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Biodegradable plastic mulch is potentially a suitable alternative to conventional polyethylene mulch because of the limited disposal options of the latter. However, biodegradable plastic mulch must perform better or comparably to polyethylene mulch to be widely adopted. Gas exchange and soil microclimate are important factors impacted by the use of plastic mulch, which in turn have implications on crop productivity. A controlled-environment study was established in a greenhouse to assess gas exchange and soil microclimate dynamics under biodegradable plastic, polyethylene, and paper mulches with and without planting holes, as well as the impact of the mulches on the growth of sweet corn (Zea mays). A no-mulch condition was included as control. In addition, we monitored CO2 concentrations in the vicinity of planting holes (chimney effect) in a greenhouse and agricultural field conditions under sweet corn production. The plastic mulches (both biodegradable plastic and polyethylene mulches) decreased the soil O2 concentration to a minimum of 181-183 mmol mol–1, and when compared to the no-mulch, the plastic mulches reduced water loss within 50 days by 35-68 mm. The paper mulch inhibited light penetration more than did the plastic mulches. There was an increase in the CO2 concentration at 2.5 cm above the planting holes in the plastic mulches compared to that under the no-mulch. The plastic mulches (both biodegradable plastic and polyethylene mulches) decreased the soil growth of sweet corn, possibly, because the canopy height of sweet corn was more than 15 cm within a few days after planting. Overall, the plastic mulches did not reduce O2 concentration below 100 mmol mol–1, the minimum level at which plant growth becomes impaired. Also, the often reported improved growth of sweet corn from plastic mulching could be attributable to other factors, such as weed control, reduced water loss, and early season soil warming, rather than elevated CO2 concentrations and fluxes in the vicinity of planting holes. [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]

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]

The Jiangmen Underground Neutrino Observatory is constructing the world's largest liquid scintillator detector, with a 20 kt target mass and approximately 700 m of overburden. The total underground space of civil construction is around 300,000 m 3 , with the main hall comprising about 120,000 m 3 , making it the largest experimental hall in the world. Maintaining a low radon concentration in the underground air is crucial for both human health and the accuracy of experiments involving rare decay detection, such as neutrino and dark matter experiments. To ensure human health and the integrity of neutrino physics experiments, the nominal radon concentration in the main hall must be kept below 200 Bq/m 3 with a maximum value below 400 Bq/m 3 . Introduction of fresh air from above ground can significantly lower radon concentration. A benchmark experiment conducted in the refuge room near the main hall revealed that the radon emanating from underground water is a significant source of radon in the underground air. The total underground ventilation rate is approximately 160,000 m 3 /h of fresh air with about 30 Bq/m 3 222 Rn from the bottom of the vertical tunnel after the installation of powerful fans. Of this, 55,000 m 3 /h is used for ventilation in the main hall. As a result of these measures, the radon concentration inside the main hall has decreased from 1600 Bq/m 3 to below 200 Bq/m 3 under stable working conditions, with exceptions during rare adverse weather events or fan failures. The employed strategies to control radon concentration in the underground air are described in this paper. [ABSTRACT FROM AUTHOR]

Splash erosion, the first step in water erosion process, occurs because of raindrops collusion with soil aggregates and pushing soil particulates into the air. The objective of this study was to test the usability of water sensitive paper (WSPs) in assessment of splash erosion. Soil losses from three texturally different soils by splash erosion were determined under artificial rainfall conditions as a function of splash distance and direction. The results indicated that the amount of soil removed by splash erosion was significantly affected by soil texture, splash direction and distance, and was the highest in clay soil and the lowest in sandy loamy soil. About half of the splashed soil material moved down slope, 34% in the lateral direction, and 17% moved upslope. A significant positive correlation between the WSPs-D10 diameter and the WSPs-surface coverage rate was obtained, which indicates that the higher the D10 diameter, the higher the surface coverage rate. The results obtained in this study reveal that the WSPs cards could successfully be used and its parameters (WSPs-D10 diameter and WSPs-surface coverage rate) might be considered as a new approach in assessing and evaluating splash erosion. [ABSTRACT FROM AUTHOR]

Effective diffusion is an important macroscopic property for assessing transport in porous media. Numerical computations on segmented 3D CT images yield precise estimates for diffusive properties. On the other hand, geometrical descriptors of pore space such as porosity, specific surface area and further transport-related descriptors can be easily computed from 3D CT images and are closely linked to diffusion processes. However, the investigation of quantitative relationships between these descriptors and diffusive properties for a diverse range of porous structures is still ongoing. In the present paper, we consider three different soil samples of each loam and sand for a total of six samples, whose 3D microstructure is quantitatively investigated using univariate as well as bivariate probability distributions of geometrical pore space descriptors. This information is used for investigating microstructure–property relationships by means of empirically derived regression formulas, where a particular focus is put on the differences between loam and sand samples. Due to the analytical nature of these formulas, it is possible to obtain a deeper understanding for the relationship between the 3D pore space morphology and the resulting diffusive properties. In particular, it is shown that formulas existing so far in the literature for predicting soil gas diffusion can be significantly improved by incorporating further geometrical descriptors such as geodesic tortuosity, chord lengths, or constrictivity of the pore space. The robustness of these formulas is investigated by fitting the regression parameters on different data sets as well as by applying the empirically derived regression formulas to data that is not used for model fitting. Among others, it turns out that a formula based on porosity as well as mean and standard deviation of geodesic tortuosity performs best with regard to the coefficient of determination and the mean absolute percentage error. Moreover, it is shown that regarding the prediction of diffusive properties the concept of geodesic tortuosity is superior to geometric tortuosity, where the latter is based on the creation of a skeleton of the pore space. [ABSTRACT FROM AUTHOR]

