From soil to gas – high resolution insights into plant-soil interactions by integrating planar oxygen optodes, porewater chemistry, soil microbial analysis and trace soil gas flux using a rhizobox approach

Baseline radon concentrations in uranium-rich and faulted zones of the Eastern Cordillera, Central Andes, Peru.

The gas permeability of building materials is a critical factor influencing structural durability, energy efficiency, and indoor air quality. This study presents a preliminary investigation into a method for reducing the permeability of concrete and gypsum using a novel penetrative organosilicon composition. The composition is based on the reaction product of polyethylhydride siloxane (PEHS) and alkyltriethoxysilane (ATES) hydrolysate. Experimental measurements using air and argon as proxy gases demonstrate that the optimized layer-by-layer treatment can significantly increase the gas impermeability coefficient (K0/Kt). Given the correlation between molecular size and permeation, these findings suggest a theoretical potential for blocking hazardous soil gases such as radon (222Rn). This potential was further explored through initial pilot field tests in residential buildings, which yielded promising preliminary results. However, these findings emphasize the need for extensive long-term evaluations and direct radon diffusion studies to fully validate the efficacy and durability of the proposed treatment under diverse environmental conditions.

Transfer of belowground carbon into forest vegetation in Icelandic volcanic geothermal fields: Implications for 14C transfer from subsurface sources.

The Western Qinling Orogen (WQO) is a major gold region in China, with gold reserves exceeding 1, 200 tons. Its complex topography, climate, and semi-humid grassland cover provide an ideal setting for evaluating deep-penetrating geochemical (DPG) methods. In this study, three DPG methods-the Fine-Grained Soil Prospecting Method (FGSPM), leaching of mobile forms of metals in overburden (MOMEO), and soil gas geochemical survey (H2S, SO2, and CO2)-were employed in the southern Zhaishang concealed gold deposit, which is covered by semi-humid grassland and various overburden materials. Results indicate that no single method reliably identifies concealed orebodies or alteration zones, yet their combination improves detection, especially for deep and thin ores. Gas geochemistry exhibits higher sensitivity. Differences in response between FGSPM and MOMEO likely stem from variations in sampling and chemical analysis. For FGSPM, fine-grained soil fractions (< 75μm and 75-125μm) exhibit similar capacities for adsorbing mobile Au, predominantly occurs in water-soluble and clay-adsorbed forms, with strong spatial heterogeneity. H2S and SO2 serve as effective gas indicators in semi-humid regions, though uncertainties affected by various factors (e.g., biological activity) require further verification. These findings offer a valuable case study for DPG applications and enhance the understanding of geochemical exploration in covered terrains.

Soil gas geochemical survey exploring for concealed sediment-hosted Au deposits in the semi-humid region: A case study from the Zhaishang Au-deposit, West Qinling, China

ABSTRACT Pot Cover effect describes a process in which vapor migrates upward along a temperature gradient, condenses and accumulates as liquid water or ice at the base of a covering impermeable layer, ultimately resulting in pavement damage. Although numerical simulation, analytical calculation and empirical models are widely used to calculate vapor migration caused by Pot Cover effect, there are limitations in their computational efficiency under specific conditions. To overcome this limitation, an analytical approach based on Fick's law and fundamental physical assumptions is developed to quantitatively describe vapor migration. Validation using field test data from Beijing Daxing International Airport confirms the accuracy of this approach in capturing vapor migration in freezing unsaturated soils. Furthermore, the analytical approach is applied to investigate the influence of the separation layer's depth and gas permeability on vapor migration. The optimal configuration is identified as a layer positioned at the maximum freezing depth (40 cm in this study) with nearly 0% gas permeability, which most effectively inhibits vapor migration induced by Pot Cover effect. Finally, by integrating analytical and experimental results, the influence of soil gas permeability, initial water content, and dry density on vapor migration is investigated. The analysis indicates that higher initial water content and dry density diminish soil gas permeability, thereby restraining vapor migration and alleviating the water accumulation characteristic of Pot Cover effect. The derived analytical framework provides a practical and efficient tool for designing mitigation strategies against Pot Cover effect in cold‐region engineering.

