Search

The study of whether life exists, is extinct, or not depends on various sophisticated experimental studies, as many different signatures of life can be used. The experimental procedures that can be performed to identify life can be further restricted by time, resources, and mobility constraints. Therefore, any research analyzing the presence of extraterrestrial life must be precise and unambiguous. This research focuses on the objective of the extraterrestrial life detection domain and seeks to provide an efficient protocol that can produce life detection decisions based on empirical data obtained through chemical analysis under time and resource-constrained conditions. While the majority of existing frameworks in this field are designed to identify biomolecules, our goal is to accomplish the same with minimal operational expense and mission complexity. We argue that the thoughtful integration of multiple biomolecular detections with lesser complexity and a robust framework can improve overall mission performance by satisfying the necessary time and resource constraints. In this study, a rapid multiple biomolecules-based life detection protocol (MBLDP-R) from soil samples is developed from scratch and embedded in an operational scientific rover subsystem targeted for planetary analysis missions. The study uses artificial biomolecule samples and simulated extraterrestrial environments to illustrate the suggested protocol's end-to-end process. First, we list a few significant biomolecules, including lipids, proteins, carbohydrates, nucleic acids, ammonia, and pigments. Then, a weighted qualitative test scoring is applied to sort out the best test method for the finally selected biomolecules which are used as operational analogue to showcase the protocol's in-situ analysis and decision-making capabilities. Based on the suitable biomolecules, a scientific exploration subsystem is developed, and the implemented protocol is built to perform onboard sample analysis. Evaluation results show that: (1) the proposed MBLDP-R protocol could effectively predict the classes with an average f1-score of 98.65% (macro) and 90.00% (micro), (2) the area under the Receiver Operating Characteristics (AUC-ROC) curve shows the sample categories to be correctly predicted 92% of the time (97% for Extant, 88% for Extinct, and 92% in the case of NPL), and (3) the protocol is time-efficient with an average completion time of 17.60 min, demonstrating the protocol's rapid nature in detecting biosignatures in soil samples. The research outcome yields useful additional data for related future studies, particularly in the design of scientific frameworks for mission-specific requirements with limited resources while also serving as a reference point for constraint evaluation methods for similar systems. [ABSTRACT FROM AUTHOR]

The grouted gravel pile is a new method of pile foundation, which has been widely used in engineering fields in recent years. However, the grout diffusion characteristics and full-field displacement response of soil during grouting have not been fully revealed and systematically studied in previous publications. This paper employed a transparent soil model test system to explore the effects of the grouting pressure (GP), soil pre-consolidation pressure (SPCP), and initial viscosity of grout (GIV) on the grouting performances and load-bearing characteristics of grouted gravel piles. The development laws of the grouting duration, displacement field of the soil, and ultimate load-bearing capacity of the pile were analyzed. The results show that the total grouting duration decreases with a higher GP, increases with the increasing GIV, initially increases and then decreases as SPCP increases. Both the range of horizontal and vertical displacements of the soil around the pile and the distribution of vertical displacements of the soil at the pile end were obviously enlarged with GP as well as with GIV. However, with the increasing SPCP, they showed a decreasing tendency. The vertical ultimate load-bearing capacity of the grouted gravel pile increases with GP, SPCP, and GIV to varying degrees. The findings of this study contribute to the understanding of the pile-soil interaction during grouting process of the grouted gravel pile, which may improve the design of construction parameters. [ABSTRACT FROM AUTHOR]

The one-dimensional consolidation analysis of clays considering creep compression is a classical issue in soil mechanics and geotechnical design. The major debate lies in how to predict the consolidation settlement for a thick layer in the field using parameters obtained from a thin specimen from the laboratory. Different hypotheses have been advocated, based on which various methods and constitutive models have been developed. However, there are still some questions unaddressed and concepts inconsistently used, which may mislead engineers in the selection of methods/models and may result in settlements underestimated on a risk design side. In this paper, a state-of-the-art review and a thorough comparison study are performed on the existing methods and models for the consolidation analysis of clays exhibiting creep, from theoretical derivations to numerical simulations in comparison with soil test data. An in-depth discussion is carried out on several key issues related to the thickness effects on the time-dependent compression behaviour of clays. The arguments of Hypothesis A and Hypothesis B are revisited based on the current development of constitutive theories. Three existing elastic visco-plastic (EVP) models that consider the creep compression implicitly during the whole consolidation process can perform well in predicting the settlement of clay layers with different thicknesses, and are in line with Hypothesis B. It is concluded that using existing EVP models based on porous-media continuum mechanics is a rigorous scientific method (also called "rigorous" Hypothesis B method), which is superior to the old Hypothesis A method which has logic errors and may result in unsafe underestimation of settlements. [ABSTRACT FROM AUTHOR]

The dynamic effects in soil water retention curves (SWRCs) have been the focus of much research. However, most studies implemented short column tests in a few centimeters, under which a semi-permeable porous media inevitably minimizes or magnifies the dynamic effects. In this study, full-scale sand column tests were conducted to eliminate this flaw by preparing a saturated zone under the unsaturated one. The soil suction and moisture profiles were monitored using high-precision tensiometers and spatial time-domain reflectometry, thereby providing a rational overshooting range of the dynamic SWRC. The results confirm that the dynamic primary drainage curve overshoots the static one. The dynamic effects were estimated quantitatively from the soil moisture re-equilibrium time (τS) and dynamic coefficient (τp), falling within reasonable ranges from previous studies. The τp increases log-linearly with decreasing moisture content and can be estimated well from the corresponding τS and the first derivative of SWRC. Also, the τp increases as the soil becomes finer and better graded, which agrees with more-prominent dynamic effects for lower-permeability reservoirs from petroleum studies but disagrees with more-significant dynamic effects for higher-permeability sand from soil-hydrology studies. The analysis shows that the dynamic effects are not dominated solely by the τp or permeability but also by the groundwater dynamics, which can be seen as a pressure boundary from the saturated zone. This finding explains the significant dynamic effects for both high- and ultra-low-permeability geomaterial. Therefore, the present full-scale soil column setup with a prepared saturated zone is recommended for academic investigations of dynamic SWRCs. [ABSTRACT FROM AUTHOR]

A test plot of 15 ha in area has been set as a climate monitoring facility in Shchelkovo district, Moscow oblast, in 2022. Within the boundaries of the test plot, which represents one forest survey unit, a significantly diverse soil cover has been revealed, i.e., 18 soil varieties ranging from subtype to subspecies. Microrelief is considered to be the main factor of carbon stock heterogeneity: the soils of closed depressions occupied by sphagnum mosses differ significantly in carbon stocks in the litter and in the upper 10 cm of soil. For the rest of the territory, the main factors influencing the carbon stock are the percentage of physical clay in the illuvial part of the soil profile, as well as the composition and phytomass of ground vegetation. The highest variation coefficient in C stocks (40%) was registered for the 10–30 cm layer, being due, above all, to the varying thickness of the genetic horizons composing it. Geospatial analysis allows us to pass to the spatial assessment of variation in soil properties and further modeling and forecasting the carbon stock dynamics taking into account the spatial heterogeneity of the territory. Identifying the factors that control carbon stocks in soils will help to work out modeling scenarios aimed at developing measures on increasing carbon accumulation in forest ecosystems through changes in the vegetation structure. [ABSTRACT FROM AUTHOR]

This study evaluates the possible agricultural application of calcium carbonate derived from niobium extraction. This carbonate is stored in dams, and it is enriched with radionuclides from 232Th series, which imposes restrictions on its use. Activity concentration evaluation in soil was performed before the tillage of lettuce (Lactuca sativa L.) and the soil–plant transfer factor was determined. Results showed the dilution factor applied to the carbonate in the soil causes insignificant increments in soil activity concentration. In cultivated lettuce, high activity concentrations of 228Ra and 226Ra were found independently when using either the control or carbonate amended soil. [ABSTRACT FROM AUTHOR]

