In recent years, excessive accumulations of iron (Fe), manganese (Mn), and nitrogen (N) have been observed in the groundwater of agricultural regions, particularly in flood irrigation areas. Nevertheless, the causes of this phenomenon and the associated hydrobiogeochemical processes remain elusive. This study demonstrated that redox fluctuations instigated by flood irrigation triggered a synergistic interaction between the N cycles and the activation of Fe and Mn oxides, thereby resulting in elevated concentrations of Fe, Mn, and N simultaneously. Static experiments revealed that the properties of the topsoil exerted a profound influence on the N induced release of Fe and Mn. The black soil (TFe: 1.5-2.3 times, Mn(II): 1.1-1.5 times, nitrate: 1.3-1.4 times) had greater release potential than meadow and dark brown soils due to higher electron donors/acceptors and substrates. Dynamic column experiments further elucidated that the wet-dry cycles induced by agricultural cultivation regulated the release process through the formation of zonal redox gradients and the structuring of microbial community. Organic nitrogen mineralization, chemolithotrophic nitrification, and Feammox/Mnammox were identified as the primary mechanisms responsible for the reductive dissolution of Fe-Mn oxides. On the other hand, autotrophic denitrification, with nitrate serving as the electron acceptor, constituted the main process for the reoxidation of Fe and Mn. Furthermore, the agricultural activities exerted a significant impact on the nitrate attenuation process, ultimately resulting in the recurrence of TFe (black soil: 1.5-6.3 times) and nitrate (black soil: 1.4-1.6 times) pollution during the phase after harvesting of rice (days 40-45) in saturated zone. The findings of this study not only deepened the understanding of the intricate interactions and coupled cycles between primary geochemical compositions and anthropogenic pollutants, but also provided a scientific foundation for the effective management and prevention of groundwater pollution stemming from agricultural cultivation processes.

The thermo-mechanical (TM) behaviour of the energy pile (EP) group becomes more complicated in the presence of seepage, and the mechanism by which seepage impacts the EP group remains unclear.In the current work, a 2 x 2 scale model test bench of EP group was set up to investigate the TM behaviour of EP group with seepage. The test results indicate that the heat exchange performance of EP group with seepage can be significantly enhanced, but also leads to obvious differences in the temperature distribution of pile and surrounding soil along the seepage direction, and thus causes evident differences in the mechanical properties between the front pile and the back pile in pile group. Compared with the parallel connection form, the thermal performance of EP group with the series connection form is slightly attenuated. However, the mechanical properties of various piles in the EP group differ significantly. Under the action of seepage, the mechanical balance properties of various piles in the forward series form are optimal, followed by the parallel form, and the reverse series form is the least optimal. A 3-D CFD model was established to further obtain the influence of seepage and arrangement forms on EP group. The findings indicate that seepage can not only mitigate thermal interference between distinct piles but also expedite the process of heat transfer from pile-soil to reach a state of stability. Concurrently, the thermal migration effect induced by seepage will be superimposed along the seepage direction, resulting in the elevation of thermal interference of each pile along the seepage direction, and the superposition of thermal migration effect increases with the time. Under the same seepage condition, the cross arrangement can enhance the thermal performance of EP group, optimize the temperature distribution of pile and soil, and thus the imbalance of mechanical properties among pile groups can be reduced. In addition, the concepts of thermal interference coefficient and heat exchange rate per unit soil volume are introduced to facilitate a more precise evaluation of the thermal interference degree of each pile in the pile group and the heat exchange performance under different pile arrangement forms.The standard deviation and mean value in the statistical method are used to evaluate the equilibrium of mechanical properties of pile group, which is more intuitive to compare the differences in mechanical properties of pile groups under different working conditions.

Gas station sites pose potential risks of soil and groundwater contamination, which not only threatens public health and property but may also damage the assets and reputation of businesses and government entities. Given the complex nature of soil and groundwater contamination at gas station sites, this study utilizes field data from basic and environmental information, maintenance information for tank and pipeline monitoring, and environmental monitoring to develop machine learning models for predicting potential contamination risks and evaluating high-impact risk factors. The research employs three machine learning models: XGBoost, LightGBM, and Random Forest (RF). To compare the performance of these models in predicting soil and groundwater contamination, multiple performance metrics were utilized, including Receiver Operating Characteristic (ROC) curves, Precision-Recall graphs, and Confusion Matrix (CM). The Confusion Matrix analysis revealed the following results: accuracy of 85.1-87.4 %, precision of 86.6-88.3 %, recall of 83.0-87.2 %, and F1 score of 84.8-87.8 %. Performance ranking across all metrics consistently showed: XGBoost > LightGBM > RF. The area under the ROC curve and precision-recall curve for the three models were 0.95 (XGBoost), 0.94 (LightGBM), and 0.93 (RF), respectively. While all three machine learning approaches demonstrated satisfactory predictive capabilities, the XGBoost model exhibited optimal performance across all evaluation metrics. This research demonstrates that properly trained machine learning models can serve as effective tools for environmental risk assessment and management. These findings have significant implications for decision-makers in environmental protection, enabling more accurate prediction and control of contamination risks, thereby enhancing the preservation of ecological systems, public health, and property security.