The occurrence of sinkhole phenomena in Italy is a prevalent and very uncertain class of geological hazards that pose a significant threat to human infrastructure and individuals. These events are characterized by their unpredictability and the challenges associated with their accurate forecasting. Both natural and anthropic factors influence the occurrence of these events; therefore, accurate identification of the above factors is critical for effective proactive and predictive efforts. The work presented in this paper refers to a collapse that occurred in a volcanic region in northern Latium (central Italy) on 31 January 2023. The area has been monitored using drones since the early stages of the sinkhole's formation and has continued to date. Then, the collapse and the neighboring area were examined via geophysical and geochemical investigations to identify potential underlying factors. Geophysical and geochemical data were combined to provide a preliminary hypothesis on the collapse's genesis. The obtained data indicate that the structural collapse can be attributable to the fluctuation in groundwater levels as well as the development of instabilities along its banks, leading to a growth in its dimensions. [ABSTRACT FROM AUTHOR]

This paper presents a triggering factor causing landslide in stable gentle soil slope. The triggering factor is a small mass of pressurized pore gas in the soil slope and illustrated with a flume soil slope model. The pore gas has a small mass of oxygen and is generated via the injection of a small volume of H2O2 solution into the cement powder core of the soil slope. The core is covered by a layer of saturated soft clay that forms a trap for the new pore gas to build its pore gas pressure. The pore gas pressure is the driving force to cause the landslide in the stable gentle soil slope. The mass of the pore gas is smaller than 0.1% of the mass of either the gentle soil slope or the landslide body. The videos of the landslide are captured and used for the analysis of movement and displacement of the sliding soil mass with time. The pressure of the pore gas is estimated from the acceleration model of the sliding soil mass. A calibration test is further carried out for the generation of the oxygen gas mass and pressure via the decomposition of the H2O2 solution in cement powder. The results quantitatively demonstrate that the small mass of the oxygen gas in the voids of the cement powder core can have enough pressure to trigger the landslide in the stable gentle soil slope model. Such pressurized pore gas triggering factor is generally not noticeable since its mass can be very small and disappear rapidly without a trace. This triggering factor could be responsible for the huge and disastrous landslide that suddenly and dramatically occurred in a huge gentle fill soil slope on December 20, 2015, at Hengtaiyu Industrial Park, Shenzhen, China. [ABSTRACT FROM AUTHOR]

Expansive soils change volume due to changes in moisture content, which results in ground movement. Lightweight shallow-depth structures such as pavements, residential footings, and pipelines can suffer distress as they face additional stresses from the moving ground. The soil reactivity (the ability of soil to expand or contract due to change in moisture content) and the interactions at the soil-atmosphere-vegetation boundary are two of the major contributing factors to the ground movement. The current methodology used in design to account for ground movement is based on limited field and laboratory observations. Aiming at a better understanding of the interaction at the soil-atmosphere-vegetation boundary and its correlation with ground movement, this paper presents results from a field study. The research site was located in a semi-arid climate area and consisted of moderately to highly reactive clay soils. Part of the site was vegetated with mature trees, and part was occupied by grass. The order of 10 s of mm difference was observed in the magnitude of movement across the site owing to site soil variability as well as differences in vegetation. The areas with large trees showed relatively lower ground movement over the study period compared to the area occupied by grass, which was attributed to the microclimate created by the tree canopy and the already established deeper drying of the soil near the trees. [ABSTRACT FROM AUTHOR]

OpenToolFlux 1.0 is an open-source software designed to estimate soil gas fluxes from gas concentration time-series data generated by automatic chamber systems. This paper describes the physical equipment used as well as the software design and workflow. The software is a command-line application that imports tabular time-series data from the analyzer following the instructions specified in a configuration file by the user, performs configurable data-cleaning operations, and outputs a data file with volumetric flux estimates as well as diagnostic plots. The software can be configured according to the specifics of the physical equipment and experimental setups, and it is, therefore, applicable to a wide range of studies. [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]

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]

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]

Agriculture is the primary food source for humans and livestock in the world and the primary source for the economy of many countries. The majority of the country's population and the world depend on agriculture. Still, at present, farmers are facing difficulty in dealing with the requirements of agriculture. Due to many reasons, including different and extreme weather conditions, the abundance of water quality, etc. This paper applied the Internet of Things and deep learning system to establish a smart farming system to monitor the environmental conditions that affect tomato plants using a mobile phone. Through deep learning networks, trained the dataset taken from PlantVillage and collected from google images to classify tomato diseases, and obtained a test accuracy of 97%, which led to the publication of the model to the mobile application for classification for its high accuracy. Using the IoT, a monitoring system and automatic irrigation were built that were controlled through the mobile remote to monitor the environmental conditions surrounding the plant, such as air temperature and humidity, soil moisture, water quality, and carbon dioxide gas percentage. The designed system has proven its efficiency when tested in terms of disease classification, remote irrigation, and monitoring of the environmental conditions surrounding the plant. And giving alerts when the values of the sensors exceed the minimum or higher values causing damage to the plant. The farmer can take the appropriate action at the right time to prevent any damage to the plant and thus obtain a high-quality product. [ABSTRACT FROM AUTHOR]

Plant leaf temperature and its environmental parameters provide valuable information on plant growth. This paper presents the development of a plant monitoring system using an IoT-based SCADA (Supervisory Control and Data Acquisition). The developed SCADA system monitors the leaf temperature and the air parameters of temperature and humidity, as well as the soil parameters of temperature, moisture, pH, electrical conductivity, nitrogen, phosphorous, and potassium. A novel method is proposed for measuring the leaf temperature using a low-cost 8 × 8 array thermal camera. The sensor systems in the field are developed to wirelessly communicate with the Hawell IoT Cloud HMI via a Modbus TCP protocol. To visualize the thermal image on the HMI dashboard, a novel approach is proposed wherein the data are transferred using the Modbus TCP protocol. The HMI is connected to a cloud server and can be accessed by the users using the web browser or mobile application on a smartphone. The experimental results show that the proposed hardware, software, and communication protocol are reliable for real-time and continuous plant monitoring. Further, the evaluation of sensor data shows that the data from the thermal camera and air parameters sensor can be independently interpreted. However, the data from the soil sensor should be interpreted in consideration of the other parameters. [ABSTRACT FROM AUTHOR]

