Environmental Earth Sciences最新文献

High prevalence of uranium in groundwater and associated potential health hazards to human population of Bathinda and Moga districts of south-west Punjab, India is presently a matter of great concern, as the groundwater is a major source of drinking water for human consumption as well as irrigation. So, the current integrated study was carried out to understand the spatial and vertical distribution of uranium, associated physico-geochemical parameters and allied path finder elements using hydro-geochemical tools of chemometric statistics. In this study, in comparison to the samples from deeper aquifers, high prevalence (surpassing WHO limit 30 µg/L in drinking water) of uranium was observed in 63% and 43% of groundwater samples from shallow depth (< 200 ft) in Bathinda and Moga districts, respectively. Substantial nitrates (mg/L) contamination (Bathinda: 0.16–525.20; Moga: 0.17–71.28) followed by fluoride (mg/L) (Bathinda: 0.56–2.67; Moga: 0.11–2.15) was found in groundwater of both districts. The health risk assessment revealed that cancer risk (CR) and hazard quotient (HQ) values decrease with groundwater depth, indicating higher uranium-related health risks in shallow aquifers, particularly in Bathinda district. The groundwater from deeper aquifers of the study area has been determined to be appropriate for irrigation purpose. From the hydro-geochemistry study in Bathinda district, it was observed that both water–rock interactions and high saline water intrusions were responsible for ionic solubility whereas in Moga district, the primary source of dissolved ions is water–rock interactions. Further, U mobilisation was found to be facilitated by the association of Ca-Mg-SO₄ in the saline groundwater. A strong positive correlation of uranium was observed with its path finder elements (Cr, Mo, Se) in both districts indicated that the geogenic sources are predominantly responsible for the origin of U in groundwater of two districts. So, this study may serve as a baseline dataset for uranium distribution in groundwater of both districts to local communities, state and central government and other associated organizations for designing the policies and remediation strategies to tackle water pollution.

The usability of rocks as dimension stones is influenced by several geological parameters, including the reserve, material properties, block size, quarry production efficiency, factory production efficiency, and the color-pattern characteristics of the rock mass. The initial preparation costs are particularly high in dimension stone quarries. Numerous dimension stone quarries are prematurely abandoned as a result of inadequate geological investigations conducted before production. This not only results in economic loss but also unnecessary destruction of nature. Consequently, an assessment of the rock mass characteristics and material properties is a critical factor to consider prior to initiating quarry operations. This study aims to identify the geological parameters influencing the production of dimension stone in Manisa limestone. In this context, detailed field observations were conducted on the bench faces and on the abandoned stone blocks in the waste disposal areas of 15 quarries (7 active and 8 abandoned) located in Manisa region. According to the findings of the geological studies conducted at the quarries, it was determined that the most important primary geological parameters affecting the dimension stone production are discontinuities; secondary geological parameters were determined as brecciation, cherts, autobrecciation, fossil presence, Neptunian dyke infillings, onyx zones, color changes, stylolites, weathering along discontinuity, and black dots. Results of the scan-line surveys shows that the mean discontinuity spacing of the discontinuity planes is wider than 1 m and the volumetric joint count (Jv) value is lower than 1.35 joint/m³ of the working quarries.

Research on cementation in natural moraine soils remains limited. To address this gap, a series of tests, including field surveys, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), grain sieve analysis, and a pretreatment using hydrochloric acid (HCl) and hydrogen peroxide (H₂O₂), were conducted. The results reveal that clay-carbonate cementation is widespread in moraine soils, which are primarily composed of clay minerals and calcite (CaCO₃). XRD analysis revealed a clay mineral content ranging from 6% to 27%, with illite as the dominant mineral. The calcite and dolomite content ranged from 0% to 9%. Scanning electron microscopy (SEM) and EDS mapping confirmed that the cementation enhances the connection and density of particles. Additionally, the pretreatment altered the cumulative grain size distribution (CGSD), reducing the gravel content and increasing the proportion of smaller particles, particularly those smaller than 0.25 mm. This shift resulted in changes in soil texture classification, from poorly graded gravel (GP) to fine and clayey gravel (GF and GC). A new Sigmoid-TL model was proposed to quantify cementation, using the absolute integral area between the fitted CGSD curves before and after pretreatment on a logarithmic particle size scale, thereby providing a reliable measure of its effect on soil cementation. The study highlights the significant role of cementation in enhancing slope stability, though external factors, such as acidic and alkaline rain, can weaken it, leading to increased instability.

