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The urgency of protecting ecosystems and their recovery from contamination has been highlighted in several recent European strategies because Europe's biodiversity and landscapes are declining rapidly due to different human pressures. Despite the existence of EU and national laws addressing environmental contamination, practical procedures are often missing. For example, competent authorities must deal promptly and effectively with environmental accidents, noncompliance, and criminal offenses but relevant tools that facilitate these processes are often lacking. For example, thorough planning is crucial for effective investigation and assessment to improve environmental damage assessments in line with the European Environmental Liability Directive (ELD, 2004/35/EC). With regard to soils, a specific European legislation for their protection, the European Soil Monitoring Law, is currently being developed. However, it is crucial that this law bridges the gaps between existing chemical regulations and that it aligns with current European strategies for environmental protection and sustainability. Continuous feedback of soil monitoring results to regulatory frameworks will be essential. This feedback loop ensures that chemical regulations are relevant and effective in protecting soil health. In this context, development and sharing of effective and practical procedures for recovering ecosystems from contamination are crucial. This was the case at the RemTech Europe meeting, which was held online and onsite in Ferrara, Italy, in September 2022. The discussion covered all aspects of environmental contaminants. It ranged from the basic understanding of these contaminants to the various types that pose a threat to organisms, studies of their environmental fate, detection methods, and sustainable practices for contaminant management. The special series dedicated to RemTech Europe 2022 is particularly relevant to these purposes and resulted in six articles that were selected from oral presentations. The articles emphasize the need for integrated approaches to risk management and remediation to address the problems of soil, sediment, and groundwater contamination. Integr Environ Assess Manag 2024;20:1982–1986. © 2024 The Author(s). Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: The RemTech Europe community is an important forum for discussing best practices, experiences, scientific and technological research results, and methodological approaches.A special emphasis is placed on phytoremediation as an inexpensive and environmentally friendly tool for recovering contaminated soils, as applied using conceptual models.Practical guidelines and operating procedures to monitor the environmental impact of human activities are reported here to guide the recovery of polluted sites.The European experience in recovering from contamination can help other countries, in addition to learning from past mistakes. [ABSTRACT FROM AUTHOR]

The study of the variability of soil gas concentrations is crucial for defining effective monitoring and remediation strategies and for the risk assessment related to the emission of vapors from the subsurface. The traditional soil gas monitoring strategy consists of seasonal surveys based on short‐time‐averaged sampling. Soil gas monitoring results are often used to assess the risk associated with the emission of volatile contaminants from the subsurface, using models mainly based on molecular diffusion and therefore assuming continuous emission from the soil. At two contaminated sites located in the Veneto region (Italy), continuous monitoring using a photoionization detector, pressure gauges, and an ultrasonic anemometer was used to relate soil gas variability to surface and subsurface physical parameters. At both sites a cyclic diurnal variation of volatile organic compounds concentration in soil gas was observed, correlated with the variation of several meteorological parameters and in particular with the variation of the differential pressure between soil and atmosphere and the buoyancy vertical flux. These findings question the reliability of the conventional methodology employed in the collection and assessment of soil gas data. Integr Environ Assess Manag 2024;20:2023–2032. © 2024 SETAC Key Points: Continuous monitoring at the two study sites showed that the cyclic variation of VOC concentration in soil gas correlated with the variation of differential pressure and buoyancy vertical flux.As evidenced by the differential pressure measurements conducted in this study, there is an alternation of nonemission phases, and phases in which the soil gas emission from soil to atmosphere may be enhanced due to pressure‐driven advective fluxes.The findings raise questions about the reliability of the conventional methodology employed in the collection and assessment of soil gas data. [ABSTRACT FROM AUTHOR]

A key challenge in helium (He) exploration is determining the efficacy of surficial soil gas surveys. While soil gas surveys can detect helium, the mechanisms leading to these signals are often poorly understood, hindering reliable interpretation for exploration purposes. Here we present the results of seven new He soil gas surveys (n = 1974) at the Akah Nez Field, Beautiful Mountain Field, Porcupine Dome area, Rattlesnake Field, Tom area, Tohache Wash area, and White Rock area, on the Colorado Plateau, Four Corners area, United States. Utilizing 2D seismic, well logs, and geophysical potential field data, structural maps were constructed of potential He reservoirs at depth and relationships were examined. Given geospatial relationships are being examined using the soil gas survey data, it is important to understand the mechanism that allows subsurface He to migrate upwards into the soil. In several fields interpreted basement faults act as migration conduits from the basement to the surface (i.e., leaky reservoir seals), and in other cases there is evidence for reservoir flank/crest fracturing likely due to differential compaction. Based on the regional geologic history, advective systems are likely responsible for the observed He soil gas signatures. Additionally, based on the Tohache Wash data (most prospective He area) an effective and risk-reducing novel technique is presented that constructs a predictive He exploration model utilizing soil gas geochemistry, high-resolution geophysical data, well data and seismic data using Bayesian ANOVA techniques, which may be translated to areas outside of the Four Corners area, United States. [ABSTRACT FROM AUTHOR]

Soil autotoxic chemosensory substances have emerged as the predominant environmental factors constraining the growth, quality, and yield of Codonopsis pilosula in recent years. Among a vast array of chemosensory substances, benzoic acid constitutes the principal chemosensory substance in the successive cultivation of C. pilosula. However, the exploration regarding the stress exerted by benzoic acid on the growth and development of C. pilosula remains indistinct, and there is a scarcity of research on the mechanism of lobetyolin synthesis in C. pilosula. In the current research, it was discovered that exposure to benzoic acid at a concentration of 200 mmol/L conspicuously attenuated the plant height, root length, total length, fresh weight, root weight, root thickness, chlorophyll content, electrolyte osmolality, leaf intercellular CO2 concentration (Ci), net photosynthesis rate (Pn), transpiration rate (Tr), and leaf stomatal conductance (Gs) of C. pilosula. Benzoic acid (200 mmol/L) significantly enhanced the activity of root enzymes, including superoxide dismutase (SOD), malondialdehyde (MDA), and peroxidase (POD), as well as the accumulation of polysaccharides and lobetyolins (polyacetylene glycosides) in the roots of C. pilosula. In this study, 58,563 genes were assembled, and 7946 differentially expressed genes were discovered, including 4068 upregulated genes and 3878 downregulated genes. The outcomes of the histological examination demonstrated that benzoic acid stress augmented the upregulation of genes encoding key enzymes implicated in the citric acid cycle, fatty acid metabolism, as well as starch and sucrose metabolic pathways. The results of this investigation indicated that a moderate amount of benzoic acid could enhance the content of lobetyolin in C. pilosula and upregulate the expression of key coding genes within the signaling cascade to improve the resilience of C. pilosula lobetyolin against benzoic acid stress; this furnished a novel perspective for the study of C. pilosula lobetyolin as a potential substance for alleviating benzoic acid-induced stress. [ABSTRACT FROM AUTHOR]

Agricultural intensification has increased the consumption of inputs, mainly fertilizers, which may increase emissions of greenhouse gases (GHG). The improvement of our knowledge on GHG dynamics in the soil is mandatory to optimize the use of fertilizers and reduce environmental impacts. We developed an electronic sensor prototype based on Arduino to monitor concentrations of carbon dioxide (CO2), ethylene (C2H4), ammonia (NH3), and nitrogen oxides (N2O/NOx) in the soil air in a greenhouse experiment with soybean (Glycine max L.) under two treatments: single inoculation (Bradyrhizobium spp.) or triple co-inoculation (Bradyrhizobium spp. Azospirillum brasilense and Pseudomonas fluorescens) in a completely randomized design. One-way analysis of variance, as well as correlation between plant traits at 35 days of emergence and the average daily concentration of gases in the soil air were performed. Although not affecting plant growth or yield-related traits, co-inoculation increased CO2, while decreased NOx concentrations compared with single inoculation, whereas C2H4 emission changed with the plant growth stage. Although co-inoculation increased respiration, decreased N losses by denitrification, mitigating the total emissions of GHG. The prototype showed to be efficient for monitoring GHG across the experiment at a low cost and easy use, contributing for monitoring GHG concentrations in the soil air. [ABSTRACT FROM AUTHOR]