Long-term measurements of 222Rn in soil gas and at different height levels in Amazon tall tower observatory.

In India, a majority of menstruating women prefer using sanitary pads, which are typically disposed through burning or as sanitary waste, eventually reaching the soil. This study aimed to analyze the chemical composition of sanitary pads and menstrual cups and assess their environmental impact post-disposal. Fourier-Transform Infrared (FTIR) analysis was employed to identify the materials constituting the sanitary products. Unused pads were found to be composed of polyethylene, silica gel, and several unidentified aromatic chemicals. In contrast, menstrual cups consisted solely of silicone, which is a commonly used biocompatible material suitable for making biomaterials used as inserts inside the human body. Experiments were conducted to determine the impact of pads on air and soil quality. Simulated menstrual fluid (SMF), mimicking blood and vaginal fluid, was utilized in all in vitro experiments. In contaminated soil samples comprising used sanitary pads, there was a significant reduction in macronutrients such as nitrogen and phosphates, and micronutrients including iron, chlorides, copper, manganese, boron, molybdenum, nickel, and zinc. There was an average decrease of 85.48% organic matter and 84.24% moisture across all pad-contaminated soils. No significant variation in pH was observed among the soil samples. The total plate count in soil exposed for 182 days showed a reduction of more than 99% in microflora compared to the control. In contrast, soil exposed to used cups and SMF exhibited no significant reduction in macronutrients, micronutrients, pH, moisture content, or organic matter. Combusted gas analysis revealed that burning menstrual pads at room temperature and ambient air conditions emitted particulate matter and harmful gases, including methane, HCl, HF, SO2, CO, CO2, aromatic volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs). The chemical analysis of soil and combustion gases indicated that the disposal of single-use sanitary pads posed environmental hazards, suggesting the potential benefits of using reusable menstrual cups. This study brings forth valuable evidence about the adverse effects of disposable sanitary pads on the environment, thus highlighting the need for alternative menstrual products such as reusable cups to mitigate ecological harm.

While natural hydrogen (H 2 ) anomalies in the Pyrenean domain are often attributed to mantle serpentinization, the spatial disconnection of the Aquitaine Basin from this mantle source suggests that alternative thermogenic origins must be considered. To assess this potential, we present a new dataset of 25 Paleozoic samples from the Aquitaine Basin (SW France) and the Pyrenean domain. Organic matter maturity was quantified by Raman spectroscopy, yielding maximum burial temperatures between ∼220 °C and ∼410 °C. These results document strong spatial variability: mean peak temperatures reach 337 ± 49 °C in the South Variscan domain, 258 ± 26 °C in the Variscan foreland, and 352 ± 15 °C in the Western Pyrenees. One-dimensional basin modeling, calibrated against this new dataset and previous maturity data, identifies two distinct thermal events: (i) a Variscan high-temperature/low-pressure phase and (ii) a Cretaceous rifting phase. Both episodes likely triggered natural hydrogen generation. Critically, while the South Variscan domain and the Western Pyrenees appear largely depleted, the Variscan foreland retains a significant residual potential, with present-day conditions in the Arzacq Basin still falling within the effective H 2 generation window (∼220–330 °C; ∼3.5–5 %Ro). This integrated approach provides the first robust thermal framework for assessing hydrogen generation in the Paleozoic basement, refines the location of prospective domains beyond the North Pyrenean Zone, and offers a possible explanation for unexplained soil gas H 2 anomalies. • Thermogenic H 2 forms in overmature Paleozoic rocks rich in organic matter. • Raman data confirm peak burial temps from ∼220 °C to ∼410 °C. • 1D modeling shows two main heating phases: Variscan and Mesozoic. • Present geothermal gradients favor deep H 2 exploration zones. • Organic origin explains H 2 anomalies beyond serpentinization zones.

Dominant determinants of indoor radon concentration and skewed health risk in Al Khums and Al Sahel, Libya.