In peatlands drained for forestry, the soil carbon (C) or carbon dioxide (CO 2) balance is affected by both (i) higher heterotrophic CO 2 -C release from faster decomposing soil organic matter (SOM) and (ii) higher plant litter C input from more vigorously growing forests. This balance and other greenhouse gas (GHG) sinks and sources in managed lands are annually reported by national GHG inventories to the United Nations Climate Change Convention. In this paper, we present a revised, fully dynamic method for reporting the CO 2 balance of drained peatland forest soils in Finland. Our method can follow temporal changes in tree biomass growth, tree harvesting and climatic parameters, and it is built on empirical regression models of SOM decomposition and litter input in drained peatland forests. All major components of aboveground and belowground litter input from ground vegetation as well as live trees and trees that died naturally are included, supplemented by newly acquired turnover rates of woody plant fine roots. Annual litter input from harvesting residues is calculated using national statistics of logging and energy use of trees. Leaching, which also exports dissolved C from drained peatlands, is not included. The results are reported as time series from 1990–2021 following the practice in the GHG inventory. Our revised method produces an increasing trend of annual emissions from 0.2 to 2.1 t CO 2 ha -1 yr -1 for the period 1990–2021 in Finland (equal to a trend from 1.4 to 7.9 Mt CO 2 yr -1 for the entire 4.3 Mha of drained peatland forests), with a statistically significant difference between the years 1990 and 2021. Across the period 1990–2021, annual emissions are on average 1.5 t CO 2 ha -1 yr -1 (3.4 Mt CO 2 yr -1 for 2.2 Mha area) in warmer southern Finland and - 0.14 t CO 2 ha -1 yr -1 (- 0.3 Mt CO 2 yr -1 for 2.1 Mha area) in cooler northern Finland. When combined with data on the CO 2 sink created by the growing tree stock, in 2021 the drained peatland forest ecosystems were a source of 1.0 t CO 2 ha -1 yr -1 (2.3 Mt CO 2 yr -1) in southern Finland and a sink of 1.2 t CO 2 ha -1 yr -1 (2.5 Mt CO 2 yr -1) in northern Finland. We compare these results to those produced by the semi-dynamic method used earlier in the Finnish GHG inventory and discuss the strengths and vulnerabilities of the new revised method in comparison to more static emission factors. [ABSTRACT FROM AUTHOR]

This paper presents the measurement results of environmental radioactivity levels for Şebinkarahisar district (uranium–thorium area), Giresun, Turkey. The radioactivity concentrations of 238 U, 232 Th, 40 K and the fission product 137 Cs in soil samples collected from 73 regions from the surroundings of the study area were determined. In situ measurements of the gamma dose rate in air were performed in the same 73 locations where the soil samples were collected using a portable NaI detector. Also the mean radioactivity concentrations of 238 U, 232 Th and 40 K in rock samples collected from 50 regions were determined. The mean estimated cancer risk value was found. The seasonal variations of the indoor radon activity concentrations were determined in the 30 dwellings in the study area. In addition, the mean gross alpha, gross beta and radon activities in tap water samples were determined in the same 30 dwellings. The excess lifetime cancer risk was calculated using the risk factors of International Commission on Radiological Protection and Biological Effects of Ionizing Radiation. Radiological maps of the Şebinkarahisar region were composed using the results obtained from this study. [ABSTRACT FROM AUTHOR]

Odor emission from the soil of pesticide-contaminated sites is a prominent environmental problem in China, but there are very few researches about the component and spatial distribution of odorous substances in the soil of contaminated sites. In this paper, to investigate the odor pollution condition of an organophosphorus pesticide production site in a city of South China, the odor pollutants in the soil and soil gas were analyzed and the key odor–contributing substances were identified. Besides, the correlation between the concentrations of odorous substances in soil and soil gas was analyzed, and the measured results were compared with the predicted results by the linear model and DED model. An off-line soil gas sampling device was designed to collect the gas emitted from soil because the groundwater level in the site was too shallow to build a soil gas well. The key odor substances were screened from the detection results of soil gas via odor activity value (OAV) analysis, which revealed that the key odorous substances included benzene, ethylbenzene, ammonia, toluene, m,p-xylene, methyl sulfide, dimethyl disulfide, and formaldehyde. Furthermore, the spatial distribution of the odor substances in the soil of the pesticide-contaminated site was closely related to the layout and geologic structure of the site. The odor pollutants in soil were mainly distributed near the phosmet production workshop and the drainage ditch network. As for the deep distribution, the odorous substances were mainly enriched in the silty clay or clay layer (5.6–11 m), followed by the sludge layer (1–3.6 m). Finally, the predicted model (linear model and DED model) analysis suggested that the linear model was more suitable for predicting the concentration of odorous substances in the soil gas with the detection data of soil in this pesticide-contaminated site. [ABSTRACT FROM AUTHOR]

The soil-air exchange behavior of persistent organic pollutants (POPs) plays a significant role in the distribution and fate in the two phases. This paper summarizes the selective behaviors of typical POPs contaminants and their homologues and isomers in soil-air exchange from the four aspects: sampling techniques, fugacity models, exchange directions and fluxes, as well as influencing factors. Dichlorodiphenyltrichloroethane (DDTs) and their metabolites o, p'-DDT ... p,p.-DDD show the trend of net deposition from various studies. α-, β- hexachlorocyclohexane (HCHs) prefers to migrate from soil to atmosphere than γ-, δ- HCH. Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) with lower molecular weight compounds are generally volatilized to the atmosphere. Polybrominated diphenyl ethers (PBDEs) with low bromination degree have higher liquidity. Compared with other organophosphorus flame retardants, tributyl phosphate has a higher volatilization trend. For the novel pollutants, the exchange fluxes of perfluorooctanesulfonate (PFOS) and short-/medium-chain chlorinated paraffins (CPs) have been reported. The direction of soil-air exchange is also affected by temperature and soil organic carbon content. [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]