To enhance our understanding of soil behavior at critical states, considering that natural soil is composed of granular matter, a quasi-static inertia number taking soil compaction into account is proposed. In analyzing classical triaxial test data of soil, the scaling law of quasi-statically deforming grains at the critical state is explored; a simple linear relationship is found between the coefficient of friction and the proposed number. This scaling law describes quantitatively the influence of initial compaction, shear rate, confining pressure, and particle size on the frictional strength of granular soils when they reach the critical state. The number proposed is employed to describe the scaling of volumetric behavior of granular soils undergoing quasi-static deformation. The difference between the particle volume fraction at the critical state and that at the initial compacted state is also found to be linearly correlated with the quasi-static inertia number, for soil at the critical state. [ABSTRACT FROM AUTHOR]

Soil salinization poses a significant ecological challenge, emerging as a critical constraint to agricultural development in the arid and semi-arid regions of China, especially in southern Xinjiang. In particular, Yuepuhu County, situated in Kashgar, faces a distinctive issue. Impermeable thin clay layers within the vadose zone impede year-round leaching of salts, significantly impacting the growth of cotton. Through a combination of indoor testing, experiments, and statistical analyses, this study elucidated the varying permeability of soil layers at different depths and explored the forms and accumulation characteristics of soil salts in Yuepuhu County. It unveiled patterns of water and salt movement in soils with variable permeability layers, identifying key influencing factors. The research also proposed an irrigation regime suitable for cultivating vadose zone soils in the local context. The findings revealed a progression of increasing soil complexity and decreasing burial depth of clay layers from northwest to southeast, aligned with the direction of groundwater flow. With increasing depth, a noticeable reduction in soil saturated hydraulic conductivity was observed, indicating significant variability in permeability. Predominantly chloride-sulfate type saline soils in Yuepuhu County contained potassium (K+) and sodium (Na+) as the main cations in surface soils. Salinity strongly correlated with calcium (Ca2+) and magnesium (Mg2+). Chloride (Cl−), sulfate (SO42−), K+, Na+, and bicarbonate (HCO3−) reflected the degree of soil salinization in Yuepuhu County. The clay interlayers in variable permeability zones significantly impeded water and salt movement in the vadose zone. Moving from west to east, thicker and shallower clay interlayers hindered downward water movement, increasing the difficulty of salt leaching. Additionally, the irrigation regime influenced water and salt movement in the vadose zone. Under the same soil structure, flood irrigation with a higher water flux resulted in more significant salt leaching, and lower total dissolved solids (TDS) in irrigation water were more favorable for effective salt leaching. Collectively, our findings provided a theoretical foundation for improving and managing local saline soils, as well as guiding the implementation of rational agricultural irrigation practices. [ABSTRACT FROM AUTHOR]

Biodegradability testing in soil helps to identify safe synthetic organic chemicals but is still obscured by the formation of soil-bound 'non-extractable' residues (NERs). Present-day methodologies using radiocarbon or stable (13C, 15N) isotope labeling cannot easily differentiate soil-bound parent chemicals or transformation products (xenoNERs) from harmless soil-bound biomolecules of microbial degraders (bioNERs). Hypothesizing a minimal retention of hydrogen in biomolecules, we here apply stable hydrogen isotope – deuterium (D) – labeling to unravel the origin of NERs. Soil biodegradation tests with D- and 13C-labeled 2,4-D, glyphosate and sulfamethoxazole reveal consistently lower proportions of applied D than 13C in total NERs and in amino acids, a quantitative biomarker for bioNERs. Soil-bound D thus mostly represents xenoNERs and not bioNERs, enabling an efficient quantification of xenoNERs by just measuring the total bound D. D or tritium (T) labeling could thus improve the value of biodegradability testing results for diverse organic chemicals forming soil-bound residues. Non-extractable residues formation limits biodegradability testing in soil. Here, the authors show that hydrogen isotope tracers are hardly retained in microbial biomass, enabling an efficient distinction between biogenic and xenobiotic residues. [ABSTRACT FROM AUTHOR]

The aim of this study is to carry out a petrological and geotechnical study of the lateritic soils of Ngaoundal (Adamawa-Cameroon). Hence, geotechnical identification, X-ray difractometry, and chemical analysis (XRF) were used to characterize soils. Field investigations show that the average thickness of the lateritic layers is 1.3 m; the soils encountered are nodular with a silty/clay matrix. The dominant color is dark brown (7.5YR 5/6) with a lumpy structure and silty or clayey texture. Mineralogical analysis (XRD) and chemical data (XRF) show that these materials are made up of quartz (38.27%), goethite (13.98%), gibbsite (10.59%), kaolinite (8.62%), hematite (7.88%), magnetite (8.38%), anatase, and boehmite. These soils are silico-ferrugino-aluminous. Their silica/sesquioxide ratios correspond to those of true laterites. X-ray diffraction analysis of the soil samples revealed the absence of swelling clays. Geotechnical analyses indicate that these soils have specific weights between 2.580 and 2.648 g/cm3. The liquidity limits show an average of 54.5%, with an average plasticity index of 29.73%. According to the (HRB) classification, these soils belong to the class of silty/clayey gravels and sands known as A-2–7. The values for maximum dry density and optimum water content range from 2.040 to 2.188 g/cm3 and from 9.5 to 13.6% respectively. The CBR bearing capacity index shows values ranging from 78.0 to 95.1%, which proves that these materials belong to bearing capacity class S5. The geological and geotechnical data confirm that the Ngaoundal materials are suitable for road construction (sub-base and base layers). [ABSTRACT FROM AUTHOR]

To accurately assess the bioavailability risk of heavy metals (HMs) in a representative polymetallic mining region, we undertook an exhaustive analysis of Cu, Pb, Ni, Co, Cd, Zn, Mn, and Cr in soils from diverse land-use types, encompassing agricultural, forest, residential, and mining areas. We employed speciation analysis methods and a modified risk assessment approach to ascertain potential ecological threats posed by the HMs. Our findings reveal that both the total potential ecological risk and the modified bioavailability risks are most pronounced in the soil of the mining area. The modified bioavailability threats are primarily caused by Pb, Ni, Cd, and Co. Although the total potential ecological risk of Cu is high in the local soil, the predominance of its stable forms reduces its mobility, thereby mitigating its detrimental impact on the ecosystem. Additionally, medium modified bioavailability risks were identified in the peripheries of agricultural and forest areas, potentially attributable to geological processes and agricultural activities. Within the urban district, medium risks were observed in residential and mining areas, likely resulting from mining, metallurgy, industrial operations, and traffic-related activities. This study provides critical insights that can assist governmental authorities in devising targeted policies to alleviate health hazards associated with soils in polymetallic mining regions. [ABSTRACT FROM AUTHOR]

In Ghana, widespread backyard farming on arable land with refuse waste is driven by the enriched physicochemical properties of dumpsite soils, supporting crop growth. However, the enhanced levels of heavy metals have raised concerns among policymakers focusing on the environmental challenges posed by dumpsites soil. The purpose of the study was to assess the awareness of dumpsites farmers on soil physicochemical properties and dangers posed by accumulated toxic heavy metals. A total of 100 vegetable farmers were interviewed in three communities to gauge their awareness of dumpsite soil properties and potential contamination. A semi-structured questionnaire was purposively used to solicit for information from farmers. Chi-square (χ2) test of homogeneity was used to ascertain if there was any uniformity among respondents in the different communities studied. The findings showed that the level of education of the famers had no relationship (p = 0.21) with farmers' educational level. Dumpsites farmers' knowledge on soil physicochemical properties had a significant (p = 0.02) relationship with farmers' awareness of toxic elements in dumpsites. Farmers' soil physicochemical knowledge further had a significant (p = 0.03) relationship with their awareness that, plants on dumpsites absorb toxic elements. Furthermore, ailments commonly associated with heavy metals as reported by farmers included skin rashes, cough, diarrhoea, and cholera. It can be concluded that although dumpsite farmers exhibit some awareness about the physicochemical properties of their soil and the risks associated with toxic heavy metals, there is still room for improvement. Despite education levels not significantly impacting awareness, targeted intervention programs are necessary to enhance understanding and address this pressing issue effectively. We recommend an implementation of a tailored educational programs for dumpsite farmers to enhance understanding of soil properties and heavy metal risks. There should be improved access to soil testing and interpretation to enable informed decision-making among farmers. Foster collaborations among stakeholders for sustainable waste management, soil remediation, and health monitoring to mitigate heavy metal contamination are also recommended. [ABSTRACT FROM AUTHOR]

