Search Results (385)

In the coal pillar dam of underground water reservoirs, groundwater exerts a certain degree of dissolution and erosion on the coal body, inducing the development of internal cracks and the deterioration of its mechanical properties. To this end, coal samples with varying moisture contents were prepared through a water-absorption experiment; the changes in the mechanical strength of coal samples with five moisture contents (0%, 3.62%, 4.93%, 5.52%, and 6.11%) were tested via uniaxial compression tests, uniaxial tension tests, and variable-angle shear tests; and the degradation in mechanical performance in water-immersed coal samples and their sensitivity to moisture content were evaluated. The experiment yielded the following results: (1) The moisture content of coal samples increases with the increase in immersion time, and the water-absorption rate first rises, then decelerates and gradually becomes stable. When the immersion time is about 72 h, the coal sample reaches a saturated state. (2) As the samples transition from a dried state to full saturation, the uniaxial compressive strength of coal samples decreases from 29.17 MPa to 7.38 MPa, and the uniaxial tensile strength decreases from 0.78 MPa to 0.33 MPa. The peak shear strength also decreases with an increase in immersion time and the increase in shear angle, while the deterioration degree gradually increases with the increase in immersion time and tends to be stable. (3) Based on a sensitivity analysis, the mechanical performance evolution of water-immersed coal samples can be divided into four stages based on the moisture content: tensile-dominated stage, shear-dominated stage, compression catching-up stage, and compression-dominated stage. Full article

Per- and polyfluoroalkyl substances (PFASs) are emerging pollutants of global concern due to their high environmental persistence and bioaccumulative characteristics. This study investigates PFAS concentrations in soils from China through an extensive literature review, covering soil samples from seventeen provinces and the years from 2009 to 2024. It was found that the total concentration of PFAS in soil ranged from 0.25 to 6240 ng/g, with the highest contamination levels observed in coastal provinces, particularly Fujian (620 ng/g) and Guangdong (1090 ng/g). Moreover, Fujian Province ranked the highest among multiple regions with a median PFAS concentration of 15.7 ng/g for individual compounds. Ecological risk assessment, focusing on areas where perfluorooctanoic acid (PFOA) or perfluorooctane sulfonate (PFOS) were identified as the primary soil PFAS compounds, showed moderate ecological risk from PFOA in Shanghai (0.24), while PFOS posed a high ecological risk in Fujian and Guangdong, with risk values of 43.3 and 1.4, respectively. Source analysis revealed that anthropogenic activities, including PFAS production, firefighting foam usage, and landfills, were the primary contributors to soil contamination. Moreover, soil PFASs tend to migrate into groundwater via adsorption and seepage, ultimately entering the human body through bioaccumulation or drinking water, posing health risks. These findings enhance our understanding of PFAS distribution and associated risks in Chinese soils, providing crucial insights for pollution management, source identification, and regulation strategies in diverse areas. Full article

With the large-scale closure of coal mines leading to groundwater pollution, in order to systematically identify the sources of major chemical ions in surface water and groundwater. This study comprehensively applied methods such as Piper’s trilinear diagram, linear fitting, and correlation analysis to quantitatively analyze the hydrochemical characteristics of closed coal mining areas in southwest Shandong and to clarify the sources of geochemical components in surface water and groundwater, and the PMF model was used to analyze the sources of chemical components in mine water and karst water. The results show that the concentrations of TDS ( Total Dissolved Solids), SO₄²⁻, Fe, and Mn in the mine water of the closed coal mine area are higher than in the karst water. Both water bodies are above groundwater quality standards. Ca²⁺, SO₄²⁻, and HCO₃⁻ dominate the ionic components in surface water and different types of groundwater. The hydrochemical types of surface, pore, and mine waters are mainly SO₄-HCO₃-Ca, whereas SO₄-HCO₃-Ca and HCO₃-SO₄-Ca dominate karst waters. SO₄²⁻ is the leading ion in the TDS of water bodies. The mineralization process of surface water is mainly controlled by the weathering of silicate minerals, while that of the groundwater is mainly controlled by the dissolution of carbonate minerals. The impact of mining activities on surface water and groundwater is significant, while the impact of agricultural activities on surface water and groundwater is relatively small. The degree of impact of coal mining activities on SO₄²⁻ concentrations in surface water, pore water, and karst water, in descending order, is karst water, surface water, and pore water. The PMF (Positive Matrix Factorization) model analysis results indicate that dissolution of carbonate minerals with sulphate and oxidation dissolution of sulfide minerals are the main sources of chemical constituents in mine waters. Carbonate dissolution, oxidation dissolution of sulfide minerals, domestic sewage, and dissolution of carbonate minerals with sulphate are ranked as the main sources of chemical constituents in karst water from highest to lowest. These findings provide a scientific basis for the assessment and control of groundwater pollution in the areas of closed coal mines. Full article

