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• Combined with the actual site groundwater characteristics. • Discussed the design of MFCs, including configuration and size, electrode, membranes and separators, contaminants. • Reviewed the progress of research on groundwater removal with MFCs in the last decade. • Considerd the efficiency and practicability of MFCs. Microbial fuel cells (MFCs) have become more prevalent in groundwater remediation due to their capacity for power generation, removal of pollution, ease of assembly, and low secondary contamination. It is currently being evaluated for practical application in an effort to eliminate groundwater pollution. However, a considerable majority of research was conducted in laboratories. But the operational circumstances including anaerobic characteristics, pH, and temperature vary at different sites. In addition, the complexity of contaminants and the positioning of MFCs significantly affect remediation performance. Taking the aforementioned factors into consideration, this review summarizes a bibliography on the application of MFCs for the remediation of groundwater contamination during the last ten decades and assesses the impact of environmental conditions on the treatment performance. The design of the reactor, including configuration, dimensions, electrodes, membranes, separators, and target contaminants are discussed. This review aims to provide practical guidance for the future application of MFCs in groundwater remediation. [Display omitted] [ABSTRACT FROM AUTHOR]

Groundwater resource is crucial for the development of agriculture and urban communities in valley basins of arid and semiarid regions. This research investigated the groundwater chemistry of a typical urbanized valley basin on the Tibetan Plateau to understand the hydrochemical status, quality, and controlling mechanisms of groundwater in arid urbanized valley basins. The results show groundwater is predominantly fresh and slightly alkaline across the basin, with approximately 54.17% of HCO3-Ca type. About 12.5% and 33.33% of sampled groundwaters are with the hydrochemical facies of Cl-Mg·Ca type and Cl-Na type, respectively. Groundwater is found with the maximum TDS, NO3−, NO2−, and F− content of 3066 mg/L, 69.33 mg/L, 0.04 mg/L, and 3.12 mg/L, respectively. Groundwater quality is suitable for domestic usage at all sampling sites based on EWQI assessment but should avoid direct drinking at some sporadic sites in the urban area. The exceeding nitrogen and fluoride contaminants would pose potential health hazards to local residents, but high risks only existed for infants. Both minors and adults are at medium risk of these exceedingly toxic contaminants. Groundwater quality of predominant sites in the basin is suitable for long-term irrigation according to the single indicator of EC, SAR, %Na, RSC, KR, PI, and PS and integrated irrigation quality assessment of USSL, Wilcox, and Doneen diagram assessment. But sodium hazard, alkalinity hazard, and permeability problem should be a concern in the middle-lower stream areas. Groundwater chemistry in the basin is predominantly governed by water-rock interaction (silicate dissolution) across the basin in natural and sporadically by evaporation. Human activities have posed disturbances to groundwater chemistry and inputted nitrogen, fluoride, and salinity into groundwater. The elevated nitrogen contaminants in groundwater are from both agricultural activities and municipal sewage. While the elevated fluoride and salinity in groundwater are only associated with municipal sewage. It is imperative to address the potential anthropogenic contaminants to safeguard groundwater resources from the adverse external impacts of human settlements within these urbanized valley basins. [ABSTRACT FROM AUTHOR]

Groundwater serves as a crucial resource, with its quality significantly impacted by both natural and human-induced factors. In the highly industrialized and urbanized Yangtze River Delta region, the sources of pollutants in shallow groundwater are more complex, making the identification of groundwater pollution sources a challenging task. In this study, 117 wells in Wujiang District of Suzhou City were sampled, and 16 groundwater quality parameters were analyzed. The fuzzy synthetic evaluation method was used to assess the current status of groundwater pollution in the study area; the principal component analysis (PCA) was employed to discern the anthropogenic and natural variables that influence the quality of shallow groundwater; and the absolute principal component scores–multiple linear regression (APCS-MLR) model was applied to quantify the contributions of various origins toward the selected groundwater quality parameters. The results indicate that the main exceeding indicators of groundwater in Wujiang District are I ( 28 % ), N H 4 - N ( 18 % ), and Mn ( 14 % ); overall, the groundwater quality is relatively good in the region, with localized heavy pollution: class IV and class V water are mainly concentrated in the southwest of Lili Town, the north of Songling Town, and the south of Qidu Town. Through PCA, five factors contributing to the hydrochemical characteristics of groundwater in Wujiang District were identified: water–rock interaction, surface water–groundwater interaction, sewage discharge from the textile industry, urban domestic sewage discharge, and agricultural non-point source pollution. Additionally, the APCS-MLR model determined that the contributions of the three main pollution sources to groundwater contamination are in the following order: sewage discharge from the textile industry ( 10.63 % ) > urban domestic sewage discharge ( 8.69 % ) > agricultural non-point source pollution ( 6.26 % ). [ABSTRACT FROM AUTHOR]

Contemporary issues of ground contamination, exacerbated by elevated heavy metal levels due to industrial activities and improper waste disposal, significantly impact soil properties, the biosphere, and result in various geotechnical problems. This study delves into the efficacy of Chrysopogon zizanioides (vetiver) root micro powder (VRMP) in immobilizing Lead (Pb), Cadmium (Cd), and Chromium (Cr) within contaminated soil to prevent groundwater pollution and bioavailability. Leaching experiments were conducted to evaluate the individual immobilization of heavy metals and determine the optimal VRMP dosage, testing four dosages (0%, 1%, 5%, and 10%) for their effectiveness in immobilizing Pb, Cd, and Cr in contaminated soil. The findings suggest that addition of VRMP led to an increase in pH, facilitating the enhanced immobilization of Pb, Cd, and Cr from the contaminated soil due to the reduction in mobility of these metals. Soil treated with 10% VRMP exhibited exceptional immobilization efficiency, achieving over 90% removal across all treatments. However, agglomeration caused the leaching process to take slightly longer. Consequently, a 5% VRMP dosage is considered optimal. In conclusion, vetiver root micro powder promotes a sustainable approach to immobilize Pb, Cd, and Cr in contaminated soils, underscoring the effectiveness of eco-friendly methodologies. [ABSTRACT FROM AUTHOR]

Diisopropylamine (DIPA), aminomethyl propanol (AMP), amino ethoxy ethanol (AEE), diethanolamine (DEA), ethanolamine (EA), pyridine (PYR) and methyl diethanolamine (MDEA) are used for carbon capture and to sweeten sour gas, and are found in groundwater. They are also used in cosmetic products. Taurine is abundant in the body, with key biological functions linked to its charged SO groups. Interactions between SO and amines have not been studied, but can strongly affect the biological function of taurine. Fourier transform infrared spectroscopy indicates SO...HN hydrogen bonding between taurine and DIPA, AMP, AEE, DEA, EA and MDEA. These interactions induce the formation of hydrophobic amine-taurine clusters, thus decreasing amine miscibility in water, as revealed by light scattering. This effect is most marked for DIPA, leading to turbid mixtures indicative of micron-sized droplets. PYR and taurine likely interact via S...N bonding. This study offers insights regarding potential mechanisms of amine toxicity to humans. [ABSTRACT FROM AUTHOR]

ABSTRACT Groundwater quality assessment is crucial for ensuring safe drinking water, protecting public health, and maintaining sustainable water resources for agricultural and industrial uses. The Awash River basin faces significant groundwater quality challenges due to rapid population growth, high urbanization, large‐scale irrigation, and industrial pollution. The main objective of this study is to evaluate the intrinsic vulnerability of aquifers to pollution in the Awash Basin and identify hotspots requiring urgent intervention using a modified DRASTIC overlay analysis method. In addition to the seven parameters considered in the generic DRASTIC overlay analysis (depth to the water table, recharge, aquifer media, slope, soil media, vadose zone, and hydraulic conductivity), we incorporated land use/land‐cover (LULC) and lineament density (LD) distributions (DRASTIC‐LU‐LD). This modification allowed us to produce more realistic groundwater vulnerability maps for the basin. To identify the most influential parameters in the overlay, sensitivity analysis was conducted using Map Removal Sensitivity Analysis (MRSA) and Single Parameter Sensitivity Analysis (SPSA). Initially, the generic DRASTIC index in the area ranges from 69 to 181, categorizing the area into four vulnerability zones: very low (21%), low (51%), medium (27%), and high (1%). After incorporating LU and LD, the index values ranged from 90 to 240. Based on the percentage of the total area studied, the inclusion of LU decreased the very low and low vulnerability zones from 72% to 44% and the inclusion of LD increased the high‐ and very‐high‐vulnerability zones from 14% to 27%. The areas most vulnerable to groundwater pollution are in the western (upper Awash), middle Awash, and northwestern regions, particularly in city centers where groundwater abstraction is significant. These high‐vulnerability zones coincide with municipal, industrial, and agricultural pollution sources. The vadose zone parameter has the highest impact in both MRSA and SPSA, with a variation index value of 3.08% and a mean effective weight of 27.93%, respectively. By identifying areas vulnerable to groundwater pollution, this study provides a valuable basis for informed decision‐making and the development of effective strategies for protecting groundwater from urban, industrial, and agricultural pollution sources. [ABSTRACT FROM AUTHOR]