A method of digital colorimetric determination of ammonium and nitrate in soils is proposed. The method is based on corresponding photometric procedures of ammonium and nitrate determination after potassium chloride extraction from soil samples. Ammonium is determined as an indophenol dye, and nitrate is determined as an azo dye. The original procedures were modified to overcome the lower sensitivity of the digital colorimetric method. For ammonium determination, the time required for the reaction to proceed completely was studied. Along with the use of a 96-well microplate protected from ambient light by a special frame, mathematical correction of scattered radiation using black ink and taking the images by a scanner in transmission mode without any post-processing, the resulting colorimetric methods proved to provide accuracy and sensitivity close to those of the spectrophotometric method, and the overall analysis speed for tens of samples was even higher. Limits of detection and quantitation for NO3– were 0.42 and 1.4 mg/kg, and for NH4+, they were 1.1 and 3.7 mg/kg, which is lower than for standard methods. The methods' validity was proven by the analysis of standard samples and by the analysis of soil samples collected in several districts of the Moscow region. [ABSTRACT FROM AUTHOR]

The establishment of a soil indicator is essential to predict the potential for phosphorus (P) movement from a nonpoint soil source to surface water bodies, causing environmental pollution. The present study was undertaken with two pedogenically different acidic soils (terai and lateritic) in eastern India to estimate their environmental threshold degree of P saturation (DPS) values as an index of the potential risk for P loss. Additionally, this study rigorously evaluates the feasibility of Bray-1 as a standardized extractant for environmental phosphorus loss risk assessment, analogous to the recognized effectiveness of Mehlich-1 across diverse locations. Both Bray-1 and Mehlich-1 methods are equally efficient in determining environmental P-threshold, and the change point DPS at which water-soluble P increased sharply with these extractants was around 20%. The DPS (%) calculated using the Bray-1 method (DPSB-1) revealed that even a high agronomic soil test rating could not indicate the environmental risk. Based on a multiple linear regression model including soil properties like, clay content (%) and pH analyzed in most soil analysis laboratories along with Bray-1 P, was found to be an efficient method (DPSest) in predicting change point DPS. Considering the change points, confidence intervals, and agronomic soil test values, three categories of DPSB-1/ DPSest < 20%, 20–40%, and > 40% were established as safe, warranting attention, and critical levels of P loss from acidic Indian soils, respectively. [ABSTRACT FROM AUTHOR]

The necessity of predicting geotechnical parameters in soft ground tunnelling is crucial for selecting the appropriate tunnel boring machine (TBM), evaluating the operating limit of earth pressure balance (EPB) machines' parameters, and ensuring the safety and efficiency of TBMs during tunnel construction. In this research, various EPB operating parameters such as cutterhead torque, thrust force, chamber pressure, and cutterhead rotation speed (RPM) were utilized to estimate geotechnical parameters like friction angle (φ) and shear strength (τ) for engineering geological units ET1 to ET5 (fine-grained and coarse-grained soils) along the tunnels route, which serve as indicative units for the entire tunnels path. Statistical methods and computational techniques, namely support vector regression (SVR) and feed-forward neural network (FFNN), were trained using EPB operating parameters and geotechnical data from Tehran metro line 6—southern extension sector (TML-SE6) and the East–west section of line 7, Tehran metro project (TML-EW7). A comprehensive dataset comprising borehole logging results along the tunnel path was gathered, with 85% of the data randomly selected for training and the remaining 15% reserved for model testing. Various loss functions and statistical metrics were employed to evaluate the accuracy and precision of the method. The results of the proposed models demonstrate satisfactory and reliable accuracy of the approaches. Highlights: Database collected, generated, and analyzed using daily operational records, TBM data logger, in-situ analysis, laboratory tests, and statistical investigations; New formulas developed to predict geotechnical parameters of soil materials by incorporating various operating parameters of the Tunnel boring machine; Investigation of predictive abilities of smart algorithms in estimating shear strength and internal friction angle; Comprehensive evaluation conducted to compare and contrast empirical and machine learning outcomes; Accuracy of models evaluated using multiple assessment metrics. [ABSTRACT FROM AUTHOR]

Potentially toxic elements from heavy metal pollution in soils and water pose significant health risks to humans and ecosystems. This study aims to assess heavy metal pollution in active dumpsite soils in northern Ondo State, Nigeria, and evaluate associated hazards across different Nigerian geological environments using multi-pollution indices and statistical optimization. Twenty-seven soil samples from three major active dumpsites around Owo and Ikare-Akoko were collected from nine profiles at different depths. These samples were analyzed for concentrations of various heavy metals including Na, K, Ca, Mg, Cr, Fe, Pb, Zn, Ni, and Mn. The concentration of earth and heavy metals were considerably low compared to other parts of Nigeria and Africa. Pairwise correlations among heavy metal concentrations in the three dumpsite soils revealed both strong and weak correlations. Only Fe–Zn showed a strong correlation. Interestingly, no common correlation was found among the three geological environments, indicating that the concentrations might not be impacted by the varying geological conditions. In Ondo State's dumpsite soils, contamination factor (CF) ratings indicate moderate to very high contamination, while pollution load index (PLI) values suggest very high pollution. Index of geo-accumulation (Igeo) and ecological risk factor (ERF) values reflect moderately high to very high pollution and low ecological risk, respectively. The mean Igeo values follow this order: Cr < Ni < Mn < Zn < Pb < Fe (Tertiary environments); Cr < Ni < Mn < Pb < Zn < Fe (Cretaceous environments); and Ni < Cr < Zn < Mn < Pb < Fe (Basement environments). For mean ERF values, the order is Cr < Zn < Ni < Mn < Pb < Fe in Tertiary, Cr < Zn < Mn < Ni < Pb < Fe in Cretaceous, and Zn < Cr < Ni < Mn < Pb < Fe in Basement environments. The CF sequence is Cr < Ni < Zn < Mn < Pb < Fe in Tertiary, Cr < Zn < Ni < Mn < Pb < Fe in Cretaceous, and Cr < Ni < Zn < Pb < Mn < Fe in Basement environments. All samples exhibit extremely high contamination, with basement areas dominated by notably high Fe and other heavy metal concentrations, while the Tertiary environments show the lowest concentrations. Based on the research findings, regular monitoring and remediation efforts are essential in other areas to mitigate imminent pollution and risks. [ABSTRACT FROM AUTHOR]

A comprehensive study was conducted at three coal mines with thin bedrock zones to understand the occurrence of water–sand inrush accidents in overlying rock strata induced by the combined effects of ground stress generated by the loading of a thick loose layer, secondary mining-induced stress, and bottom aquifer pressure. This study involved field sampling at the Yangcun, Xinglongzhuang, and Baodian coal mines through underground drilling, as well as particle size and microscopic analysis, laboratory model experiments, and numerical simulations. The clay and sandy gravel layers in the lower group of the Quaternary strata in the study area were found to be interlaced. Particle size analysis and microscopic testing of the soil samples had consistent patterns, revealing the compositional structure of the soil samples. The composition structure of the bottom aquifer of the three sampling boreholes differed; using a self-designed experimental device, water–sand inrush tests were conducted with different crack widths. The critical hydraulic gradient decreased with increasing crack width, while it increases with increasing clay content, showing a good correlation; The PFC3D software was used to simulate the process of water–sand inrush under the influence of mining. The simulation and model testing indicate that water–sand inrush is more likely to occur, the process of water–sand inrush will be more intense, and the duration will be shorter when the inclination angle and crack widths are larger. [ABSTRACT FROM AUTHOR]

Triaxial compression testing of frozen soils is analyzed, emerging problems are discussed, and the solutions are proposed. A lack of reasonable regulatory recommendations for triaxial testing by the kinematic loading scheme for frozen soils is observed. Static loading methods, the value of loading steps, criteria for test completion, and principles for the experimental determination of long-term strength are discussed. [ABSTRACT FROM AUTHOR]

