Search Results (40)

Karst groundwater systems are critical to water supply and ecological sustainability in northern China, yet their heterogeneity poses challenges for flow characterization. The Yuquan Mountain (YM) Spring, historically a major karst spring in western Beijing, has experienced persistent drying, raising concerns about its recharge and flow mechanisms. This study integrates published isotope data, spatial distributions of Na⁺ and Cl⁻ as hydrochemical tracers, groundwater age estimates, and geophysical survey results to assess the recharge sources and flow pathways within the YM Spring catchment area. The analysis identifies two major recharge zones: the Tanzhesi area, primarily recharged by direct infiltration of precipitation through exposed carbonate rocks, and the Junzhuang area, which receives mixed recharge from rainfall and Yongding River seepage. Three potential flow pathways are proposed, including shallow flow along faults and strata, and a deeper, speculative route through the Jiulongshan-Xiangyu syncline. The synthesis of multiple lines of evidence leads to a refined conceptual model that illustrates how geological structures govern recharge, flow, and discharge processes in this karst system. These findings not only enhance the understanding of subsurface hydrodynamics in complex geological settings but also provide a scientific basis for future spring restoration planning and groundwater management strategies in the regions. Full article

With the intensification of human activities, the water resource environment in the karst mountainous area of central Shandong has undergone significant changes, directly manifested in the cessation of karst spring flows and the occurrence of karst collapses within the spring basin in the Laiwu Basin. To support the scientific development and management of karst water, this study utilizes comprehensive analysis and deuterium-oxygen isotope test data from surveys and sampling of 20 typical karst springs conducted between 2016 and 2018. By integrating mathematical statistics, correlation analysis, and ion component ratio methods, the study analyzes the genesis, hydrochemical ion component sources, and controlling factors of typical karst springs in the Laiwu Basin. The results indicate that the genesis of karst springs in the Laiwu Basin is controlled by three factors: faults, rock masses, and lithology, and can be classified into four types: water resistance controlled by lithology, by faults, by basement, and by rock mass. The karst springs are generally weakly alkaline freshwater, with the main ion components being HCO₃⁻ and Ca²⁺, accounting for approximately 55.02% and 71.52% of the anion and cation components, respectively; about 50% of the sampling points have a hydrochemical type of HCO₃·SO₄-Ca·Mg. Stable isotope (δ¹⁸O and δD) results show that atmospheric precipitation is the primary recharge source for karst springs in the Laiwu Basin. There are varying degrees of evaporative fractionation and water–rock interaction during the groundwater flow process, resulting in significantly higher deuterium excess (d-excess) in the sampling points on the southern side of the basin compared to the northern side, indicating clear differentiation. The hydrochemical composition of the karst groundwater system is predominantly governed by water–rock interactions during flow processes and anthropogenic influences. Carbonate dissolution (primarily calcite) serves as the principal source of HCO₃⁻, SO₄²⁻, Ca²⁺, and Mg²⁺, while evaporite dissolution and reverse cation exchange contribute to the slight enrichment of Ca²⁺ and Mg²⁺ alongside depletion of Na⁺ and K⁺ in spring waters. Saturation indices (SI) reveal that spring waters are saturated with respect to gypsum, aragonite, calcite, and dolomite, but undersaturated for halite. The mixing of urban domestic sewage, agricultural planting activities, and the use of manure also contributes to the formation of Cl⁻ and NO₃⁻ ions in karst springs. Full article

[Objective] This study aims to assess and predict the risks of water inrush and leakage during tunnel excavation in karst regions, where groundwater intrusion poses serious threats to construction safety and long-term hydrogeological sustainability. [Study area] This study is conducted in the Qigan Mountain, involving detailed hydrogeological surveys and hydrochemical analyses to understand the subsurface conditions. [Methods] Numerical simulation methods are employed to model the regional seepage field distribution under natural conditions and two excavation conditions, using MODFLOW. [Challenges] One of the main challenges is accurately estimating tunnel water inflow under varying geological and hydrological conditions. [Results] The simulation results indicate that under excavation with blocking conditions, tunnel water inflow reaches 31,932 m³/d, whereas without blocking, inflow surges to 359,199 m³/d. In contrast, the theoretical calculation estimates a water inflow of 131,445 m³/d, revealing considerable discrepancies between the methods. [Recommendations] These findings highlight an important point of reference for the prevention of water influx in karst tunnel construction. Full article

