Environmental Earth Sciences最新文献

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.

The Gravity Recovery and Climate Experiment (GRACE) satellite offers a contemporary methodology for analyzing regional groundwater dynamics, addressing the limitation of sparse groundwater monitoring networks. To investigate the groundwater storage dynamics in the Huaibei Plain, Anhui Province, China, this study quantifies the changes in groundwater storage from 2004 to 2023 using GRACE and Global Land Data Assimilation System (GLDAS) data. A comprehensive analysis is conducted on the spatiotemporal variations, influencing factors, and sustainability of groundwater resources. Results indicate that groundwater storage in the Huaibei Plain increased at an average rate of 0.027 cm/a during the study period. Spatially, groundwater storage exhibited a decreasing trend from the central to the peripheral regions of the plain, with more pronounced changes in the southwestern areas compared to the northeastern regions. The classification of GWSA revealed irregular patterns. The correlation coefficient between inverted results and observed groundwater level changes from monitoring wells was determined to be 0.61. Geodetector and grey relational analysis were employed to identify factors influencing GWSA, revealing that groundwater extraction (63.6%) and population growth (53.8%) were predominant contributors. Over the study period, the groundwater drought condition in the region transitioned from partial mild drought to partial extreme drought and eventually to no drought across the entire area. Furthermore, the groundwater storage in the study area was found to be in an extremely unsustainable state. These findings underscore the practical utility of satellite-based groundwater storage estimation as a viable solution for overcoming the challenges posed by insufficient groundwater monitoring networks.

This research investigates the groundwater quality in the Mahanadi Upper Basin, a crucial tropical agricultural region in India, where understanding water properties is vital for optimizing crop production and promoting sustainable water use. As freshwater resources face growing pressures from agricultural activities and climate change, assessing groundwater quality becomes essential for maintaining sustainable practices. Using Geographic Information Systems (GIS) and geostatistical methods, the study mapped and modelled spatial variations in water quality parameters. The excellent, good and poor water quality covered 10850.90 Km², 18845.1 Km² and 1003.8 Km², respectively. Key findings include that 20% of samples show high-risk nitrate levels, 68% face risks from fluoride, and 25% of the area is unsuitable for irrigation based on Kelly's ratio. The study highlights significant variations in electrical conductivity, pH, and major ions, providing essential insights for water resource management and agricultural practices in similar tropical regions globally. These findings lay the groundwork for future research into the complex hydrogeological systems of tropical agricultural zones.

Water-induced soil erosion remains a major constraint to sustainable land management (SLM) and long-term agricultural productivity, especially in landscapes experiencing rapid land use and land cover (LULC) changes. This study assesses the spatiotemporal dynamics of LULC changes and its impacts on soil erosion in the Bilate River Catchment (BRC) of Ethiopia’s Rift Valley Lakes Basin (RVLB) using integrated remote sensing and geospatial soil erosion modelling for the years 1990, 2003, and 2019. Multispectral Landsat images (30 m), edaphic data, fluviometric records, and a 30 m DEM were processed using supervised classification with the Maximum Likelihood Algorithm in ERDAS Imagine 2015. Classification accuracy was high, with overall accuracies of 86.72%, 91.41%, and 92.19%, and Kappa coefficients of 0.8290, 0.8902, and 0.8998, respectively. The Revised Universal Soil Loss Equation (RUSLE), implemented in ArcGIS 10.7.1, estimated mean annual soil loss rates rising from 27.34 t.ha⁻¹.yr⁻¹ in 1990 to 52.94 t.ha⁻¹.yr⁻¹ in 2019, well above the Ethiopian tolerance threshold of 2–18 t.ha⁻¹.yr⁻¹. Agricultural lands, now covering over half the catchment, showed the highest erosion rates (31.27 to 64.88 t.ha⁻¹.yr⁻¹), largely due to cultivation on steep slopes and lack of conservation. Degraded lands also saw severe increases, while forests, despite shrinking by 295.74 km², retained the lowest erosion rates. Areas under very high erosion risk (> 100 t.ha⁻¹.yr⁻¹) tripled, while low-risk zones (< 10 t.ha⁻¹.yr⁻¹) declined by nearly 7%. The maximum soil loss surged from 609.81 to 1919.57 t.ha⁻¹.yr⁻¹, indicating intensifying localized degradation. LULC changes, driven by population growth, have replaced forests and grasslands with agriculture and settlements. The results highlight the need for integrated catchment management and erosion mitigation strategies, prioritizing high-risk zones for intervention and promoting ecosystem restoration for sustainable, climate-resilient land use planning.