The dynamic properties of coarse-clastic soils based on triaxial dynamic compression and low-amplitude resonant column tests are analyzed. Combination of these methods allows the ultra-small fundamental shear deformations relationship and accumulated by the time deformations to be obtained. [ABSTRACT FROM AUTHOR]

The stability of gentle slopes is rarely accessed in existing studies, which are at risk of below-toe failure in soils with low shear strength. The inherent spatial variability of soil shear strength poses a huge complication to the probabilistic stability evaluation of large-scale three-dimensional gentle slopes, which usually forces a trade-off between precision and efficiency. In view of this, a semi-analytical method is developed in the framework of discretized limit analysis, which gives a unified mathematical representation of toe failure and below-toe failure of slopes. The proposed method inherits the high efficiency of analytical methods and has the ability to integrate spatially variable shear strengths into the slope mechanical model. The model validation is conducted by comparisons with a widely recognized analytical method developed for uniform soils. The random fields are introduced to achieve a relatively accurate characterization of soil shear strength, and the Monte Carlo simulation is employed to obtain a sufficient number of factors of safety of slopes for the subsequent statistical analyses. In the parametric study, spatial variability-related parameters, including the coefficient of variation of soil cohesion covc or internal friction angle covφ, the autocorrelation lengths along vertical and horizontal directions ξ and k, the cross-correlation coefficient ρcφ, are varied systematically to reveal their influences on the slope stability from a statistical perspective. It is found that the ranking of the impact on the probabilistic stability of a gentle slope is given as: covc or covφ > ξ > k > ρcφ. Finally, the failure probabilities of the gentle slope are computed considering the variations of key parameters, which may have implications for practical slope designs. [ABSTRACT FROM AUTHOR]

Unsaturated soil is widely distributed around the world but less considered in design due to the absence of a convenient analysis method in practice. The Morgenstern–Price (MP) method incorporating the extended Mohr–Coulomb shear strength equation provides a reliable approach to evaluate slope stability in such conditions. However, this method is time-consuming due to the need for a tedious trial-and-error process in determining the scaling factor, which involves complex iterations during each trial. Furthermore, since the relatively complicated nature of unsaturated soil, a dense slice division is necessary to obtain reliable results, making the analysis even more cumbersome. In this paper, an improved MP method for unsaturated soil slope stability analysis is presented, which eliminates the need for a dense slice mesh by employing only a few strategically placed Gauss points along the slip surface. Moreover, the trial-and-error process for determining the scaling factor with the corresponding complex iterations is replaced by an efficient search algorithm with a more concise iteration process, resulting in a more convenient implementation of the proposed method. Extensive examples are provided to validate the effectiveness of the proposed improved MP method, indicating its potential as an accurate and efficient analysis method for unsaturated soil slopes in practical application and relative study involving repetitive analyses. [ABSTRACT FROM AUTHOR]

Water drives the decay of road subgrades such as frost heave in cold areas and collapse in saline soil areas, which influences the safety and comfort of vehicle transportation. This paper proposes a novel geotechnical material, namely hydrophobized soil, as a subgrade fill material to mitigate water-induced degradation of subgrade. Hydrophobized soil has a low affinity to water and therefore can prevent the subgrade from water infiltration, enhancing the volume stability of subgrades. To demonstrate its feasibility, the hydrophobicity and its durability were investigated in this study. A one-year outdoor weathering test on hydrophobized soil columns was conducted, with the hydrophobicity measured. The results show that hydrophobized sand has different durabilities and exhibits different degradations depending on the chosen hydrophobizing agent and its concentration. Based on the testing results and capillary rise model, the design of hydrophobic hydraulic barrier in subgrade was discussed at the end. [ABSTRACT FROM AUTHOR]

The parametric seismic fragility model of elephant-foot buckling (EFB) in the tank wall of the unanchored storage tanks is introduced by utilizing the results of a parametric study of eighteen tank-soil configurations. The model can be used to rapidly assess the seismic vulnerability to EFB for a larger number of tanks. The parametric study involved a 1D cloud-based soil response analysis to relate the ground-motion intensity measure at the bedrock with that at the free surface, and a pushover analysis of the refined finite element model of the tank to assess the engineering demand parameter in terms of axial compressive stress in the tank wall and the critical value that triggers EFB. As a consequence, the parametric seismic fragility model can be applied to intensity measures at the bedrock, as it is demonstrated for the spectral acceleration at the tank's impulsive period, Se,bedrock,EFB, and the peak ground acceleration, PGAbedrock,EFB. The input parameters of the introduced seismic fragility model are the harmonic average shear-wave velocity in the top 30 m of soil, Vs,30, the slenderness ratio of the tank, H/R, the ratio between radius and wall thickness of the tank, R/t, and the standard deviation of log values for the intensity measure causing EFB. The model reliably predicts the median intensity measure causing the onset of EFB in the investigated tank-soil configurations, especially when Se,bedrock,EFB is selected for the intensity measure. However, further investigation is required to enhance the accuracy of predicted intensity measures that trigger EFB by considering the dynamic impact between the base plate and the foundation during an earthquake and accounting for the complete soil-structure interaction effects. [ABSTRACT FROM AUTHOR]

Subgrade is the foundation of the pavement, and its properties affect the performance of the pavement. The strength or stiffness parameters of the subgrade need to be evaluated with great precision, and this motive can be achieved by conducting the plate load test (PLT) and California bearing ratio (CBR) test of the soil. Generally, the PLT and CBR test are performed to evaluate the modulus of subgrade reaction (ks) and CBR of the soil, respectively. The effective combined contribution of the borrow material soil (subgrade) and the native soil must be considered for the design of pavements. In the present study, the effective CBR of the two-layered soil media consisting of the top layer as borrow material soil with varying thicknesses is evaluated. The load versus displacement curves of PLT and CBR test are similar and considering this similarity, an attempt to evaluate effective CBR of two-layered soil media from equivalent ks of two-layered soil media is made. The finite element (FE) evaluated effective CBR results are found to be in good agreement with the solutions available in the literature. Then, the design charts for evaluating the effective CBR of the two-layered soil media for the wide practical range of borrow material soil thicknesses are proposed. [ABSTRACT FROM AUTHOR]

In recent years, individuals have begun to pay more attention to non-traditional stabilizers due to the problems connected with traditional stabilizers. Traditional stabilizers have undergone extensive investigation, and the mechanisms by which they act are well understood. This paper presents findings of the effect of sugarcane vinasse wastewater (VI) and sodium alginate (SA) polymer on the compressibility behavior, and microstructural evolution of clay soil using mixing method. The premise of this paper is to eliminate waste material from nature and compare the performance of this material against the use of polymers that have recently been used in improvement. The additives were dissolved in water and then introduced to the dried stratified soil to produce improved soil samples using the mixing technique. Transported unconfined compressive strength (UCS) was examined for 1, 14, and 28 days of treatments with additive ranges of 3–15% for VI and 0.25–1.25% for SA. In clay with high plasticity, the findings show that VI significantly influences increasing the UCS. With the addition of 9% vinasse to the soil at the age of 28 days, the UCS has increased by 78.8%. Additionally, the introduction of 1.25% SA to the soil has increased by 261.9% for the 28-day treatment efficiency significantly. Microstructural and chemical examination revealed that the mineralogical and morphological contents of the stabilized soil were influenced due to the pozzolanic reaction. The results showed that waste by-product liquid was able to significantly increase the strength and compressibility of the clay soil. Using a large volume of waste by-product liquid to stabilize soil, the researchers discovered a straightforward application method. [ABSTRACT FROM AUTHOR]