Ensuring water resources for livestock production in Kazakhstan presents a multifaceted challenge. Pastoral systems in Southern Kazakhstan are facing a critical groundwater shortage, with 56.5% of pastures currently unused due to limited water access, jeopardizing around 2 million head of livestock and the region’s food security. This study presents the first comprehensive groundwater assessment in over 40 years, integrating hydrochemical analysis (55 samples) and field surveys conducted in the Almaty and Zhetysu regions. Key findings include: the total water demand for livestock is estimated at 53,735 thousand m³/year, with approximately 40% of samples exceeding WHO guidelines for total mineralization. It was determined that 45% of exploitable groundwater reserves in the Almaty region and 15–17% in the Zhetysu region are suitable for irrigation. This study also provides updated hydrogeological data, identifying three priority aquifer systems. A novel Groundwater Sustainability Index for pastoral zones of Central Asia is introduced, demonstrating that strategic aquifer development could expand watered pastureland by 30–40%. These findings directly inform Kazakhstan’s Agricultural Development Plan through 2030 and provide a replicable framework for sustainable water management in arid regions. With 69,836 rural residents currently lacking access to safe water, our results underscore the urgent need for infrastructure investment to meet SDG 6 targets (ensure availability and sustainable management of water and sanitation for all). Full article

The terminal tributaries of karst rivers are often under-researched, with low investigation coverage and incomplete surveys. These areas face significant human activity disturbances, fragile soil and water environments, and insufficient research on water quality conditions. Residents in their basins are confronted with urgent issues of water scarcity and deteriorating water quality. This study focused on the Zhongdu River Basin, a terminal tributary in the Pearl River system in Southwest China. By measuring the conventional hydrochemical parameters and stable isotope ratios (e.g., δ¹⁸O and δ²H), this study employed methods such as hydrological and geochemical approaches, as well as classical statistical analyses, to reveal the hydrochemical characteristics, regulatory mechanisms, and water health status in the basin. Data show that the water in the Zhongdu River Basin is generally weakly alkaline, with a pH range between 6.46 and 8.28. The highest values for electrical conductivity (EC) and total dissolved solids (TDSs) are found upstream, reaching 497 μS/cm and 324.5 mg/L, respectively. The average dissolved oxygen (DO) value is 71.3 mg/L. The hydrochemical type is primarily HCO₃⁻-Ca²⁺, with Ca²⁺ and HCO₃⁻ as the dominant ions. The surface water in the middle and lower reaches of the basin is strongly influenced by evaporation, with atmospheric precipitation as the main recharge source. Rock weathering is the primary influencing factor in the basin, with most minerals in a dissolved state. Agricultural activities are the primary pollution source in the basin, with domestic pollution having a minimal effect on water quality. Water quality was assessed using the entropy-weighted water quality index (EWQI) based on 11 parameters, indicating overall good water quality, classified as Grade I. The findings indicate that human activities have a minimal impact on the water quality in the region, and the basin is expected to maintain its healthy condition for an extended period. Full article