Groundwater nitrate pollution is a serious environmental problem worldwide, which is demonstrated influenced by land use/land cover (LULC) patterns. The current study was carried out to investigate the effects of LULC patterns to the nitrate pollution of shallow groundwater in the north piedmont plain of the Qinling Mountain (NPQM) using an ensemble machine learning method named random forest. Groundwater nitrate data and existing LULC patterns datasets were utilized to conduct the study. LULC patterns were quantified using a curved streamline shaped contributing area stratagem, and subsequently used to create training and test datasets together with the groundwater nitrate data for construction of random forest model. The results of this study indicated arable and urban land were the main LULC types in the NPQM, and urbanization induced the occupation of arable land by urban land from 2015 to 2019. Shallow groundwater in the NPQM was polluted by nitrate in both 2015 and 2019, with area of groundwater nitrate concentration exceeding the standard limitation recommended by the WHO (50 mg/L as NO3—) reduced from 2762.2 km2 in 2015 to 2184.3 km2 in 2019, showing an alleviating trend. Arable and urban land were the main LULC types contributing to groundwater nitrate pollution. Nitrate accumulated in the soil from manure and chemical fertilizer was the main source for groundwater nitrate pollution in arable land, while manure and sewage were the main source in urban land. The study provides scientific insights for sustainable groundwater protection in the NPQM. [ABSTRACT FROM AUTHOR]

Selecting representative groundwater monitoring wells in polluted areas is crucial to comprehensively assess groundwater pollution, thereby ensuring effective groundwater remediation. However, numerous factors can affect the effectiveness of groundwater monitoring well network optimizations. A local sensitivity analysis method was used in this study to analyze the hydrogeological parameters of a simulation groundwater solute transport model. The results showed a strong effect of longitudinal dispersion and transverse dispersion on the output results of the simulation model, and a good fit between the backpropagation neural network (BPNN)-based alternative model's results and those obtained using the solute transport simulation model, accurately reflecting the input and output relationship of the simulation model. The optimized groundwater monitoring layout scheme consisted of four groundwater monitoring wells, namely no. 7, no. 16, no. 23, and no. 24. These wells resulted in a groundwater fluoride pollution rate of 98.44%, which was substantially higher than that obtained using the random layout scheme. In addition, statistical analysis of the fluoride groundwater pollution results obtained using the Monte Carlo random simulation highlighted continuous and high groundwater fluoride levels in the second and third pollution sources and their downstream groundwater. Therefore, more attention should be devoted to these sources to ensure the effective remediation of groundwater pollution in the study area. [ABSTRACT FROM AUTHOR]

A computationally inexpensive and data parsimonious direct model for identification of groundwater pollution sources that captures their location, spatial extent and flux intensities at a chosen reference time is presented in this study. The model is based upon instantaneous micro-level mass balance that is depicted by a pseudo steady state solute transport equation. Clusters of polluting locations were identified by finite differencing the solute transport equation and applying K-means clustering algorithm. The model is validated by the problem taken from Singh, Datta, and Jain (2004) and is also illustrated by applying it to an area lying between river Krishni and Hindon. Validation results showed that the model captured closely the pollution source locations; their corresponding spatial extents and flux intensities. Model captured the sources even when the concentration plumes are far away from the source locations due to advection dominated contaminant transport. Illustration results showed that the model identified the leachate flux intensity from irrigation in the form of a regional source. Further, it established a few local sources arising possibly out of localized industrial and/or municipal waste water disposal. [ABSTRACT FROM AUTHOR]

Groundwater salinization poses a critical threat to sustainable development in arid and semi-arid rurbanizing regions, exemplified by Kerman Province, Iran. This region experiences groundwater ecosystem degradation as a result of the rapid conversion of rural agricultural land to urban areas under chronic drought conditions. This study aims to enhance Groundwater Pollution Risk (GwPR) mapping by integrating the DRASTIC index with machine learning (ML) models, including Random Forest (RF), Boosted Regression Trees (BRT), Generalized Linear Model (GLM), Support Vector Machine (SVM), and Multivariate Adaptive Regression Splines (MARS), alongside hydrogeochemical investigations, to promote sustainable water management in Kerman Province. The RF model achieved the highest accuracy with an Area Under the Curve (AUC) of 0.995 in predicting GwPR, outperforming BRT (0.988), SVM (0.977), MARS (0.951), and GLM (0.887). The RF-based map identified new high-vulnerability zones in the northeast and northwest and showed an expanded moderate vulnerability zone, covering 48.46% of the study area. Analysis revealed exceedances of WHO standards for total hardness (TH), sodium, sulfates, chlorides, and electrical conductivity (EC) in these high-vulnerability areas, indicating contamination from mineralized aquifers and unsustainable agricultural practices. The findings underscore the RF model's effectiveness in groundwater prediction and highlight the need for stricter monitoring and management, including regulating groundwater extraction and improving water use efficiency in riverine aquifers. [ABSTRACT FROM AUTHOR]

Anning Refinery, a large-scale joint venture in southern China, possesses significant potential in regard to polluting local groundwater environments due to its extensive petroleum raw materials. This study aims to mitigate the substantial risks associated with oil spills and prevent consequential groundwater pollution by developing a robust groundwater flow model using the MODFLOW module in GMS software that aligns closely with natural and pumping test conditions. Furthermore, by integrating the MT3DMS model, a groundwater solute transport model is constructed and calibrated using sodium chloride tracer dispersion data. Notably, the wax hydrocracking unit and aviation coal finished product tank area are identified as key pollution sources warranting attention. By considering local constraints such as karst collapse, ground subsidence, and single-well water output capacity, the study introduces a tailored groundwater pollution management model. The research simulates various scenarios of petroleum pollutant migration in groundwater and proposes multi-objective emergency response optimization plans. In Scenario 1, simulations show that petroleum pollutants migrate within the unconfined aquifer and enter the karst aquifer as low-concentration plumes over an extended period. Detection of these plumes in karst water monitoring wells indicates upstream unconfined aquifer contamination at higher concentrations, necessitating immediate activation of the nearest monitoring or emergency wells in both layers. Conversely, in Scenario 2, pollutants reside briefly in the unconfined aquifer before entering the karst aquifer at relatively higher concentrations. Here, low-efficiency pollutant discharge through unconfined aquifer monitoring wells prompts the activation of nearby karst aquifer monitoring or emergency wells for effective pollution control. This model underscores the necessity for proactive monitoring and validates the efficacy of coupled numerical modeling in understanding pollutant behavior, offering valuable insights into pollution control scenario assessments. In summary, the study emphasizes the importance of targeted monitoring and emergency protocols, demonstrating the benefits of integrated modeling approaches in industrial areas prone to pollution risks, and provides critical theoretical and practical guidance for groundwater protection and pollution management, offering transferable insights for similar industrial settings worldwide. [ABSTRACT FROM AUTHOR]

Stormwater management in coastal urban cities, where drainage networks are influenced by marine dynamics and specific soil and altimetry conditions, has specific challenges that need to be addressed to ensure adequate management in such areas, which are also heavily affected by floods. Their location downstream of drainage basins and the interaction of network outfalls with current and tidal variability increases the vulnerability of populations and should therefore be the target of specific studies. This article presents a literature review, where publications that focus on stormwater management in coastal urban areas were identified and analyzed. The main objective was to present the key issues related to drainage in coastal areas, the most relevant challenges, the solutions and strategies that reveal the greater potential for application and the challenges for modeling this type of case. It is intended to provide a grounded basis for new ways of optimizing stormwater drainage in coastal areas and promote a sustainable urban water cycle. This review reveals the necessity to implement a multidisciplinary approach to minimize three main issues: urban flooding, stormwater pollution and groundwater salinization, including the adaptation of existing infrastructures, complementing them with control solutions at source, correct urban planning and the involvement of populations. For an effective management of urban stormwater drainage in coastal areas, this approach must be carried out on a watershed scale, duly supported by reliable decision support tools and monitoring systems. [ABSTRACT FROM AUTHOR]