The aim of the study was to assess potential health risks associated with a large-scale environmental release of benzene following a railway accident in Moravia, Czech Republic, in 2025, with emphasis on differences between population and occupational exposure. An assessment of potential health risks associated with exposure was performed using available environmental monitoring data. Conservative exposure scenarios were defined for the general population and for remediation workers. Non-carcinogenic risk was expressed as the hazard quotient (HQ), and carcinogenic risk as excess lifetime cancer risk (ELCR). Short-term peaks in ambient air benzene concentrations were observed in the period immediately following the accident and during remediation activities, with occasional hourly values reaching the order of tens of µg.m-3. During the accident and its immediate aftermath, benzene concentrations at the accident site ranged from < LOQ-32.3 mg.m-3 (LOQ - limit of quantification) in soil gas (March-April 2025), 0.0004-2.43 g.l-1 in groundwater (March-May 2025), < LOQ-19.9 µg.l-1 in surface water (March-June 2025), and < LOQ-849.7 mg.kg-1 in soils (March-April 2025). Extreme values were confined to the immediate accident zone and represented the dominant exposure for workers rather than residents. For the general population, HQ values remained below 1 and ELCR ranged from 10-6 to 10-5. In contrast, remediation workers exhibited substantially higher risks, with HQ values reaching 104-105 and ELCR up to 10-3, particularly for inhalation exposure. While population exposure remained within acceptable limits, occupational exposure during remediation represented the dominant health risk. Two workers involved in remediation activities were excluded from further work based on the results of biological monitoring of benzene exposure. The results highlight the need for strict exposure control and health surveillance of exposed workers.

Radon (222Rn) is a globally recognized Class A carcinogen, and its accumulation in urban areas presents a critical challenge for public health and spatial planning. Effective environmental management requires accurate and scalable risk assessment, especially in geologically complex cities. The study presents the first systematic assessment of soil gas 222Rn in Yerevan, Armenia, combined with multi-depth profiling of natural radionuclides (226Ra, 232Th, 40K). This study addresses this issue by integrating a robust, data-driven Principal Component Regression (PCR) predictive framework to generate a hazard map of soil gas 222Rn activity across the urban environment of Yerevan, Armenia, and reveal key environmental and geological factors influencing soil gas 222Rn. The model integrates 222Rn activity measurements (ranging from 483.0 to 38,375.0 Bq/m3) with a comprehensive dataset of key predictor variables: multi-depth natural radionuclide activity concentrations, soil texture properties, and meteorological parameters, collected across a stratified sampling network. The resulting PCR prediction model with three component explains 33.6% of the variance in log-transformed 222Rn. Predictive power is primarily driven by PC1 (gamma-emitting radionuclide abundance and fine-grained soil texture) and PC2 (measurement depth and coarse-textured soils). Leave-One-Out Cross-Validation (LOOCV) confirmed structural model stability (cross-validated R2 = 0.115 on log scale), although extreme values were conservatively underestimated. The resulting hazard map delineates radon-prone zones primarily in central-eastern and southern districts associated with permeable sedimentary formations. Despite moderate explanatory power, the PCR framework provides an interpretable and statistically robust basis for preliminary radon hazard zoning in geologically heterogeneous urban areas.

Mid-intertidal mangrove belts concentrate ecosystem multifunctionality in a semi-enclosed estuary.

X-ray CT-derived pore structure determines soil gas transport under high soil water content in clayey but not sandy soils