In recent years, deep–penetrating geochemical exploration techniques have played a crucial role in the detection of concealed minerals. These methods effectively detect deep−seated anomalies and have been tested in various landscape–covered areas, yielding remarkable results. This study focuses on the covered areas of the southern margin of the Kuqa Basin, utilizing deep–penetrating geochemical methods for systematic sampling to explore concealed potassium salt. This study examines the chemical composition of several underground brine samples, revealing salinity levels ranging from 9.41 to 26.16 g/L and potassium concentrations of between 0.04 and 0.22 g/L. The hydrochemical coefficients indicate a high nNa⁺/nCl⁻ value, with low K⁺ × 10³/Cl⁻ values. The average nNa⁺/nCl⁻ ratio is approximately 0.97, and the Br⁻ × 10³/C1⁻ value is about 0.07. The brine samples fall within the halite phase region of the Quaternary system Na⁺, K⁺, Mg²⁺//C1⁻–H₂O at 25 °C, concentrated at the high Na terminal, suggesting halite dissolution. In the metastable phase diagram of the Na⁺, K⁺, Mg²⁺//C1⁻, SO₄²⁻–H₂O five−element water system, all the brine samples were cast in the glauberite phase area, which may indicate that the shallow underground brine is still in the initial stage of potassium salt deposition. The underground brine mainly dissolved and filtered the stone salt in the formation during the process of runoff underground and then was squeezed by the strong active structure and discharged to the surface along the formation fault or fissure channel. The deep–penetration geochemical survey of the fracture reveals that certain profile points show significantly higher potassium and other salt contents than others, indicating a potassium anomaly. This suggests the potential ascent and migration of potassium–rich brine along deep fracture segments, providing preliminary evidence of potassium richness in the Kuqa Basin’s depths and offering significant guidance for key exploration areas in potassium salt prospecting. Full article

Groundwater is essential for water resources, serving as a key drinking source in China. It supports daily needs for urban and rural residents, aids development, and maintains ecological balance. This study conducted a sampling survey of groundwater in the Wen River basin (WRB), assessing hydrochemical features, genesis mechanisms, water quality, and health risks. The findings reveal that groundwater in the WRB is weakly alkaline, with an average total dissolved solids (TDS) concentration of 755.24 mg/L. Freshwater constitutes approximately 81.48% of the groundwater, with the following order of concentration for cations: Ca²⁺ > Na⁺ > Mg²⁺ > K⁺, and for anions: HCO₃⁻ > SO₄²⁻ > NO₃⁻ > Cl⁻. The predominant hydrochemical types are SO₄·Cl-Ca·Mg and HCO₃-Ca·Mg. The chemical composition of the groundwater is primarily influenced by silicate rock weathering, dissolution processes, cation exchange, and human activities. The average Environmental Water Quality Index (EWQI) value of 74.65 for the WRB signifies that the overall quality of the groundwater is quite good, indicating that the majority of the groundwater is suitable for drinking purposes. Notably, the inferior quality water is predominantly found downstream of the Wen River. Calculations of the sodium adsorption ratio (SAR), residual sodium carbonate (RSC), and percentage of sodium (%Na) indicate that groundwater at most sampling points is suitable for irrigation. Furthermore, the human health risk assessment (HRA) reveals that oral intake presents a greater health risk to individuals than dermal contact. The mean Hazard Index (HI) for children is 3.24, with a staggering 79.89% of non-carcinogenic health risk (NHR) values surpassing the acceptable standards. For adults, the mean HI is 1.39, with 53.44% of NHR values exceeding the standards. These data indicate that children are more susceptible to health risks than adults and that the midstream and downstream of the river exhibit higher health risks compared to the upper reaches. These findings can provide critical data for groundwater quality assessment and risk management in the WRB and offer guidance for future groundwater resource management and pollution control efforts. Full article

A comprehensive hydrogeological, geophysical, and hydrochemical investigation was conducted in southeastern Hitchcock County, Nebraska, within the Driftwood Creek alluvial aquifer. This study assessed groundwater contamination stemming from the surface disposal of saline wastes from oilfield activities. A contaminated area, initially identified through regional groundwater sampling, was examined in detail. Monitoring wells were installed, and groundwater and soil samples were collected for chemical analysis. Surface electrical resistivity surveys were also performed to delineate contamination patterns. The findings revealed that the groundwater contamination originated from the leaching of residual evaporative salts through the vadose zone, beneath an abandoned emergency-evaporation brine storage pit. Data from down-hole specific conductance logs, water quality analyses, and computer-generated interpretations of surface electrical resistivity indicated that contaminant migration was primarily influenced by gravity, bedrock topography, and the local hydraulic gradient. An initial surface electrical resistivity profile survey was conducted to optimize the placement of monitoring wells and soil sampling sites within the vadose zone. Following well installation, a contaminant source with complex brine contamination patterns was detected within the shallow aquifer. Vertical electrical soundings were then carried out as the final investigative step. The data from these soundings, combined with test hole records, water level measurements, brine contaminant distribution, and soil analyses, were refined through a computer program employing the method of steepest descent. By incorporating known layer thicknesses and resistivities as constraints, this approach minimized the common issue of non-unique electrical sounding interpretations, providing information on the distribution of brine contaminants within the alluvial aquifer. Full article