The dynamism of carbon pools and flows in landscapes requires special attention to the methods and tools for measuring all carbon-containing soil components. An important component of the carbon budget in carbonate geosystems is the dissolved inorganic carbon, part of which is carried out by surface and lateral flows into water bodies, which requires attention to assessing the total alkalinity (TA) of soils on calcareous rocks. Analysis of soils and parent rocks in the Polar Urals with a CaCO3 content of 0 to 100% revealed the factors that influence the value of their TA, namely, (a) the method used for preparing soil samples and water extraction (the ratio of soil weight to the volume of distilled water, ms : , and the quality of separation of solid and liquid phases); (b) the moment of recording the acid titration endpoint for extracts; and (c) the presence of organic acids with pKa < 4.4. The latter reduces the content of bicarbonate ion by converting it into carbonic acid, not measurable by titration. This mechanism is confirmed by (a) analysis of the model solutions of sodium bicarbonate and formic (pKa = 3.75), tartaric (pKa1 = 3.04 and pKa2 = 4.37), and malic (pKa1 = 3.46) acids; (b) cation–anion balance of soil water extracts; and (c) a negative shift in the titration TA values (the sum of carbonate and organic alkalinities) relative to the amount of equivalents of dissolved inorganic carbon determined by high-temperature catalytic oxidation at the same ms : ratios in both methods. It is possible to compare the TA of soils measured by different laboratories only strictly performing all experimental conditions. It is recommended to use a centrifuge to separate the solid and liquid phases of carbonate soils and a pH-meter or a titrator to record the endpoint of titration. [ABSTRACT FROM AUTHOR]

Earth ovens are a ubiquitous feature of eastern North America, used throughout many cultures and periods, leaving a highly visible signature of habitational life. This study focusses on one of the four uniquely outsized earth ovens from the center of a woodhenge at Hopewell Mound Group, the type site of the Hopewell culture. Cleaned of artifacts and fire-cracked rock, this feature required specialized analysis to shed light on its function: macrobotanical methods of seed identification and wood charcoal analysis along with phytolith and soil micromorphological analysis. These analyses create a holistic picture of the earth oven, the woodhenge, and the nature of feasting and ritual at Hopewell Mound Group, along with a snapshot of the paleoenvironment. Results show ritual use of ash wood (Fraxinus sp.), Eastern Agricultural Complex seeds seasonally timed with a summer solstice ritual, and grass leaf phytoliths deposited deeper than the surrounding natural strata. Feasting at this site seems to be focused on feeding large numbers of people, as opposed to a small set of competitive elites. [ABSTRACT FROM AUTHOR]

In order to realize the coordinated development of coal resources exploitation and ecological protection in arid climate area, this paper selects Xilin Hot steppe mining area as the main research region, analyzing the variation features of soil water content (SWC) in horizontal and vertical directions through ECH2O-5TM water content sensors. Based on the geotechnical test of the soil samples, a profile model of lithology was developed to find out the effects of humus thickness on SWC by Hydrus. The results showed that in the horizontal direction, the SWC was higher around the waste dump and Xilin river, but lower in the steppe and mining areas. In the vertical direction, the SWC presented a descending-ascending-descending distribution ranging from 5 to 70 cm depth, among which the maximum SWC reaching 0.043 m3/m3 at depth of 52 cm. Affected by the rainfall infiltration, the average SWC decreased successively in rainy season, normal season and dry season. Compared with the steppe area, the SWC of the waste dump was rose higher after soil reconstruction. Humus exhibited superior water-holding capacity, and the humus with a thickness of 40 cm can meet the SWC requirements of herbage in the research region. The research findings can better clarify the variation regularities of SWC affected by the soil reconstruction in steppe mining area, which lay fundamental theory and reference case for the conservation of soil water and vegetation protection in arid climate. [ABSTRACT FROM AUTHOR]

The fault zone represents one of the unfavorable geological conditions responsible for tunnel collapse in undersea tunnels. To reveal the collapse mechanism of an undersea tunnel triggered by the fault zone during excavation, a large-scale tunnel disaster model system was developed, capable of true triaxial loading and providing a sufficient supply of high-pressure water. A hydro-solid coupling similar model test was performed based on the engineering background of the under-construction second Jiaozhou Bay undersea tunnel. The results show that subsea tunnel fault collapse had an obvious progressive nature under excavation disturbance and seawater seepage. Soil arches repeatedly formed and moved upward during the collapse evolution process. When the overburden thickness was insufficient to form a soil arch, the tunnel collapse evolved into a water inrush. In addition, the multi-physics field changed obviously before the collapse, which could be used as precursor information for tunnel instability. Before the collapse, the horizontal stress rose slowly and then dropped suddenly, the pore water pressure drastically fluctuated and peaked, and the loosened zone's displacement rate increased suddenly. This study provided improved insight into the failure behavior of subsea tunnels and identified early warning signs of collapse. [ABSTRACT FROM AUTHOR]

The main aim of this study is to explain periglacial processes on the summits of Mount Honaz (2571 m a.s.l.), define periglacial landforms, and determine the relationships between morphometric features and topographic factors. Mud circles, stony earth circles, non sorted steps, and non sorted stripes were identified on the summits of Mount Honaz. Pearson's correlation coefficient (r) and linear regression analyses were performed by taking metric measurements from 125 periglacial landforms to describe their morphometric features (length, width, height) of periglacial landforms and explain the relationships between them and topographic factors (elevation, slope). To explain the relationships between periglacial landforms and soil properties, soil samples from 11 periglacial landforms were taken and analysed. Periglacial landforms, which continue to develop on the summits of Mount Honaz today, have been evaluated with present climate data. Analysis of soil samples indicates a notable impact of parent material on the genesis of periglacial landforms. The high ratio of organic matter in mud circle and non sorted step landforms and the high lime ratio in stony earth circle landforms prove a strong relationship between the formation mechanisms of landforms and the soil properties. Furthermore, it is consistent with the findings obtained from the analysis that severe periglacial processes and washing and scavenging events are experienced more on the northern slopes. [ABSTRACT FROM AUTHOR]

To perform the stability analysis of soil slopes, the traditional limit equilibrium method (LEM) based on geostresses calculated by the standard finite element method (LEM-FEM) appears to be competitive. In LEM-FEM, the stress variables are stored at the Gaussian points within each element, so stress interpolation from the Gaussian points for each line segment of trial slip surfaces shall be inefficient for stability analysis of soil slope. To improve the accuracy and efficiency of stress interpolation, an implicit stabilized node-based smoothed finite element method (NsFEMstab) in conjunction with 3-node triangular (T3) elements, in which stress variables are stored at the element nodes, is implemented to calculate the stresses at each line segment. Furthermore, a novel method of LEM-NsFEMstab is developed by replacing the standard FEM in LEM-FEM with NsFEMstab. Based on four plane-strain slope examples, the stability analysis results disclose that the factor of safety (FOS) and the slip surfaces predicted by LEM-NsFEMstab agree well with those predicted by LEM-FEM in conjunction with 6-node triangular (T6) elements. Additionally, the search of the critical slip surface is accelerated using the OpenMP parallel platform. Compared to the serial implementation of LEM-FEM(T6) and the serial implementation of LEM-NsFEMstab, the computational efficiency of the parallel version of LEM-NsFEMstab may be increased by 5~7 and 4~6 times, respectively, and based on comparisons of threads parallel performance, it is found that one half of the total number of CPU threads can be utilized to achieve optimal computational efficiency. [ABSTRACT FROM AUTHOR]

The establishment of discrete element method (DEM) model for simulating the behavior of viscous soil can significantly contribute to the development of agricultural machinery, particularly in hilly areas worldwide. There is limited research on the parameter calibration of the DEM for purple soil in the Southwest China and its interaction mechanism between very narrow tine. Piling up test, rotating drum test and design-expert 12.0 software were used to design Plackett–Burman test, steepest climb test and Box–Behnken test successively. Combined with soil intrinsic parameter measurement test, soil simulation parameter calibration and optimization were completed. Based on the optimized DEM simulation parameters, the average relative errors of static repose angle and dynamic repose angle were 1.934 and 2.289%, respectively. The accuracy of parameter calibration results of DEM simulation was proved. Three kinds of very narrow tines were designed and processed. The interaction model and mechanism between soil-touch parts and soil was established. The average relative errors between the DEM simulation results of the forward resistance and disturbance area of the three soil-touch parts and the soil bin test results were 7.22% and 11.24%, respectively, which further proved that the calibration results of DEM parameters of purple soil and the interaction model with the soil-touch parts in this study were reliable. The physical and interaction parameters of slope cultivated purple soil in Southwest China were determined based on static-dynamic repose angle, providing more accurate parameters for study of soil-touch parts. [ABSTRACT FROM AUTHOR]

