to the building age shows that attenuation factors observed for building less than 50 years are lower than attenuation factors for buildings 50 years old and above. These results show the utility of creating databases for consolidating and refining attenuation factors and therefore improving their use. [ABSTRACT FROM AUTHOR]

Copyright of Research of Environmental Sciences is the property of Research of Environmental Sciences Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, we introduce a screening method for the evaluation of the natural attenuation rates in the subsurface at sites contaminated by petroleum hydrocarbons. The method is based on the combination of the data obtained from standard source characterization with dynamic flux chambers measurements. The natural attenuation rates are calculated as difference between the flux of contaminants estimated with a non-reactive diffusive model starting from the concentrations of the contaminants detected in the source (soil and/or groundwater) and the effective emission rate of the contaminants measured using dynamic flux chambers installed at ground level. The reliability of this approach was tested in a contaminated site characterized by the presence of BTEX in soil and groundwater. Namely, the BTEX emission rates from the subsurface were measured in 4 seasonal campaigns using dynamic flux chambers installed in 14 sampling points. The comparison of measured fluxes with those predicted using a non-reactive diffusive model, starting from the source concentrations, showed that, in line with other recent studies, the modelling approach can overestimate the expected outdoor concentration of petroleum hydrocarbons even up to 4 orders of magnitude. On the other hand, by coupling the measured data with the fluxes estimated with the diffusive non-reactive model, it was possible to perform a mass balance to evaluate the natural attenuation loss rates of petroleum hydrocarbons during the migration from the source to ground level. Based on this comparison, the estimated BTEX loss rates in the test site were up to almost 0.5 kg/year/m 2 . These rates are in line with the values reported in the recent literature for natural source zone depletion. In short, the method presented in this work can represent an easy-to-use and cost-effective option that can provide a further line of evidence of natural attenuation rates expected at contaminated sites. [ABSTRACT FROM AUTHOR]

In this paper, we are treating the results of radon concentration in soil gas, which are obtained by a detailed study carried out during 2000-2005 years in the urban area of Tirana, Capital City of Albania. The field measurements were done by using Luk-4 equipment (Lucas method) and based on technique [12, 18-20, 21-24]. Based on the analysis of the data taken by this research, was concluded that the level of the radon concentration in soil gas of Tirana urban area depends on the soil type. The highest level of radon gas (130.0 kBqm-3) was observed in inorganic clays and very fine sands with beige-red color (soils type 1), which is extended on the second terrace of Tirana River. This paper gives conclusions of soil gas radon concentration, where its value ranges from 0.9-1.54 kBqm-3 up to 92.03-130.0 kBqm-3. The results indicate that more than 50% of Tirana urban area is made of soils, which are characterized by high soil radon gas concentration, which constitutes a real risk for the Tirana's residents. [ABSTRACT FROM AUTHOR]

Soil-gas radon concentrations and exhalation rates have generally been observed to be anomalously high along active faults in many parts of the world. The soil-gas method is based on the principle that faults and fractures in rocks are highly permeable pathways along which gases can migrate upward from deep crust and mantle to soil cover, retaining their source signatures. The present study summarizes the influence of fault zones on anomalous radon concentrations in soil by integrated geophysical and geo-structural analyses in three study areas of Central-Northern Calabria (Southern Italy). Soil-gas radon surveys have been carried out by means of an alpha scintillation counting system, at 12,509 locations between 2002 and 2004. A geostatistical approach has been used to estimate the spatial distribution of soil radon concentrations. Relations among soil-gas distribution and geo-structural features have been evaluated by ordinary multi-Gaussian kriging. Highest soil radon concentrations (ca. 90 kBq m−3) have been measured in the Rossanese sector. In the three study areas, no appreciable differences can be noticed among lithotypes, with the highest concentration values (ca. 89 kBq m−3) measured in alluvial deposit and in clay. Measurements of soil-gas radon reveal anomalies clearly connected to the tectonic structures. Increased signals are linearly distributed along regional WNW-ESE trending shear zones, with main pathways of concentration also recognizable along the E-W fault system in the Rossanese sector, the N-S fault system in the Crati Graben and the Catanzaro Trough, and the NE-SW fault system in the Catanzaro Trough. The distribution of epicentres of historical earthquakes occurred between 1184 and 2001 confirms the recent activity of the same fault systems. Soil-gas radon concentrations generally increase, as expected, with decreasing distance to the faults. [ABSTRACT FROM AUTHOR]