As one of the most abundant and widely distributed aerosols in the troposphere, dust aerosols act as condensation nucleus to alter the life cycle of clouds and precipitation, thus affecting weather and climate. However, the exact effect of dust aerosols on precipitation, specifically polluted dust, remains to be fully understood and warrants further exploration. Based on raindrop size distribution data in Pudong, Shanghai, China, from 2021 to 2022, two precipitation episodes with polluted dust are taken as examples to clarify the mechanism of the inhibition of polluted dust on weak precipitation. Compared to the dust-free precipitation event, the average concentration of small raindrops increased by 13.8%, while that of large raindrops decreased by 19.2% in polluted dust precipitation event. This may be attributed to the participation of polluted dust aerosols in cloud microphysical processes, which led to the suppression of precipitation efficiency and the significant reduction of large raindrop concentration. However, anthropogenic aerosols have the opposite effect in convective precipitation. It is found that, compared with clean conditions, the average concentration of small raindrops in stratiform precipitation decreases by 63.5%, whereas that of large raindrops in convective precipitation increases by 8.04 times under high pollution conditions. These findings highlight the inhibition effect of polluted dust aerosols on weak precipitation and the promotion effect of anthropogenic aerosols on convective precipitation, which can provide scientific insights for weather and climate prediction.

Effective water resources planning and management require a robust understanding of groundwater level (GWL) dynamics, which in turn depends on the reliability of simulation models. Modeling GWL in anisotropic settings remains a significant challenge, particularly in poorly monitored basins. This study investigates a hybrid modeling framework that integrates state variables from the Water Partition and Balance (WAPABA) model into Extreme Gradient Boosting (XGBoost), Support Vector Regression (SVR), and Shapley Additive Explanations (SHAP) algorithms to improve GWL prediction in the Bouregerg Catchment in Morocco. The WAPABA model demonstrated strong performance in simulating runoff, achieving Nash–Sutcliffe Efficiency (NSE) values of 0.88 and 0.77 during calibration and validation, respectively. Sobol sensitivity analysis identified key parameters, including the catchment consumption curve and groundwater yield proportion. Incorporating WAPABA-derived state variables into SVR and XGBoost models substantially enhanced GWL prediction, yielding NSE values between 0.53 and 0.96 and Kling–Gupta Efficiency (KGE) values between 0.779 and 0.962. SVR exhibited a slight performance advantage over XGBoost, and the hybrid models consistently outperformed standalone machine learning approaches. SHAP-based interpretability analysis highlighted the dominant influence of hydrological state variables such as potential evapotranspiration, soil water storage, and groundwater fraction on GWL dynamics, with their relative importance varying according to geological conditions. Overall, the proposed hybrid framework offers a powerful and process-consistent approach for modeling GWL in anisotropic environments, supporting improved decision-making in water resources management.

Over the past three decades, China’s coal production has undergone a strategic westward shift. Several important coal production bases are now located in ecologically fragile, arid regions. The surface subsidence caused by large-scale coal mining could adversely affect these vulnerable ecosystems. To understand this impact, this study investigates the moisture migration process and evaporation losses of fissure-filled soil moisture in semi-arid mining areas. We collected fissure-filled and undisturbed soil samples from depths of 0-300cm, analyzed their structure and soil moisture content (SMC), and used hydrogen and oxygen stable isotopes ((delta ^2 H) and (delta ^{18} O)) to trace soil moisture infiltration and evaporation processes. This study revealed distinct structural differences between fissure-filled soil and undisturbed soil layers. Fissure-filled soil received more precipitation recharge, resulting in higher moisture content in deeper layers. Conversely, the shallow layer of fissure-filled soil experienced stronger evaporation. Consequently, the evaporation loss rate within the fissure-filled soil in the 0-180cm depth range was 10-20% higher than that of the undisturbed soil. The results show that after the tension fissures in the coal mining subsidence area are filled, fissure-filled soil texture changes, the deep soil moisture content increases, and the evaporation in the shallow layers are intensified. This leads to more frequent and severe soil dry-wet cycles within fissure-filled soil. Furthermore, the fissure-filled soil exhibits enhanced water recharge capacity, suggesting its potential as a hotspot for ecological reclamation in arid mining regions.

Acid rain can dissolve carbonate rocks and affect karst carbon sinks. This study investigated the effect of acid rain on the dissolution of carbonate rocks within a karstic soil–carbonate rock system and quantified the relationship between the carbon sink and karst carbon sink flux. A subtropical karst spring catchment in southwestern China was chosen as the study area. The hydrochemistry of acid rain and spring water, along with the δ¹³C of dissolved inorganic carbon (DIC), was systematically monitored. NH₄⁺, H₂SO₄, and HNO₃ from precipitation contributed 3.57%, 3.49%, and 1.57% to carbonate rock dissolution, and 1.74%, 1.70%, and 0.77% to groundwater DIC, respectively. These acidic ions reduced the karst carbon sink flux by approximately 17.37%. The carbon sink flux reached 43.93 mg C/L during the wet season, whereas the karst carbon sink flux was 11.61 mg C/L. Overall, the total carbon sink flux in the spring catchment was about 3.8 times higher than the karst carbon sink flux. The dissociation of carbonic acid produces H⁺, which can be exchanged with soil base ions. This process contributed more DIC to groundwater in the Yaji karstic soil–carbonate rock system than direct carbonate rock erosion by H⁺ from carbonic acid dissociation. While this study demonstrates that karstic soil processes significantly buffer acid rain and strengthen the carbon sink effect, their wider applicability may be limited by site-specific factors such as soil composition, hydrological conditions, and land use.