In this review article, the main techniques for spectroscopic studies of gases in field conditions are considered. The issues related to the study of gas emissions from soils and the determination of their concentrations are analysed. The main types of spectroscopy used in portable devices for soil gas analysis, along with their design features and sampling approaches, are provided. Various studies aimed at optimising the operation of devices for analysing gases emitted from the soil, taking into account agronomic, agrochemical, and ecological specifics, are also presented. The effect of using different types of lasers and reflecting elements on the accuracy of optical measurements and the sensitivity to various substances in the gases is analysed. [ABSTRACT FROM AUTHOR]

We measured dark CO2 fluxes and CH4 emissions from two naturally vegetated ecosystems of the Mezquital Valley irrigated with wastewater from Mexico City. The ecosystems were characterized by high groundwater levels; the vegetation was represented mainly by saltgrass in the first plot and chairmaker's bulrush in the second. A dark chamber technique was used for the study from August 2008 to June 2009. For the two studied plots, mean values (mean ± SE) for dark ecosystem CO2 fluxes (Rtot), soil CO2 emission (Rsoil), and heterotrophic respiration (Rhet) were 26 ± 5, 14 ± 3 and 12 ± 3 mg C m–2 h–1, respectively, The annual cumulative fluxes Rtot, Rsoil and Rhet equal to 234, 127 and 103 g C m–2 y–1, respectively. The contribution of Rsoil to Rtot, and Rhet to Rsoil varied significantly over the study period, with no clear relationship to seasonal dynamics. The observed low CO2 fluxes may be due to soil salinization resulting from wastewater flooding. The fluxes of CH4 were observed in the flooded plot, with peaks up to 370 µg C m–2 h–1. The fluxes of CH4 were significantly higher when plants were present in the measurement chamber than when there were no plants, confirming the important role of plant cover in CH4 transport. Unlike CH4 fluxes, CO2 fluxes show seasonal dynamics, mainly due to their strong dependence on temperature. The observed results may be useful for properly estimating the global C budget and the contribution of saline soils to C fluxes. [ABSTRACT FROM AUTHOR]

The magnitude and spatial variability of CO2 surface emissions and processes involving CO2 released to the atmosphere from the soils are relevant issues in the context of climate change. This work evaluated CO2 fluxes and 13C/12C ratio of vegetation, organic matter, and soil gases from no disturbed soils of Chaco Pampean Plain (Argentina) with different soil properties and environmental conditions (PL and PA units). Soil organic decomposition from individual layers was accompanied by δ13C of total organic carbon (δ13C-TOC) values more enriched to depth. δ13C-TOC values in the upper soil profile ~ ca. 0–15 cm were like the plant community of this area (~−33 to −29 ‰) while δ13C-TOC varied stronger bellow horizon A, till ~ −24‰. Both δ13C-TOC and soil δ13C-CO2 were similar (~ −24 to 26 ‰) at deeper horizons (~ 50–60 cm). Toward the superficial layers, δ13C-TOC and δ13C-CO2 showed more differences (till ~ 4 ‰), due influence of the diffusion process. Horizon A layer (~ 0–20 cm) from both PL and PA units contained the most enriched δ13C-CO2 values (~ −15–17 ‰) because atmospheric CO2 permeated the soil air. A simple two-component mixing model between sources (atmospheric δ13C-CO2 and soil CO2) confirmed that process. Isotopically, CO2 fluxes reflected the biodegradation of C3 plants (source), diffusive transport, and CO2 exchange (atmosphere/soil). Soil moisture content appeared as a determining factor in the diffusion process and the magnitude of CO2 surface emissions (12–60 g·m−2·d−1). That condition was confirmed by CO2 diffusion coefficients estimated by air-filled porosity parameters and soil radon gradient model. [ABSTRACT FROM AUTHOR]

Soil CO2 concentration and flux measurements are important in diverse fields, including geoscience, climate science, soil ecology, and agriculture. However, practitioners in these fields face difficulties with existing soil CO2 gas probes, which have had problems with high costs and frequent failures when deployed. Confronted with a recent research project's need for long-term in-soil CO2 monitoring at a large number of sites in harsh environmental conditions, we developed our own CO2 logging system to reduce expense and avoid the expected failures of commercial instruments. Our newly developed soil probes overcome the central challenge of soil gas probes—surviving continuous exposure to soil moisture while remaining open to soil gases—via three approaches: a 3D printed housing (economical for small-scale production) following design principles that correct the usual water permeability flaw of 3D printed materials; passive moisture protection via a hydrophobic, CO2-permeable PTFE membrane; and active moisture protection via a low-power micro-dehumidifier. Our CO2 instrumentation performed well and yielded a high-quality dataset that includes signals related to a prescribed fire as well as seasonal and diel cycles. We expect our technology to support underground CO2 monitoring in fields where it is already practiced and stimulate its expansion into diverse new fields. [ABSTRACT FROM AUTHOR]

Gas exchange in the soil is determined by the size and connectivity of air‐filled pores. Root mucilage reduces air‐filled pore connectivity and thus gas diffusivity. It is unclear to what extent mucilage affects soil pore connectivity and tortuosity. The aim of this study was to gain a better understanding of gas diffusion processes in the rhizosphere by explaining the geometric alterations of the soil pore space induced by mucilage. We quantified the effect of a root mucilage analogue collected from chia seeds without intrinsic respiratory activity on oxygen diffusion at different water contents during drying–rewetting cycles in a diffusion chamber experiment. Quantification of oxygen diffusion showed that mucilage decreased the gas diffusion coefficient in dry soil without affecting air‐filled porosity. Without mucilage, a hysteresis in gas diffusion coefficient during a drying–rewetting cycle was observed. The effect depended on particle size and diminished with increasing mucilage content. X‐ray computed tomography imaging indicated a hysteresis in the connectivity of the gas phase during a drying–rewetting cycle for samples without mucilage. This effect was attenuated with increasing mucilage content. Furthermore, electron microscopy showed that mucilage structures formed in drying soil increase with mucilage content, thereby progressively reducing the connectivity of the gas phase. In conclusion, the effect of mucilage on soil gas diffusion highly depends on soil texture and mucilage content. The diminishing hysteresis with the addition of mucilage suggests that plant roots secrete mucilage to balance oxygen availability and water content, even under fluctuating moisture conditions. [ABSTRACT FROM AUTHOR]

Climate change and aridification have increased the risk of salinization and organic carbon loss in dryland soils. Enrichment using biochar and organic fertilizers has the potential to reduce salt toxicity and soil carbon loss. However, the effects of biochar and organic fertilizers on CO2 and CH4 emissions from saline soils in dryland areas, as well as their microbial mechanisms, remain unelucidated. To clarify these issues, we performed a 5-month incubation experiment on typical soda-type saline soil from the western part of the Songnen Plain using five treatments: control treatment (CK), 5% urea (U), straw + 5% urea (SU), straw + 5% urea + microbial agent (SUH), and straw + 5% urea + biochar (SUB). Compared with the SU treatment, the SUH and SUB treatments reduced cumulative CO2 emissions by 14.85% and 35.19%, respectively. The addition of a microbiological agent to the SU treatment reduced the cumulative CH4 emissions by 19.55%, whereas the addition of biochar to the SU treatment increased the cumulative CH4 emissions by 4.12%. These additions also increased the relative abundances of Proteobacteria, Planctomycetes, and Ascomycota. Overall, the addition of biochar and organic fertilizer promoted CO2 emissions and CH4 uptake. This was mainly attributed to an improved soil gas diffusion rate due to the addition of organic materials and enhanced microbial stress due to soil salinity and alkalinity from the release of alkaline substances under closed-culture conditions. Our findings have positive implications for enhancing carbon storage in saline soils in arid regions. [ABSTRACT FROM AUTHOR]

The grassland biome is an important sink for atmospheric methane (CH4), a major greenhouse gas. There is considerable uncertainty in the grassland CH4 sink capacity due to diverse environmental gradients in which grasslands occur, and many environmental conditions can affect abiotic (e.g., CH4 diffusivity into soils) and biotic (e.g., methanotrophy) factors that determine spatial and temporal CH4 dynamics. We investigated the relative importance of a soil's gas diffusivity versus net methanotroph activity in 22 field plots in seven sites distributed across the US Great Plains by making approximately biweekly measures during the growing seasons over 3 years. We quantified net methanotroph activity and diffusivity by using an approach combining a gas tracer, chamber headspace measurements, and a mathematical model. At each plot, we also measured environmental characteristics, including water‐filled pore space (WFPS), soil temperature, and inorganic nitrogen contents, and examined the relative importance of these for controlling diffusivity and net methanotroph activity. At most of the plots across the seven sites, CH4 uptake rates were consistently greatest when WFPS was intermediate at the plot level. Our results show that variation in net methanotroph activity was more important than diffusivity in explaining temporal variations in net CH4 uptake, but the two factors were equally important for driving spatial variation across the seven sites. WFPS was a significant predictor for diffusivity only in plots with sandy soils. WFPS was the most important control on net methanotroph activity, with net methanotroph activity showing a parabolic response to WFPS (concave down), and the shape of this response differed significantly among sites. Moreover, we found that the WFPS level at peak net methanotroph activity was strongly correlated with the mean annual precipitation of the site. These results suggest that the local precipitation regime determines unique sensitivity of CH4 uptake rates to soil moisture. Our findings indicate that grassland CH4 uptake may be predicted using local soil water conditions. More variable soil moisture, potentially induced through predicted future extremes of rainfall and drought, could reduce grassland CH4 sink capacity in the future. [ABSTRACT FROM AUTHOR]