The soil nematode communities in typical tundra soils of southern Chukotka have been analyzed. Five types of shrub and grass-shrub biotopes on Cryosols, Fluvisols, Histosols, Gleysols, and Cambisols were examined. The animals were extracted from the soil by the Baermann technique with subsequent determination of taxonomic diversity, total and relative abundance, and trophic groups. The highest number (7044 individuals/100 g of soil) and biomass (12.15 mg) of nematodes were found in the Histosol, and the minimum one (1000 individuals/100 g of soil; 1.96 mg) of nematodes in the Cryosol. Bacterivorous nematodes dominated in all soil types. The maximum percentage of bacterivorous nematodes (94%) were found in the Cambisol. The percentages of fungivorous nematodes in the studied soils ranged from 1 to 42%. Predatory and omnivorous nematodes were present in all soils except for the litter of the Cambisol. Their percentage ranged from 2 to 32%. Phytonematodes were few, their highest number was found in the Gleysol (18%). The nematode fauna of the soils under analysis differed significantly. The greatest diversity of nematodes was found in the peat horizon of the Fluvisol, and the smallest diversity of nematodes was recorded in the litter of the Cambisol. The values of Sigma Maturity Index ranged between 2 and 3. The Enrichment Index had low and moderate (1.40–41.02) values, and the Structure Index had high values (59.51–84.07). The Eudorylaimus and Plectus genera were eudominants in all soil types. The soil food webs formed in the biocenoses under consideration can be characterized as stable and structured except for the alder biocenosis. [ABSTRACT FROM AUTHOR]

The Ryshkovo paleosol of the Mikulino Interglacial (MIS 5e), Late Moscow loess (MIS 6), and buried small erosional landforms were studied in the Taneyev Quarry of Kursk oblast, in the center of the East European Plain. Macro- and micromorphological and palynological analyses of the soil samples were carried out, and the OSL age and physicochemical properties were determined. The history of erosional landforms, soils, and landscapes was reconstructed on the basis of the facial analysis of the paleosol catena. It was concluded that the differentiation of the paleosol profile into the Ah–E–Bt horizons was developed during the Mikulino Interglacial, whereas the initial heterogeneity of the parent material had been formed earlier, during the Late Moscow (Saalian) Glaciation, under the impact of slope and cryogenic processes. The lithological matrix of the Ryshkovo paleosol did not remain unchanged due to the different history of interaction of eolian and slope (solifluction and colluvial) processes, initial pedogenesis, and interglacial soil formation. [ABSTRACT FROM AUTHOR]

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

This study focuses on the potential quantity of soil lead (Pb) remediation in a typical karst region of China, an area where previous research on the potential remediation quantity of Pb in soil has been scarce. In this study, 12,547 surface soil samples and 54 sets of soil-profile samples were collected. This analysis investigated the sources, concentrations, distribution, and reserve properties of soil Pb in the study region. Building upon these findings, a formula for calculating the potential remediation quantity of Pb in karst soils was derived. The results disclose variations in Pb content within the surface soil, with values spanning from 9.4 to 376.4 mg/kg and a background level of 72.97 mg/kg. Additionally, the Pb content in deep soil shows a spectrum from 1.6 to 160.9 mg/kg. Principal component analysis showed that the sources of Pb in karst soil were related to the geological background, agricultural fertilization, and mineral resources. Single-factor variance analysis demonstrated significant influences of topography, parent rock type, soil utilization, and soil type on soil Pb content. The spatial distribution of soil Pb, as determined by principal component analysis, was influenced by mineral distribution, geological background, and agricultural fertilization. The soil profile analysis showed that Pb concentrations followed a logarithmic distribution pattern with increasing depth. A formula for the potential remediation quantity of Pb was derived using a logarithmic model. This rational and representative formula establishes a foundation for the management of Pb-influenced soils in karst regions. [ABSTRACT FROM AUTHOR]

It is well known that long-term chemicalised agricultural practices harmfully affect soil health and prevent sustainable management of fertility in crop fields, including that of plantation crops. Accordingly, an investigation was carried out to check how soil fertility characteristics such as soil pH, soil mineral nutrient and organic carbon content are altered in long-term chemicalised rubber plantations of Kerala, located in the ecologically sensitive Western Ghats of South India. Soil fertility status concerning soil types in the Rubber fields (USDA soil orders - suborders) such as Inceptisols - Oxic Dystrudepts (IOD), Ultisols - Ustic Haplohumults (UUH), Ultisols - Typic Kandiustults (UTK) and Mollisols - Pachic Argiustolls (MPA) involving six soil series are critically analysed. A negative impact of long-term chemicalised agriculture was visible in low soil pH and nutrient levels. In general, rubber fields in the region, even in the generally alkaline Mollisols, showed a pH of 6.23. The soils showed reduced nutrient and carbon content and a comparatively poor soil fertility index specific to soil types. The soil available NPK and soil total cations were found to be comparatively low and soil specific. However, rubber fields in Mollisols were significantly higher in STK, STMg, STCa, and STNa while those in Ultisols were significantly higher in SAP and SAK than other soil orders. The Inceptisols were significantly higher in SAN, STP, and soil organic carbon than others. Therefore, balanced fertilizer application concerning soil types per proper soil fertility monitoring has become significant to sustainable soil productivity management in rubber plantations. [ABSTRACT FROM AUTHOR]

Droughts continuously threaten human life, livestock, and agriculture across the Horn of Africa (HOA). As climate change exacerbates drought frequency and severity, accurately quantifying spatiotemporal drought patterns is critical to developing evidence-based policies that mitigate impacts and build resilience among vulnerable communities. This study conducted a spatiotemporal analysis of soil moisture drought over the HOA, utilizing high-resolution ERA5 reanalysis data between 1951 and 2020. The Standardized Precipitation Evapotranspiration Index (SPEI) was calculated at 3-, 6-, 9-, and 12-month timescales to identify historical drought events and assess drought duration and intensity changes over 70 years. Spatial analysis revealed decreasing soil moisture levels across HOA, with the most substantial reductions of 45% occurring in Djibouti and Northern Somalia. Comparisons between the baseline period (1951–1985) and the recent period (1986–2020) showed increasingly negative SPEI intensities, indicating a shift towards drier conditions, especially in Somalia, Kenya, and Ethiopia. The results also pointed to rising frequencies of moderate droughts by around 15% and severe droughts by 5–10% from 1986 to 2020 in the baseline period. The findings can inform policy to improve regional drought monitoring systems and the development of climate-resilient agriculture strategies, water resource management, and disaster risk reduction planning to protect lives and food security. [ABSTRACT FROM AUTHOR]

Purpose: In threatened diversity hotspots, such as mountain cloud forests, microbiome studies have focused essentially on bacteria. Unlike prokaryotic microbiomes, the study of the microeukaryotes has largely been restricted to the visual identification of specific groups. Herein, microeukaryotic edaphic diversity from a pristine mountain cloud forest (MCF) of Mexico was analyzed via the metabarcoding of the ITS1 region of ribosomal DNA. Materials and methods: An exploratory triangular sampling was conducted in the mountain cloud forest located in El Relámpago Mount, Santiago Comaltepec, Oaxaca, Mexico. Each vertex was located adjacent to a dominant plant species in the ecosystem (Oreomunnea mexicana and Alsophila salvinii). After DNA extraction the ITS1 region (rDNA) was amplified. Microeukaryotic sequences were filtered by computational subtraction against the ITS2 Database. Next, alpha and beta diversity indexes were calculated, and the relationship between abiotic variables and diversity patterns were inferred by means of a Canonical Correspondence Analysis. Results: Overall, 138 inferred sequence variants were identified, including 87 protists, 35 animals (microfauna), and 16 algae. Within the animals, the nematodes were the dominant group, chlorophytes dominated algae, and in Protista, no dominance patterns were observed given the high diversity and equitability of this group. Soil available carbon, carbon degrading enzymes and the pH play a key role in modeling the community structure. Remarkably, high beta diversity levels were obtained, evidencing a strong spatial heterogeneity at the small scale. Conclusions: The ITS metabarcoding proved to be a useful tool to conduct multi-taxa diversity assessments for microeukaryotes, allowing the identification of alpha and beta diversity patterns and overcoming limitations of sampling and the direct observation of individuals. The results presented in this work evidenced high microeukaryotic diversity levels in the soil of MCF and encourage future studies aiming to explore the taxonomic diversity of individual taxa. [ABSTRACT FROM AUTHOR]