A modified DRASTIC model, named DRASTLZ, has been proposed to better assess the sensitivity of groundwater systems to pollution by replacing the vadose zone media type (I) and hydraulic conductivity of the aquifer (C) with land use type (L) and groundwater quality (Z) indicators. First, a scoring system for the DRASTLZ model was established, assigning different weights to seven influencing factors. Using the ArcGIS platform, collected data were processed and statistically analyzed. Evaluation score maps were constructed for seven assessment indicators: groundwater depth (D), net recharge of groundwater (R), aquifer media (A), soil media (S), surface slope (T), land use type (L), and groundwater quality (Z). These maps were then overlaid, and the composite vulnerability index of Juxian County was calculated according to the assigned weights. The natural breaks classification method was employed to divide the area into five vulnerability zones: low vulnerability, relatively low vulnerability, moderate vulnerability, relatively high vulnerability, and high vulnerability. The groundwater vulnerability assessment for Juxian County was thereby completed. The calculated results indicate that the overall vulnerability of groundwater in Juxian County is relatively high, with the highest proportion (approximately 38%) falling in the high vulnerability zone, followed by moderate vulnerability (36%) and high vulnerability (15%) zones. The proportions of relatively low and low vulnerability zones are smaller, accounting for 10% and 1%, respectively. There is a positive correlation between groundwater vulnerability assessment results and the exceedance of water quality sampling points, suggesting the applicability of the developed DRASTLZ model in Juxian County closely reflects actual conditions. The successful application of the DRASTLZ model provides valuable experience and guidance for future groundwater vulnerability assessment studies in similar regions. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effects of indiscriminate disposal of coal fly ash on surface and groundwater hydrochemistry and heavy metal(loid)s (HMs) occurrence through a comprehensive assessment around a thermal power plant located in the central Ganga Plain, India. Both surface and groundwater in the region are slightly alkaline in nature. Groundwater samples are marked by high concentrations of HCO3‒ (~ 78%), which is likely influenced by both anthropogenic and geogenic activities. High Pb concentrations were found in 40% of groundwater samples. Ca2+ – Mg2+ – HCO3‒ and Na+ – K+ – HCO3‒ are the principal hydrochemical facies, while silicate weathering is a dominant process controlling the chemistry of groundwater. PHREEQC modeling, a method for simulating geochemical reactions in natural waters, indicates oversaturation with aragonite, dolomite, and calcite and undersaturation with fluorite, anhydrite, halite, gypsum, and sylvite. The entropy-weighted water quality index (EWQI), based on physicochemical concentrations, suggests samples have excellent to good water quality. However, the modified heavy metal pollution index (m-HPI) reveals that ~60% of groundwater samples fall into the 'high pollution' category, with 30% in the 'medium pollution' class. Health risk assessments (HRA) indicate both children and adults face non-carcinogenic and carcinogenic risks, with children being more vulnerable. Irrigation water quality results demonstrate that ~ 50% of samples are unacceptable for agricultural practices, and samples in proximity to the dumping site display poor water quality. This study recommends regular monitoring of water quality near coal fly ash disposal sites, which is necessary to ensure early detection and management of any contamination. [ABSTRACT FROM AUTHOR]

Nitrate contamination in drinking water is now gaining global attention because of its potential effect on human health. In this study, nitrate concentrations and their potential sources in groundwater and surface water were investigated using hydrochemical and isotopic methods. The physical parameters were measured in-situ using multi parameter meters; major ions, stable isotopes (δ2H and δ18O of H2O) and δ15N and δ18O of NO3− were measured using the Ion Chromatography, laser spectrometry and titanium (III) reduction method respectively. The results indicate that the dominant water type is Ca-Mg-HCO3, followed by the Ca–Mg–Cl hydrogeochemical facies. The plot of NO3−/Cl− against Cl− revealed that the dominant sources of NO3− in the groundwater are manure/sewage with few traces from soil inputs. Meanwhile the plot of δ2H-H2O against δ18O-H2O showed that rainfall is the main source of groundwater recharge with few groundwater samples showing evidence of recharge from an enriched source (Black Volta River). The plot of δ18O – NO3− against δ15N – NO3− suggests that a significant percentage of nitrate is from manure and sewage, followed by the soil zone, hence leading to nitrification and denitrification being important biological processes affecting NO3− concentrations in groundwater in the study area. The stable isotope mixing model suggests manure contributed a mean proportional contribution of about 74% of NO3− to groundwater in the study area, while soil nitrogen contributed 10%. The Nitrate Pollution Index (NPI) suggests that about 80.2% of water samples were pollution free, while anthropogenic activities resulted in about 8.3% of the pollution index. Since most samples with lower nitrate pollution indices were observed around recharged areas and increased toward the discharge points, our study suggests the possibility that recharge areas of the water was free or lowest in nitrate contamination. [ABSTRACT FROM AUTHOR]

Excessive intake of iodine will do harm to human health. In recent years, high iodine groundwater has become a global concern after high arsenic and high fluorine groundwater. A deep understanding of the environmental factors affecting iodine accumulation in groundwater and the mechanism of migration and transformation is the scientific prerequisite for effective prevention and control of iodine pollution in groundwater. The paper comprehensively investigated the relevant literature on iodine pollution of groundwater and summarized the present spatial distribution and hydrochemical characteristics of iodine-enriched groundwater. Environmental factors and hydrogeological conditions affecting iodine enrichment in aquifers are systematically summarized. An in-depth analysis of the hydrologic geochemistry, physical chemistry, biogeochemistry and human impacts of iodine transport and transformation in the surface environment was conducted, the results and conclusions in the field of high iodine groundwater research are summarized comprehensively and systematically. Stable isotope can be used as a powerful tool to track the sources of hydrochemical components, biogeochemistry processes, recharge sources and flow paths of groundwater in hydrogeological systems, to provide effective research methods and means for the study of high iodine groundwater system, and deepen the understanding of the formation mechanism of high iodine groundwater, the application of isotopic technique in high iodine groundwater is also systematically summarized, which enriches the method and theory of high iodine groundwater research. This paper provides more scientific basis for the prevention and control of groundwater iodine pollution and the management of groundwater resources in water-scarce areas. [ABSTRACT FROM AUTHOR]

The evaluation, visualization of environmental data from long-term monitoring, and making them accessible in a processed form in user-friendly interfaces on the Internet are important tasks of our time. The pollution of groundwater resources in settlements is a global phenomenon, the mitigation of which requires a number of environmental measures. In this study, water quality changes following the construction of a sewerage network were examined in the course of long-term monitoring between 2013 and 2022, during which 40 municipal groundwater wells were regularly sampled. Classifying the monitoring data into pollution categories based on water quality index (WQI) and degree of contamination index (Cd), a high degree of contamination was found in the period before the installation of the sewerage network (2014), as the majority of the wells were classified as contaminated and heavily contaminated. In the monitoring period following the installation of the sewerage network, a significant positive change was found in the case of most of the water chemical parameters tested (EC, NH4+, NO2−, NO3−, PO43−). Based on interpolated maps, it was found that an increasing part of the area shows satisfactory or good water quality. This was confirmed by the discriminant analysis as well, as it is possible to determine with an accuracy of 80.4% whether the given sample originates from the period before or after the installation of the sewerage network based on the given water chemical parameters. However, 8 years after setting up the sewerage network, the concentration of inorganic nitrogen forms and organic matter remains high, indicating that the accumulated pollutants in the area are still present. To understand the dynamics of purification processes, additional, long-term monitoring is necessary. Making these data available to members of the society can contribute to appropriate environmental measures and strategies. [ABSTRACT FROM AUTHOR]

Nitrate pollution of surface and groundwater could be a worldwide issue resulting in the threat to the environment and public health. The removal of nitrate from water was carried out using gamma aluminum oxide (γ-Al2O3) nano powder. The nano powder was synthesized from aluminum oxide powder using the aqueous-based reflux method and applied for nitrate removal. The surface properties of the activated γ-Al2O3 were characterized using FTIR, XRD, and BET surface area analysis. Analysis of variance (ANOVA) was used to analyze nitrate removal to determine the appropriate regression model, which was found to be the quadratic model with a coefficient of determination (R2 = 0.99). The adsorption process was observed to be dependent on initial nitrate concentration, adsorbent dose, and time. The optimized nitrate removal efficiencies were 97.01% using a dose of 2.26 gL−1, an initial nitrate concentration of 10 mgL−1, and a contact time of 45 min. Additionally, the kinetics of nitrate ion adsorption was discussed based on pseudo-first order and pseudo-second order kinetic models. The experimental data fitted well with the pseudo-second order kinetic model, indicating that the adsorption mechanism is chemisorption. The equilibrium adsorption of nitrate experimental data followed the both Freundlich and Langmuir isotherm (R2 = 0.95), implying a homogeneous nature of the γ-Al2O3 surface sites. These results suggest further consideration of the practical application of γ-Al2O3 for nitrate treatment for domestic purposes. [ABSTRACT FROM AUTHOR]