All humans are exposed to radon, the primary source of natural radiation, which can harm people due to natural processes rather than human activity. Thus, it is of significant importance to determine the levels of radon in indoor, soil gas, water, and outdoors. Radon concentration (CRn) was measured in Kiraz district, İzmir, and the correlation between the indoor and soil gas CRn values was investigated. The indoor CRn values measured in 40 randomly selected dwellings in Kiraz exhibited a wide range from 19.50 ± 2.50 to 204.70 ± 8.00 Bq m−3 with an average value of 61.11 ± 4.23 Bq m−3. The measured indoor CRn values were compared to the reference levels in the world to help control radon in the dwellings. Indoor CRn values were lower than the ICRP reference level of 300 Bq m−3 in all of the dwellings studied. Furthermore, in 34 dwellings (representing 85% of the total number of dwellings studied), indoor CRn values were lower than the WHO reference level of 100 Bq m−3. Health hazard indices, namely annual effective dose (AED) and excess lifetime cancer risk (ELCR), were also calculated for each dwelling and compared with internationally acceptable levels to estimate the risk to human health. The AED values varied from 0.49 ± 0.06 to 5.16 ± 0.20 mSv y−1 with an average value of 1.54 ± 0.11 mSv y−1, which exceeds the world average of 1.15 mSv y−1 as reported by UNSCEAR. The ELCR values ranged from 2.05 ± 0.26 × 10−3 to 21.55 ± 0.84 × 10−3 with an average value of 6.43 ± 0.44 × 10−3, exceeding the world average of 0.29 × 10−3 as reported by UNSCEAR. The soil gas CRn values measured exhibited a wide variation ranging from 129.25 ± 6.38 Bq m−3 to 6172.64 ± 44.06 Bq m−3 with an average value of 1291.79 ± 18.70 Bq m−3. The soil gas CRn values were less than 10,000 Bq m−3; hence, the research area is categorized as "low radon risk areas" according to Sweden Criteria, and so no special constructions are required in the studied area. When soil gas CRn values were compared to indoor CRn values, no linear relationship was found between the CRn values. However, a strong positive linear correlation was found between indoor and soil gas CRn values less than 200 Bq m−3 and 2500 Bq m−3, respectively. [ABSTRACT FROM AUTHOR]

CO2 flux measurements and soil gas samples were collected to determine the origin and distribution characteristics of soil gas discharged at Andeok area, Jeju, South Korea. Additionally, this study aims to discuss agricultural activities that may contribute to increased soil CO2 emissions. CO2 flux was measured at 127 points, while soil gas sampling for gas components and carbon-13 (δ13CCO2) analysis was performed at 56 points. The measured CO2 fluxes in the study area ranged from 0.8 to 83.8 g/m2/d (mean: 14.3 g/m2/d), which was lower than CO2 fluxes observed in areas with geogenic CO2 discharge (e.g., near active volcanoes, faults, and CO2-rich water sources). The soil gas analysis revealed that the CO2 concentration and δ13CCO2 ranged from 491 to 23,722 ppmv (mean: 3,205 ppmv) and from −25.2 to −10.7‰ (mean: −19.4‰), respectively. In the cumulative probability diagram, the threshold values for CO2 flux and soil CO2 concentration were 41.3 g/m2/d and 6,693 ppmv, respectively. Samples exceeding the CO2 flux threshold were affected by urea fertilizer application based on land use nearby, and did not overlay with samples exceeding the soil CO2 threshold, indicating different transport mechanisms. Results from a detailed survey near a soil gas sampling location close to high soil CO2 showed that soil CO2 concentrations increased with depth, especially during summer when atmospheric temperatures increased. Spatially, higher soil CO2 concentrations were observed in areas with accumulated plant debris from tangerine orchards. The δ13CCO2 and relationships among CO2-O2, N2-CO2, and N2/O2-CO2 indicated that all collected samples had a biogenic origin. Although geogenic soil gases were not observed in this study, our findings are useful for future research on Jeju Island, as they provide baseline values for distinguishing geogenic soil gas from those with natural and agricultural origins. Moreover, this result provides insights into agricultural activities such as urea fertilization and plowing and their contribution to soil CO2 increase, and inspires future research on negative soil CO2 flux. [ABSTRACT FROM AUTHOR]

Radon (Rn) and helium (He) gases from uranium decay form distinct anomalies related to buried uranium deposits. In order to trace the geochemical anomalous sources from the volcanic-related uranium deposits in deeply buried areas, systematical Rn contents and He isotope ratios were analyzed from the Daguanchang uranium deposit. The soil gas Rn concentrations above the deep uranium are ten times higher than those in barren areas, indicating that instantaneous Rn content measurements can be used to detect deeply buried uranium. The helium isotope ratios (3He/4He) of the unmineralized samples from the mineralized drill hole (ZK1) are relatively lower and uniform compared to those of the samples from no-mineral drill hole (ZK2). However, the Th and U contents of the drill core samples from ZK1 are slightly lower than those of the samples from ZK2, indicating that the lower 3He/4He ratios in ZK1 are most likely due to the addition of 4He from underlying uranium intervals. The differences in the instantaneous Rn contents are consistent with the variations in the He isotope ratios of the drill core samples. These results demonstrate that soil gas Rn and 3He/4He ratios are useful tracers and can indicate the existence of deeply buried volcanic-related hydrothermal uranium ores. [ABSTRACT FROM AUTHOR]

Effective management of surface emissions from abandoned gob methane (AGM) is crucial for mitigating greenhouse gas emissions and ensuring public safety. An important geochemical characteristic of near-surface AGM migration is the potential presence of abnormal component concentrations in near-surface soil gas over abandoned coal gobs. To investigate this phenomenon, a surface geochemical survey was conducted based on four survey lines in the Dongyi and Dongsan abandoned gob groups in the Xinghua Coal Mine, Jixi Basin, in China. The gas chromatography technique was used to analyze the concentrations of methane, carbon dioxide, ethane, propane, and butane in the collected 43 soil gas samples. The results revealed a significant anomaly of soil gas concentrations, particularly methane and carbon dioxide anomalies, in the near-surface soil over abandoned gobs. The background concentration for methane was determined to be 7.49 ppm, with an anomalous threshold set at 10 ppm based on a statistical analysis and an iterative method. This threshold could be confirmed by examining the coupling and decoupling relationship between methane, carbon dioxide, and C2–3 as well. A spatial correlation between regions exhibiting anomalous methane and carbon dioxide concentrations and the positions of gob areas, abandoned surface wells, and faults was observed. Abandoned and sealed coalbed methane surface wells and faults near gas-rich gob areas have the potential to act as conduits for AGM leakage to the surface. Furthermore, concentrations of methane, carbon dioxide, and C2–3 in soil gas over abandoned coal gobs were significantly higher compared to areas unaffected by mining activities. This suggests that elevated concentrations of methane, carbon dioxide, and C2–3 in soil gas may originate from underground AGM. [ABSTRACT FROM AUTHOR]