ABSTRACT Soil air‐filled porosity (AFP) in non‐rigid soil is closely associated with the coupled changes in soil moisture and total porosity due to the high shrinkage‐swelling capacity. Although the dynamic of AFP during soil shrinkage (AFP sh ) has been well quantified by using a soil shrinkage model, the changes in AFP during soil swelling (AFP sw ) remain poorly understood. The objectives were to (1) characterize the dynamic of AFP sw during soil swelling and (2) evaluate the effect of initial bulk density (ρ b ) and wetting/drying (WD) cycles on the dynamic of AFP sw for a Vertisol. Repacked soil samples with different initial ρ b of 1.15, 1.30, and 1.45 g cm −3 were subjected to two WD cycles. Soil shrinkage/swelling curves, water/air‐filled porosity, and relative gas diffusion coefficient (D s /D 0 ) were determined during the two WD cycles. Our results showed that the dynamic of AFP sw was well described by the established AFP sw equation. Soil swelling curves intersected across ρ b treatments, whereas the shrinkage curves remained parallel between the 1.30 and 1.45 g cm −3 treatments. Soils with higher initial ρ b exhibited greater changes in porosity and AFP sw during swelling. Although neglecting soil shrinkage led to an overestimation of AFP (0.12–0.18 cm 3 ), ignoring the swelling‐derived pore deformation resulted in a greater underestimation of AFP (0.12–0.33 cm 3 cm −3 ). Over the two WD cycles, the soil exhibited the greatest structural change and the largest ΔAFP between AFP c and AFP sw in the first wetting process. Although soil swelling increased the AFP sw at θ FC and expanded the θ v range for AFP &gt; 0.10 cm 3 cm −3 , the D s /D 0 at AFP sw = 0.10 cm 3 cm −3 did not reach the non‐limiting value of 0.02. Our result demonstrated that quantifying the dynamic of AFP sw/sh improved the assessment of soil aeration condition WD cycles and enhanced the accuracy of soil gas transport predictions in non‐rigid soils.

Abstract Purpose In recent years, intercropping in olive groves has become a sustainable practice for mitigating climate change. Therefore, the objective of this study was to determine whether crop diversification in rainfed olive groves modifies carbon dioxide (CO 2 ), nitrous oxide (N 2 O), and methane (CH 4 ) emissions and key chemical and enzymatic properties of the soil in the short term. Materials and methods A field experiment was conducted under semi-arid Mediterranean conditions using four treatments: a conventional olive monocrop (CP) and three crop diversification systems: saffron ( Crocus sativus ) (D-S), oats and vetch ( Vicia sativa and Avena sativa ) (D-O) and lavandin ( Lavandula × intermedia ) (D-L). CO 2 , N 2 O, and CH 4 emissions were measured periodically using closed static chamber techniques. Simultaneously, soil samples were analyzed to determine physicochemical parameters (pH, total nitrogen (TN), total organic carbon (TOC), P available, K, and Fe) and enzymatic activities (β-1,4-glucosidase (BG), leucine aminopeptidase (LA), N-acetylglucosaminidase (NAG), Arylsulfatase (AS) and phosphatase (AP) and dehydrogenase (DH)) in order to evaluate the interactions between soil properties and gas fluxes. Results and discussion The results showed that CO 2 emissions were significantly higher in D-S (385.2 mg CO 2 m -2 h -1 ) and D-O (335.2 mg CO 2 m -2 h -1 ) compared to CP, which was attributed to increased microbial and root activity promoted by the vegetation cover. In contrast, N 2 O fluxes (0.002 mg N 2 O m -2 h -1 in CP, 0.007 in D-S, 0.001 in D-O, and − 0.002 in D-L) and CH 4 (–0.2 mg CH 4 m -2 h -1 in CP, 0.1 in D-S, 0.2 in D-O, and 0.2 in D-L) did not show significant differences between all treatments ( p &gt; 0.05 ), probably due to the prevailing semi-arid conditions. D-O had higher values of P available, Fe, and TN, while D-S and D-L stood out for higher values of K and TOC, both compared to CP. Enzymatic activities were particularly higher in D-S and D-O, specifically BG, LA, and AS. In addition, positive and significant correlations were observed between CO₂ accumulation and several soil parameters: in D-S, with POC, total Zn, exchangeable Na, total Cu, and BG, LA, and AS activities; and in D-L, with POC, exchangeable Na, total Mn, P available, TN, and LA and AS activities, highlighting that these indicators contribute to the regulation of greenhouse gas (GHG) emissions. Conclusion It was concluded that crop diversification in rainfed olive groves increases CO 2 emissions in the short term due to intensified biological activity, but at the same time improves soil fertility and biochemical functionality. However, long-term monitoring is required to determine whether these systems contribute to carbon stabilization and net sequestration, ensuring their potential as sustainable strategies for climate change mitigation in Mediterranean agroecosystems.