Nitrate leaching from farmland pollutes the surrounding environment, such as groundwater, causing health hazards to inhabitants. To mitigate the leaching, biochar can be applied. The effect of biochar application differs depending on the application depth; however, the effect of the application depth remains unclear. To evaluate the effect, we conducted a pipe experiment with no plant using bagasse biochar with four treatments: no biochar application, surface application (0−5 cm), plow layer application (0−30 cm), and subsurface application (25−30 cm). The results showed that surface and plow layer applications reduced nitrate leaching, whereas subsurface application did not affect leaching. This difference was due to changes in the soil water movement and water budget. Surface application reduced evaporation, inducing increases in both drainage and the amount of water in the pipe. The increased amount of water might contribute to an increase in the amount of nitrogen in the pipe, reducing the leaching. Plow layer application increased evaporation, leading to decreased drainage and nitrate leaching. Subsurface application did not affect drainage and nitrate leaching; however, the change in the volumetric water content at a depth of 10 cm was the most significant among the treatments. Our study indicated that, although the same amount of biochar was applied, the effect of biochar application differs depending on the application depth. [ABSTRACT FROM AUTHOR]

In coastal plains, saline water intrusion (SWI) and potentially hazardous pollutants are harmful to local human health. The southern Laizhou Bay has become a typical representative of the northern silty coast due to its extensive silt sedimentation and the significant impact of human activities. This research focuses on a portion of the southern Laizhou Bay, using GIS-based spatial analysis, water quality index methods and health risk assessments to evaluate the impact of saltwater intrusion and potential hazardous pollutants. The results show that the groundwater in the study area is significantly impacted by saline water intrusion, leading to major ion concentrations that far exceed World Health Organization (WHO) standards. The groundwater chemical types of brine and brackish water in the study area are mainly Cl-Na, and the main chemical types of fresh water are HCO3-Ca·Na. The average concentration sequence of the main ions in groundwater is K+ > HCO3− > Cl− > Na+ > SO42− > Ca2+ > Mg2+. The average hazard quotient (HQ) sequence in typical pollutants is Cl− > F− > NO3-N > Se > Mn > NO2-N > Cu > Pb > Zn > Fe, and the carcinogenic risk (CR) sequence caused by carcinogenic heavy metals is Cd > As > Cr. The noncarcinogenic health risk area is mainly distributed in the northwest of the study area, while the potential carcinogenic risk area is in the central region. The Cl is the greatest noncarcinogenic risk to adults and children. The mean HQ values for adults and children were 95.69 and 146.98, indicating a significant noncarcinogenic risk. The mean CR values for adults and children were 0.00037 and 0.00057, suggesting a relatively low carcinogenic risk. SWI is the main influencing factor on human health; therefore, it is necessary to prevent and control SWI. Moreover, potentially hazardous pollutants are carcinogenic and noncarcinogenic risks and are caused by agriculture, industry and other human activities. The findings of this research offer scientific insights for groundwater pollution control and saline water intrusion management in similar coastal areas. [ABSTRACT FROM AUTHOR]

With the development of industry and agriculture, eutrophication caused by increasing amounts of phosphorus in the environment has attracted people's attention. On the other hand, copper tailings (CT) is a kind of solid waste with large quantity, large area, and easy to cause groundwater and soil pollution. CT is also a potential resource because of its large specific surface area. CT is intended to be used as an adsorbent for removal phosphate in water, but trace heavy metals and a small amount of phosphate in CT may bring negative effects. Calcium hydroxide (Ca(OH)2) was used to modify CT (CCT), hoping to fix the heavy metals and phosphate in CT at the same time. It was found that the removal capacity of CCT was significantly higher than that of CT. The process of phosphate removal by CCT involves electrostatic sorption and surface precipitation, and there is a synergistic effect between CT and Ca(OH)2. The phosphate removal rate of CCT-0.4 increased with the increase of pH value under alkaline conditions. The XRD patterns of phosphate sorption by CCT mean that Ca3(PO4)2, Ca5(PO4)3(OH) and AlPO4 exist in CCT after phosphate removal, indicating that surface precipitation occurs during the removal process. In summary, the removal mechanism of phosphate by CCT is mainly electrostatic attraction and surface precipitation. [ABSTRACT FROM AUTHOR]

This study investigates the chemical characteristics, formation, and sources of inorganic nitrogen (IN) of shallow groundwater across the Sanjiang Plain, aiming to enhance drinking water safety management and pollution control. A total of 167 groundwater and 27 surface water samples were collected for constituents and isotopes (H2 and O18). The hydrogeochemical characteristics showed that the major type is HCO3‐ Ca·Mg, with low total dissolved solids and a neutral to weak alkaline nature. Rock weathering processes govern the hydrochemical composition of groundwater. Hydrogen and oxygen stable isotopes analyses revealed that precipitation serves as the main water source. In alluvial areas, oxidative conditions lead to the enrichment of NO3‐N concentrations, with sewage, manure, and fertilizers being the primary IN sources. In lacustrine areas, intensive rice cultivation results in reductive conditions and strong denitrification processes, causing the loss of NO3‐N and leaving NH4‐N as the dominant IN form. Organic matter mineralization is likely a more significant contributor to NH4‐N concentrations than ammonium fertilizers. These findings provide valuable information for further research on natural sources and groundwater pollution in areas with similar hydrogeological conditions. Practitioner Points: Rock weathering processes govern the hydrochemical composition of groundwater, and precipitation serves as the main water source.In alluvial areas, oxidative conditions lead to the enrichment of NO3‐N. In lacustrine areas, intensive rice cultivation results in reductive conditions and strong denitrification processes.Organic matter mineralization is likely a more significant contributor to NH4‐N concentrations than ammonium fertilizers.These findings provide references for water management and information for further research on natural sources and groundwater pollution in areas with similar hydrogeological conditions. [ABSTRACT FROM AUTHOR]

The accuracy of pollution source identification significantly depends on the amount of effective information derived from monitoring data. Currently, most of the comprehensive studies on groundwater contamination source identification and optimal design of monitoring solutions are based on hypothetical cases, whereas relevant studies on actual cases only consider one characteristic of the pollution source (either locations or fluxes). An optimal monitoring network (OMN)-based pollution source characterisation framework that takes source locations and source fluxes into account is presented to enhance the accuracy of pollution source identification. The genetic algorithm (GA) and particle swarm optimization (PSO) were used to solve the optimization model of pollution source characteristics identification. The framework is applied to a landfill for waste located in Baicheng City, China. The results showed that the identification results based on OMN has a smaller mean relative error and higher accuracy, compared with those based on random monitoring network (RMN). This study shows that OMNs can provide more effective information for pollution source identification and effectively enhance the accuracy of the groundwater sources characteristics identification. [ABSTRACT FROM AUTHOR]

Poly-aluminium chloride (PAC) sludge is a waste product created during drinking water treatment, usually generated in large quantities and typically landfilled. More attention must be directed to environmental-friendly management and economically sustainable of Al-based sludge. In this work, a low-cost and environmental-friendly adsorbent prepared by sodium alginate coated PAC sludge (SPS) was investigated for fluoride removal. Basic preparing parameters including heating temperature (200–800°C), sodium alginate concentration (0.5–5 wt%), particle size (1–2 mm, 2–3 mm, 3–4 mm) and operating parameters including dosage (1–14 g/L), solution pH (4–11), temperature (10–35°C), co-existing anions (NO3−, Cl−, SO42-, PO43-) were examined to evaluate the optimum defluoridation capacity. The prepared SPS adsorbents reached a high removal efficiency of 95.6% with initial fluoride concentration of 10 mg/L, dose of 8 g/L, contact time of 24 h, pH value of 7 and temperature of 10°C. The kinetic study indicated that fluoride adsorption followed the pseudo-second-order kinetics well (R2 = 0.9942), and adsorption isotherms can be well described by Freundlich model (R2 = 0.9952). Thermodynamic studies showed the fluoride adsorption was spontaneous and exothermic. The elements and functional groups of SPS adsorbents were analysed by using EDS and FTIR, respectively. The adsorption mechanism involved physisorption, ligand-exchange and electrostatic attraction. According to N2 adsorption–desorption isotherm, the SPS was mesoporous material which facilitated the adsorption of fluoride ions. Also, aluminium presented in form of Al-OH in SPS adsorbents had significant contribution in fluoride adsorption. The concentration of the residual aluminium ions was 4.48 × 10−3 mg/L which is lower than the China Drinking Water Standard. The encouraging results of this preliminary study indicated that SPS is an environmental-friendly and cost-effective treatment option for groundwater with fluoride pollution. [ABSTRACT FROM AUTHOR]