The objectives of the current study are to carry out soil gas radon (Rn) measurements, to evaluate the total inhalation effective dose, to determine risk levels over the lithological formations of the study area. The behavior investigation of Rn activity concentration distributions in dwellings and soils, and soil Rn mapping were also conducted. Soil gas Rn measurements were made at 102 sampling points by Markus 10 instrument. This data was combined with previously reported results from 140 indoor Rn RADTRAK dosimeters to determine the total inhalation effective dose and to conduct a statistical analysis. Overall, the Rn activity concentrations in soil and dwellings range from 4 to 66 kBq m−3 and from 15 to 140 Bq m−3, with averages of 31 ± 15 kBq m−3 and 41 ± 24 Bq m−3 respectively. The corresponding total inhalation effective dose ranges from 0.35 to 3.53 mSv y−1, with a mean value of 1.37 ± 0.58 mSv y−1. For soil gas Rn, the chlorite schist lithology showed the highest average concentration level. Which could be justified by the possible presence, within chlorite minerals, highly emitting zones of alpha particles, leading to the formation of radioactive halos. Normal and high‐risk level of Rn were found for about 82% and 11% of the total area surveyed respectively. These findings highlight the need for preventive measure against Rn exposure in homes within the investigated areas. This study contributes valuable insights into Rn distribution patterns and risk assessment, offering a basis for targeted interventions in the region. Plain Language Summary: Radon (222Rn (Rn or radon)) is the ubiquitous natural radioactive gas in the earth's crust. It is responsible for about 50% of the total dose received by the public from exposure to natural ionizing radiation. This gas have been recognized as the second leading cause of lung cancer in the world. The current work objectives are to measure the soil gas Rn activity concentrations, to assess the total inhalation dose received by the public and to determine risk levels of various lithological formations. In general, we found that the chlorite schist lithology had the highest average concentration level, due to the presence of minerals such as biotite and chlorite. Public exposure to Rn is greater indoors than outdoors with average inhalation dose relatively higher than the worldwide average. This is due to the numerous factors such as type of construction, building materials, low indoor air renewal rates, etc. The whole study area surveyed were classified as normal‐risk zones. These results reveal that preventive and protective measures against the public exposure to Rn are required from the construction of dwellings. Based on the activity concentrations distribution model and risk assessment, areas that could be targeted for potential intervention could be identified. Key Points: First in situ direct measurement of soil gas Rn activity concentration using Markus‐10 instrument in the various lithological formationsValuable insights into indoor and soil gas Rn distribution patterns and risk assessment, offering a basis for targeted interventionsProduction of a map of Rn distribution in the soil in this part of the country for the first time [ABSTRACT FROM AUTHOR]

A study on the dynamics of Radon and meteorological parameters was conducted in Bengaluru (12056′44'' N, 77030′25″ E, 840 m AMSL) during monsoon of 2014. All measured parameters exhibited a clear diurnal pattern, except for pressure, and are attributed to morning temperature inversion and afternoon enhanced vertical mixing. Concentration of Radon is higher during north eastern monsoon compared with south western monsoon and is due to the presence of continental air mass from north east of India. Monthly average Radon activity has exhibited a positive link with long wave radiation while displaying a negative correlation with ambient temperature, accumulated rainfall and soil temperature. During the study, ambient gamma dose rate of 190.8 nSv hour−1, shortwave radiation of 184.4 Wm−2, longwave radiation of −40.4 Wm−2, soil temperature (at 10 cm) of 26.3°C, humidity of 62.9%, pressure of 918.1 mbar and radon activity of 8.4 ± 0.5 Bq m−3 were recorded. [ABSTRACT FROM AUTHOR]

Indoor radon (222Rn), thoron (220Rn) and their progeny concentrations have been measured in different types of buildings at different locations in different dwellings in different seasons in Hassan city, Karnataka, using time-integrated passive radon dosemeters containing LR-115 Type II solid-state nuclear track detectors. The annual effective dose due to radon and thoron has been estimated. The activity concentrations were observed to be highest in winter and lowest in summer, and the data also shows that bathrooms and kitchens have significantly higher radon-thoron concentrations and annual effective doses. [ABSTRACT FROM AUTHOR]

The Fast Fourier Transform (FFT) analysis of the activity concentration of radon and selected meteorological parameters was carried out at Department of Physics, Bangalore University, Bengaluru (12056′44"N, 77030′25″E, 840 m above MSL). All of the measured parameters, with the exception of pressure, showed a clear diurnal trend, which can be explained by the presence of typical atmospheric processes such as temperature inversion in the morning and greater vertical mixing in the afternoon. Radon's time series has a latent memory of sub-diurnal cycles, as shown via FFT analysis. The monthly average radon has higher levels of activity during winter months compared with monsoon and summer months. Days during the monsoon season had the lowest radon activity, which may be ascribed to the fact that less radon was being exhaled from the soil as a result of the rain. Radon was recorded at 8.06 ± 0.56 Bq/m3, temperature at 28.9 °C, humidity at 55.2% and pressure at 918 mbar. [ABSTRACT FROM AUTHOR]

Appropriate mechanized straw returning and tillage sowing techniques were effective means to optimize soil physical properties and enhance agricultural productivity, as well as important measures for the conservation and restoration of mollisols region in Northeast China. Under the condition of full-scale maize straw returning, four mechanized tillage and sowing modes were set, including plough tillage and sowing (PTS), combined tillage and sowing (CTS), no-tillage and sowing (NTS), and no-tillage and sowing with straw mulching (NTSM). In 2020 and 2021, the study investigated the effects of different mechanized tillage and sowing modes on soil physical properties, soybean yield and economic benefits. The results showed that during the pod-setting and pod-filling period of soybean, the NTS and NTSM treatments exhibited better effects on deep soil insulation and shallow soil moisture retention, the soil physical structure of PTS and CTS treatments were relatively ideal. Compared with PTS and CTS treatments, NTS and NTSM treatments significantly increased soil gravimetric water content (SWC) by 2.35% to 7.98% in the 5-15 cm soil layer and increased soil temperature (ST) by 3.94% to 10.42% in the 2535 cm soil layer (p<0.05), significantly increased soil bulk density (SBD) by 2.98% to 6.72% and significantly reduced soil total porosity (STP) by 3.88% to 6.53% in the 5-25 cm soil layer, and significantly reduced soil gas phase ratio by 8.26% to 6.27% at the 15-25 cm soil layers, which caused soil three-phase ratio (STPR) of PTS and CTS treatment in 15-25 cm soil layer were relatively ideal. The soybean yield of NTSM treatment in 2020 was not significantly different from PTS and CTS treatment (p>0.05), the soybean yield of NTSM treatment in 2021 significantly increased by 7.30% and 5.84% over PTS and CTS treatments, respectively. And the average annual profit per unit area of NTSM treatment increased by 12.84%, 12.41% and 8.57% compared with PTS, CTS and NTS treatments, respectively. Therefore, it was recommended to combine NTSM technique with PTS or CTS technique in a maize-soybean rotation system in mollisols region. The research results provided reference for the selection of appropriate mechanized tillage and sowing techniques in Northeast China's mollisols region and had important guiding significance and practical value for the construction of rational plow layers and the implementation of conservation tillage. [ABSTRACT FROM AUTHOR]

When studying the fault tectonics of the Vychegodskii trough, we detected an area of high concentrations of soil radon, confined to the zone of the Vychegda–Lokchim fault. To localize the radon anomaly, we carried measurements of the volumetric radon activity out over a network of observation points. Air sampling at each point was performed from the wellhead with a depth of 0.5 m and a diameter of 0.1 m. Based on the data obtained, an intense radon anomaly was contoured. At different times, the anomaly changed in the size, shape, and intensity, but its center always remained fixed. According to areal observations, in the central part of the 2 × 2-km anomaly, the radon concentration reached 3800–4800 Bq/m3. The results of continuous daily monitoring in the center of the anomaly showed that the of radon concentration is subject to daily dynamics, which directly depends on meteorological parameters, namely on temperature and humidity. At night, with a decrease in temperature and an increase in air humidity, the level of radon increased to 6000–8000 Bq/m3 on average, in rare cases up to 10 000–12 000 Bq/m3. In the daytime, with an increase in temperature, a decrease in the volumetric radon activity was noted. In addition to the daily dynamics, seasonal variability of the radon field was observed. In autumn, the radon concentration is lower than in summer, which is associated with short-term precipitation and, as a result, the filling of the pore space with water. The Archean–Early Proterozoic basement composed of gneisses, amphibolites, quartzites, and migmatites at a depth of 2 km is considered as the main source of radon. Due to the fact that the anomaly is located in the zone controlled by the Vychegda–Lokchim fault, the latter is considered the main pathway for fluid transport to the surface. [ABSTRACT FROM AUTHOR]