The Anninghe fault (ANHF) and the Zemuhe fault (ZMHF) with left-lateral strike-slip, located along the eastern boundary of the Sichuan-Yunnan block (southwestern of China), are some of the most active faults. These faults mainly control the seismicity of southwestern area of China. Measurement of soil gas radon (Rn) emitted from fault along the ANHF and the ZMHF has been carried out for the research of tectonic activity. We obtained the Rn concentrations at 394 sampling points along 15 profiles across the ANHF and the ZMHF in 2016. The measurement results show that the values of Rn in the ANHF are significantly higher than that in the ZMHF. The relative coefficient K Q of Rn activity attained in profiles of the ANHF ranges from 3.3 to 9.1, which are obviously higher than that of 2.1–2.5 in profiles of the ZMHF. The radon flow brings up the deeper and radon-richer gas upward through the high-level cracked strata caused by the tectonic activity accounts for the anomalously high values attained. The spatial variation of Rn in the concentration profile and the relative coefficient K Q calculated indicate that the tectonic activity of the south segment of the ANHF is significantly higher than that of the north segment of the ZMHF. [ABSTRACT FROM AUTHOR]

The entry of soil gas pollutants into buildings has been the subject of many studies and some analytical airflow models have been developed to estimate this entry into buildings. The existing airflow models do not include the sub-slab gravel layer that can influence significantly the airflow from soil into buildings. In this paper, an analytical airflow model, which considers this sub-slab gravel layer has been developed. Moreover, a 2D finite-element model has been used for numerical comparison. This comparison gave a satisfactory agreement with the analytical model. The airflow model is presented as flow-pressure equation and can be integrated easily in vapour intrusion models or ventilation models to enable the quantification of the impact of these pollutants on indoor air quality. [ABSTRACT FROM AUTHOR]

Copyright of Research of Environmental Sciences is the property of Research of Environmental Sciences Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A sampling method for determining vapour concentrations of chlorinated contaminants, specifically trichloroethene (TCE), present in the vadose zone has been developed, and was applied at the Tucson International Airport Area Superfund site. The method, modified from the National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods # 1022 for ambient-air sampling of TCE, is targeted to situations requiring costeffective sample collection, particularly for cases in which concentrations are at or below maximum contaminant. In our method, TCE vapour is sampled using a solid-sorbent tube. Gas chromatography with mass spectrometry is used to confirm and quantify the presence of TCE. The results of laboratory tests demonstrate a maximum TCE vapour load of ~22 mg before breakthrough to the secondary sorbent-tube section, and an extraction efficiency of ~97%. The results of a performance comparison test conducted in the field show that concentrations obtained with the sorbent tube samplers (~5 µg/L) are similar to those obtained with the use of standard summa canisters (~3 µg/L). The quantitative detection limit for the new method was 0.03 µg/L under the operative conditions, a significant improvement on current analytical methods. The results indicate that use of the sorbent-tube method will be effective for vapour sample collection at sites contaminated with volatile organic compounds, particularly in characterising low concentrations for applications such as assessing groundwater contamination risk and the need for remedial action via soil vapour extraction or other methods. [ABSTRACT FROM AUTHOR]