This paper presents a novel theoretical and numerical approach for an infinitesimal current source (ICS) located in a planar isotropic multilayer medium. Using the mixed-potential integral equation (MPIE) formulation for depicting the electromagnetic disturbance created by the ICS, a detailed definition of Green's functions of Lorenz potentials and fields is provided in this paper. The proposed Green's functions are valid for the considered multilayer isotropic medium, which can have arbitrary layer parameters. This paper also analyzes two commonly observed special cases of the multilayer medium | the multilayer soil including air and the multilayer lossless dielectric | and the proposed equations are modified to meet the requirements of the medium. Green's functions can be obtained from the systems of linear equations proposed in this study. In comparison to other approaches, the advantage of the proposed procedure is that the solutions of the equations are immediately obtained in any field layer of the multilayer medium. In addition, the proposed system of linear equations can be solved easily using well-known numerical computation methods. Furthermore, this paper offers an alternative way of obtaining Green's functions, which are closed-form expressions for the kernels of spectral-domain Green's functions. [ABSTRACT FROM AUTHOR]

This review paper aims at understanding natural and anthropogenic sources of rare earth elements (REEs) in the environment, their mechanisms of action, individual toxicity of REEs, and individual toxicity of their mixtures, including with other toxicants. We also summarized the scientific knowledge on REE bioaccumulation by plants, animals, and fungi. The purpose of the work was to analyze published scientific information and identify unsolved scientific issues in the selected areas. At present, both natural positive geochemical anomalies of REEs and "spots" of anthropogenic origin are discovered. There is a relationship between natural and anthropogenic sources of REEs in the environment. Increasing REE mining leads to the exposure of rock layers rich in target elements, which are then leached from natural and waste rocks. As a result, the total content of REEs in soils of their extraction areas reaches 2.3 µg/kg, and in the snow of cities it ranges from 0.411 to 1.463 µg/kg, which is comparable with natural anomalies of elements. Most often such levels of REE accumulation are not dangerous for biota. REEs, like many trace elements, have an essential effect in low concentrations and have harmful effects only when the dose is increased. However, stimulation effects proven for agricultural plants and animals in the natural environment can influence the change in population and community structures. The effects of REE compounds have many uncertainties under the conditions of their joint action with each other and with other substances containing biogenic or potentially toxic elements. The article provides examples of additive, synergistic, and antagonistic actions of a mixture of elements. Further, it is shown that the bioaccumulation of REEs is comparable to the accumulation of heavy metals in living organisms. Data on the transfer of REEs along trophic chains are single and contradictory. Thus, REEs contribute to the toxic load on living organisms. The main "blank spots" in knowledge about the action of REEs that require further research are identification of the most sensitive and vulnerable species, establishment of long-term effects and clarification of the joint action of REEs with other substances. [ABSTRACT FROM AUTHOR]

In the search for precursors to earthquakes, correlation has been found between geochemical characteristics of soil gases and seismic activity. In this paper we present evidence that seismic waves can trigger emission of soil radon (Rn) and carbon dioxide (CO2). An active experiment was performed in two fault zones in China, the Annighe fault in Sichuan province and the Xiadian fault in Heibei province. An active seismic source was used to generate seismic waves at 10 m depth in wells within bedrock. Rn and CO2 detectors were placed around the wells at a distance of ∼1 m for observing the effects of the seismic waves on the emission of the gases. The observations confirm that the seismic waves have a significant and direct effect on the concentration and flux of soil radon and carbon dioxide. When the seismic events were triggered, the observed concentrations of Rn and CO2 immediately increased and reached peak values within 5–50 min and 30–60 min, with corresponding increases of Rn and CO2 concentrations by 10.5%–238.7% and 3.1%–54.1%, respectively. The measured concentrations and flux of CO2 and Rn after the passage of the seismic waves showed strong correlation, confirming the suggestion that CO2 is the carrier gas for Rn. To the best of our knowledge this is the first direct, in‐situ measurement of gas emission caused by the passage of seismic waves and provides important constraints for better understanding of geochemical earthquake precursors. Plain Language Summary: Observed geochemical properties of soil gases migrated from the deep Earth can be used to survey seismicity, volcanic activity and emission of greenhouse gases. However, due to difficulty in natural earthquake prediction, most observations on the geochemical effects linked to seismic activity are conducted after or away from naturally occurring events, with the effects normally inferred from seismic parameters. In this study, an active seismic source based on methane gaseous detonation was employed to artificially produce seismic events along two fault zones, and in‐situ measurements of concentrations and flux of radon (Rn) and carbon dioxide (CO2) were conducted. These observations showed strong correlation between concentrations and flux of CO2 and Rn after the events, in agreement with the hypothesis that CO2 is the carrier gas for Rn in tectonically active settings. Key Points: Soil CO2 and Rn emission triggered by a new type active source that excited at 10 m deep well in bedrock are observed at first timeQuantitative effect of seismicity on the concentration and flux of soil CO2 and Rn are presentedEmission of CO2 and Rn after the seismicity show strong correlation and proved that CO2 is the carrier gas for Rn [ABSTRACT FROM AUTHOR]

Abstract—The results of a three-dimensional numerical simulation of the oblique impacts of ten-kilometer asteroids at an angle of 45° onto a solid surface and into an ocean with a depth of 1 to 6 km are presented. The maximum masses of water, impactor, and soil ejected into the atmosphere and the masses of water, impactor material, and soil remaining in the atmosphere 10 min after the impact are calculated. The mass of vaporized ejecta is determined. It is shown that there are 2–5 times more impactor material and soil ejected into the atmosphere during oblique impacts than during vertical impacts. [ABSTRACT FROM AUTHOR]