Soil gas radon (Rn) serves as an effective indicator for assessing fault activity in fault zones. Measurement of Rn degassing at the active faults was conducted twice in 2017 and 2018 to assess fault activity in the western margin of the Ordos block. The concentration and flux values of Rn ranged from 0.41 to 40.93 kBq m−3 and 5.17 to 140.33 mBq m−2 s−1, respectively. The compression of the Tibetan Plateau has led to higher Rn concentration and flux in the southern part compared with the northern part. The fault activity is evaluated by the index of IRn calculated from Rn concentrations. The Haiyuan arcuate tectonic region exhibited the most intensive fault activity, followed by the Yinchuan Basin and Jilantai‐Linhe Basin. These findings enhance our understanding of the relationship between fault activity and Rn emission and provide a significant geochemical reference for the fault activity. [ABSTRACT FROM AUTHOR]

The present study deals with the observation of Rn-222 emanation process in terms of its exhalation rate for 48 h from sub-surface soil at 3 h intervals, using a continuous Rn-222 monitoring system RAD7 at Sidho-Kanho-Birsha University campus in Purulia district, located in the easternmost part of the Chotanagpur Plateau, India based on local weather conditions, over five different seasons. For every season, the diurnal variations of the Rn-222 exhalation rate increase after sunset, reaching to its maximum at mid-night and thereafter starts decreasing until it falls to the minimum around noon time. Local meteorological parameters such as ambient temperature, relative humidity, atmospheric pressure were also recorded during the observation period to study the possible influences of these parameters on the soil gas Rn-222 emission rates using Pearson's correlation matrix. There exists a strong positive correlation between relative humidity and Rn-222 exhalation rate and a positive correlation between atmospheric pressure and Rn-222 exhalation rate for all the observation periods. On the other hand, negative correlations between the atmospheric temperature and the Rn-222 exhalation rate exist for all the seasons. [ABSTRACT FROM AUTHOR]

Long-term internal exposure to radon and its progenies may lead to lung cancer. An experimental setup was arranged to assess the impact of temperature and humidity on the distribution of radon concentration in a walk-in type stability test chamber. Different temperature and humidity conditions were established between 15–35 °C and 45–85%, respectively. Passive measurement of radon concentration was carried out using pinhole dosimeters on a monthly basis. The average radon concentration was found to increase with an increase in temperature and decreases with an increase in humidity. The distribution of radon concentration was found to be highly affected by ventilation and air circulation patterns inside the chamber. [ABSTRACT FROM AUTHOR]

Site owners, regulators, and consultants now have decades of experience with vapor intrusion (VI), but guidance for the evaluation of VI continues to vary significantly among states. For those with sites in different regulatory jurisdictions, one challenge is addressing how the requirements or expectations for VI investigation and mitigation differ from one jurisdiction to the next. The overall lack of consensus can make it difficult to manage sites in a consistent manner between jurisdictions. This paper takes into account VI guidance, petroleum hydrocarbon‐specific VI guidance, and/or media‐specific volatilization criteria found in broader regulatory programs. This is an update of the author's previous reviews published in 2007, 2012, and 2018. Since our most recent update, 30 states have revised their guidance, issued new guidance or updated criteria or other VI‐related information. For each State and the District of Columbia, the review includes tabulations of the available types of screening values (e.g., soil, groundwater, soil gas, and indoor air), the screening values for selected chemicals that commonly drive VI investigations (e.g., trichloroethylene [TCE], tetrachloroethylene [PCE], benzene, and other selected volatile organic compounds [VOCs]), and the basis of risk levels used for cancer and non‐cancer risk. Federal values are also included for comparison. In addition, we summarize available key policy criteria for each state including: trigger distances, default subsurface to indoor air attenuation factors, policies for evaluation of petroleum VI, strategies for preferential pathways, and policies for mitigation of VI. The details presented in this paper provide a useful technical reference and regulatory summary for practitioners and the regulated community nationwide. [ABSTRACT FROM AUTHOR]

Subslab soil gas (SSSG) samples were collected as part of an investigation to evaluate vapor intrusion (VI) into a building. The June 2015 Office of Solid Waste and Emergency Response (OSWER) VI Guide (U.S. Environmental Protection Agency [U.S. EPA] 2015) does not provide specific, detailed recommendations regarding how to collect SSSG samples. The data collected in this study will be used to provide input into future OSWER VI Guidance documents on SSSG sample collection. To this end, three different types of subslab sampling ports were constructed with various sampling techniques within a hexagon‐shaped grid in near proximity to each other. Conventional‐, Vapor Pin‐, and California‐style ports were established in duplicate for continual analysis by onsite gas chromatography‐electron capture detection (GC‐ECD). Triplicate ports were established to evaluate active and passive long‐term sampling methods to determine short range temporal differences. Active sampling methods included evacuated stainless‐steel canisters fitted with capillary flow controllers (Modified U.S. EPA Method TO‐15 [U.S. EPA 1999a]) and sorbent tubes collected using a syringe (Modified EPA TO‐17 [U.S. EPA 1999b]). The Passive sampling method used was sorbent tube samples collected following the EPA TO‐17 sampling method (Modified). This study did not identify any systematic differences in sample results between conventional, Vapor Pin, and CA‐style probes for used in SSSG sampling. The decisions for site management would probably be the same for data from any subslab port style, active or passive sampling techniques over durations less than 2 weeks. [ABSTRACT FROM AUTHOR]

This study investigates the temporal variations in methane concentration and flare activity in the Hola trough (offshore Norway) during May 2018 and June 2022. Between these time periods, methane seep activity exhibits 3.5 times increase, as evidenced by hydroacoustic measurements. As the seep area in the Hola trough is constantly within the hydrate stability zone, the observed increase cannot be attributed to migration of its shallow boundary due to temperature increase. However, a combination of low tide conditions resulting in a lower sediment pore pressure and a bottom water temperature increase resulting in a lower methane solubility is likely to explain the increase in the number of seeps observed in June 2022. The hypothesis of tide influence is supported by data collected from a piezometer deployed and recovered during the cruise showing that the tidal effect was observed 3 m below the seafloor. Despite the numerous methane seeps detected, methane concentration and gas flow rates near the seafloor were low (<19 nM and <70 mL min−1, respectively) compared to other areas with methane seep activity. This is likely due to strong currents rapidly dispersing methane in the water column. Sub‐seafloor investigations identified pathways for gas migration in methane seep areas, influenced by topography. This study provides valuable insights into the temporal dynamics of methane concentrations, flare activity, and gas distribution in the Hola trough, contributing to our understanding of offshore methane dynamics in the region. Plain Language Summary: The Hola Trough, offshore Norway's Lofoten‐Vesterålen (LoVe) area, has been of interest for many years due to its rich marine life and potential oil and gas resources. There, coral mounds thrive around methane seepage. The LoVe observatory network monitors this unique environment. Using this observatory platform, associated data set and research expeditions at sea, the project EMAN7 (Environmental impact of Methane seepage and sub‐seabed characterization at LoVe‐Node 7) aims to understand the environmental impact of methane seepage as well as its spatio‐temporal variability. The comparison of methane seep activity during two summers with different environmental conditions revealed 3.5 times more seeps when a combination of warmer bottom water and low tide changes the sediment pore properties. A sensor recording subseafloor pore pressure and bottom temperature supports these findings. Sub‐seafloor investigations identified routes for gas migration in methane seep areas, influenced by topography. Key Points: A combination of warmer bottom water and low tide increases methane seeps 3.5 times by altering sediment gas solubility and pore pressureIntermittent seeps and strong oceanic currents explain the limited microbial mats and the low methane concentration in the water columnWe found sub‐seafloor pathways for gas migration in methane seep areas, influenced by topography [ABSTRACT FROM AUTHOR]

Various anomalies occurring before earthquakes are currently being studied to predict seismic events, with one of them being the radioactive element radon (222Rn). Radon concentrations in the soil, water, and atmosphere fluctuate in response to crustal movement. Recent research has statistically detected anomalies by analyzing the fluctuations in radon concentrations before earthquakes and conducting quantitative evaluations of radon. However, the method used to determine the parameters in the analysis was problematic. Therefore, in this study, we compared observed atmospheric radon concentration data with predicted values based on typical annual patterns using Random Forest analysis. We conducted a more objective analysis by employing this method and statistically determining anomalies using thresholds. This analysis was conducted using atmospheric radon concentration observation data obtained at Kobe Pharmaceutical University (KPU) before the 1995 Kobe Earthquake, and ionization currents emitted when radon decays were obtained at Fukushima Medical University (FMU) before the 2011 Tohoku-oki Earthquake. Consequently, before the major earthquakes occurred at both locations, the difference between the predicted and observed values exceeded the standard deviation by a factor of three. These results indicate the potential of Random Forest analysis to identify anomalies in atmospheric radon concentrations before earthquakes occur. [ABSTRACT FROM AUTHOR]