Judicious application of nitrogen (N) fertilizers in crop production is critical for reducing the nitrate pollution of groundwater and greenhouse gas emissions. It is, thus, important to improve the nitrogen use efficiency under the reduced application of nitrogen. A genotypic variation in N-uptake and N-use efficiency particularly under low N-input conditions exists across crops that can be deciphered and exploited for environmentally sustainable farming without any significant penalty of yield and quality. The present research conducted under the nutrient solution culture aimed to explore the inherent variability in the growth response of ten genetically diverse wheat varieties to low fertilizer N-application (N-, 10 µM N) in comparison to N sufficient control (N+, 8.5 mM N) viz., a viz., the activity of various key N-assimilating enzymes and to delineate the indirect effect of low N on uptake and partitioning of other major macronutrients viz., P, K, S, which may indirectly regulate the N-use efficiency. A notable increase in sulfur, potassium, and phosphorus content was observed under nitrogen-deficient conditions. Varieties such as Carnamah and HD 2824 exhibit a significant increase in shoot phosphorus content, emphasizing their potential to optimize phosphorus acquisition and utilization efficiency under nutrient-limited conditions. The findings highlight the complex interplay between nutrient availability and plant responses, showcasing varietal-specific adaptations to nitrogen limitations. [ABSTRACT FROM AUTHOR]

Groundwater contamination from non-engineered landfills has been extensively documented. However, there is a gap in extensive field research regarding whether engineered landfills can also contribute to groundwater contamination. We selected 62 engineered municipal landfills in Eastern China and collected both leachate samples from the landfills and groundwater samples from nearby wells. Through the analysis of inorganic solute indicators in both groundwater and leachate samples, we explored the impact of landfill leachate on the inorganic solute composition of groundwater. Our findings revealed that over half of the groundwater samples surrounding the landfill sites exceeded recommended drinking water limits for inorganic solutes. The correlation analysis demonstrates a significant relationship between Cl−, SO42−, Na+, and K+ levels in leachate and groundwater, highlighting the direct impact of landfill activities on groundwater quality. Moreover, specific characteristics of the landfill, such as its age, the total waste volume, and geographic location, were found to influence the inorganic solute composition in the groundwater. This effect was apparent in the positive correlations between the age of the landfill and NH3-N, Ca2+, and Mg2+ levels in groundwater, the total waste volume of the landfill and Ca2+ content in groundwater, and the latitude of the landfill and Cl− and HCO3− concentrations in groundwater. This work carries implications for assessing environmental risks associated with engineered landfills and enhancing landfill design, management, and monitoring practices. [ABSTRACT FROM AUTHOR]

Abstract: The increasing population has subjected rivers and streams to high levels of both industrial and domestic pollution. Significant environmental challenges have been brought about by their effects, particularly with regard to biota, ecosystem processes, soil quality, and groundwater pollution. This study examined the effects of human activity by applying pollution index models to evaluate the input of toxic elements in river sediments. Prior to sediment quality analysis, the total amount of arsenic (As), lead (Pb), cadmium (Cd), mercury (Hg), thorium (Th), and uranium (U) was determined in the concentration range of 1.09–10.0 mg/kg, 8.53–475 mg/kg, 0.12–0.16 mg/kg, 4.85–77.5 mg/kg, 3.14–5.9 mg/kg and 0.93–2.86 mg/kg, respectively. The enrichment factor, contamination factor, pollution load index, and geo-accumulation index revealed alarmingly high levels of Pb and Hg contamination at some sampling points, which are related to possible human input, ranging from severe enrichment to considerable contamination. The low ranges of pollution indices of some toxic elements suggest enrichment through the natural weathering process and atmospheric deposition. The Pearson correlation coefficient revealed a significant correlation between Pb-Fe and As-Fe, suggesting the possibility of acid mine contamination. Continual monitoring of river sediment is essential to minimize the impact of toxic elements to sustain sediment health and quality. [ABSTRACT FROM AUTHOR]

Fe(II) minerals can mediate the abiotic reduction of trichloroethylene (TCE), a widespread groundwater contaminant. If reaction rates are sufficiently fast for natural attenuation, the process holds potential for mitigating TCE pollution in groundwater. To assess the variability of abiotic TCE reduction rate constants, we collected pseudo‐first‐order rate constants for natural sediments and rocks from the literature, as well as intrinsic (surface‐area‐normalized) rate constants of individual minerals. Using a Bayesian hierarchical modeling approach, we were able to differentiate the contributions of natural variability and experimental error to the total variance. Applying the model, we also predicted rate constants at new sites, revealing a considerable uncertainty of several orders of magnitude. We investigated whether incorporating additional information about sediment composition could reduce this uncertainty. We tested two sets of predictors: reactive mineral content (measured by X‐ray diffraction) combined with surface areas and intrinsic rate constants, or the extractable Fe(II) content. Knowledge of the mineral composition only marginally reduced the uncertainty of predicted rate constants. We attribute the low information gain to the inability to measure the (reactive) surface areas of individual minerals in sediments or rocks, which are subject to environmental factors like aqueous geochemistry and redox potential. In contrast, knowing the Fe(II) content reduced the uncertainty about the first‐order rate constant by nearly two orders of magnitude, because the relationship between Fe(II) content and rate constants is approximately log–log‐linear. We demonstrate how our approach provides estimates for the range of cleanup times for a simple example of diffusion‐controlled transport in a contaminated aquitard. [ABSTRACT FROM AUTHOR]

Based on a polluted site in Tianjin area, the experiment was designed to compare two soil columns in the addition group and the control group by using the screened petroleum hydrocarbon degrading functional bacteria. The effects of the functional bacteria on petroleum hydrocarbon degradation were investigated by measuring the concentrations of petroleum hydrocarbon, HCO3 - and CO3 2-, combining with 16S high-throughput sequencing, comparing the microbial community structure before and after the reaction, and predicting the function of the sequencing results. The results showed that the addition of functional bacteria had a significant effect on the degradation of petroleum hydrocarbons. The species composition of the column showed that the addition of functional bacteria changed the microbial community diversity in the soil column, and the addition of functional bacteria promoted the growth of Desulfobrunum phylum and inhibited the reproduction of Actinobacterium phylum. Desulfoprunum was mainly present at the water outlet of the two groups of experiments, and it was speculated that sulphate redox reactions existed at the water inlet for both groups of experiments. The relative abundance of Thermincola was higher at the outlet of the bacterial addition group, which was accompanied by strong redox reactions such as denitrification and iron reduction. The analyses of alpha diversity showed that the microbial community diversity was higher in the two groups of test outfalls, while the analyses of beta diversity indicated that the microbial community structure may be related to the spatial location of the test columns. In addition, ecological network analysis revealed that Ascomycota was the key phylum in the tests, and the addition of functional bacteria promoted the synergistic and cooperative relationship among species. PICRUSt2 functional prediction analysis showed that the addition of functional bacteria only enhanced the abundance of bamB, bamC in the water intake, and badA, badDEFG in the water outflow. [ABSTRACT FROM AUTHOR]

Fluoride and nitrate contamination in groundwater is a global concern due to their toxicity and associated negative health effects. This study incorporated a comprehensive methodology, including hydrogeochemical analysis, drinking and irrigation water quality assessment, source apportionment, and health risk estimation of groundwater fluoride and nitrate in a lithium ore deposit basin in western Serbia. Groundwater major ion hydrogeochemistry was governed by water–rock interactions, with Ca-Mg-HCO3 identified as the predominant groundwater type. The entropy-weighted water quality index (EWQI), sodium adsorption ratio (SAR), and sodium percentage (%Na) revealed that 95% of the samples were of excellent to good quality for both drinking and irrigation. Moreover, the results showed that fluorides were of geogenic origin, whereas nitrates originated from agricultural activities. Although the fluoride and nitrate levels in groundwater were relatively low, averaging 1.0 mg/L and 11.1 mg/L, respectively, the results of the health risk assessment revealed that the ingestion of such groundwater can still lead to non-cancerous diseases. The threshold of one for the hazard index was exceeded in 15% and 35% of the samples for adults and children, respectively. Children were more vulnerable to non-carcinogenic risk, with fluorides being the primary contributing factor. The study outcomes can serve as a reference for other lithium-bearing ore areas and guide the management of regional groundwater resources. [ABSTRACT FROM AUTHOR]

Most coal in India originates from the Korb basin (Chhattisgarh), where coal mines, thermal power, and aluminum plants operate. Groundwater in this region faces severe pollution due to land reclamation, leaching of coal‐related contaminants, waste disposal, and industrial effluent seepage. This work presents results from monitoring groundwater pollution in the Korba basin from 2012 to 2017. Fluoride, aluminum, manganese, and iron levels exceeded acceptable quality limits across all 28 studied locations, with excessive nitrate, magnesium, calcium, and lead levels in specific sites. Tracking seasonal and temporal fluctuations in the most polluted site, namely Kudurmal, revealed peak solute concentrations during the monsoon period and a sustained 18% increase during the study period. Factorial analysis suggests groundwater contamination arises from both human activities and natural sources. These findings underscore the urgent necessity of devising remediation strategies for the drinking water supply. [ABSTRACT FROM AUTHOR]