This study was carried out to fill the present research gap in the study area by assessing water chemistry, potential heavy metal contamination, and the associated health risk evaluation that goes along with it in surface water bodies and groundwater in the NE of Maramureș County, near the Tisa River. The main methods we applied were Piper, Ficklin–Caboi, and Gibbs diagrams for determining the water typology and chemistry, the Overall Water Quality Index (OWQI) and vegetation cover to determine the water quality, a contamination index for analyzing the contamination degree, and a human health risk assessment through water ingestion after exposure of children and adults. This article’s main findings specify that waters were characterized and classified into the CaMgHCO₃⁻ dominant category of water type, with precipitation, agricultural, and domestic inputs, related to the Cl⁻ (mean ranging between 1.01–5.65 mg/L) and NO₃⁻ (mean ranging between 2.23–5.52 mg/L) content. The OWQI scores indicated excellent quality, below the critical value, ranging between 0.70 and 6.57. The applied risk assessment indicated that the daily intake of toxins is higher in the case of children than in adults, up to four and five times. The hazard quotient scores, ranging between 0.00093 and 0.248 for adults and between 0.0039 and 1.040 for children, indicated that if consumed, the studied waters can pose potential negative effects on children. Full article

Inorganic arsenic [As(III) and As(V)] is a pervasive environmental contaminant in groundwater systems, early-life exposure to which is associated with an impaired cognitive ability and an increased risk of neurobehavioral disorders. Although the effect of As(III) on the neurons is well studied, the involvement of the microglia remains unclear. In this study, the effects of sodium arsenite (NaAsO₂) on microglial activation and the underlying NLRP3 inflammasome mechanism were determined. Pregnant rats were gavaged with NaAsO₂ (0, 1, 4, and 10 mg/kg body weight), which dissociates in aqueous solutions into bioactive arsenite species [As(OH)₃], from gestational day 1 (GD1) to postnatal day 21 (PND21). The results showed that As(III) induces learning and memory impairments and microglial activation in the hippocampus of offspring rats (PND21). Increased expression of NLRP3, the activation of caspase-1, and the production of interleukin-1β were observed in both the hippocampus of As(III)-exposed offspring rats and As(III)-exposed microglial BV2 cells under culture conditions. Interestingly, blocking the NLRP3 inflammasome using MCC950 mitigated its activation. Furthermore, inhibition of NADPH oxidase 2 (NOX2) using apocynin or specific siRNA significantly reduced As(III)-induced microglial NLRP3 inflammasome activation. In addition, inactivation of the microglial NLRP3 inflammasome or NOX2 markedly rescued As(III)-induced neurotoxicity in the hippocampal HT22 cells. Taken together, this study reveals that NOX2/NLRP3-inflammasome-dependent microglial activation promotes As(III)-induced learning and memory impairments in developmental rats. Full article

Groundwater storage refers to the water stored in the pore spaces of underground aquifers, which has been increasingly affected by both climate change and anthropogenic activities in recent decades. Therefore, monitoring their changes and the factors that affect it is of great importance. Although the influence of natural factors on groundwater is well-recognized, the impact of human activities, despite being a major contributor to its change, has been less explored due to the challenges in measuring such effects. To address this gap, our study employed an integrated approach using remote sensing and the Google Earth Engine (GEE) cloud-free platform to analyze the effects of various anthropogenic factors such as built-up areas, cropland, and surface water on groundwater storage in the Lake Urmia Basin (LUB), Iran. Key anthropogenic variables and groundwater data were pre-processed and analyzed in GEE for the period from 2000 to 2022. The processes linking these variables to groundwater storage were considered. Built-up area expansion often increases groundwater extraction and reduces recharge due to impervious surfaces. Cropland growth raises irrigation demand, especially in semi-arid areas like the LUB, leading to higher groundwater use. In contrast, surface water bodies can supplement water supply or enhance recharge. The results were then exported to XLSTAT software2019, and statistical analysis was conducted using the Mann–Kendall (MK) non-parametric trend test on the variables to investigate their potential relationships with groundwater storage. In this study, groundwater storage refers to variations in groundwater storage anomalies, estimated using outputs from the Global Land Data Assimilation System (GLDAS) model. Specifically, these anomalies are derived as the residual component of the terrestrial water budget, after accounting for soil moisture, snow water equivalent, and canopy water storage. The results revealed a strong negative correlation between built-up areas and groundwater storage, with a correlation coefficient of −1.00. Similarly, a notable negative correlation was found between the cropland area and groundwater storage (correlation coefficient: −0.85). Conversely, surface water availability showed a strong positive correlation with groundwater storage, with a correlation coefficient of 0.87, highlighting the direct impact of surface water reduction on groundwater storage. Furthermore, our findings demonstrated a reduction of 168.21 mm (millimeters) in groundwater storage from 2003 to 2022. GLDAS represents storage components, including groundwater storage, in units of water depth (mm) over each grid cell, employing a unit-area, mass balance approach. Although storage is conceptually a volumetric quantity, expressing it as depth allows for spatial comparison and enables conversion to volume by multiplying by the corresponding surface area. Full article