From autumn 2021 through summer 2023, scientists from the National Oceanic and Atmospheric Administration (NOAA) and partners conducted the Study of Precipitation, the Lower Atmosphere, and Surface for Hydrometeorology (SPLASH) campaign in the East River Watershed of Colorado. One objective of SPLASH was to observe the transfer of energy between the atmosphere and the surface, which was done at several locations. Two remote sites were chosen that did not have access to power utilities. These were along the valley floor near the East River in the vicinity of the unincorporated town of Gothic, Colorado. Energy balance measurements were made at these locations using autonomous, single-level flux towers referred to as Atmospheric Surface Flux Stations (ASFS). The ASFS were deployed on 28 September 2021 at the "Kettle Ponds Annex" site and on 12 October 2021 at the "Avery Picnic" site and operated until 19 July and 21 June 2023, respectively. Measurements included basic meteorology; upward and downward longwave and shortwave radiative fluxes, and subsurface conductive flux, each at 1-minute resolution; 3-d winds from a sonic anemometer and H2O/CO2 from an open-path gas analyser, both at 20 Hz from which sensible, latent heat, and CO2 fluxes were derived; and profiles of soil properties in the upper 0.5 m (both sites) and temperature profiles through the snow (at Avery Picnic), each reported between 10 min and 6 hours. For most measurements, uptime was 96 % (Kettle Ponds) and 89 % (Avery Picnic), and collectively 1,184 days of data were obtained between the stations. The purpose of this manuscript is to document the ASFS deployment at SPLASH, the data acquisition and post-processing of measurements, and to serve as a guide for interested users of the data sets, which are archived under the Creative Commons 4.0 Public Domain licensing at Zenodo. [ABSTRACT FROM AUTHOR]

In this work, a full characterization of the new user-friendly version of the Atmospheric Radon MONitor (ARMON), used to measure very low activity concentrations of the radioactive radon gas in the outdoor atmosphere, is carried out. The ARMON is based on the electrostatic collection of 218 Po + particles on a semiconductor detector surface. A main advantage of this instrument is that it offers high-resolution alpha-energy spectra, which will allow us to separate radon progeny (210 Po, 218 Po, and 214 Po). The monitor feature may also allow measurements of thoron (220 Rn) by collection of 216 Po + , although the instrument is not calibrated for this gas. In the paper, the physical principle; the hardware configuration; and the software development of the automatic and remotely controlled ARMON, conceived and constructed within the MAR 2 EA and the traceRadon projects, are described. The monitor efficiency and its linearity over a wide span of radon concentration activities have been evaluated and tested here using theoretical and experimental approaches. Finally, a complete budget analysis of the total uncertainty of the monitor was also achieved. Results from the application of a simplified theoretical approach show a detection efficiency for 218 Po + of about 0.0075 (Bq m -3) -1 s -1. The experimental approach, consisting of exposing the ARMON at controlled radon concentrations between a few hundreds to a few thousands of becquerels per cubic metre (Bq m -3), gives a detection efficiency for 218 Po + of 0.0057 ± 0.0002 (Bq m -3) s -1. This last value and its independence from the radon levels were also confirmed thanks to a new calibration method which allows us, using low-emanation sources, to obtain controlled radon levels of a few tens of becquerels per cubic metre (Bq m -3). The total uncertainty of the ARMON detection efficiency obtained for hourly radon concentrations above 5 Bq m -3 was lower than 10 % (k= 1). The characteristic limits of the ARMON – being those dependent on the presence of thoron in the sampled air – were also calculated. A detection limit of 0.132 Bq m -3 was estimated in the absence of thoron. At a typical thoron concentration at atmospheric sites of 0.017 min -1 , the detection limit was calculated to be 0.3 Bq m -3 , but this can be reduced if using a delay volume, obtaining a decision threshold of 0.0045 Bq m -3. Current results may allow us to confirm that the ARMON is suitable to measure low-level radon activity concentrations (1–100 Bq m -3) and to be used as a transfer standard to calibrate secondary atmospheric radon monitors. [ABSTRACT FROM AUTHOR]

Afyonkarahisar and its surroundings are in the middle of the Akşehir-Simav Fault System. Before the earthquakes in the region, radon anomalies were observed in some well waters. Linear equations between radon minima and earthquake magnitudes (Mw) were obtained, and correlation coefficients (R2) were calculated. The correlation coefficient (R2) values of the wells from 1 to 6 were obtained as 0.93, 0.83, 0.82, 0.97, 0.87 and 0.85, respectively. Good correlations (high R2 values) were obtained between the radon minimum and the earthquake magnitude (Mw) in 6 wells. The precursory minimum observed at the radon concentration in groundwater decreased as the earthquake's magnitude increased. [ABSTRACT FROM AUTHOR]

Afyonkarahisar and its surroundings are in the middle of the Akşehir-Simav Fault System. Before the earthquakes in the region, radon anomalies were observed in some well waters. Linear equations between radon minima and earthquake magnitudes (Mw) were obtained, and correlation coefficients (R2) were calculated. The correlation coefficient (R2) values of the wells from 1 to 6 were obtained as 0.93, 0.83, 0.82, 0.97, 0.87 and 0.85, respectively. Good correlations (high R2 values) were obtained between the radon minimum and the earthquake magnitude (Mw) in 6 wells. The precursory minimum observed at the radon concentration in groundwater decreased as the earthquake's magnitude increased. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to assess the spatial distribution of carbon reserves in the surface of organic and mineral soil layers, in a carbon landfill. The studied areas are located within the broad-leaved forests of the Southern Urals. Methods: The analysis of the forest carbon cycle was conducted in early spring on trees, shrubs, and grass vegetation. Soil gas flux measurements were performed using a Smart Chamber connected to a LI-COR 7810 gas analyser. CO2 flux emission from the soil surface reached up to 493.2 Gf a day, under the tree canopy and did not exceed 471.8 Gf in uncovered areas (glades). Results: Thus, in early spring, the CO2 flux emissions from the soil surface in forest stands is higher in absolute terms, than in uncovered areas. It can presumably be explained by the difference in vegetation cover, along with the size, depth, and spatial distribution of roots from trees, shrubs and herbaceous plants. Conclusion: Forest litter and humus, mainly composed of potassium, nitrogen, and phosphorus, are critical for maintaining the carbon balance in forest areas. [ABSTRACT FROM AUTHOR]

Gas hydrates deposits in the Andaman forearc basin are inferred from seismic data and confirmed by drilling/coring during the NGHP-01 expedition. We present new evidence of gas flares in the Andaman forearc basin, detected through water column image (WCI), subbottom profiling, and high-resolution seismic data acquired onboard RV Sindhu Sadhana (SSD-085) in November- December 2021. The gas flares are located over an elongated sedimentary ridge, featuring two prominent mounds (M1 and M2) with distinct geological features. Compressional tectonics induced by the Diligent fault (DLF) formed the ridge with varying slopes and elevations. Gas flares observed above the mound M1 in WCI and sub-bottom profiler data. Seafloor samples reveal carbonate rocks with visible pores, indicating gas/fluid migration or burrows. The regional seismic profile delineates three sedimentary sequences: folded and faulted strata, mass transport deposits, and horizontal-to-sub-horizontal sedimentary layers. Additionally, we observed a bottom simulating reflector (BSR), indicating potential subsurface gas hydrate deposits. Detailed high-resolution seismic data revealed complex fault systems near bathymetry mounds (M1 and M2), which may serve as pathways for vertical fluid/gas migration. [ABSTRACT FROM AUTHOR]