Soil characteristics have a decisive influence on theleakage behaviorof hydrogen-blended natural gas pipelines, the gas migration and diffusionlaws, and the hazard range. However, existing studies are mostly limitedto idealized and homogeneous soil conditions, failing to truly reflectthe key restrictive role of the complex heterogeneity of backfillsoil on the leakage and diffusion process. At the same time, thereis a significant deviation between the diffusion mode of the leakedgas and the simulation results under normal homogeneous soil conditions.To obtain the physical property parameters of soil heterogeneity,this study adopted soil ring knife tests combined with the kerneldensity estimation (KDE) method for actual measurements, and usedthe heterogeneous soil parameters to modify the leakage model of buriedhydrogenated natural gas (HBNG). The research results show that theheterogeneity of soil significantly affects the diffusion of leakedgas. The horizontal diffusion range of gas in backfill soil is 0.44m higher than that in typical loam soil and 0.28 m higher than thatin typical sandy soil; with the increase of hydrogen blend ratio (HBR),the mass flow rate of gas in backfill soil shows a downward trend;the average relative error between the gas mass flow rate predictionmodel established based on soil heterogeneity characteristics andthe simulation results is 1.24%. The results of this study can providenumerical reference basis for the optimization of actual engineeringschemes.

Accumulation of Radon in groundwater from aquifer lithologies can pose significant health risks. This study investigates its concentration in coastal Alappuzha from the Kerala state in India to assess health risks from ingestion and inhalation in groundwater samples of both the pre-monsoon and post-monsoon seasons. The activity(RAD7detector)in post-monsoon samples remained relatively higher (2.59–66.46 Bq/L; average:20.25 Bq/L) compared to the pre-monsoon (1.63–46.38 Bq/L; average: 13.78 Bq/L), reflecting the effect of precipitation on enhanced Radon contamination. However, the samples presently do not exceed the World Health Organization recommended maximum value (100 Bq/L). Relatively higher average radiation doses for stomach and lungs (6.12–6.20 Svy-1) in post-monsoon samples compared to pre-monsoon (4.12–4.22 Svy-1) show more exposures in the post-monsoon season. Our estimations of the total effective dose from two different pathways provide valuable baseline data on radon exposure in a coastal region of India, where health risks could increase due to higher precipitation and more frequent heavy rainfall events in the near future. Such conditions may enhance groundwater recharge and promote the downward migration of radon-rich soil gases into aquifers, potentially elevating radon concentrations, particularly in uranium-bearing lithological settings.

Radon, a naturally occurring radioactive gas produced from the decay of uranium in the subsurface, migrates upward through soil by diffusion and advection before being released into the atmosphere. As the second leading cause of lung cancer after smoking, understanding its behavior in the near-surface environment is essential for assessing environmental radiation risks. This study investigates depth-wise radon concentrations in soil gas, surface exhalation rates, and transport parameters in the soil ofChakrata region, Garhwal Himalaya, India. Radon measurements were performed using a portable Smart RnDuo monitor at depths (Z) of 15, 30, and 45cm. Soil-gas radon concentrations ranges from 237 to 6540Bqm-3 at 15cm, 854 to 7831Bqm-3 at 30cm, and 1020 to 8540Bqm-3 at 45cm, indicating a systematic increase with depth. Surface exhalation rates varies between 1.25 and 16.19Bqm-2h-1, with a mean value of 6.42Bqm-2h-1, respectively. Radon transport parameters were derived using Fick's diffusion model, resulting in average values of 0.49m for diffusion length (ls) and 0.002 m2s-1 for diffusion coefficient (Ds). Spearman's rank correlation analysis revealed that surface radon exhalation and diffusion parameters exhibit strong correlations. These findings provide baseline information on radon mobility and soil-gas dynamics in the region and will support future radon hazard assessment and environmental monitoring efforts in the Chakrata area of the Lesser Indian Himalaya.