Chromium is a heavy metal used in tanneries, leather industries, electroplating, and metallurgical operations, but improper disposal of waste from these industries leads to environmental contamination. Chromium exists primarily in trivalent and hexavalent forms, with hexavalent chromium (Cr (VI)) being highly toxic. Cr (VI) is carcinogenic, damages fish gills, and negatively impacts crops. Considering these negative impacts of Cr (VI), several physical, chemical, and biological remediation methods have been implemented at contaminated sites, but in most instances, these methods could be uneconomical, highly labor-intensive, and not sustainable. Therefore, a crucial goal is to implement an effective and sustainable remediation technique with consideration of actual site conditions. The aim is to develop a sustainable remediation strategy for a hexavalent chromiumcontaminated site in Ranipet, Tamil Nadu. The comprehensive risk assessment for the site has depicted hazard quotients greater than 1 for both onsite and offsite conditions, indicating the necessity of remediation. To address this, it is suggested to build permeable reactive filters (PRFs) packed with scrap iron filings to reduce Cr (VI) to Cr (III), and succeeding filters with locally produced waste coconut shell biochar to aid in adsorption. The use of waste here aims to eliminate the need to procure any commercially available materials for remediation, completely cutting down the environmental impact of raw material extraction or processing. A continuous chambered set-up packed with contaminated soil and PRFs with biochar and iron filings aided in the decrease of the peak concentration of Cr (VI) by 61 % as compared to a set-up without intervention. Moreover, the outlet concentration after 7 days reduced to 0.08 mg/L, which was 97.6 % less than that in the set-up without intervention.

This study employed geo-electrostratigraphic and hydrogeological information to model and assess subsurface structure and hydrogeological properties within a major coastal environment in Nigeria's Niger Delta region, offering a high-resolution approach to groundwater resource management. The selection of the study area was predicated on its critical residential, agricultural, and economic significance, as well as its susceptibility to hydrogeological challenges arising from rapid urbanization and industrial activities. Unlike previous studies that utilized these methods independently, this research combined different geoelectrical technologies to enhance the accuracy of subsurface characterization. The results delineated four distinct geo-layers characterized by specific resistivity values, thicknesses, and depths, providing crucial insights into groundwater infiltration, storage potential, and contamination risks. The first geo-layer (motley topsoil) had resistivity values ranging from 95.2 to 1463.7 Qm. The second layer (sandy clay) exhibited resistivity values ranging from 8.8 to 2485.1 Qm. The third layer, identified as fine sand, exhibited resistivity values ranging from 72.5 to 1332.7 Qm. The fourth layer comprised coarse sands and it exhibited a mean resistivity of 525.98 Qm, indicating a well-drained permeable formation that could serve as an additional aquifer unit. A key innovation of this study was the quantitative assessment of hydrogeological parameters, including anisotropic coefficient, transverse resistance, longitudinal conductance, and groundwater yield potential index. The anisotropic coefficient ranged from 1.0 to 1.78 (mean: 1.17), revealing minimal sediment invasion and confirming the dominance of arenaceous sediments in the Benin Formation. The groundwater yield potential index varied from 3.14 x 102 to 8.1465 x 104 Qm2, highlighting areas of significant aquifer potential. The longitudinal conductance analysis revealed that 69 % of the study area has low aquifer protectivity, underscoring the region's vulnerability to contamination. Another novel contribution was the evaluation of soil corrosivity, which has direct implications for infrastructure longevity. Results indicate that 86 % of the study area is non-corrosive, making it suitable for long-term pipeline installation, a factor rarely integrated into groundwater assessments. The study alsoadvances understanding of the Benin Formation by linking resistivity variations to arenaceous-argillitic intercalations, and this significantly influences groundwater movement and contaminant transport. By synthesizing resistivity models, hydrogeological parameters, and contamination risk assessments, this research provides a more holistic framework for sustainable groundwater management. Furthermore, this research offers a robust framework for similar hydrogeophysical assessments in other regions with comparable geological and hydrological settings. (c) 2025 Guangzhou Institute of Geochemistry, CAS. Published by Elsevier BV. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Significant movement of in-situ retaining walls is usually assumed to begin with bulk excavation. However, an increasing number of case studies show that lowering the pore water pressures inside a diaphragm wall-type basement enclosure prior to bulk excavation can cause wall movements in the order of some centimeters. This paper describes the results of a laboratory-scale experiment carried out to explore mechanisms of in situ retaining wall movement associated with dewatering inside the enclosure prior to bulk excavation. Dewatering reduces the pore water pressures inside the enclosure more than outside, resulting in the wall moving as an unpropped cantilever supported only by the soil. Lateral effective stresses in the shallow soil behind the wall are reduced, while lateral effective stresses in front of the wall increase. Although the associated lateral movement was small in the laboratory experiment, the movement could be proportionately larger in the field with a less stiff soil and a potentially greater dewatered depth. The implementation of a staged dewatering system, coupled with the potential for phased excavation and propping strategies, can effectively mitigate dewatering-induced wall and soil movements. This approach allows for enhanced stiffness of the wall support system, which can be dynamically adjusted based on real-time displacement monitoring data when necessary.