This study aimed to investigate the shallow groundwater status around the Sheba Leather Tannery area, Wikro, North Ethiopia, through geophysical and hydrochemical methods. Seventeen Vertical Electrical Soundings (VESs) acquisitions, 4 upstream and 13 downstream, of the leather tannery area were conducted. Using the data, four geoelectric profiles were generated. The aquifers’ geoelectrical layers, depth, and lateral extent were delineated. The VES curves depicted three to four resistivity layers. These alternating layers of low, moderate, and high resistivity values, traced at different VES points, were attributed to the formations’ composition and the groundwater quality status. Besides the geophysical survey, 32 water samples were collected from the area. Parameters such as electrical conductivity (EC), total dissolved solids (TDSs), pH, major ions, and heavy metals were analyzed. Moreover, PHREEQC was used to determine the groundwater mineral saturation indices where most minerals, except halite, were found supersaturated. The quality status for drinking purposes was also evaluated using the water quality index (WQI), and the water was classified as good (56.3%), poor (37.5%), and very poor (6.2%). The sodium adsorption ratio (SAR) and the percentage of sodium (Na⁺%) were calculated, and the results indicated that the water is suitable for direct use in irrigation. Full article

For deep underground coal mining ecosystems, research on microbial communities and geochemical characteristics of sediments in different functional zones is lacking, resulting in the knowledge of zone-level mine water pollution prevention and control being narrow. In this study, we surveyed the geochemical distinctions and microbial communities of five typical functional zones in a representative North China coalfield, Xinjulong coal mine. The data indicated that the geochemical compounds and microbial communities of sediments showed distinguishing features in each zone. The microbial community richness and diversity were ranked as follows: surface water > rock roadways > sumps > coal roadways ≥ goafs. Canonical Correlation Analysis (CCA), Spearman correlation and co-occurrence network analysis demonstrated that microbial communities were sensitive and closely related to hydrochemical processes. The microbial community distribution in the underground mine was closely related not only to nutrient elements (i.e., C, S, P and N), but also to redox-sensitive substances (i.e., Fe and As). When it comes to mine water pollution prevention and control, the central zones are goafs. With the increase in goaf closure time, total nitrogen (TN), total organic carbon (TOC) and total sulfur (TS) decreased, but As, Fe and total phosphorus (TP) gradually increased, and the characteristic pollutant SO₄²⁻ concentration in water samples decreased. Additionally, the sulfate-reducing bacteria (SRB) had relatively higher proportions in goafs, suggesting goafs were able to purify themselves. In practical engineering, in situ nitrogen injection technology used to expel oxygen and create an anaerobic environment can be implemented to enhance SRB reducing sulfate in goafs. Meanwhile, because coal mine pollution discharge generally only discharges mine water and leaves sediment underground, the pollutants can be transferred to the sediment by strengthening the relevant reactions including the heavy metal solidification and stabilization function of bacteria. Full article

In previous investigations, the demarcation of capture zones within a specific research area predominantly relied on a singular method, leading to pronounced limitations and uncertainties. To address this challenge, an extensive field survey was conducted, focusing on the systematic classification of water sources in the Linfen City region. Building upon this classification, an intricate fusion of a hydrogeological analysis and formulaic methodology was employed. This integrated approach, coupled with independent numerical simulation methods, was applied to delineate recharge areas for both alluvial fan pore water in piedmont regions and exposed karst water in small- to medium-sized water sources. Simultaneously, precise spatial interpolation was carried out on water quality monitoring data from supply wells within the water source area for the year 2020. This meticulous analysis facilitated the determination of the spatial distribution characteristics of hydrochemical elements. To assess the water quality within the capture zone, the class III groundwater quality standards of China were employed as a pivotal tool for validating the results of the delineation of water source recharge areas. In the final analysis, a comparative study between the integrated coupling method and numerical simulation outcomes revealed the successful delineation of the boundaries for the water supply areas of Tumen and Caojiapo in Linfen City, covering areas of 5.5 km² and 22.29 km², respectively. Simultaneously, the combination of the three methods accurately outlined the boundary of the Hexi water supply area, encompassing an area of 2.5224 km². These results vividly illustrate that the amalgamation of various methodologies proves more beneficial for the precise delineation of capture zones, particularly in diverse types and scales of groundwater sources. The synergy exhibited by these three methods underscores their collective efficacy, providing a more comprehensive and intuitive delineation of the recharge areas for small- to medium-sized water sources. Consequently, these findings significantly enhance the practical application value of the study and hold promise in making substantial contributions to local groundwater security and management initiatives. Full article