To investigate the effect of in-pit vehicle load on the stability of the pit against overturning, a long tunnel foundation pit project in Suzhou is used as a case. In-pit vehicle load effects are modelled using the improved equivalent soil thickness method. Through the utilization of the upper limit theory of limit analysis of finite soils and considering the spatial distribution of suction force in the matrix of unsaturated soils, a deduced method for calculating the stability coefficient of the unsaturated finite soil pit against overturning under vehicle load is established. The results indicate that in-pit vehicle load favours pit stability against overturning relative to conventional outside-pit vehicle load. The change in pit stability is more significant when the soil rupture angle is corrected by using the improved equivalent soil thickness method. The increased suction in the unsaturated soil matrix contributes to the pit's stability against overturning. When calculating the stability coefficient against overturning, the finite earth pressure theory proves to be more realistic than the classical earth pressure theory. The results of this study can provide a valuable reference for similar types of pits to prevent overturning. [ABSTRACT FROM AUTHOR]

Sodium chloride (NaCl) can cause oxidative stress in plants, which represents a potential obstacle to the development of monocultures worldwide. Onion (Allium cepa L.) is a famous vegetable consumed and used in world cuisine. In the present study, we analyzed the influence of soil physicochemical profile and the remedial capacity of linalool on seed emergence, roots, and leaf growth in onions subjected to salt stress, as well as its in vivo and in vitro antioxidant potential, Fe2+chelating activity, and reducing power of Fe3+. The outcome of the soil analysis established the following order of abundance: sulfur (S) > calcium (Ca) > potassium (K) > magnesium (Mg) > sodium (Na). NaCl (150 mM) significantly reduced the emergence speed index (ESI), leaf and root length, while increasing the peroxidation content. The length of leaves and roots significantly increased after treatment with linalool (300 and 500 μg/mL). Our data showed negative correlations between seed emergence and K+ concentration, which was reversed after treatments. Linalool (500 μg/mL) significantly reduced oxidative stress, but increased Fe2+ concentration and did not show potential to reduce Fe3+. The in vivo antioxidant effect of linalool is thought to primarily result from an enzymatic activation process. This mechanism underscores its potential as a therapeutic agent for oxidative stress–related conditions. Further investigation into this process could unveil new avenues for antioxidant therapy. [ABSTRACT FROM AUTHOR]

Particle size distribution (PSD) of a significant number of soil samples of various geneses from the Komi Republic was studied by the Kachinskii method (KM). Calculated, procedural, random, and systematic factors influencing the precision and correctness of measurement results performed with the KM protocol are considered. The influence of sample preparation (the degree of grinding of soil samples) and procedures for measuring the mass fraction of elementary soil particles (ESPs) on the quality of the results of studying soil PSD was assessed. The instability of measuring the mass of fine sand (0.05–0.25 mm) and coarse silt (0.01–0.05 mm) fractions with the KM protocol was shown. The dependence of the uncertainty of measurement results caused by random factors on the mass fraction of ESPs of particular size fractions is noted: the lower the mass of ESPs in the fraction, the higher the uncertainty of the measurement results. A modification of the Kachinskii method (KM) has been developed to improve the quality of soil PSD analysis. It includes: (1) separation of fine sand particles using a sieve with a mesh size of 0.05 mm (instead of calculating this fraction by difference according to the MK protocol); (2) use of scales of the first class of accuracy to measure the mass fraction of silt and clay particles; (3) control of the PSD research based on the summation of the measured values of the mass fraction of ESPs of six fractions and acid-soluble compounds (losses from HCl treatment). The standard for operational control of the mass fraction of the sum of ESPs after dividing them into fractions is 100 ± 5%. A metrological study of the Kachinskii method and its modifications was carried out. The proposed modification of Kachinskii's method made it possible to reduce the uncertainty in the measurement results of the mass fraction of ESPs of small fractions (ωn < 10%) and shift the lower limit of measurements to 1%. [ABSTRACT FROM AUTHOR]

Efficient utilization of agricultural soil phosphorus (P) and mitigation of loss risks necessitate a precise evaluation of soil P storage capacity (SPSC). This study compared the effectiveness of four soil test P methods (Oxalate, Bray, Olsen, and Mehlich-1) to accurately estimate SPSC and simplify P loss risk assessment of soils located in a typical red soil in the Sunjia Watershed, Yingtan, Jiangxi Province, China. The extraction efficiencies of these methods for Fe, Al, P, and P saturation ratio (PSR) were compared, and conversion equations between SPSCOx (extracted using Oxalate) and soil test P (Bray, Olsen, and Mehlich-1) were derived through fitting analysis. The results underscored Oxalate as the optimal extractant for gauging P loss risk in red soils. Structural equation modeling (SEM) unveiled the substantial impact of amorphous iron-aluminum oxides (Feo, Alo) on SPSC, with Feo exerting a more pronounced influence than Alo. Among soil physicochemical properties, total carbon emerged as the most influential, and a strong interaction was noted between the physicochemical properties and Feo and Alo. The study delineated three crucial P concentration ranges for practical P management in red soils. When Bray-P < 48.2 mg kg–1, the soil acted as a P sink with no P loss risk, allowing for continued P application to augment crop yield. Conversely, within 48.2 mg kg–1 < Bray-P ≤ 55.2 mg kg–1, the soil attained its maximum secure P capacity; further P application significantly escalated the peril of P loss. Subsequently, when Bray-P > 55.2 mg kg–1, the soil turns into a source of P release. This signifies an escalated risk of P loss, demanding the immediate implementation of environmental protective measures. [ABSTRACT FROM AUTHOR]

Previous studies found that the strengthening mechanism of piles in composite foundation is related to the cross sectional shape of piles. However, the mechanism of plum blossom cast-in-place pile (plum blossom pile), as a novel kind of pile, strengthening mechanism is still unclear. In the present study, based on the transparent soil model test technique and Coupled Eulerian–Lagrangian (CEL) approach, single pile penetration tests were conducted. The load-vertical displacement characteristics of composite foundation and the variation of soil around piles are analyzed, and compared with circular piles with same cross sectional area. The results show that the ultimate bearing capacity of plum blossom pile is 1.45 times that of circular pile with the same cross sectional area. The compaction transition zone is observed in the soil around the plum blossom pile during the penetration process, and the radial distance of the compaction transition zone around the plum blossom pile is about 1.5 times that of the circular pile with the same cross sectional area. With the help of geotechnical engineering infinite element software Abaqus/Explicit, the variation of the mean pressure, radial stress and vertical stress of the soil around the plum blossom pile, and the evolution of the compaction transition zone and stress of soil around the pile are analyzed. With the penetration of plum blossom pile, the compaction transition zone at the pile side gradually increases, and the load can be transferred to a wider range in the composite foundation through the pile side compacting the soil around the pile. The research results can provide technical guidance for the design of the plum blossom pile composite foundation. [ABSTRACT FROM AUTHOR]

Groundwater contamination caused by hydrocarbons is a common issue worldwide. Determining the volume of light non-aqueous phase liquids (LNAPL) that contaminate the subsurface environment is crucial for planning effective groundwater and soil remediation strategies, as well as determining the remediation endpoint. However, accurate approaches for quantifying the LNAPL volume in subsurface environments are scarce. To address this gap, we developed and tested a novel approach to quantify the volume of oil phase filling the soil pores. Our approach involves using a high-resolution technique, the laser induced fluorescence (LIF), to identify the presence of the oil phase, which was then correlated to total petroleum hydrocarbons (TPH) quantifications. For that, first, we obtained an empirical model to estimate the TPH present in the soil using fluorescence intensity and then, we converted the fluorescence intensity data in each log to equivalent TPH values. We used the model block approach, commonly used for ore resource estimation, to compute and discretize the volume of the aquifer contaminated by LNAPL into a set of blocks using the LIF data. Each block was assigned a mean TPH mass, which we used as a proxy for the LNAPL mass in the block. By summing the LNAPL mass in all blocks, we estimated the total LNAPL volume/mass in the investigated site. Our approach provides a simple and effective way to determine the amount of LNAPL contaminating the soil and groundwater, offering a new perspective for investigating hydrocarbon-contaminated sites. [ABSTRACT FROM AUTHOR]

