Concentrations In Groundwater Research Articles

Assessment of heavy metal contamination in groundwater and its implications for dental and public health

Groundwater contamination with heavy metals is a critical environmental issue, especially in regions heavily reliant on groundwater for drinking purpose. These metals can seep into groundwater from soil and rock weathering or through improper disposal of industrial waste and effluents. Access to safe drinking water is essential for maintaining public health. This study aimed to assess heavy metal contamination in groundwater and its implications for dental and public health. The objective of the study was to measure the concentration of the heavy metals in the dentine of extracted tooth of the study population. The study concurrently measured heavy metal concentrations in groundwater and tooth dentine samples, analyzing demographic profiles, heavy metal correlations, and underlying structures using Principal Component Analysis (PCA). The average level of heavy metals in the groundwater samples varied from 9.763 ± 3.362 μg/L for Cd to 3426.204 ± 875.264 μg/L for Fe. The mean concentrations (μg/g) in teeth dentine showed significant variations, with iron (Fe) ranging from 0.149 ± 0.03 μg/g in water purifiers to 4.62 ± 0.578 μg/g in local water sources. Similar variations were observed for other heavy metals across different water sources. Principal component analysis (PCA) revealed seven principal components, with the first two components explaining 96.1% of the total variance. The findings revealed varied concentrations of heavy metals across all water sources. Statistical analyses underscored the complex relationship between water sources and heavy metal contamination levels, highlighting the need for targeted interventions to improve water quality and mitigate health risks. The study highlights the urgent need for monitoring and mitigation efforts to ensure safe drinking water and mitigate health risks associated with heavy metal contamination.

Iodine nutrition status of children 3-13 years of age in areas with high groundwater iodine content in China

BackgroundAdequate iodine status is crucial for children's health and normal development. However, there is a paucity of research on the iodine status of children from areas with high groundwater iodine content. ObjectivesTo monitor the iodine status of children in Shandong, China (regions primarily characterized by high iodine concentrations in groundwater) and to describe the factors influencing children's iodine status. MethodsA cross-sectional study was conducted from 2013 to 2023 on 3,253 children aged 3-13 years. We collected drinking water, spot urine, and 24-hour urine samples from children to assess their iodine status (measuring drinking water iodine concentration (WIC), water iodine intake (WII), urine iodine concentration (UIC), 24-hour urine iodine excretion (24-h UIE), daily iodine intake (DII), etc.), and analyzed influencing factors. ResultsThe median WIC for children was 183 (IQR: 70.2, 362) μg/L, and the median spot UIC was 428 (IQR: 194, 737) μg/L, surpassing the WHO cutoff (300 μg/L). Children at risk of iodine excess numbered 1750 (61.8%). Approximately 61% of iodine intake came from drinking water. Boys had significantly higher iodine intake than girls (P < 0.001). Children's age showed positive correlations with spot UIC, 24-h UIC, and 24-h UIE. There were no significant differences in 24-h UIC and 24-h UIE among children with different BMIs. The logistic regression model revealed that the risk of iodine excess was increased by boy gender, increment in age (OR = 1.05, 95% CI: 1.02, 1.08), and every 10 μg (OR = 1.04, 95% CI: 1.03, 1.04) or 50 μg (OR = 1.19, 95% CI: 1.16, 1.22) increment in WII. ConclusionChildren in areas with high groundwater iodine content are at a risk of iodine excess. As age increases, the risk of iodine excess in children rises, with boys at a higher risk than girls.

Modeling PFAS Subsurface Transport in the Presence of Groundwater Table Fluctuations: The Impact on Source‐Zone Leaching and Exploration of Model Simplifications

AbstractAir–water interfacial adsorption represents a major source of retention for many per‐ and poly‐fluoroalkyl substances (PFAS). Therefore, transient hydrological fluxes that dynamically change the amount of air–water interfaces are expected to strongly influence PFAS retention in their source zones in the vadose zone. We employ mathematical modeling to study how seasonal groundwater table (GWT) fluctuations affect PFAS source‐zone leaching. The results suggest that, by periodically collapsing air–water interfaces, seasonal GWT fluctuations can lead to strong temporal variations in groundwater concentration and significantly enhance PFAS leaching in the vadose zone. The enhanced leaching is more pronounced for longer‐chain PFAS, coarser‐textured porous media, drier climates, and greater amplitudes of fluctuations. GWT fluctuations and lateral migration above the GWT introduce a downgradient persistent secondary source zone for longer‐chain PFAS. However, the enhanced leaching and the secondary source zone are greatly reduced when subsurface heterogeneity is present. In highly heterogeneous source zones, GWT fluctuations may even lead to overall slower leaching due to lateral flow (in the GWT fluctuation zone and above the GWT) moving PFAS into local regions with greater retention capacities. Model simplification analyses suggest that the enhanced source‐zone leaching due to GWT fluctuations may be approximated using a static but shallower GWT. Additionally, while vertical 1D models underestimate source‐zone leaching due to not representing lateral migration, they can be revised to account for lateral migration and provide lower‐ and upper‐bound estimates of PFAS source‐zone leaching under GWT fluctuations. Overall, our study suggests that representing GWT fluctuations is critical for quantifying source‐zone leaching of PFAS, especially the more interfacially active longer‐chain compounds.