Rainforests play an important role in hydrological and carbon cycles, both at regional and global scales. They pump large quantities of moisture from the soil to the atmosphere and are major rainfall hotspots of the world. Satellite-observed stable water isotope ratios have played an essential role in determining sources of moisture in the atmosphere. Satellites provide information about the processes involving vapour transport in different zones of the world, identifying sources of rainfall and distinguishing moisture transport in monsoonal systems. This paper focuses on major rainforests of the world (Southern Amazon, Congo and Northeast India) to understand the role of continental evapotranspiration in influencing tropospheric water vapour. We have used satellite measurements of 1H2H16O/1H216O from Atmospheric InfraRed Sounder (AIRS), evapotranspiration (ET), solar-induced fluorescence (SIF), precipitation (P), atmospheric reanalysis-derived moisture flux convergence (MFC) and wind to discern the role of ET in influencing water vapour isotopes. A global map of the correlation between δ2Hv and ET-P flux indicates that densely vegetated regions in the tropics show the highest positive correlation (r > 0.5). Using mixing models and observations of specific humidity and isotopic ratio over these forested regions, we discern the source of moisture in pre-wet and wet seasons. [ABSTRACT FROM AUTHOR]

This study was conducted to examine the relationship between 222Rn/220Rn activity concentration in soil gas and proxies within each soil type in Johor state, Malaysia, and identify the best possible predictor of 222Rn/220Rn in soil gas. In this paper, we present the result of correlation analysis between measured 222Rn/220Rn in soil gas and soil gas permeability, geogenic radon potential, 222Rn/220Rn in outdoor air, and terrestrial gamma dose, as well as the recorded relative humidity and temperature during measurement. The measured 222Rn and 220Rn in soil gas were found to have a positive correlation with the soil gas permeability measured within the study area, except for the data measured in a region covered with the marine alluvium and peat soils where a negative and very weak correlation was observed between 220Rn in soil gas and (Rn220S) and sol gas permeability, respectively. Measurement over four soil types (from granitic rocks, soils from metamorphic and sedimentary rocks, soils of steep lands, and soils of urban and mined land) reveals that the terrestrial gamma dose rate is a possible predictor of 220Rn in soil gas. In addition, in a region covered with a soil of steep lands and soils of urban and mined lands, 222Rn and 220Rn in outdoor air were found to be good indicators of 222Rn and 220Rn in soil gas. The result of principal component analysis yields a four-component representation of the total data acquired with 71% of the total variance explained, while the dendrogram of the resulting hierarchical cluster analysis categorizes the measured data into four clusters which are in good agreement with the result of principal component analysis. [ABSTRACT FROM AUTHOR]

This paper provides a description of ICLASS 1.1, a variational Inverse modelling framework for the Chemistry Land-surface Atmosphere Soil Slab model. This framework can be used to study the atmospheric boundary layer, surface layer, or the exchange of gases, moisture, heat, and momentum between the land surface and the lower atmosphere. The general aim of the framework is to allow the assimilation of various streams of observations (fluxes, mixing ratios at multiple heights, etc.) to estimate model parameters, thereby obtaining a physical model that is consistent with a diverse set of observations. The framework allows the retrieval of parameters in an objective manner and enables the estimation of information that is difficult to obtain directly by observations, for example, free tropospheric mixing ratios or stomatal conductances. Furthermore, it allows the estimation of possible biases in observations. Modelling the carbon cycle at the ecosystem level is one of the main intended fields of application. The physical model around which the framework is constructed is relatively simple yet contains the core physics to simulate the essentials of a well-mixed boundary layer and of the land–atmosphere exchange. The model includes an explicit description of the atmospheric surface layer, a region where scalars show relatively large gradients with height. An important challenge is the strong non-linearity of the model, which complicates the estimation of the best parameter values. The constructed adjoint of the tangent linear model can be used to mitigate this challenge. The adjoint allows for an analytical gradient of the objective cost function, which is used for minimisation of this function. An implemented Monte Carlo way of running ICLASS can further help to handle non-linearity and provides posterior statistics on the estimated parameters. The paper provides a technical description of the framework, includes a validation of the adjoint code, in addition to tests for the full inverse modelling framework, and a successful example application for a grassland in the Netherlands. [ABSTRACT FROM AUTHOR]

A tremendous volumetric increase in waste marble powder as industrial waste has recently resulted in high environmental concerns of water, soil and air pollution. In this paper, we exploit the capabilities of machine learning to compressive strength prediction of concrete incorporating waste marble powder for future use. Experimentation has been carried out using different compositions of waste marble powder in concrete and varying water binder ratios of 0.35, 0.40 and 0.45 for the analysis. Effect of different dosages of superplasticizer has also been considered. In this paper, different regression algorithms to analyse the effect of waste marble powder on concrete, viz., multiple linear regression, K-nearest neighbour, support vector regression, decision tree, random forest, extra trees and gradient boosting, have been exploited and their efficacies have been compared using various statistical metrics. Experiments reveal random forest as the best model for compressive strength prediction with an R2 value of 0.926 and mean absolute error of 1.608. Further, shapley additive explanations and variance inflation factor analysis showcase the capabilities of the best achieved regression model in optimizing the use of marble powder as partial replacement of cement in concrete. [ABSTRACT FROM AUTHOR]

Greenhouse technology is a way to improve crop production. Technology has advanced swiftly in the fields of agriculture and food production and is still paving the way for the optimization and achievement of maximum plant growth. In the current age of Android smartphone applications, a precise mechanism would undoubtedly bring about change. The Internet of Things (IoT) is one of the latest achievements in the field of information and communication technologies, providing global communication and control of sensors, devices, and users with information. This paper proposes a greenhouse monitoring and control system using IoT. The temperature sensor, air quality sensor, soil moisture sensor, Light Dependent Resistors (LDR) sensor, Liquid-Crystal Display (LCD) module, 12-volt Direct Current (DC) fan, electric bulb, water pump motor, and the servo motor with the Internet of Things (IoT) technology make up this greenhouse's monitoring and control system to measure nitrous oxide, temperature, humidity, illumination, CO, and irrigation to create a plant-2 friendly atmosphere. The farmers may use the IoT platform to receive the collected environmental parameter data to their smartphones in online mode so they can make the correct decisions without visiting the field. [ABSTRACT FROM AUTHOR]