As one of the world’s largest coal producers, China has shifted its coal mining focus from the eastern to the western regions, which has, however, resulted in a more significant impact on the fragile ecological environment in the western areas. Among the influencing factors, surface subsidence due to coal mining is the primary cause of damage to the ecological environment of mining areas and negatively impacts sustainable mining practices. Therefore, monitoring the deformation of the primary mining face and analyzing its characteristics is crucial for reconstructing the coal mine subsidence area and mitigating geological hazards. However, due to the shallow mining depth, significant thickness of coal seams and relatively harsh observation environment in the western mining areas of China, it is challenging to study the characteristics of surface subsidence merely by setting up observation points on the main cross-section of the mining face and adopting traditional data collection methods (such as traverse surveying and leveling). In this context, this paper proposes a method for extracting high-precision surface subsidence basins by combining Unmanned Aerial Vehicle Laser Scanning (ULS) and Interferometric Synthetic Aperture Radar (InSAR) data. This method employs Small Baseline Subset InSAR (SBAS) to capture small deformation areas within the subsidence basin, ULS for larger deformation areas, and polynomial fitting to interpolate the remaining regions, thereby creating a complete subsidence basin. This study focuses on the 3-1501 mining face of Hongqinghe Mine. Using this method, two epochs of point cloud data and 35 Sentinel-1 images were used to derive the high-precision surface subsidence basin of the mining face. Surface mobile observation station data were then used for accuracy assessment, and the results indicate that the root mean square error of the subsidence basin is 0.022 m. Finally, combined with experimental analysis of the subsidence basin and the rock fragmentation coefficient, it was found that the surface subsidence basin of the 3-1501 mining face at Hongqinghe Mine exhibits steep edges, a limited impact range, and a low surface subsidence coefficient. This phenomenon is attributed to the weakly cemented overburden, which has a high fragmentation coefficient and a prolonged compaction cycle. Based on multi-source measured data from mining areas in western China, this study proposes an integrated approach to construct a high-precision and complete subsidence basin. By incorporating the rock mechanics parameters of the mining area, the characteristics and formation mechanisms of surface subsidence are systematically analyzed. The findings enhance the accuracy and integrity of subsidence basin prediction and provide a solid theoretical foundation and practical guidance for safe mining operations and disaster prevention under similar mining conditions in western China.

This study presents a decadal, multi-seasonal evaluation of groundwater quality evolution in the Zegrir alluvial aquifer, located in the hyper-arid Guerrara region of Algeria. A total of 16 groundwater samples were collected during dry and wet seasons across three time points (2009, 2013, and 2019), enabling a comprehensive assessment of temporal and spatial hydrogeochemical trends. Analytical parameters included major ions, physico-chemical indicators, Water Quality Index (WQI), and Sodium Adsorption Ratio (SAR), supported by multivariate statistical methods such as Principal Component Analysis (PCA). Findings reveal progressive groundwater salinization, with over 60% of samples classified as poor to unsuitable for drinking and more than 70% falling into moderate to high SAR categories, indicating serious irrigation constraints. Spatial analysis highlights those areas with shallow static levels and low recharge potential are particularly vulnerable. The dominance of Na⁺, Cl⁻, and SO₄²⁻, along with Na–Cl and mixed-type hydrochemical facies, indicates the persistent influence of evapoconcentration, evaporite dissolution, and cation exchange processes. The adopted multi-year, multi-seasonal framework proved essential for distinguishing between transient recharge-driven dilution events and long-term degradation trends, offering a more nuanced understanding of aquifer evolution under arid conditions. This integrative approach provides valuable insight into de-signing adaptive groundwater management strategies and underscores the critical need for continuous monitoring and distributed recharge interventions in climate-stressed regions.