Val d'Agri is a seismically active intermontane basin in southern Italy known for hosting the largest on-shore hydrocarbon reservoir in western Europe. Despite extensive study of the basin, important questions remain regarding fluid circulation and the possible link between deep hydrocarbon reservoirs, faults, natural and induced seismicity, and gas migration towards the surface. To address some of these issues we performed near-surface gas geochemistry and structural geology surveys throughout the basin at both the regional and local scale. While carbon dioxide data are due to shallow, biological processes in the soil, anomalous results for other gas species are interpreted as being linked to structural discontinuities. Coincident methane and ethane anomalies, which imply a deep thermogenic origin, occur primarily in the northern part of the Val d'Agri basin. The most dominant alignment of these gases starts from a surface hydrocarbon seep and extends above a buried, NE-SW-striking fault that transects the valley. In contrast, radon anomalies are localized in the southern part of the basin along the western border, in correspondence with the Monti della Maddalena Fault System (MMFS) and a cluster of background natural seismicity. The origin and implications of the observed anomalies are discussed. • Gas geochemistry / structural surveys were performed at Val d'Agri, host of Europe's largest onshore hydrocarbon reservoir. • Coincident methane and ethane anomalies along known / inferred faults imply upward migration of reservoir hydrocarbons. • hydrocarbon gas alignment above buried fault shows possible link between exploited reservoirs on either side of the valley. • The correlation between radon anomalies and recent low-level seismicity implies fracture enhanced emanation. [ABSTRACT FROM AUTHOR]

Intercomparison exercises of radon instruments play an important part when it comes to domestic survey as well as international or national mapping in dwellings, soil or water. Therefore, it is of prime interest to improve and standardize technical methods of measurement and also to verify quality assurance through comparison between different instruments and techniques. In the present paper is described the latest intercomparison exercise performed between the Laboratory of Environmental Radioactivity (hereafter called LER) of our department and other 15 different teams around Europe. The test has been held at two radon reference sites located 60 km SW of Prague, Czech Republic.

In this paper, we study (1) the spatial anomalies and (2) the temporal anomalies of soil gas in northern Taiwan. The spatial anomalies of soil gas are related to tectonic faults, while the temporal anomalies of soil gas are associated with pre-earthquake activities. Detailed soil gas sampling was systematically performed, and the analysis of the collected gas species shows that high helium and nitrogen concentrations appear in samples from specific sites, which coincide with the structural setting of the area studied. This analysis indicates the possibility of using these soil gases to determine fault zones in the studied area. Based on the soil gas data, a station (Tapingti) for automatic soil gas monitoring was constructed on an appropriate site at the fault zone. Some anomalous high radon concentrations at certain times can be identified from the dataset, which was generated by the continuous monitoring of soil gas for over a year. Notably, many of these anomalies were observed several hours to a few days before the earthquakes (M L > 3) that occurred in northern Taiwan. By combining the information of epicenters and fault plane solutions of these earthquakes, we find that the shallow earthquakes (<15 km) were mainly strike-slip and normal-type earthquakes, and concentrated within a distance of 30 km to the monitoring site (Group A). The deep earthquakes (>20 km) were mainly thrust-type earthquakes and distributed in greater distances (>45 km) east of the monitoring site (Group B). Such focal mechanisms of earthquakes suggest an extensional and compressional structural domain in the continental crust for Group A and Group B earthquakes, respectively. It is suggested that the pre-earthquake activities associated with the seismicity of Group B may be transmitted along the major decollement in the region below the Tapingti station, leading to the observed soil gas enhancements. [ABSTRACT FROM AUTHOR]