In this study, we selected a series of pothole wetlands to investigate their nucleation, evolution, and recent anthropogenic degradation in the Alcores Depression (AD), southern Iberian Peninsula, where over 100 closed watersheds containing shallow, ephemeral water bodies up to 2 hm² have been identified. We surveyed the regional geological framework, utilized digital elevation models (DEMs), orthophotos, and aerial images since 1956. Moreover, we analyzed precipitation and temperature data in Seville from 1900 to 2024, collected hydrometeorological data since 1990 and modelled the water level evolution from 2002 to 2025 in a representative pothole in the area. Our observations indicate a flooded surface reduction by more than 90% from the 1950s to 2025. Climatic data reveal an increase in annual mean temperatures since 1960 and a sharp decline in annual precipitation since 2000. The AD’s inception due to tectonic isolation during the Quaternary favoured the formation of pothole wetlands in the floodplain. The reduction in the hydroperiod and wetland degradation was primarily due to agricultural expansion since 1950, which followed an increase in groundwater extraction and altered the original topography. Recently, decreased precipitation has exponentially accelerated the degradation and even the complete disappearance of many potholes. This study underscores the fragility of small wetlands in the Mediterranean basin and the critical role of human management in their preservation. Restoring these ecosystems could be a highly effective nature-based solution, especially in semi-arid climates like southern Spain. These prairie potholes are crucial for enhancing groundwater recharge, which is vital for maintaining water availability in regions with limited precipitation. By facilitating rainwater infiltration into the aquifer, recharge potholes increase groundwater levels. Additionally, they capture and store run-off during heavy rainfall, reducing the risk of flooding and soil erosion. Beyond their hydrological functions, these wetlands provide habitats that support biodiversity and promote ecological resilience, reinforcing the need for their protection and recovery. Full article

The acidification modification treatment of coal is a key technical means to improve the permeability of coal seams and enhance the efficiency of coalbed methane extraction. Yet, current acidic fracturing fluids are highly corrosive, corroding downhole pipelines and contaminating groundwater. By compounding environmentally friendly and non-polluting acidic fracturing fluids and combining fractal theory and the Frenkel–Halsey–Hill (FHH) model, this paper systematically investigates their effects on the pore structure, permeability, and mechanical properties of coal bodies. It was found that the complex acid treatment significantly reduced the surface fractal dimension D₁ and spatial fractal dimension D₂ of the coal samples and optimized pore connectivity, thus improving gas transport efficiency. Meanwhile, a static splitting test and digital image analysis showed that the fracture evolution pattern of the treated coal samples changed from a centralized strain extension of the original coal to a discrete distribution, peak stress and strain were significantly reduced, and permeability was significantly increased. These findings can offer dramatic support for the optimal optimization of acidic fracturing fluids. Full article

Increasing pressures on groundwater in the last decades have led to a deterioration in the quality of groundwater for human consumption around the world. Beyond the essential evaluation of groundwater dynamics and quality, analyzing the situation from the perspective of the Ecosystem Services Assessment (ESA) approach can be useful to support aquifer management plans aiming to recover aquifers’ capacity to provide good quality water. This work illustrates how to implement the ESA using groundwater flow and nitrate transport modelling for evaluating future trends of the provisioning service Groundwater of Good Quality for Human Supply. It has been applied to the Medina del Campo Groundwater Body (Spain), where the intensification of agricultural activities and groundwater exploitation since the 1970s caused severe nitrate pollution. Nitrate status and future trends under different fertilizer and aquifer exploitation scenarios were modelled with MT3DMS coupled to a MODFLOW model calibrated with piezometric time series. Historical land use and fertilizer data were compiled to assess nitrogen loadings. Besides the uncertainties of the model, the results clearly show that: (i) managing fertilizer loads is more effective than managing aquifer exploitation; and (ii) only the cessation of nitrogen application by the year 2030 would improve the evaluated provisioning service in the long term. The study illustrates how the ESA can be incorporated to evaluate the expected relative impact of different management actions aimed at improving significant groundwater services to humans. Full article