Hydrogen exploration in the municipality of Maricá (Rio de Janeiro State, Brazil) indicates that important hydrogen and helium gas fluxes are emitted through reactivated faults. The gas concentrations in the soils, and the modelled gas fluxes, are among the most intense measured so far in the world. This exploration has shown new surface expression of hydrogen micro-seeps, observed along reactivated large tectonic accidents instead of "fairy circles", most common proxy for hydrogen systems in cratonic formation. The geology of Maricá, consisting in Neoproterozoic metamorphic rocks without any already documented evidence of hydrogen-prone formations, appears as a very new field of investigation for natural hydrogen. Results indicate the presence of systematic hydrogen saturation of the usual detectors plugged at 80 cm depth, as well as a permanent recharge of hydrogen through time, without relaxation time. Moreover, positive helium anomalies are associated with this hydrogen soil gas, proving the existence of a gas flux coming from deep horizons of the subsurface. This reduces the risk of misinterpretation of surface hydrogen measurement, since the fear of drill bit metamorphism or superficial biological activity inducing hydrogen artefacts is always a possibility. These hydrogen and helium micro-seeps are associated with positive thorium concentration superficial anomalies, as it was already observed in other places associated with hydrogen exudations. We present a model of soil gas behavior, with a differential process of adsorption/desorption of each gas compound (N 2 , O 2 , Ne, H 2 and He), associated with a deep flux of hydrogen and helium. It is possible to assess a quantification of hydrogen flux of 0.32 m3 m−2.day−1. The surface flux ratio He/H 2 is much higher than any published value of generative flux. This may be explained by a subsurface accumulation, where hydrogen is severely altered whereas helium is preserved, increasing the relative proportion of helium versus hydrogen. [Display omitted] • The Marica municipality (Brazil) reveals important potential for natural hydrogen. • Reactivated faults are excellent proxies for natural hydrogen exploration. • Hydrogen seeping out of reactivated faults may be larger than in fairy circles. • Association of hydrogen and helium in soils indicates that no artefact concerns the hydrogen measurements in soils. • Metamorphic formations may be excellent candidates for hydrogen exploration. [ABSTRACT FROM AUTHOR]

Over the last decades and due to the current climate change situation, the study of the impacts of human activities on climate has reached great importance, being agriculture one of the main sources of soil greenhouse gas. There are different techniques to quantify the soil gas fluxes, such as micrometeorological techniques or chamber techniques, being the last one capable to assess different treatment at the same site. Manual chambers are the most common one. However, due to the low sampling frequency, this approach cannot resolve short-term emission events, like fertilization or rewetting. For this reason, automated chamber systems are an opportunity to improve soil gas flux determination, but their distribution is still scarce due to the cost and challenging technical implementation. The objective of this study was to develop an automated chamber system for agricultural systems under Mediterranean conditions and compare measured GHG flux rates to those derived using manual chambers. A comparison between manual and automated chamber systems was conducted to evaluate the soil gas fluxes obtained by the automated system. Moreover, over a period of one month the soil gas fluxes were determined by both systems to compare their capabilities to capture the temporal variability of soil gas emissions. The automated system reported higher soil GHG fluxes compared to the manual chamber system. Additionally, the higher sampling frequency of the automated chamber system allowed for the capture of daily flux variations, resulting in a more accurate estimation of cumulative soil gas emissions. The study emphasises the importance of chamber dimension and shape, as well as sampling frequency, in the development of chamber systems, especially when using the manual chamber system. [ABSTRACT FROM AUTHOR]

At many dormant volcanoes, magmatic gases are not channeled through preferential degassing routes as fumaroles and only percolate through the flanks of the volcano in a diffuse way. This type of volcanic gas emission provides valuable information, even though the soil matrix contains an important atmospheric component. This study aimed to demonstrate that chemical ratios such as He/CO2 in soil gases provide excellent information on the evolution of volcanic unrest episodes and help forecast the volcanic eruption onset. Before and during the occurrence of the October 2011–March 2012 submarine of El Hierro, Canary Islands, more than 8500 soil He analyses and diffuse CO2 emission measurements were performed. The results show that the soil He/CO2 emission ratio began increasing drastically one month before eruption onset, reaching the maximum value 10 days before. During the eruptive period, this ratio also showed a maximum value several days before the period with the highest magma emission rate. The He/CO2 ratio was also helpful in forecasting the eruption onset. We demonstrate that this tool can be applied in real-time during volcanic emergencies. Our results also encourage a reevaluation of the global He emission from the subaerial volcanism. [ABSTRACT FROM AUTHOR]

The geochemical monitoring of volcanic activity today relies largely on remote sensing, but the combination of this approach together with soil gas monitoring, using the appropriate parameters, is still not widely used. The main purpose of this study was to correlate data from crater gas emissions with flank emissions of soil gases at Mt. Etna volcano from June 2006 to December 2020. Crater SO2 fluxes were measured from fixed stations around the volcano using the DOAS technique and applying a modeled clear-sky spectrum. The SO2/HCl ratio in the crater plume was measured with the OP-FTIR technique from a transportable instrument, using the sun as an IR source. Soil CO2 efflux coupled with the 220Rn/222Rn activity ratio in soil gases (named SGDI) were measured at a fixed monitoring site on the east flank of Etna. All signals acquired were subject both to spectral analysis and to filtering of the periodic signals discovered. All filtered signals revealed changes that were nicely correlated both with other geophysical signals and with volcanic eruptions during the study period. Time lags between parameters were explained in terms of different modes of magma migration and storage inside the volcano before eruptions. A comprehensive dynamic degassing model is presented that allows for a better understanding of magma dynamics in an open-conduit volcano. [ABSTRACT FROM AUTHOR]

Indoor radon surveying and remediation were implemented in a single-family home affected by high levels of indoor radon in the Celleno municipality (central Italy) with the aim of identifying the contribution of radon sources, evaluating the factors affecting radon entry into the building, and reducing radon risk. Average radon levels were relatively low at the ground floor (286 ± 202 Bq m−3) and first floor (167 ± 84 Bq m−3) in autumn when the temperature was still warm and the windows were open, but increased up to 2776 ± 1768 Bq m−3 and 970 ± 202 Bq m−3 in the first half of December, when the heating system was on and the windows were closed. The inner walls of the pilot room at the ground floor, semi buried on one side, were then treated with a waterproof product (a silane terminated polymer) and the average radon was halved (1475 ± 1092 Bq m−3) in the following month, which was still characterised by winter conditions. Radon entry in the room was identified and sealed with the same product, and a radon accumulation space behind a NE-SW oriented wall was naturally ventilated, reducing radon below the reference level in April with northerly winds conditions. [ABSTRACT FROM AUTHOR]

The severe health risk associated with elevated levels of indoor radon gas is well known and widely reported. Measuring residential indoor radon-in-air levels is expensive, labour- and time-intensive. Two of the most important estimators of high levels of indoor radon gas are the underlying geology of an area and the climatic conditions, especially temperature and wind. While varying geology leads to different exhalation rates of radon gas, the climate can mitigate or enhance indoor radon gas levels. The research in this study developed and tested a novel approach to rapidly identify the most probable areas of high indoor radon levels, potential targets for indoor radon measurements. The study utilizes GIS tools to superimpose overlays of geology, climate, and wind to identify possible radon hotspots. South Africa was selected as a study site due to its varying climatic conditions and unique geology which have large areas of underlaying uranium-bearing rock units. Several of the identified hotspots were compared to actual indoor radon measurements, and a good similarity between actual and estimated indoor radon levels was found. This method can easily be applied to other sites or regions, giving it both practical and theoretical values. [ABSTRACT FROM AUTHOR]

When optimizing irrigation methods, much consideration is given to crop growth indicators while less attention has been paid to soil's gaseous carbon (C) and nitrogen (N) emission indicators. Therefore, adopting an irrigation practice that can reduce emissions while maintaining crop yield and quality is of great interest. Thus, open-field experiments were conducted from September 2020 to January 2022 using a single-factor randomized block design with three replications. The lettuce plants ("Feiqiao Lettuce No.1") were grown using four different irrigation methods established by setting the lower limit of drip irrigation to 75%, 65%, and 55% of soil water content at field capacity corresponding to DR1, DR2, and DR3, respectively. Furrow irrigation (FI) was used as a control. Crop growth indicators and soil gas emissions were observed. Results showed that the mean lettuce yield under DR1 (64,500 kg/ha) was the highest, and it was lower under DR3 and FI. The lettuces under DR3 showed greater concentrations of crude fiber, vitamin C, and soluble sugar, and a greater nitrate concentration. Compared with FI, the DR treatments were more conducive to improving the comprehensive quality of lettuce, including the measured appearance and nutritional quality. Among all the irrigation methods, FI had the maximum cracking rate of lettuce, reaching 25.3%, 24.6%, and 22.7%, respectively, for the three continuous seasons. The stem cracking rates under DR2 were the lowest—only 10.1%, 14.4%, and 8.2%, respectively, which were decreased to nearly half compared with FI. The entropy model detected that the weight coefficient evaluation value of DR2 was the greatest, reaching 0.93, indicating that the DR2 method has the optimal benefits under comprehensive consideration of water saving, yield increase, quality improvement, and emission reduction. [ABSTRACT FROM AUTHOR]