The long-term environmental legacy of mining in sulfide-rich regions remains a critical concern due to the persistent generation of acid mine drainage (AMD) and the mobilization of potentially toxic elements (PTEs). This study presents a comprehensive, site-specific assessment of mine waste from two contrasting geochemical zones, Nuestra Señora del Carmen (NSC) and Volta Falsa (VF), within the historically under-characterized Trimpancho Mining Complex, located in the Iberian Pyrite Belt (IPB). A multidisciplinary approach combining mineralogical characterization, physicochemical and geochemical analyses, multivariate statistics, and contamination indices, provided insights into the behavior, mobility, and ecological risk of key PTEs such as Cu, As, and Zn. The NSC zone is dominated by pyrite and secondary sulfates, promoting acidic conditions (pH values ranging from 2.42 to 3.60) and high Cu mobility, whereas VF waste materials show a more heterogeneous mineralogy, higher pH (ranging from 2.77 to 5.05), and broader PTE enrichment. Principal Component Analysis revealed distinct geochemical regimes shaped by the presence of sulfides or silicates. Contamination indices underscored significant ecological risk in both zones, but with distinct pollution signatures. This integrated framework supports site-specific environmental risk management and remediation strategies and applies to other AMD-impacted volcanogenic massive sulfide (VMS) mining environments facing renewed exploration pressures.

Acid mine drainage (AMD) is a global problem that threatens nearby water sources, poses risks to aquatic ecosystems and humans, and has lasting environmental impacts. Conventional remediation of high fluoride and high acid mine drainage in one of the deepest and largest abandoned mine pits in eastern China was challenging due to its immense volume and vertical stratification, and was estimated to take nearly several years through pilot testing and monitoring. The Integrated Treatment Station (ITS), consisting of the pump and dosing tank, was designed to promote vertical mixing, with deep water being drawn to the surface by the pump and supplemented by an appropriate amount of neutralizer being added in the dosing tank, and then sprayed nearby. A three-dimensional (3D) k-ε hydrodynamic coupled water exchange model was established to predict the feasibility and optimality of the solution, and was also used to track the efficiency of the real treatment operation. There are three schemes, referred to as V1, V2, and V3. The first scheme, V1, involves a few high-capacity land-based ITS, while V2 employs many low-capacity floating ITS, and V3 uses a moderate number of low-capacity floating ITS, deployed in varying areas depending on the bathymetry. Based on the simulation results, after running V1, V2 and V3 schemes ran for 3 months, the water exchange efficiency of the total alkaline addition reached 71.37%, 76.18% and 81.56%, respectively, which can meet the efficiency requirements for AMD treatment. According to a comprehensive cost–benefit analysis, V3 was determined as the optimal solution for operation in AMD treatment. During the operation of the selected V3 scheme, the fluoride ion levels in the surface and bottom layers were monitored synchronously to assess the effectiveness of the treatment, and the total fluoride ion concentration showed a remarkable logarithmic decrease, with surface, bottom and total water body levels following a consistent downward trajectory as predicted by the model. The use of model simulation reduced the trial and error, increased the efficiency of AMD remediation, and greatly reduced the treatment time. Within approximately one year, the water had substantially achieved the treatment objectives. The study focuses on the entire AMD treatment process of a large-deep mine pit using a 3D numerical model to guide the design, optimization and implementation of the scheme, providing a successful demonstration of AMD water environmental remediation for a large mine pit.

Fault zones, which are common geological structures, are characterized by a “hard–soft–hard” structure. To simulate both “soft” and “hard” rock masses, versatile similar materials with tuneable properties were developed for application under true three-dimensional (3D) geostress conditions. Using iron ore powder, barite powder, quartz sand, rosin, alcohol, and white cement as raw materials, similar materials for rock masses with evident “soft” or “hard” characteristics were formulated through orthogonal design. The density, uniaxial compressive strength, elastic modulus, Poisson’s ratio, cohesion, and internal friction angle of the similar materials were measured through laboratory tests. The sensitivity of the factors was assessed via range analysis, and the effect of white cement was further analysed. Finally, the developed similar materials were successfully applied to a geomechanical model test on the tunnel response under true 3D geostress and fault dislocation. The results show that the similar materials have a wide range of physical and mechanical parameters, and can meet the requirements of different kinds of rock masses. The mass ratio of aggregates has the greatest influence on the material density, whereas the mass concentration of rosin has the greatest impact on the uniaxial compressive strength, elastic modulus, cohesion, and internal friction angle. White cement has a significant enhancement effect, and it can increase the mechanical properties of the similar materials and improve their brittleness and hardness. After fault dislocation, the rupture of the surrounding rock in the hanging wall is more severe, resulting in the lining suffering more severe failure. The observable failure range of the lining is located on both sides of the fault zone, and does not exceed 1.5 times the width of the fault zone. The materials can provide material support for obtaining good test results and can serve as a reference for the selection of similar materials for rock masses in similar model tests.