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This paper reports the analysis of soil radon data collected from March 2013 to July 2016. LR-115 Type II solid-state nuclear track detectors were deployed to determine the concentration of radon in the soil at a depth of 80 cm. The data on soil radon were collected using the integrated measurement technique over a 7-day period. Soil radon is affected by environmental parameters in addition to geophysical phenomena. To study the effect of the environmental parameters on the measured radon data, we have performed the analysis of soil radon with the environmental parameters using the ARIMA model. We have used the ARIMA (2,0,2) model to calculate the predicted value of soil radon. The predicted value of radon obtained from the model was primarily due to variations in environmental parameters. Therefore, we calculate the difference (residual) between the actual and predicted values of radon and correlate it with the seismic events that occurred around the investigation area. An anomalous variation in the residual radon was recorded a few days prior to the M5.4 earthquake, which occurred at a distance of 123.9 km from the study area. [ABSTRACT FROM AUTHOR]

Gas diffusion is an important process in thermo-hydro-mechanical coupled problems of unsaturated soils, e.g., nuclear waste repositories or heated pipeline engineering, which usually strongly affects process of liquid water evaporation and water vapor condensation, migration of air and water, heat transfer, and skeleton deformation. This paper develops a simple model to assess the effects of gas diffusion on multifield coupled process of unsaturated soils, providing predicting guidance and uniform judgment rather than establishing a numerical coupled model by the traditional methods. A dimensionless characteristic number is first proposed and expressed by sediment properties and environmental conditions. Rationality of this characteristic number is then assessed and validated by numerical results, and studies indicated that the gas diffusion is crucial when the characteristic number exceeds a critical one, which is reflected in early valleys of gas/liquid pressure and effective stresses/strains induced by vapor condensation and the final maximum values. It can be found from the expression that this characteristic number is highly relevant to diffusion coefficient, permeability, temperature, initial saturation, and gas pressure. Parametric studies indicate that gas diffusion appears to be critical for unsaturated clayey soils, provided that the diffusion coefficient is larger than 10–7 m2/s and permeability smaller than 10–14 m2. The effect can be neglected for soils with diffusion coefficient lower than 10–9 m2/s or permeability greater than 10–14 m2. [ABSTRACT FROM AUTHOR]

Soil contamination with organic contaminants and various heavy metals has become a global environmental concern. Biochar application for the remediation of polluted soils may render a novel solution to soil contamination issues. However, the complexity of the decontaminating mechanisms and the real environment significantly influences the preparation and large-scale application of biochar for soil ramification. This review paper highlights the utilization of biochar in immobilizing and eliminating the heavy metals and organic pollutants from contaminated soils and factors affecting the remediation efficacy of biochar. Furthermore, the risks related to biochar application in unpolluted agricultural soils are also debated. Biochar production conditions (pyrolysis temperature, feedstock type, and residence time) and the application rate greatly influence the biochar performance in remediating the contaminated soils. Biochars prepared at high temperatures (800 °C) contained more porosity and specific surface area, thus offering more adsorption potential. The redox and electrostatic adsorption contributed more to the adsorption of oxyanions, whereas ion exchange, complexation, and precipitation were mainly involved in the adsorption of cations. Volatile organic compounds (VOCs), dioxins, and polycyclic aromatic hydrocarbons (PAHs) produced during biochar pyrolysis induce negative impacts on soil alga, microbes, and plants. A careful selection of unpolluted feedstock and its compatibility with carbonization technology having suitable operating conditions is essential to avoid these impurities. It would help to prepare a specific biochar with desired features to target a particular pollutant at a specific site. This review provided explicit knowledge for developing a cost-effective, environment-friendly specific biochar, which could be used to decontaminate targeted polluted soils at a large scale. Furthermore, future study directions are also described to ensure a sustainable and safe application of biochar as a soil improver for the reclamation of polluted soils. [ABSTRACT FROM AUTHOR]

Radon is an isotope gas that has no color or smell. According to the World Health Organization, it is the second most important cause of pulmonary cancer after the use of cigarette smoking. In this paper, we propose a new deep learning model to predict the radon (Rn-222) activity concentration in soil layers by combining different mechanisms of transport including diffusion, advection, decay and generation mechanisms. This work deals with the use of the so-called deep neural network to solve the transport equation described in a one-dimensional case under the effect of soil layer characteristics such as diffusion coefficient, porosity and initial radon concentration. In the first, This model is validated by the analytical solution. Then a comparison of the radon concentration by the analytical solution and the proposed deep learning model is performed and shows a good correlation. Three simulated and compared scenarios show that the generation and advection mechanisms can increase the radon activity concentration at the ground surface. [ABSTRACT FROM AUTHOR]

Soil radon anomaly is a common phenomenon in karst areas. In this paper, the geochemical behavior of radium (Ra) in the process of carbonate rock weathering and soil formation was used to reveal the accumulation mechanism of soil radon. In the karst area and non-karst area, 24 soil points were collected to measure radon and radium, and a carbonate weathering profile was collected in the karst area. The research showed that: (1) the theoretical radon value obtained from Ra is far greater than the radon value measured on site, indicating that soil Ra can provide a potential source for the source of soil Rn; (2) through the study of the geochemical behavior of Ra during the weathering process, it was found that Ra was significantly enriched during carbonate weathering. This paper deepened the understanding of the geochemical behavior of radionuclides (Ra, Rn) in karst environments. [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]

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]

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 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]