Indoor radon source potential from unground soil was monitored using prototype devices approaching a dwelling with a cellar basement at 1 depth from the soil-atmosphere interface. Therefore, the radon concentrations in soil gas were monitored at 1 m depth. Integrated radon measurements were performed, and the results correlated with meteorological parameters. The influence of the difference in outdoor and device-soil temperature was considered, and the infiltration rate was calculated. The effect of the soil temperature gradient on the soil radon entry rate was evaluated. The indoor radon entry rate due to the soil gas was 7.0 ± 2.7 Bq m−3 h−1. The radon entry rate was 5.0 ± 0.8 Bq m−3 h−1 due to diffusion. In contrast, the advection-drive flow of soil gas is ranged up to ± 4.0 Bq m−3 h−1. So, the infiltration rate of the model dwelling was 0.7 (± 0.5) × 10−1 h−1 if only the stack effect occurred. The radon levels in tap water were measured, and the radon entry rate was estimated at 1.3 ± 0.7 Bq m−3 h−1. If the ventilation rate is low or seismic faulting appears, the soil radon entry is increased by one order of magnitude. The soil radon appeared like the building materials, having 1/3 of the total indoor radon entry, while outdoor air was slightly lower (28%), with tap water at 5%. The resident's mortality risk occurred at < 2.5% for typical dwellings in temperate climate areas founded on sand-gravel underground. The risk rises to 34% with an extremely low ventilation rate between indoors and outdoors or high radon entry from the soil due to seismic faulting. [ABSTRACT FROM AUTHOR]

222Rn activity was measured in Asansol city and the adjacent mining area, West Bengal, India. 222Rn concentrations were found to vary in the range 6.4–145, 1080–91002, and 2070–180000 Bqm−3 in indoor air, soil gas, and groundwater, respectively. Total effective doses (TEDs) due to 222Rn exposure were also estimated. In some sampling locations, TEDs appear to exceed the maximum permissible limit (100 µSvy−1). 222Rn concentration variation contour mapping was prepared. Carcinogenic health risk factors (HRF) due to 222Rn activity were also estimated. In some places, HRFs are found to be very high (> permissible limit ~ 1.0). [ABSTRACT FROM AUTHOR]

The aim. To study the behaviour of enisamium iodide, thiloron dihydrochloride, morpholinium thiazotate, and the suitability of the previously developed GC-FID methodology in soil. Materials and methods. The determination of the Enisamium iodide, Tilorone dihydrochloride, and Morpholinium thiazotate in soil gas chromatography with a flame ionization detector using the Rxi-5 ms (30 m long, 0.25 mm outer diameter and 0.25 μm liquid stationary phase thickness). Results. A study was conducted on the behaviour of enisamium iodide, thiloron dihydrochloride, and morpholinium thiazotate in soil, along with the assessment of the suitability of the developed GC-FID methodology for determination in soil. The half-life in soil was investigated, which amounted to 45 days for enisamium iodide, 30 days for thilorone dihydrochloride, and 7 days for morpholinium thiazotate, with corresponding decay rate constants of 0.001 mg/mL, 0.001 mg/mL, and 0.0005 mg/mL, respectively. Conclusions. The previously developed GC-FID methodology is suitable for the determination of enisamium iodide, thilorone dihydrochloride, and morpholinium thiazotate in soil, with necessary analysis conditions established. Under aerobic conditions, the selected pharmaceutical preparations' dispersion rate followed the following decreasing order: enisamium iodide>thilorone dihydrochloride > morpholinium thiazotate in soil [ABSTRACT FROM AUTHOR]

Agricultural landscape management and climate seasonality can influence soil structure, hydraulic conductivity, and air permeability within the context of soil water and soil gas mobility. To investigate this, in situ and laboratory-based data were collected from three agricultural landscape positions within a watershed in eastern Ontario, Canada during a growing season. Macropore classification, water infiltration tests, and air permeability measurements were conducted in situ and standard soil characterizations were carried out on soil samples. Hydraulic conductivity of the soil matrix, based on grain size data, indicated that the highest values were consistently measured in the B horizon at each landscape setting. Macropores were found to be more abundant within uncultivated drainage ditch bank soils, compared to the adjacent cropped fields. Macropores in the ditch bank soils were exclusively consisted of circular biopores, while both circular and linear macropores were observed in the cultivated field soils. Air permeability, vertical hydraulic conductivity, and horizontal hydraulic conductivity were also greater in the uncultivated soils, relative to the cultivated soils. Field saturated hydraulic conductivity measurements offered evidence of anisotropy, likely due to the vertical nature of the macropore features. Macropore disposition and extent varied over the growing season, especially in the cultivated field soils where tillage and field trafficking are physically disruptive. Seasonality of macropore development will influence temporal changes in advection-based mass exchange of gas and water in the vadose zone. Modeling of mass exchange in agricultural soils should consider time variability in macroporosity to more realistically characterize infiltration and soil gas emissions. [ABSTRACT FROM AUTHOR]

Methane spikes observed in the Martian atmosphere require the abrupt release of large amounts of methane from the Martian subsurface. The mechanism for such release has not been identified. We tested whether gas traps can form under Mars‐like conditions in the shallow Martian regolith due to salt migration in the icy soil. Experiments were performed on various soil samples in a Mars Simulation Chamber comprising different perchlorate salts and water concentrations mixed with JSC Mars‐1A. Inside the chamber, the samples were exposed to a range of temperatures from −20°C to 10°C and maintained CO2 gaseous pressure between 8 and 10 mbars. As a methane analog, Neon was injected periodically underneath the soil sample. It was found that over a wide range of Mars‐like soil parameters, a gas impermeable soil seal can form over a relatively short period (3–13 days) but requires 5%–10% of perchlorate salt content in the soil. It was determined that such a seal could sustain several mbars of neon above the Martian atmospheric pressure in the soil. Based on our experiments, substantial amounts of gaseous methane may accumulate under the soil seal and get released abruptly into the atmosphere upon seal cracking. An abrupt release of methane from the shallow subsurface may help explain methane variability at the Martian surface, as the Mars Science Laboratory detected. Plain Language Summary: Spikes of atmospheric methane on Mars, recently observed by the Mars Science Laboratory mission, are puzzling. To explain rapid variations in methane abundance in the Martian atmosphere, methane has to be released abruptly. Our experiments in the Mars simulation chamber demonstrated that perchlorate salts can be transported toward the surface regolith via water migration and subsequent sublimation. We showed that under Mars‐like conditions, the soil with migrated salts can become cemented and form a solid gas impermeable seal. Methane and other volatiles can accumulate under the soil seal. Methane seasonal variability and occasional methane spikes in the Gale crater on Mars can be due to a sudden release of methane from the soil gas pockets when the Curiosity rover breaks soil seals by moving or drilling. Key Points: Gas impermeable seals can form in Mars‐like conditions in the soil with 5%–10% perchlorate salts by mass and a shallow permafrost layerMethane could accumulate under the seal in the shallow subsurface and be released abruptly into the atmosphere when the seal breaks [ABSTRACT FROM AUTHOR]

This study looks at the annual variations in landfill gas concentrations within the surface layer of the dump as well as the effect of climatic factors on these variations under the tropical climate. The experiment was carried out at part of the Karadiyana landfill, Sri Lanka, containing old mixed municipal solid waste covered by vegetation. The gas concentrations of the landfill surface layer were measured from three gas wells established on the dump surface layer, which contains 2.5 m depth, throughout the year with the measuring of climatic factors. The results show the annual fluctuation of temperature, cumulative rainfall, relative humidity, and atmospheric pressure were 27–42°C, 66.7–357.7 mm, 24.7%–78.2%, and 999.5–1014 mbar around the studied landfill area, and the average concentration value of the CH4, NH3, H2S, and VOCs gases were 18.94 ± 11.49%, 15.48 ± 15.17 mg m−3, 15.06 ± 19.02 mg m−3, and 0.83 ± 0.99 mg m−3, respectively. The rainfall and atmospheric temperature were significant metrological factors influencing the surface layer gas concentrations and showed a significant positive correlation with cumulative rainfall and a negative correlation with atmospheric temperature. The relative humidity shows a moderate positive correlation, and there was no evidence of a considerable impact of atmospheric pressure on the surface layer concentrations. Annual fluctuation is a critical factor for landfill gas emission quantification, and surface layer concentration variation can be used to study the emission fluctuation by considering their relationship. [ABSTRACT FROM AUTHOR]