Recently the limited freshwater resources have become one of the most significant challenges facing Egypt. Thus, new resources of drinkable water are required to meet the growing population demands and the national projects, to support the country’s economy. Saline groundwater desalination is an option that can support limited freshwater resources. This research represents a detailed analysis of hydrogeological and hydrochemical characteristics of a coastal aquifer in the West Port Said area, northeastern Egypt, to assess the desalination suitability of the aquifer, especially when the nearby seawater is contaminated. The hydrogeological characterization included various integrated approaches: geophysical survey, field investigations, wells drilling, well logging, pumping tests, and water sampling. The results show that: (1) The subsurface lithology consists of sandstone and clay, and three water bearing layers: A, B and C. (2) The average porosity values are 22%, 27.5%, and 25% for layers A, B, and C, respectively. The hydraulic conductivity values fall in the ranges of 5.8–12.7 m/day for layer A, 7.6–11.7 m/day for layer B, and 11.1–19.5 m/day for layer C, while the highest transmissivity values are in ranges of 5.8 × 10²–12.7 × 10² m²/day for layer A, 7.6 × 10²–11.7 × 10² m²/day for layer B and 11.1 × 10²–19.5 × 10² m²/day for layer C. (3) The average storage values are 2.1 × 10⁻³, 1.8 × 10⁻³ and 5.3 × 10⁻³ in layers A, B and C, respectively. (4) Layers A and B showed Na-Cl-type, similar to seawater, but free from oil pollution. These results show layer B’s higher productivity and better quality. Despite the salinity, desalination technology can improve. Full article

A survey of the hydrochemistry and isotopes of the Quaternary aquifer on the southern coast of Laizhou Bay provides new insights into the hydrodynamic and geochemical relationships between freshwater, seawater, and brine at different depths in coastal sediments. This study used a combination of groundwater level analysis, hydrochemistry, and isotopic methods to study the chemical characteristics of groundwater and the origin of groundwater recharge and salinity. Because the sedimentary structure of the area and the formation background of saltwater were important factors controlling the distribution of groundwater, we analyzed the distribution of groundwater in Holocene and Late Pleistocene sediments. The variation of groundwater levels in the Holocene and Late Pleistocene sediments in the saline–freshwater transition zone over time showed that the Holocene and Late Pleistocene groundwater flow directions differed in the saltwater–freshwater transition zone. From south to north in the study area, the hydrochemical types of groundwater in the Holocene and Late Pleistocene sediments were as follows: HCO₃-Ca (freshwater), SO₄-Mg and HCO₃-Ca (brackish water), Cl-Na·Mg (saltwater), and Cl-Na (brine). The results of the hydrochemical and isotopic studies indicated that the saltwater in the Holocene and Late Pleistocene sediments and the brine in the Late Pleistocene sediments were the result of evaporation. The salinity of freshwater in the Holocene sediments was produced by rock weathering, while the salinity of freshwater in the Late Pleistocene sediments was not only derived from rock weathering, but was also affected by evaporation and precipitation. The salinity of brackish water in the Holocene and Late Pleistocene sediments was derived from evaporation and precipitation. Ultimately, the origin of groundwater recharge in the Holocene and Late Pleistocene sediments was atmospheric precipitation. Full article