The relationship between nitrate concentration and electrical conductivity (EC) in aqueous environments is crucial for water quality assessment, especially in regions with limited laboratory access and monitoring resources. This study investigates nitrate–EC correlations across standard solutions and various natural water sources, identifying where EC may serve as a reliable proxy for nitrate. In the standard and controlled laboratory solution reference samples, a strong linear correlation in controlled environments (R² ≈ 0.99) between the nitrate concentration and EC was observed, providing a reliable baseline for calibration and suggesting that EC-based estimation is feasible under ideal conditions. In shallow wells, particularly in agricultural zones, a moderate-to-strong correlation was also observed, likely due to surface contamination from fertilizers. Natural water bodies exhibit more complex relationships owing to environmental factors and their ionic composition. In contrast, deep groundwater, often subjected to geological filtration and treatment processes, displayed inconsistent relationships, underscoring the complexity of using EC as a nitrate proxy in such systems. These findings suggest that EC can support preliminary screening for nitrate in specific water types, particularly in agricultural and rural settings, while emphasizing the need for site-specific calibration and caution against overgeneralization. The study offers a foundational framework for employing EC as a low-cost, rapid monitoring tool in resource-constrained environments. Full article

The interaction of the Almone River with groundwater in the Caffarella area (Rome, Italy) was investigated using a multi-method approach based on hydrogeological and radon analyses. Eleven measurement stations were established along the river at distances of approximately 270 m from one another. Stream discharge, water physicochemical properties, and radon levels were measured from June 2024 to March 2025. The contribution of two tributaries of the Almone was evaluated, but it was found to be negligible in terms of radon contribution. Except for an average increase of 40 L/s between stations 1A and 2A, the Almone’s discharge (corrected for the streams input) was constant (around 150 L/s) in June and slightly increasing from 6A to 11A in March due to heavier rainfalls. The increased discharge between stations 1A and 2A was interpreted as groundwater overflow from the volcanic aquifer into the alluvial body and in turn into the river due to a change in geometry and volume of the volcanic aquifer. In that part of the river, radon concentration increased only in March, due to the fast transition of the groundwater from a high to a lower radon emanation unit. Radon decreased along the valley due to atmospheric evasion, as confirmed by pH growth due to CO₂ degassing. Full article

As an important ecological barrier in the upper reaches of the Yangtze River, the Jialing River Basin has complex and sensitive hydrochemical evolutionary mechanisms due to its geological structures and human activities. This study focuses on the groundwater in the Wusheng section of the Jialing River Basin, combining field investigations and Entropy-Weighted Water Quality Index (EWQI) calculations to analyze its hydrochemical characteristics and influencing factors and conduct a water quality assessment. The results show that this regional water body has a pH of 7.05–8.36, presenting weakly alkaline and low-mineralization characteristics, with differences in hydrochemical components between groundwater and surface water. The ions are predominantly controlled by rock weathering, with reactions such as halite and gypsum dissolution occurring during groundwater runoff. Groundwater in the tectonic influence zone exhibits abnormal chemical compositions due to lateral recharge from different strata along fracture channels and long-distance runoff reactions with the surrounding rocks. EWQI values for groundwater range from 6.07 to 104.02, with an average value of 37.46, generally exhibiting a trend of increasing EWQI values near the Jialing Riverbank. In this area, 96.15% of groundwater meets excellent or good quality standards and is suitable for direct drinking. The influence of the intensity of different indicators on groundwater quality decreases in the order of Ca²⁺ > Cl⁻ > Mg²⁺ > SO₄²⁻ > HCO₃⁻ > NO₃⁻. Water quality is primarily influenced by the primary geological background, while agricultural practices may also lead to its deterioration. Full article