This paper takes the extreme rainfall event in eastern Guangdong in August 2018 as a case study. We systematically compiled an inventory of 6194 rainfall-triggered landslides and combined the AutoGluon framework with SHapley Additive exPlanations (SHAP) analysis to reveal the multi-factor coupling mechanisms governing landslide occurrence. The research identifies low-to-medium elevation (74–374 m), gentle slopes (10–30°), high vegetation coverage (NDVI 210–255), and cumulative rainfall exceeding 380 mm as key characteristics of high-incidence landslide zones. Landslides were particularly pronounced in weathered Jurassic granite formations and within 2000 m of rivers. Landslide distribution is significantly controlled by the synergistic interaction of four dominant factors: elevation, cumulative rainfall, slope angle, and normalized difference vegetation index (NDVI). Binary and ternary factor coupling analyses further indicate that low-to-medium elevation topography enhances local rainfall intensity through the ‘windward slope rainfall amplification effect,’ while the combination of colluvial deposits on gentle slopes and root channels in vegetated areas accelerates rainwater infiltration. This process disrupts the critical equilibrium state of slopes, triggering landslides. The research proposes two ternary threshold frameworks: ‘low-to-medium elevation–gentle slope–intense rainfall’ and ‘low-to-medium elevation–gentle slope–high vegetation coverage’. These frameworks provide a scientific basis for rainfall-induced cluster landslide risk assessment and early warning systems in coastal South China.

Coal mine underground reservoirs contain a large number of porous media material combination structure. In order to ensure the stability of reservoir water storage, it is meaningful to study the permeability characteristics of double porous media material combination. Based on the Poiseuille equation, the permeability model of double porous media material combination (DPMMC model) is constructed by using the derived additional stress between porous media materials and the effective stress. The DPMMC model is verified by the test results under different conditions, and the influence of different parameters on the permeability ratio is analyzed. Under different cover loads, water storage pressure, initial porosity and elastic modulus, using the established DPMMC model, the permeability characteristics of coal-mortar combination (grouted area) and residual coal pillar (non-grouted area) composed of coal pillar and mortar are simulated and analyzed. The results show that the DPMMC model can verify the permeability change of double porous media material combination. The permeability ratio of the composite material decreases as the initial porosity ratio coefficient declines, whereas it increases as the elastic modulus ratio coefficient, Poisson’s ratio ratio coefficient, and Biot coefficient ratio coefficient decrease. This research holds significance in evaluating the long-term operation and stability of underground coal mine reservoirs.

Tailings dam failures can trigger destructive floods, yet their mechanisms, particularly for non-liquefied tailings, remain poorly understood. Previous studies have largely focused on liquefied tailings, purely physical experiments, or side-slope effects. This study extends prior work by integrating physical experiments with two-dimensional HEC-RAS modeling to analyze both near-abutment (NTA) and far-from-abutment (FTA) failures in a unified framework. FTA breaches with a width of 20 cm were tested under three initial water surface elevations (WSE) and compared with NTA cases to evaluate erosion patterns and the ratio of released tailings to reservoir water. Numerical simulations were calibrated and validated against laboratory data using temporal WSE, eroded dimensions, and released mass. With the validated model, the effects of breach width, initial WSE, reservoir geometry, and breach location on outflow hydrographs were systematically examined. Results showed that erosion was more pronounced in FTA breaches, while the ratio of eroded tailings volume to reservoir water remained nearly constant at ~ 1%. Breach location had minimal influence on hydrographs. Predictive formulas for WSE decline and hydrograph evolution, derived through dimensional analysis and non-dimensionalization, provided reliable peak discharge estimates and upper-bound hydrograph predictions, offering practical tools for risk assessment and mitigation.