In the current groundwater contamination investigation study, sampling point allocation methods generally rely on modeling data analysis, which undoubtedly leads to increased sampling costs. Based on this lack of sampling data, the AHP-entropy weight method is improved and applied to construct a distribution model of groundwater pollution sampling points in a plant area, reduce the sampling scale and establish a new and optimised samplimg scheme. A chemical plant in Shenyang is selected for method validation and spatial interpolation analysis, and the following conclusions are drawn. (1) The new scheme can identify areas of contaminants and reduce sampling costs. (2) After reducing the sample size, the spatial distribution characteristics of each pollutant can still be clearly distinguished. (3) The interpolation-based predictions of some pollutants were improved, and the accuracy of the predictions of other pollutants was reduced within the permissible range. [ABSTRACT FROM AUTHOR]

The present work aimed to evaluate the effects of municipal solid waste (MSW) dumping on the quality of soil and groundwater at six specific sites (S1-S6) located in the Haridwar district of Uttarakhand, India. An analysis of selected physicochemical and heavy metal characteristics (Cu, Zn, Fe, Mn, Cd, and Cr) was conducted on groundwater and soil samples collected between July 2022 and June 2023 using standard techniques. Furthermore, the composition of municipal solid waste (MSW) was also analysed, revealing a significant proportion of biodegradable waste in comparison to non-biodegradable wastes. The areas affected by urban and industrial activity showed markedly higher concentrations of physicochemical and heavy metal parameters in both soil and groundwater samples (p < 0.05). An study of groundwater revealed concentrations from BDL to 0.170 ± 0.008 mg/L (S6), 0.034 ± 0.004 mg/L (S4) to 1.565 ± 0.048 mg/L (S6), 1.786 ± 0.089 mg/L (S4) to 10.630 ± 0.279 mg/L (S6), 0.096 ± 0.006 mg/L (S4) to 0.321 ± 0.005 mg/L (S6), and 0.110 ± 0.005 mg/L (S6) for Cu, Zn, Fe, Mn, and Cd mg/kg, respectively. Cr was detected at the BDL level in all groundwater samples from all sites. Findings revealed that metals exceeded the BIS range, with Iron over the limit at all sites, Manganese at S1, S2, and S6 sites, and Cadmium at S1, S2, S3, and S6 sites. The examination of the soil samples revealed concentrations ranging from 0.399 ± 0.125 mg/kg (S5) to 2.806 ± 0.083 mg/kg (S6), 1.207 ± 0.044 mg/kg (S5) to 3.813 ± 0.238 mg/kg (S2), 24.972 ± 1.128 mg/kg (S5) to 47.417 ± 1.713 mg/kg (S3), 2.297 ± 0.43 mg/kg (S5) to 14.641 ± 0.229 mg/kg (S2), and BDL (S4, S5, and S6) to 0.194 ± 0.291 mg/kg (S2) for their respective elements. The Cr content was BDL in all soil samples from all sites. Several metals over the BIS range were detected, including Cu at site S6, Zn at sites S1, S2, S3, S4, and S6, Fe at all sites and Mn at site S2. In S1-S6, the total bacterial population in the soil ranged from 397 ± 67 CFU to 459±88 CFU, with values of 442 ± 86 CFU, 404 ± 78 CFU, 459 ± 88 CFU, 397 ± 67 CFU, 405 ± 67 CFU, and 451 ± 77 CFU, respectively. The findings revealed soil and groundwater pollution caused by the elevated levels of heavy metals in the groundwater, rendering the water unfit for drinking. The study underscores the need of adopting effective waste management strategies to reduce the adverse effects of solid waste disposal sites. The results can guide the formulation of development policies and laws aimed at enabling the implementation of suitable solid waste management techniques. [ABSTRACT FROM AUTHOR]

Abstract Diisopropylamine (DIPA), aminomethyl propanol (AMP), amino ethoxy ethanol (AEE), diethanolamine (DEA), ethanolamine (EA), pyridine (PYR) and methyl diethanolamine (MDEA) are used for carbon capture and to sweeten sour gas, and are found in groundwater. They are also used in cosmetic products. Taurine is abundant in the body, with key biological functions linked to its charged SO groups. Interactions between SO and amines have not been studied, but can strongly affect the biological function of taurine. Fourier transform infrared spectroscopy indicates SO…HN hydrogen bonding between taurine and DIPA, AMP, AEE, DEA, EA and MDEA. These interactions induce the formation of hydrophobic amine-taurine clusters, thus decreasing amine miscibility in water, as revealed by light scattering. This effect is most marked for DIPA, leading to turbid mixtures indicative of micron-sized droplets. PYR and taurine likely interact via S…N bonding. This study offers insights regarding potential mechanisms of amine toxicity to humans. Graphical Abstract

Abstract Nitrogen leaching, resulting from the inefficient use of fertilizers, pollutes the environment, such as groundwater. Biochar can be applied to farmlands to mitigate nitrogen leaching. The effect depends on the application depth. However, the effect has not been examined under crop-farming conditions. Evaluating the interactions between biochar application depth and crop growth is indispensable for considering depth in the actual field. To address this, we conducted a pipe experiment with four treatments, no biochar (control), surface (0–5 cm), plow layer (0–30 cm), and subsurface (25–30 cm) applications, and compared the results with no-crop conditions from a previous study. Biochar application depth affected soil NO3 −−N and NH4 +−N absorption ability and also influenced soil-water stress conditions, affecting crop growth. Surface biochar application improved nitrogen absorption and reduced soil-water stress, improving crop growth. The NO3 −−N leaching was reduced to 87.7%. Plow layer application worsened nitrogen absorption and resulted in frequent dry stress in the shallow-soil layer, preventing root growth in this layer. The NO3 −−N and NH4 +−N leaching increased 106.4% and 264.1%, respectively. The effects of subsurface application were similar to those in the control. Selecting an appropriate application depth can simultaneously improve crop growth and reduce nitrogen leaching.

This study investigated fluoride contamination in groundwater and associated health risks in the Badin district of Pakistan. Fifty-seven groundwater samples were analyzed for fluoride, turbidity, iron, and total dissolved solids (TDS). Pollution indices and health risk models were employed to assess contamination levels and potential health impacts. Results showed that 47 % of samples exceeded the WHO fluoride limit of 1.5 mg/L, with a mean concentration of 1.92 mg/L. Spatial analysis revealed high contamination in northern and southern areas. Health risk assessments indicated that children, particularly females, faced the highest risk of fluorosis. TDS, turbidity, and iron levels also exceeded WHO limits in significant portions of the samples. This investigation uniquely combines multiple pollution indicators, spatial analysis, and age-specific health risk assessments, presenting vibrant insights for targeted interventions, policy development, and resource allocation to address this critical public health issue in fluoride-endemic regions.

Abstract The quality of groundwater resources in artisanal mining districts in Ghana is under threat due to pollution; rendering the resource unsafe for drinking and irrigation purposes. This makes the assessment of the quality of groundwater resources a relevant aspect of groundwater studies as it informs decision making and monitoring. This study adopts 3 Machine Learning (ML) models, Support Vector Regression (SVR), Gradient Boost Regression (GBR), and Artificial Neural Network (ANN), to evaluate a variety of irrigation water quality metrics such as Sodium Percentage (Na%), Soluble Sodium Percentage (SSP), Sodium Adsorption Ratio (SAR), Residual Sodium Carbonate (RSC), Permeability Index (PI), Pollution Index of Groundwater (PIG), Kelly’s Ratio (KR), and Magnesium Hazard (MH). 105 samples were collected from a mining area in Northern Ghana and analysed through traditional methods. The Irrigation Water Quality Indices (IWQIs) demonstrate that all water samples are suitable for use as irrigable water with the exception of MH, Na%, PI, and PIG which revealed that 69.52%, 8.57%, 29.52%, and 3.81% are inappropriate for irrigation. SVR, GBR and ANN were used to establish important factors that may influence IWQIs in the area. The measured data was used as independent variables, and the derived IWQIs, the dependent variables. The results revealed that ANN, GBR, and SVR are all viable options for the prediction of IWQIs, but GBR exhibited variable performance in some indices making it lack consistency and thus falls a bit short compared to ANN and SVR. SVR models overall performed best with SVR-RSC having the highest accuracy.