To optimize the management of groundwater resources in the Bourgogne-Franche-Comté (BFC, France) region, data from the Size-Eaux database were cross-referenced with the French Reference Framework for Groundwater Bodies (GWB). The information contained in this dataset was synthesized using Principal Component Analysis (PCA), followed by Agglomerative Hierarchical Clustering (AHC) of GWBs based on their average coordinates along the main factorial axes. The results reveal 11 distinct GWB groups, each internally homogeneous in terms of chemical composition and ongoing processes responsible for intra-group variability. The distribution of the groups aligns with the region’s structural geology, lithology, and agricultural activity patterns. Livestock farming areas, prone to fecal contamination, and cereal-growing areas, characterized by high nitrate concentrations, stand out distinctly. Furthermore, the analysis of GWB groups highlights regional processes such as denitrification, confirming the existence of spatial structuring of these mechanisms beyond local specificities. The major physicochemical and bacteriological zones show strong contrasts between groups while maintaining significant internal homogeneity. Despite the region’s vast size and diversity, spanning three major watersheds, further subdivision was not necessary to obtain applicable results. These findings confirm observations made in other regions and pave the way for an optimized monitoring and surveillance strategy. Full article

Elucidating the microbial–hydrochemical interactions in distinct functional zones of coal mines holds significant implications for groundwater pollution mitigation strategies in mining regions. Taking Xinji No. 2 Coal Mine as an example, 15 water samples (including surface water, goaf water, sump water, working face drainage, rock roadway water, and coal roadway water) were collected from six surface and underground areas for hydrochemical and microbial detection analysis. The results show that bacterial genera such as Exiguobacterium and Mycobacterium cannot adapt to high-salinity environments with elevated K⁺ + Na⁺ concentrations, showing negative correlation with TDS. Microbial communities related to sulfate serve as important indicators for microbial technology-based pollution control in coal mine groundwater, where sulfate-reducing bacteria (e.g., norank_f__Desulfuromonadaceae) can reduce SO₄²⁻ concentrations and improve mine water quality. Low dissolved oxygen (DO) concentrations lead to decreased abundance of aerobic microorganisms, hindering the formation of stable microbial communities in mines. Affected by mine water quality, the confluence of mine drainage into rivers results in HCO₃⁻ and SO₄²⁻ concentrations at the confluence being higher than upstream, which gradually return to upstream concentrations after entering the downstream. However, due to the influx of nitrogen cycle-related bacteria and organic matter from mine water into surface water, increased microbial physiological activities and carbon sources cause NO₃⁻ concentrations to increase more than tenfold. The formation stages of mine water quality exhibit regional characteristics, with goaf areas showing distinct hydrochemical components and microbial communities compared to other zones. Based on this research, new microbial approaches for groundwater pollution control in coal mining areas are proposed: (1) selecting and cultivating functional microorganisms (such as SRB and organic matter-degrading bacteria) to develop biological materials for mine water remediation; (2) regulating the transformation of elements by adjusting carbon sources and oxygen supply according to indigenous microbial requirements, thereby reducing pollutant concentrations in water bodies. Full article

The increasing global demand for food caused by a growing world population has resulted in environmental problems, such as the destruction of ecologically significant biomes and pollution of ecosystems. At the same time, the intensification of crop production in modern agriculture has led to the extensive use of synthetic fertilizers to achieve higher yields. Although chemical fertilizers provide essential nutrients and accelerate crop growth, they also pose significant health and environmental risks, including pollution of groundwater and other bodies of water such as rivers and lakes. Soils that have been destabilized by indiscriminate clearing of vegetation undergo a desertification process that has profound effects on microbial ecological succession, impacting biogeochemical cycling and thus the foundation of the ecosystem. Tropical countries have positive aspects that can be utilized to their advantage, such as warmer climates, leading to increased primary productivity and, as a result, greater biodiversity. As an eco-friendly, cost-effective, and easy-to-apply alternative, biofertilizers have emerged as a solution to this issue. Biofertilizers consist of a diverse group of microorganisms that is able to promote plant growth and enhance soil health, even under challenging abiotic stress conditions. They can include plant growth-promoting rhizobacteria, arbuscular mycorrhizal fungi, and other beneficial microbial consortia. Bioremediators, on the other hand, are microorganisms that can reduce soil and water pollution or otherwise improve impacted environments. So, the use of microbial biotechnology relies on understanding the relationships among microorganisms and their environments, and, inversely, how abiotic factors influence microbial activity. The recent introduction of genetically modified microorganisms into the gamut of biofertilizers and bioremediators requires further studies to assess potential adverse effects in various ecosystems. This article reviews and discusses these two soil correcting/improving processes with the aim of stimulating their use in developing tropical countries. Full article