Boreal forests nowadays act as a sink for atmospheric carbon dioxide; however, their sequestration capacity is highly sensitive to weather conditions and, specifically to ongoing climate warming. Extreme weather events such as heavy rainfalls or, conversely, heat waves during the growing season might perturb the ecosystem carbon balance and convert them to an additional CO2 source. Thus, there is an urgent need to revise ecosystem carbon fluxes in vast Siberian taiga ecosystems as influenced by extreme weather events. In this study, we focused on the soil CO2 pulses appearing after the rainfall events and quantification of their input to the seasonal cumulative CO2 efflux in the boreal forests in Central Siberia. Seasonal measurements of soil CO2 fluxes (both soil respiration and net soil exchange) were conducted during three consecutive frost-free seasons using the dynamic chamber method. Seasonal dynamics of net soil exchange fluxes demonstrated positive values, reflecting that soil respiration rates exceeded CO2 uptake in the forest floor vegetation layer. Moreover, the heavy rains caused a rapid pulse of soil emissions and, as a consequence, the release of additional amounts of CO2 from the soil into the atmosphere. A single rain event may cause a 5–11-fold increase of the NSE flux compared to the pre-rainfall values. The input of CO2 pulses to the seasonal cumulative efflux varied from near zero to 39% depending on precipitation patterns of a particular season. These findings emphasize the critical need for more frequent measurements of soil CO2 fluxes throughout the growing season which capture the CO2 pulses induced by rain events. This approach has inevitable importance for the accurate assessment of seasonal CO2 soil emissions and adequate predictions of response of boreal pine forests to climatic changes. [ABSTRACT FROM AUTHOR]

Environmental crime poses a serious threat to security in general, and to the protection of the environment and nature in particular. There are a number of illegal activities that greatly pollute all ecosystems, water, soil and air, and thus can directly cause serious and severe consequences for the health of the entire living world. As a result of pollution and other harmful effects, human life is endangered, but also the flora and fauna. Numerous bodies and institutions within their competencies and authorities undertake measures and activities for prevention and repression of environmental crimes. These include the criminal police, uniformed police, inspectorates, judicial bodies, but customs also play an important role in combating environmental crime, both nationally and internationally. Namely, most often this type of crime is cross-border, with international characteristics and that is why the Customs Administration of the Republic of North Macedonia has an important role in finding out, proving and clarifying these crimes. Internationally, a number of special operations to combat environmental crimes are being undertaken by Interpol, Europol, and the World Customs Organization. The authors of the paper review the environmental crime and the manner in which the competent authorities in the Republic of North Macedonia are engaged in its suppression, with special reference to the Customs Administration, but also present information on the role of the World Customs Organization in combating this type of crime. [ABSTRACT FROM AUTHOR]

This paper discusses the possibility of using a new graphene-based monolith material developed at the Department of Chemistry, Moscow State University, for the identification of new oil deposits or offshoots adjacent to already registered oil fields in the course of areal geochemical surveys. Sorption of volatile organic compounds (VOCs) from soil air within an oil field was performed using two sorbents (Tenax-TA traditionally used in such analytical tests and a carbon adsorbent) with subsequent gas chromatographic determination involving mass spectrometric detection and thermal desorption as a way of sample injection (TD/GC/MS). The new material absorbs more hydrocarbons (n-alkanes and monoaromatics) in the C8–C16 range than Tenax-TA, and its chromatographic peaks are more intense. The irreversible sorption phenomenon is observed for VOCs starting from C17 and higher; however, the concentrations of such substances in soil air are low owing to the low pressure of their saturated vapors under normal conditions. Overall, chromatograms obtained using the carbon monolith reflect the oilfield characteristics better compared to Tenax-TA. To enhance the sensitivity of determination, the thermal desorption conditions were optimized: the helium flow rate through the sorbent sample and the compound desorption time were adjusted to ensure the maximum peak area. The regeneration procedure was applied to the sorbent samples with the purpose of reusing them. Unlike the carbon monolith, Tenax-TA cannot be completely purified since it decomposes into its components at lower temperatures that the carbon monolith. Overall, the new graphene-based sorbent is not only reusable but also much cheaper than the imported polymer Tenax-TA since it is produced using only domestic materials. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are emitted to the atmosphere by various anthropogenic activities as well as natural sources, they undergo long-range transport, are degraded (e.g., by photolysis) and finally they are deposited onto the surface and potentially accumulate in topsoil. The dry deposition of particle-bound PAHs dominates the accumulation of PAHs in soil and their further fate in soil is governed by sorption/desorption from these airborne particles. This paper offers an overview on concentrations of particle-bound PAHs, the dry deposition fluxes and finally concentrations of PAHs in soil. In addition, spatial and temporal variations of PAHs are considered. The results show that concentrations of particle-bound PAHs typically range from 1 mg g−1 up to 10 mg g−1 in cities with coal-based heating in winter and in countries with coal-based industry incl. electrical power production. These values are very high and exceed the legal limits set in soils by orders of magnitude. Atmospheric deposition rates typically reach several mg m−2 a−1, but in winter, especially in countries with heating, deposition rates are up to 10 times higher. PAHs concentrations in soils show a very wide variation from less than 1 µg g−1 in rural areas up to 10 µg g−1 in urban space, which is about 1000 times lower than the concentration of PAHs on particles in the atmosphere. This demonstrates the relevance of high concentrations of PAHs on airborne particles deposited on soils, which also highlights the importance of considering incremental lifetime cancer risk models for both air and soil and assessing the total health risk of PAHs to humans. [ABSTRACT FROM AUTHOR]

Metribuzin is a pre- and post-emergence triazinone herbicide used in a variety of crops. This herbicide is degraded in the environment into three major metabolites that have high water solubility, high to very high soil mobility, and low to moderate persistence in soil. This paper describes the development of an analytical method based on ultrasound-assisted extraction and GC-MS/MS determination for the determination metribuzin and its main metabolites in soil and plants. The developed method provided good recoveries for all compounds in soil and plants (from 73 to 121%). The quantitation limits obtained from plants (2.6 to 18 µg/kg) allow determining the presence of these compounds at trace levels. To evaluate the applicability of the developed methods, bean plants were grown in plastic pots with soil treated with metribuzin and collected after 23 days. At the end of the assay, only 11% of the initial concentration of metribuzin remained in soil. Metribuzin and its three metabolites were detected in plants, desamino-diketo-metribuzin is the most abundant metabolite. It is expected that the application of these methods can provide more data to monitor metribuzin residues due to herbicide treatments. [ABSTRACT FROM AUTHOR]