Surface water and groundwater interaction variations in time and space are crucial for effective water management, especially in low-precipitation regions. To comprehensively determine the hydrochemical characteristics and interaction processes of surface water and groundwater and to investigate the decreasing causes of water resources in semi-arid mountainous watersheds under changing environments, intensive field surveys were conducted in the Daqing River watershed, a tributary of the Haihe River basin in northern China, during two different times of the year: after the rainy season (September 2018) and before the rainy season (July 2019). Sixty surface water and groundwater samples were collected along the mountainous watershed. Using a combination method of hydrogen and oxygen stable isotope tracing and hydrochemical analysis, the hydrogen and oxygen isotopes and hydrochemical characteristics of surface water and groundwater in the mountainous watershed of the Daqing River were analyzed. Furthermore, the effect of elevation (altitude) on isotopes was discussed, and the correlation between hydrogen and oxygen isotope composition and hydrochemical characteristics was obtained. The results were processed using endmember mixing analysis to determine the amount of contribution of the surface water and groundwater interaction processes. The results show that the hydrochemical characteristics are relatively stable in the mountainous watersheds of the Daqing River, and the surface water and groundwater are mainly of the HCO₃-Ca type. The slope of the local meteoric water line is smaller than the slope of the global meteoric water line, and the δD and δ¹⁸O in surface water and groundwater show a good linear relationship both before and after the rainy season. There is a decreasing trend of the value of δ¹⁸O in surface water samples with decreasing altitude, but a decreasing trend of the value of δ¹⁸O in groundwater samples is not obvious. The evaporation intensity of surface water is stronger after the rainy season than before the rainy season, and the connection between the surface water and the groundwater is stronger before the rainy season. Influenced by topographic conditions and other factors, the exchange of surface water and groundwater is frequent, and there is a large difference in the exchange ratio before and after the rainy season. The exchange ratio can be more than 50% after the rainy season. Thus, the reasons for decreasing water resources in the mountains can be implied to be due to the increasing hydraulic gradient between the mountains and the piedmont plains, and the water resources are discharged more in the form of groundwater to the downstream. The conclusions help to enhance the understanding of the water cycle in the mountainous watershed and can provide some theoretical basis for the sustainable development and utilization of water resources in the Haihe River basin and the regional water ecology of the Xiong’an New Area. Full article

The Tigris River is the second-longest river in Western Asia and runs through heavily populated areas, especially in Baghdad city with nearly 8 million inhabitants. The water demand is at its highest levels, nevertheless the Tigris discharge has severely declined in the last decades; combined with the fact that the wastewater quantities are increasing, and the wastewater treatment plants are experiencing a deficiency. Four sites were chosen: the Tharthar-Tigris Canal which is located in the north part of Baghdad city, Baghdad city, the Diyala River conjunction with the Tigris River site, and Al-Azizziyah site in the south of Baghdad city near Kut government, to determine the effect of the decreasing Tigris River flow on the water quality and to identify the sources of pollution. In this research, the used method evaluates the concentration of the contaminants along the course of the Tigris River to determine the source of the contaminants as the novelty of this research. The data include the discharge of The Tigris River, a hydrochemical analysis, such as major ions and trace elements, and biological parameters (BOD₅, COD, E. coli bacteria, and coliform bacteria MPN/100 mL) as contamination indicators. Multivariate statistical techniques (factor analysis) were applied to evaluate spatial variations, for the years 2005 to 2020, and Phreeqc software was used to assess the saturation indices determine the dominant geochemical processes source responsible for surface water quality. The dominant minerals of the Tigris River were gypsum, anhydrite, and halite. The Tigris River is within the permissible limits for drinking, except at the Tharthar-Tigris Canal and Diyala River, and the main water quality deterioration factors of the Tigris River were recognized as: total dissolved solids, E. coli bacteria, fecal coliform bacteria, BOD₅, and COD. By applying the SPSS program, two factors were identified. The first anthropogenic factor discharged into the river represents 71.27% of the variance and is comprised of agricultural land wastewater and sewage water. While the second factor represents 17.02%, indicated by the variables Ca²⁺, K⁺, Mg²⁺, and SO₄²⁻. This factor accounts for the chemical weathering of rocky components. It is recommended that a periodic monitoring system is needed to_. follow up on pollution levels and water quality for the Tigris River, by conducting seasonal surveys. Full article