Soil chemical properties have a major impact on both agriculture and the environment, particularly with regard to soil fertility, soil quality, and crop production. However, little research has been done to address the spatial patterns of soil nutrients in the northwestern highlands of Amhara region of Ethiopia. The objective of this research was therefore to explore spatial variability of selected soil chemical properties that covers a broader area of 4 districts covering 560,085.2 ha of land to assess the spatial variability in the northwestern highlands of Amhara region in Ethiopia. Using Global Positioning System (GPS) (3 m precision), 363 (0–30 cm depth) soil point data were collected. Soil organic carbon (SOC), available P (AvP), electrical conductivity (EC), and soil acidity (pH) were taken into account when we explore the spatial variability. Inverse distance weighting (IDW), ordinary kriging (OK) methods, and geostatistical analysis (GS + 10) were used to analyze the spatial variability patterns of the SOC, EC, AvP, and pH concentrations. The results showed that the chemical properties vary considerably; the highest and lowest coefficients of variation (CV) were AvP (82.64%) and pH (9.12%), respectively. Moderate spatial dependencies (48.13–24.91%) were typically observed (SOC, EC, and pH), while AvP (17.84%) was strong. Cross-validation analysis showed that OK performed better (AvP, EC, and pH) than IDW (SOC). A semivariogram of log-transformed data for soil AvP, EC, and SOC was fitted with a spherical model whereas exponential model for pH. Spatial patterns of a pH map showed that the southeastern region is characterized by higher soil pH and high fertility potential for food crops. The research result/map could give useful tool for effective integrated land management to minimize soil acidification by policymakers, agriculturalists, and other stakeholder groups. We also recommended future routine update on the size and distribution of surface soil acidity, AvP, and SOC in the study area. [ABSTRACT FROM AUTHOR]

Purpose: Soil nutrients such as Nitrogen (N), Phosphorus (P), and Potassium (K) play a vital role in plant growth. It is crucial to apply the right amount of nutrients based on crop needs and soil conditions. Excessive amounts of fertilizer (overfertilization) lead to environmental pollution, nutrients runoff, financial losses, and imbalances that may harm plants. On the other hand, under fertilization causes nutrient deficiencies in soil, limiting plant growth and reducing yields. Material and methods: To measure NPK, three approaches are used: electrical conductivity testing, optical techniques, and electrochemical methods. These measurements are generally performed in a centralized laboratory. The onsite measurement of NPK levels can help farmers to apply variable-rate fertilizer and manage the resources in the most efficient and effective manner. This article enlists various electrical and optical methods for NPK measurements from soil samples. A comprehensive list of nutrient sensing techniques along with their advantages and limitations are also presented. A thorough literature search is conducted to examine various methods developed for NPK measurements. Each method is presented in detail and discussed the mechanisms for measuring NPK from soil. Results and discussion: The article discusses syntheses, technical analyses, results, and conclusions of various technologies developed for the NPK measurements. There hasn't been much utilization of optical technology for on-site analyses of soil nutrients. Optical diffuse reflectance in the Ultra-Violet Visible and Near-Infrared wavelength ranges has been used as a non-destructive method for quickly determining soil properties for site-specific management. For real-time analysis, electrochemical sensing with ion-selective electrodes or field effect transistors is a promising technique. It offers direct analyte detection in a simple, rapid, and accurate manner. Laser Induced Graphene (LIG) and Ion Selective Material Electrodes (ISME) are more promising methods. Conclusion: A practical and affordable three-in-one biosensor device for on-farm soil testing would be created in the future to help farmers. Farmers can measure real-time status of NPK from soil samples and apply the optimum amount of NPK fertilizer for getting significant financial benefits. The incorporation of real-time, cost-effective, portable, and easy-to-use sensors and devices can significantly help farmers in onsite NPK measurements. Nevertheless, this technique would require numerous field testing using different crops and soil types. To assist farmers in the future, a three-in-one biosensor device that is practical and economical for on-farm soil testing based on ion-selective material principle could be developed. This will allow farmers to have a handy tool to measure the NPK level of the soil separately. Real-time soil biosensors can be used to enable farmers for detection of NPK nutrient status of soil to choose the appropriate fertilizer application rate. [ABSTRACT FROM AUTHOR]

The novel dioxane-polyether polyurethanes underwent a 12-month outdoor soil burial test to look into how they would degrade in a natural setting. The structure, thermal properties, surface features, and mechanical strength of the polyurethane films were compared. The initial chemical structure and subsequent chemical alterations were identified using FTIR spectroscopy. The polyurethane samples were less thermally stable throughout the duration of the soil burial test, according to TG/DTG curves. According to all findings, polyurethanes containing 1,3-dioxane-5,5-dimethanol exhibit excellent physical characteristics and mild degradation levels after being buried in soil for a year. These polyether urethanes can break down if the rigid domain structure is exposed to moisture and if microorganisms can spread into the polymer matrix. The physical properties, surface features, and degradation of polyether polyurethanes can be improved by varying the molar ratios of the hard segment components and the dioxane derivative structures. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive review on microplastic from source to sink and reviews the current state of knowledge of the topic by focusing on the articles published within the last five years on identification, quantification, analyses, and effects of microplastics on soil and aqueous environments. Microplastics are materials formed either by the degradation of the plastic into smaller micro sized particles or obtained directly in daily products such as cosmetics, toothpastes, domestic cleaning products, etc. Hence, the origin of microplastics is either a primary or secondary microplastic source. The lack of information and research conducted on microplastics in soil compared to water influenced many disparities. These include variations in defining microplastics to lack of conclusive methodologies in analysis of microplastics in soil which therefore lead to gaps in identification of plastic source and comprehension of plastic pollution in soil. The effect of microplastics on different aquatic vertebrates, mammals, and humans is studied and, in most cases, various negative effects were observed in the organism's physiology. In addition to innovative control methods, there is a growing focus on exploring bioplastics as a potential substitute for traditional plastics. Numerous studies suggest that the environmental impact is more manageable with the production and use of bioplastics. Nonetheless, additional research is needed to confirm the viability of bioplastics as a potential solution. [ABSTRACT FROM AUTHOR]

Karst landforms are special geological structures in southwestern China that are closely related to local ecological environments and human activity. This study focuses on the Wuming District, Nanning City, Guangxi Province, China, to explore the influence of different factors on the organic carbon storage and density characteristics of typical karst landform soils in the Wuming area. A multi-objective geochemical investigation was conducted from five perspectives: geological age, rock type, landform type, soil type, and land-use type. Surface and deep soil organic carbon (SOC) content data were obtained, and the organic carbon density and storage were calculated for the study area. The results showed significant vertical heterogeneity in soil organic carbon content, with carbon storage increasing with depth, indicating distinct carbon sink characteristics (p < 0.01). Overall soil organic carbon density was highest in the Devonian period among the different geologic ages (up to 3.92 kg/m2 in the surface layer), with acidic rocks resulting from ancient volcanic activity showing the highest organic carbon density among the lithological classifications (4.09 kg/m2). Karst landform soils, primarily limestone, had a higher organic carbon density than that of other terrains, particularly in carbonate rocks intermingled with clastic rocks. Despite the limited distribution of Bog soil within the study area, they exhibited the greatest carbon sequestration capacity among all evaluated soil types, with a soil organic carbon Density of 4.81 kg/m2. The predominant land-use type was arable land, encompassing a vast expanse dedicated to dryland farming—72.66% of the study area's total extent—which accounted for the highest organic carbon storage, estimated at 3.14 Tg. Conversely, paddy fields demonstrated superior organic carbon density. Collectively, these results illuminate the intricate interactions among variables that affect organic carbon storage and density in the soils of karst landscapes within the study area. This contributes to a deeper understanding of carbon cycling and its management within karst ecosystems. [ABSTRACT FROM AUTHOR]