The objective of this paper is to determine the reasons, origin and character of periodical changes of methane and carbon dioxide concentrations in the near-surface zone as well as emission of these gases to atmosphere after closing bituminous coal and anthracite mines in the former Wałbrzych Coal District (SW Poland). The measurements were performed during the period including the active impact of “water piston effect” on the migration of a coal-bearing gases as well as the period of stabilization of water table of the Pennsylvanian aquifer. In the years 1997–2005, 20 sampling sessions were completed during which 3210 soil gas samples were collected at a depth of about 1.2 m and along 4 measurement lines located in the Gorce and the Sobięcin depressions. Maximum methane and carbon dioxide concentrations measured in soil gas samples reached 32.4 and 15.7 vol%, respectively. Isotopic study shows that coal-bed gases, recent microbial methane, and multigenetic carbon dioxide from degassing of ground-waters of the Upper Pennsylvanian aquifer occur within the near-surface zone of the Wałbrzych Coal District. Within the Serpukhovian Wałbrzych and Upper Bashkirian-Moscovian Žacleř coal-bearing formations three genetic types of coal-bed gases occur: Variscan thermogenic (methane, higher gaseous hydrocarbons and carbon dioxide), endogenic (abiogenic) carbon dioxide and “late” (Late Cretaceous) and recent microbial methane and carbon dioxide. Changes of mean concentrations of methane and carbon dioxide in the near-surface zone recorded during years of studies demonstrated the influence of “water piston effect”, which drives migration of coalbed gases towards the earth surface. In both the Gorce and the Sobięcin depressions, gas migrates with various intensity. Generally, the lower methane emission measured in the years 2004–2005, and compared with the period 1999–2000, resulted from the stabilization of groundwater table whereas higher carbon dioxide emission confirms the degassing of shallow groundwaters. Anomalous concentrations of methane and carbon dioxide were related to numerous faults and fracture systems cutting the steeply dipping Upper Mississippian and Pennsylvanian coal-bearing formations, and to the outcrops of these rocks. However, in the near-surface zone, multiproportional mixing of coal-bed gases, recent microbial methane and carbon dioxide is observed. Periodical changes of stable carbon isotope composition of methane and carbon dioxide of near-surface zone in particular sessions are caused by the time-related change of location of water table of Pennsylvanian aquifer in the complicated structure of the Gorce and Sobięcin depressions. Persistently anomalous concentrations of methane and carbon dioxide in the near surface zone, still observed after several-years-long stabilization of groundwater table, seem to indicate a continuous supply of coalbed gases to the near-surface zone through pervious dislocations. Such an interpretation is confirmed by the extreme value of methane emission detected at a particular sampling site after the cessation of the “water piston” effect. It was presumably caused by the secondary intensification of gas flux from deep sources, triggered by neotectonic movements in the study area. [ABSTRACT FROM AUTHOR]

Representative sampling is of great importance to decision making regarding contaminant site risks and remedial effectiveness. A focus here is whether existing groundwater monitoring wells screened across the water table can be sampled to yield representative indicators of soil gas composition. For the first time, we provide multi-phase, multi-component computational simulations to address this. We simulated high and low gas extractions rate strategies to sample the gas phase over short and extended screening intervals across the water table. We investigated the options against a field data set representative of typical hydrocarbon vapour profiles, inclusive of major gases, oxygen and carbon dioxide. We also evaluated the sampling options for uniform and non-uniform multi-component gasoline LNAPL distributions, including hazardous chemicals. Less sensitivity to the sampling option was observed for depth-wise increasing concentration profiles with a near-constant concentration across the screen. Significant discrepancy between the ratio of different compounds in the sample and in-situ (real) values was observed for high-rate gas extraction (particularly for an extended-screen). Low-rate gas extraction provided satisfactory results for all the scenarios. Shorter screening slightly improved the accuracy of this option. Graphical representations are provided to allow assessment of the applicability of each sampling option for various site conditions. [ABSTRACT FROM AUTHOR]

This study presents the preliminary results of 222Rn (radon) and 220Rn (thoron) concentrations that were measured in the soils developed on igneous rocks including mafic (pillow lavas, basalts and melaphyre) and acid (keratophyre, rhyolite and rhyolitic tuff) rocks at ten locations in the Kaczawa Mountains (SW Poland). The measurements were carried out at sampling depths of 10, 40 and 80 cm using a RAD7 portable radon system. The highest concentrations of radon (222Rn) were mainly observed in the soils overlaying acid igneous rocks. The highest value of 11 kBq m-3 was obtained at a depth of 10 cm for soils overlaying melaphyre. At depths of 40 and 80 cm, the averages of 222Rn concentrations showed the same values of 3.6 kBq m-3 for all of the soils investigated. The highest concentrations of thoron (220Rn) were observed in soils overlaying acid igneous rocks, i.e. the value of 49 kBq m-3 at a depth of 40 cm for soils overlaying rhyolitic tuff. In the soils developed on basalts, the average concentrations of 222Rn increased with the sampling depth, whereas the average concentrations of thoron (220Rn) decreased with increasing sampling depth. Positive correlations were found between 232Th activity in the parent rocks and soil gas 220Rn concentrations at all of the sampling depths, whereas a positive correlation between soil gas 222Rn and the 238U activity concentration in the parent rocks was only found at a depth of 40 cm. [ABSTRACT FROM AUTHOR]