Boké Prefecture has become a popular mining location, with various extractive corporations competing for bauxite extraction. Water samples were obtained from eighteen water wells across the Dabiss study area. All Physico-chemical parameters and major ions of groundwater were compared with World Health Organization (WHO) standard. Furthermore, using Excel and the Inverse Distance Weighted (IDW) interpolation technique in Arc GIS software, bi-plots of Physico-chemical parameters and spatial variations of water quality maps were generated respectively. A vulnerability study of groundwater pollution by mining activities was conducted by applying the standard DRASTIC method. It was found that the drinking water samples of the study areas were usually within the water quality standards of WHO. According to physicochemical analysis, most of the groundwater in the study area appears to be acidic. An equilibrium was set up in the aquifer between the chemical composition of the water and that of the rocks. The DRASTIC method enabled us to show a low vulnerability index to groundwater pollution. The results of this study could prevent diseases linked to the consumption of water contaminated and improve the quality of life of the population and will serve as a reference document in other mining areas.

This research aims at studying the intrinsic vulnerability of groundwater to diffuse environmental pollutants in the Muravera coastal agricultural area of Sardinia, Italy. The area faces contamination risks arising from agricultural practices, especially the use of fertilizers, pesticides, and various chemicals that can seep into the groundwater. The study examined the interplay among hydrological elements, including soil characteristics, groundwater depth, climate conditions, land use, and aquifer properties. To do that, the outcomes of FLOWS 1D physically-based agrohydrological model were analyzed in parallel with those of the overlay-and-index model SINTACS, in a sort of reciprocal benchmarking. By using FLOWS, water movement and solute transport in the unsaturated zone were simulated by, respectively, solving the Richard Equation (RE) and the Advection-Dispersion equation (ADE). As such, this model allowed to account for the role of soil hydraulic and hydrodispersive properties variability in determining the travel times of a conservative solute through the soil profile to the groundwater. For FLOWS simulations, a complete dataset was used as input, including soil horizons, soil physical and hydraulic properties of 36 soil profiles, average annual depth to groundwater table at each soil profile (ranging from 1 to 50 meters), and climatic temporal series data on rainfall and evapotranspiration. Detailed analyses of travel times for the movement of 25, 50, 75, and 100% of the solute mass to reach groundwater were conducted, revealing that the depth to groundwater predominantly influences vulnerability. This result was coherent with SINTACS vulnerability map due to the large impact of the depth to groundwater on SINTACS analysis. [ABSTRACT FROM AUTHOR]

This study explores the use of pine wood biochar (BC) waste gasified at 950 °C as fillers in polymer matrices to create BC@biopolymer composites with perspectives in groundwater remediation. Four biochar samples underwent different sieving and grinding processes and were extensively characterized via UV–Vis, FTIR, and FESEM–EDS, highlighting the fact that that BCs are essentially graphitic in nature with a sponge-like morphology. The grinding process influences the particle size, reducing the specific surface area by about 30% (evaluated by BET). The adsorption performances of raw BC were validated via an adsorption isotherm using trichloroethylene (TCE) as a model contaminant. A selected BC sample was used to produce hydrophilic, stable polymer composites with chitosan (CS), alginate (ALG), potato starch (PST), and sodium carboxymethylcellulose (CMC) via a simple blending approach. Pilot sedimentation tests over 7 days in water identified BC@PST and BC@CMC as the most stable suspensions due to a combination of both hydrogen bonds and physical entrapment, as studied by FTIR. BC@CMC showed optimal distribution and retention properties without clogging in breakthrough tests. The study concludes that biopolymer-based biochar composites with improved stability in aqueous environments hold significant promise for addressing various groundwater pollution challenges. [ABSTRACT FROM AUTHOR]

With the increasing environmental impacts of human activities, the problem of polygenic multipollutants in groundwater has attracted the attention of researchers. Identifying the hydrobiogeochemical characteristics of the surface sewage that replenishes groundwater is crucial to addressing this problem. The input of polygenic multipollutants into groundwater leads to not only the mechanical superposition of pollutants but also the formation of secondary pollutant types. The evolution of polygenic multipollutants is influenced by aquifer characteristics, carbon sources, microbial abundance, etc. Therefore, this study took a sewage leakage point in Northwest China as the research object, carried out a controlled laboratory experiment on the impact of sewage discharge on groundwater, and, combined with long-term field monitoring results, determined the main hydrobiogeochemical processes of polygenic multipollutants and their secondary pollutants. The results showed that the redox environment and the gradient change in pH were identified as the most critical controlling factors. In oxidative groundwater during the early stage of vertical infiltration, sewage carries a substantial amount of NH4+, which is oxidized to form the secondary pollutant NO3−. As O2 is consumed, the reduction intensifies, and secondary pollutants NO3−, Mn (IV), and Fe(III) minerals are successively reduced. Compared with the natural conditions of rainwater vertical infiltration, the reaction rates and intensities of various reactions significantly increase during sewage vertical infiltration. However, there is a notable difference in the groundwater pH between sewage and rainwater vertical infiltration. In O2 and secondary pollutant NO3− reduction, a large amount of CO2 is rapidly generated. Excessive CO2 dissolves to produce a substantial amount of H+, promoting the acidic dissolution of Mn (II) minerals and generation of Mn2+. Sewage provides a higher carbon load, enhancing Mn (II) acidic dissolution and stimulating the activity of dissimilatory nitrate reduction to ammonium, which exhibits a higher contribution to NO3− reduction. This results in a portion of NO3− converted from NH4+ being reduced back to NH4+ and retained in the groundwater, reducing the denitrification's capacity to remove secondary NO3−. This has important implications for pollution management and groundwater remediation, particularly monitored natural attenuation. [ABSTRACT FROM AUTHOR]

Impermeability and water blocking are crucial for remediating shallow groundwater contamination. Traditional methods often employ curtain-grouting technology to create impermeable layers. However, cement slurry curing is irreversible, leading to permanent closure of underground aquifers and secondary pollution. This study employs an innovative approach by fabricating cylindrical models that simulate actual strata and utilizing a high-temperature and high-pressure displacement device. It systematically analyzes the variations in soil pore structure, distribution, porosity, and permeability under different temperatures, pressures, and freezing durations. The microscopic characteristics of the freezing process in water-bearing soils were studied. Results demonstrate that longer freezing time improves the effectiveness of soil freezing, reaching complete freezing at temperatures as low as −4 °C for samples with low water content. For water-saturated samples, freezing below −6 °C results in nearly zero porosity. Increased pressure at a certain freezing temperature significantly reduces permeability. When freezing temperature falls below −4 °C, water permeability in saturated samples after freezing reaches near-zero levels, while unsaturated samples experience complete freezing. These findings provide a theoretical foundation for constructing freezing curtains in remediating shallow groundwater pollution. [ABSTRACT FROM AUTHOR]

It is challenging to interpret hydrogeochemical datasets with complex natural and anthropogenic genesis in intensive industrial areas. This paper elucidates the hydrogeochemical characteristics and pollution sources of groundwater in an industrial park, East China, combining the self-organizing map (SOM), hydrochemical graphs, and correlation analysis. The results show that the total dissolved solids of groundwater range from 73.45 to 997.92 mg/L and can be regarded as freshwater. The pH varies greatly from 6.44 to 9.90, most of samples belonging to weakly acidic-weakly alkaline. The groundwater can be classified into five clusters by SOM, representing the non- or least-polluted groundwater (cluster D), high salt groundwater (cluster A), high NH4+-N and HCO3− groundwater (cluster B), high Fe and Mn groundwater (cluster C), and high pH groundwater (cluster E), which were contaminated by industrial salts, historical agriculture activity, industrial reducing substances, and industrial alkali, respectively. The natural evolution of groundwater (cluster D) in the study area is mainly controlled by mineral weathering/dissolution. The contributions of calcite, dolomite, gypsum, halite, and silicate mineral to groundwater solute are 55.8–66.3%, 15.1–18.0%, 9.0–10.7%, 2.5–10.1%, and 2.3–9.4%, respectively, based on the mass conservation. The contaminated groundwaters (all other clusters except for cluster D) have different hydrochemical characteristics associated with the pollution sources. In addition, the relatively reductive environment in quaternary flu-lacustrine sediments favored the formation of high level of Fe, Mn, and NH4+-N in groundwater. This study provides a new insight into the characteristic contaminants and their distributions in groundwater and the associated pollution sources based on the large datasets in an intensive industrial area. The data evaluation methods and results of this study could be useful to the groundwater usage management and pollution control in this area and other industrial areas. [ABSTRACT FROM AUTHOR]