Research on the performance of solidified soil in capillary water absorption seawater environments is necessary to reveal the durability under conditions such as above seawater level in coastal zones. Taking soda residue-ground granulated blast furnace slag-carbide slag (SR-GGBS-CS) and cement as marine soil solidifiers, the deterioration characteristics of solidified soil resulting from capillary seawater absorption were elucidated systematically through a series of tests including capillary water absorption, unconfined compressive strength, swelling, local strain, and crystallization. The microscopic mechanism was analysed through nuclear magnetic resonance and X-ray diffraction tests. The results showed that cement-solidified soil exhibited higher water absorption and faster swelling compared with SR-GGBS-CS solidified soil in the one-dimensional seawater absorption state. In the three-dimensional seawater absorption state, solidified soil with low GGBS dosage experienced a significant transition from vertical shrinkage to swelling during the capillary water absorption process, leading to a substantial decrease in strength after 7 days of crystallization. Cement-solidified soil displayed non-uniform and anisotropic swelling, along with the formation of more external salt crystals. Overall, the soil solidified with 25% SR, 10% GGBS, and 4% CS demonstrated robust resistance to capillary absorption deterioration in a seawater environment due to its minimal water absorption and swelling, uniform surface strain, weak salt crystallization, and limited strength deterioration caused by capillary water absorption.

This study proposes a three-dimensional transformed differential quadrature solution for the thermo-mechanical (TM) and thermo-hydro-mechanical (THM) coupling of transversely isotropic soils considering groundwater. Initially, the governing equations for TH coupling above the water table and THM coupling below the water table are introduced. Subsequently, twodimensional Fourier integral transform and Laplace integral transform are applied, and a series of equations are discretized along the depth according to the discrete rules of the transformed differential quadrature method. Then, the boundary conditions for stress, displacement, and temperature are introduced through integral transforms and stress-strain relationships. By solving the matrix equation, the solution for transversely isotropic soils is obtained. After verifying the theory in this study, continuity conditions, the water table depth, anisotropy of thermal diffusion coefficients, and seepage are analyzed, contributing to the design of radioactive waste disposal sites, energy piles, and other projects.

The environment has been damaged due to anthropogenic activities related to the production and consumption of cattle. The present study investigated the pollution potentials of slaughterhouse effluents on groundwater qualities in Ebonyi State Southeast Nigeria, with the specific objectives to determine the effect of slaughterhouse effluents on both microbiological, physicochemical and heavy metal parameters on the quality of groundwater. Eighty-four well water samples were taken in 2022 and 2023 from slaughterhouse locations, and a control location for the determination of physicochemical properties and microbiological contents using standard analytical methods. Datasets were analyzed using Fisher's Significance Least Difference (F-LSD) at 0.05 probability level. The study recorded higher levels of physicochemical, BOD, COD, Salinity, bacterial and fungal counts in the slaughterhouses well waters when compared to the control well water. With the exception of chloride, ammonia, copper and electrical conductivity, all water parameters were significant in both years. The result of the study also demonstrated that, with the exception of ammonia, lead, biological oxygen demand, chemical oxygen demand, salinity, salmonella spp, shigella spp, E. coli, and other coliforms, the majority of the analysed parameters were within the World Health Organisation recommended standard. In addition, as compared to the first year of study, the well water parameters were generally higher in the second year. In order to prevent groundwater pollution, the present study suggests that slaughterhouse effluents be disposed of in an environmentally responsible manner through the segregation of waste materials to prevent groundwater pollution.

Deep excavation engineering often causes deformation and destruction of adjacent existing shield tunnels. In previous studies, the influence of deep excavation on tunnel was mainly concentrated on tunnel deformation caused by retaining structure deformation, and the maximum range of the influence zone was approximately 4 times the excavation depth (4He). However, there has been little research on tunnel deformation caused by groundwater drawdown when tunnels are located outside the traditional influence range (4He) of the excavation. In this study, the deformation and damage characteristics of tunnels caused by dewatering in a deep excavation project were analysed using field data, and control methods of tunnel deformation caused by excavation dewatering in leaky aquifers were proposed and discussed. In this project, the maximum settlement reached 8.23 mm for tunnel at the location far than 4He from the excavation, and the influence range of the dewatering on tunnel was nearly 8He. Furthermore, the higher stiffness of the station reduced the settlement and convergence but aggravated the dislocation of the tunnels within approximately 40 m from the station, causing many leakage points. To protect the tunnels, groundwater recharge and deep-shallow-well dewatering scheme (dewatering wells in phreatic aquifer and confined aquifer were set independently) were proposed and applied during subsequent construction, which effectively avoided further tunnel settlement. Groundwater recharge also induced slight uplift and horizontal deformation of the tunnels to the opposite side of the excavation. In addition, recharge should be started in advance and remain in operation until the groundwater level was fully restored. For deep excavations near important infrastructures in soft soil strata with leaky aquifers, the same dewatering and recharge system in this case study is suggested to adopted.