This essay distills the thoughts of the author who has spent over 30 years developing land surface models, including those for use in remote sensing. The latter includes models whose function is to serve both as a mathematical interface between remotely sensed optical/thermal measurements and land surface evapotranspiration and soil water content and as description of the physiological behaviour of plants and their interaction with atmosphere and soils. [ABSTRACT FROM AUTHOR]

To meet the increasing demand for metals to assist in a successful and rapid energy transition, it is crucial to discover more first-class mineral deposits. With most of the world's major deposits occurring near the surface, improved methods for detection at deeper levels are required. This paper summarizes the soil gas studies that have been published in English discussing the use of soil gas as a sample medium for mineral exploration. The potential and reliability of various methods and gas species (O2–CO2, sulfur gases, polymetallic studies, gaseous hydrocarbons, radiogenic daughters (He, Rn), hydrogen and other gases) are reviewed and the challenges for the broad-scale adoption of soil gas measurement as an exploration tool are discussed. Soil gas composition has promising potential for mineral exploration, but much remains to be understood about the origins and processes affecting it. There has been a great deal of variation among the studies in sampling and analytical techniques, targeted gas(es), targeted commodities and mineralization type, climatic conditions and environmental settings. Improvement is needed in technical consistency, systematic monitoring of the environmental factors shortly before and after sampling, and the impact of microbes on the composition of the gases. In addition, further study is needed into the impact of climate, the cover composition and structure as well as the biological impact of microbes and plant roots before soil gas composition is a reliable exploration method. Supplementary material: Spatial data kmz file of gas study site locations and references presented in Figure 8 are available at https://doi.org/10.25919/5eww-8f16 Thematic collection: This article is part of the Reviews in exploration geochemistry collection available at: https://www.lyellcollection.org/topic/collections/reviews-in-exploration-geochemistry [ABSTRACT FROM AUTHOR]

Compared with the deeply buried marine gas hydrate deposits, gas hydrates in the shallow subsurface, close to and at the seafloor, have attracted more attention owing to their concentrated distribution, high saturation, and easy access. They accumulate at relatively shallow depths <100–120 m and occur as gas hydrate-bearing mounds (also known as hydrate outcrops, pingoes) at the seafloor derived from the growth of hydrates in the shallow subsurface or as pure hydrate chunks formed by gas leakage. This paper reviews and summarizes such gas hydrate systems globally from the perspective of gas sources, migration pathways, and accumulation processes. Here, we divided them into four categories: fault-chimney-controlled, diapir-fault-controlled, fault-controlled, and submarine mud volcano-controlled deposits. Gas chimneys originate immediately above the restricted regions, mostly affected by faults where high gas concentrations trigger elevated pore fluid pressures. Diapirism derives a dendritic network of growth faults facilitating focused gas discharge and hydrate formation near the seafloor. Furthermore, pre-existing faults or fractures created by overpressured gas from greater depths in accretionary tectonics at convergent margins act as preferential pathways channeling free gas upwards to the seafloor. Gas flux rates decrease from the submarine mud volcano center to its margins, creating a concentric pattern of distributing temperature, gas concentrations, and hydrate contents in shallow sediments around the mud volcano. Hydrate-bound hydrocarbons are commonly of thermogenic origin and correspond to high-background geothermal conditions, whereas microbial gas is dominant in a few cases. The presence of heavier hydrocarbons mitigates the inhibition of hydrate formation by salt or heat. Fluid migration and pathways could be compared to the "blood" and "bones" in an organic system, respectively. The root of a pathway serves as the "heart" that gathers and provides considerable free gas concentrations in a restricted area, thereby triggering pore fluid pressures as one important drive force for focused fluid flow in impermeable sediments (the organic system). Besides the suitable temperature and pressure conditions, a prerequisite for the formation and stability of hydrate deposits in the shallow subsurface and at the seafloor is the sufficient supply of gas-rich fluids through the hydrate stability zone. Thus, the proportion of gas migrating from deep sources is significantly larger than that trapped in hydrates. As such, such marine hydrate deposits seem more like temporary carbon storage rather than the main culprit for climate warming at least in a short period. [ABSTRACT FROM AUTHOR]

To avoid the issues of undesired soil compaction and seeding depth variation caused by the downforce fluctuation of the corn no-till planter, the influence of the structural parameters of the air spring on the downforce was researched in this paper, by establishing the gas–solid coupling simulation model of the air spring. The downforce test bench was built to verify the simulation model; the test showed that the vertical output force error of the simulation model was 4.79%, the pitch diameter error was 0.76%, and the pressure error was 5.07%. The cord angle, piston angle and piston diameter were used as influencing factors to carry out single-factor experiments. The influences of structural parameters on downforce were analyzed from four aspects: the vertical output force, the vertical stiffness, the pressure difference and the deformation rate. The results showed that the cord angle reduced the effective area and its change rate during deformation by limiting the radial deformation of the bellow. When the cord angles were 30°, 45° and 60°, the deformation rates were 65.6%, 20.3% and 4.8%, respectively. The cord angle had a positive effect on the vertical output force when the cord angle was in the range of 30~56°, and it had a negative impact in the range of 56~60°. As the cord angle increased, the vertical stiffness decreased. As the piston angle increased, the effective area of the air spring decreased, and the change in internal pressure decreased, reducing its vertical output force and stiffness. The piston diameter had little effect on the internal pressure and deformation rate. It increased the vertical output force and stiffness by increasing the effective area. The structural parameters of the air spring had a significant impact on the stability of the downforce; the structure of the air spring should be optimized according to the downforce demand of the corn no-till planter. [ABSTRACT FROM AUTHOR]