This study integrated hydrochemical analysis, isotopic analysis, the integrated water quality index (IWQI), and the health risk assessment model to analyze hydrochemical characteristics, quality, and nitrate health risks in a typical agricultural and industrial (i.e., Holocene and Pleistocene) simultaneously affected by anthropogenic activities, as well as to explore the recharge mechanisms of the groundwater. The shallow groundwater is mainly Ca-HCO3− and deep groundwater is mainly Na-HCO3− types. In shallow and intermediate aquifers (Holocene), rainfall recharge is seen, but in deep aquifers (Holocene) and the Madhupur tract (Pleistocene), there is no evidence of recent recharge from the stable isotopic (δ2H‰ and δ18O‰) composition of groundwater. Anthropogenic sources significantly impacted the groundwater chemistry of shallow and intermediate aquifers more than geogenic sources. Most metalloids, and metals (As, and Cr, Fe, Ni, Pb, and Mn) and NO3− exceed the WHO-2011 and BD acceptable limit from shallow and intermediate groundwater. PCA analysis revealed the contamination of shallow and intermediate aquifers by metalloids, metals and from various anthropogenic activities. Based on the IWQI, HPI, HEI, and DC, groundwater samples from shallow and intermediate aquifers are unsuitable for oral consumption. The NPI shows that the metalloids, and metals are responsible for groundwater pollution in a descending order of As > Fe > Pb > Ni > Cr > Mn. Health risk assessment indicates oral and dermal consumption of contaminated water from shallow and intermediate aquifers can pose carcinogenic and non-carcinogenic health risks for both the adults and the children. The HQ and HI values of shallow and intermediate groundwater indicates higher non-carcinogenic risk. Carcinogenic risk through oral and dermal consumption follows an order of As > Ni > Cr > Pb and Ni > Cr > As > Pb, respectively. Compared to adults, children are more susceptible to both carcinogenic and non-carcinogenic risks. Potential threats to the health of people living in the study region need immediate attention from the public, government, and the scientific community. [ABSTRACT FROM AUTHOR]

Outcrops play an important role in groundwater recharge. Understanding groundwater origins, dynamics and its correlation with different water sources is essential for effective water resources management and planning in terms of quantity and quality. In the case of the Guarani Aquifer System (GAS) outcrop areas are particularly vulnerable to groundwater pollution due to direct recharge processes. This study focuses on the Alto Jacaré-Pepira sub-basin, a watershed near Brotas, a city in the central region of the state of São Paulo, Brazil, where groundwater is vital for supporting tourism, agriculture, urban water supply, creeks, river and wetlands. The area has a humid tropical climate with periods of both intense rainfall and drought, and the rivers remain perennial throughout the year. Therefore, the aim of this study is to investigate the interconnections between a spring and its potential sources of contribution, namely rain and groundwater, in order to elucidate the relationships between the different water sources. To achieve this, on-site monitoring of groundwater depth, rainfall amount, and stable isotope ratios (deuterium (2H) and oxygen-18 (18O)) from rain, spring discharge, and a monitoring well was carried out from 2013 to 2021. The results indicate that the mean and standard deviations for δ18O in rainwater exhibit higher variability, resulting in −4.49 ± 3.18 ‰ VSMOW, while δ18O values from the well show minor variations, similar to those of the spring, recording −7.25 ± 0.32 ‰ and −6.94 ± 0.28 ‰ VSMOW, respectively. The mixing model's outcomes reveal seasonal variations in water sources contribution and indicate that groundwater accounts for approximately 80 % of spring discharge throughout the year. Incorporating stable isotopes into hydrological monitoring provides valuable data for complementing watershed analysis. The values obtained support the significance of the aquifer as a primary source, thereby offering critical insights into stream dynamics of the region. [ABSTRACT FROM AUTHOR]

Arsenic is a metalloid that is naturally present in the environment. Exposure to arsenic can cause health issues like cancer, cardiovascular, neurological, and respiratory complications. With more than a million people affected due to arsenic contamination in groundwater, Bihar is one of the worst arsenic-affected states in India. Groundwater is one of the primary sources for cooking, farming, and other household chores. People are exposed to arsenic through food as well as contaminated drinking water. As a result, arsenic has made its way into the food chain. Several cases of cancer, arsenical dermatosis, and keratosis have been reported in Bihar. The source of arsenic contamination in Bihar has yet to be identified, although the Himalayan sediments have been suspected as one of the prime reasons. The government has taken steps to prevent and control arsenic contamination in the state; however, reports in recent years indicate the number of blocks affected by arsenic contamination has been rapidly increasing. This necessitates a more comprehensive arsenic mitigation tool. Various technologies can be employed to mitigate levels of arsenic in groundwater, of which bioremediation is one of the more cost-effective and sustainable methods. The current article is an attempt to give an overview of the sources and areas of Bihar with arsenic contamination, and the concentration in different regions. It also provides a piece of detailed information on arsenic contamination on health, and the current state of arsenic bioremediation. [ABSTRACT FROM AUTHOR]

An informed search strategy based on random statistical analysis was developed for synchronous recognition of groundwater pollution source information and aquifer parameters. An informed search iterative course (ISIC) was accordingly designed, and each iteration included the determination of attempt point and state transition. In this paper, two improvement techniques were first adopted for choosing attempt points and judging state transition in ISIC to improve search efficiency and precision. The first improvement was that the variable radius free search method was applied to choosing the attempt point, and the size of the search radius was constantly adjusted in ISIC, taking the search ergodicity and efficiency into account. The second improvement technique was a Tsallis formula used for state transition judgment, and the controlled factor in the Tsallis formula was regulated continuously so that the search could consider ergodicity and efficiency simultaneously. Furthermore, frequent calls to the groundwater pollution numerical simulator to calculate the likelihood have inflicted a huge computational burden during ISIC. An effective way is to construct a substitute for emulating the simulator with a low calculating load. However, the mapping relation between the import and export of the numerical simulator was complex and had many variables. The precision of the substitute based on shallow learning is low sometimes. Therefore, we adopted the deep learning method and built an improved deep confidence network (DCN) substitute to emulate the highly nonlinear simulator. Finally, the synchronous recognition results for groundwater pollution source information and aquifer parameters were gained when ISIC ceased. The above-mentioned methods were verified in a case involving groundwater pollution. The consequence indicated that the ISIC with an improved DCN substitute can synchronously recognize groundwater pollution source information and aquifer parameters with a high degree of precision and efficiency. [ABSTRACT FROM AUTHOR]

To determine the interactions between TNT and aniline adsorptions and the potential to enhance their transports in saturated Chinese loess, batch and column tests were conducted. The batch tests show that their adsorptions inhibit each other when they coexist, and their inhibitions depend on their concentrations, implying that their coexistence has the potential to enhance their transports of each other in the saturated loess. The column tests confirm this speculation, while aniline enhances TNT transport more obviously than TNT does. These findings are ascribed to TNT adsorption being primarily through surface adsorption, while aniline adsorption mainly takes place via electrostatic adsorption and inner pore diffusion adsorption, as well as surface adsorption. There is a certain competitive relationship in their adsorptions on the loess because they have same and different adsorption sites; in particular, electrostatic force is greater than surface force. Therefore, these inhibitions on adsorption are conducive to the existences of TNT and aniline in the water rather than being fixed on the loess, thus enhancing their transports in the saturated loess, indicating that their coexistence can increase the risk of soil and even groundwater pollution. [ABSTRACT FROM AUTHOR]

The article focuses on assessing groundwater quality for drinking purposes in Malda District, India, using Water Quality Index (WQI) and Geographic Information Systems (GIS) techniques. Topics include the physicochemical characteristics of groundwater, the identification of hazardous elements and their impact on water quality, and the use of GIS to enhance spatial understanding and management of groundwater resources.

The traceability of groundwater nitrate pollution is crucial for controlling and managing polluted groundwater. This study integrates hydrochemistry, nitrate isotope (δ15N-NO3− and δ18O-NO3−), and self-organizing map (SOM) and end-member mixing (EMMTE) models to identify the sources and quantify the contributions of nitrate pollution to groundwater in an intensive agricultural region in the Sha River Basin in southwestern Henan Province. The results indicate that the NO3−-N concentration in 74% (n = 39) of the groundwater samples exceeded the WHO standard of 10 mg/L. According to the results of EMMTE modeling, soil nitrogen (68.4%) was the main source of nitrate in Cluster-1, followed by manure and sewage (16.5%), chemical fertilizer (11.9%) and atmospheric deposition (3.3%). In Cluster-2, soil nitrogen (60.1%) was the main source of nitrate, with a significant increase in the contribution of manure and sewage (35.5%). The considerable contributions of soil nitrogen may be attributed to the high nitrogen fertilizer usage that accumulated in the soil in this traditional agricultural area. Moreover, it is apparent that most Cluster-2 sampling sites with high contributions of manure and sewage are located around residential land. Therefore, the arbitrary discharge and leaching of domestic sewage may be responsible for these results. Therefore, this study provides useful assistance for the continuous management and pollution control of groundwater in the Sha River Basin. [ABSTRACT FROM AUTHOR]