Modeling Cs-137 Migration in Groundwater due to Low Probability Event of Leaching from Near Surface Disposal Facility for Low Level Solid Radioactive Waste

In this paper, we present impact of Cesium-137 (Cs-137) disposal in a Near Surface Disposal Facility (NSDF) with respect to groundwater migration and its consumption for drinking. We employ the Multiple Area Source Model for simulating the fate of radionuclide in groundwater to evaluate its potential contamination due to extremely low probability event of leaching from the NSDF. The assessment conservatively assumes direct interaction between disposal trenches and the underlying aquifer neglecting the barrier provided by the unsaturated zone. Temporal profiles of concentration of Cs-137 at different down flow distances in groundwater are obtained over a period extending several years post-disposal. The results indicate that even under such a worst-case conservative scenario and for an annual disposal rate of 3 TBq/y for a period of 50y, the maximum Cs-137 concentration in groundwater remains significantly below the safe drinking water threshold of 10 Bq/L recommended by the World Health Organization. It is found that amount of Cs-137 generally disposed in NSDF is significantly lower than the allowable disposal limit corresponding to concentration defined for safe drinking water limit.

Assessment of Groundwater Quality for Irrigation Suitability in Rajangaon Shenpunji and Surrounding Area, Aurangabad, Maharashtra, India.

The quality of irrigation water available to farmers has a significant impact on crop yield. Hence, it is need to better understand irrigation water quality. The present study mainly emphasizes the assessment of the suitability of 30 water samples from dug wells, bore wells and surface water bodies in Rajangaon Shenpunji and surrounding areas, Aurangabad, Maharashtra, India. The groundwater sample datasets of post-monsoon 2013 season were collected. The water quality parameters, viz. sodium adsorption ratio (SAR), percent sodium (%Na), residual sodium carbonate (RSC), residual sodium bicarbonate (RSBC), Kelly’s ratio (KR), magnesium adsorption ratio (MAR), permeability index (PI) have been calculated. Based on these calculated parameter results, prepared spatial distribution maps in Arc GIS 10.3 software. These parameters were correlated with standard permissible/desirable limits for irrigation use for the prevailing crops. Based on these factors, most of the samples fall into the category of water suitable for irrigation. A few samples that exceeded permissible limits were discovered in various geological and anthropogenic activities near the water samples in the study area. A complete investigation of groundwater quality may be suitable remedial action. Artificial recharge techniques are developed to increase the chemical concentrations in groundwater or suitable crops are working to continue the present water quality.

Artificial intelligence – NPHIs’ role in utilizing its opportunities and addressing the risks

Abstract Issue &amp; Problem National Public Health Institutes (NPHIs) in many countries are at the forefront of action to mitigate the impact of current and future threats to health as well as improving population health and wellbeing. Through research, collaboration, and support, NPHIs can approach these new realities together. One of the many emerging realities that NPHIs will need to engage in is how NPHIs best can utilise the powers of artificial intelligence and deal with the ethical and legal issues that come with it. Methods In preparation of IANPHI’s (International Association of National Public Health Institutes) Europe Regional network meeting in April 2024 a survey was conducted among the 42 members. 16 countries replied to questions, around e.g., 1) current applications of (generative) artificial intelligence (AI) in the work of institutes, 2) which experiences were made and 3) which measures NPHIs take to best utilize the possibilities and overcome challenges of AI technologies. Within four weeks 16 replies were shared. Lessons &amp; Conclusions Some institutes have not yet adopted AI, while others report multiple applications but the primary areas of application vary considerably among Europe. Applications include summarizing and reformatting text; translation; transcribing and documenting meetings; search information in documents or databases; coding; creating visuals; literature review; surveillance of infectious diseases; disease forecasting; analysis of transmission dynamics; vaccine efficacy assessment and development; image recognition; diagnosis and prediction of diseases from medical datasets; text mining; symptom extraction; social listening; prediction of nitrate concentration in groundwater; drug analysis and measuring psychological resilience in social crisis. Key messages • AI poses opportunities and risks for public health and work of national public health institutes and capacity building initiatives are essential. • IANPHI decided to develop a joint framework for the use of AI in its member organisations with a focus on research and responsible use.

Controls on regional sulphate distribution in shallow groundwater in the western Canadian Interior Plains

Sulphate (SO4), predominantly derived from sulphur (S)-bearing glacial sediments distributed widely across the Canadian Interior Plains, contributes to high groundwater salinity and can be detrimental to riparian and dry-land ecosystems, agricultural production, and water use. While previous researchers investigated SO4 distribution and dynamics in shallow groundwater at local scales (<1500 km2), we examine SO4 occurrence in groundwater at larger scales, and to depths of ~150 m, considering variations in geology, glacial history, climate, and geochemical and hydrogeological settings in the Canadian province of Alberta. Sulphate concentrations in groundwater vary considerably, with 15 % of 139,130 samples above the 500 mg/L Canadian drinking water aesthetic objective. Analysis of δ34SSO4 and δ18OSO4 from 179 wells throughout Alberta shows SO4 is dominantly derived from oxidation of S-bearing material. At this large scale, marine shale bedrock subcrops, glacial ice flow directions, and climate control SO4 distribution. Groundwater contains less SO4 (<200 mg/L) in western Alberta compared to the east due to a lack of S-bearing bedrock, higher groundwater recharge rates, thinner glacial sediments, and increased groundwater circulation. Focusing on a region in south-central Alberta (Red Deer area), hydrogeological characteristics relating to SO4 formation, recharge, permeability, hydraulic gradient, and travel time are included in a principal component analysis to identify six groundwater groups at varying stages of evolution and SO4 concentrations depending on their hydrogeological setting. Low SO4 concentrations are associated with areas of high recharge, where SO4 has been leached from the sediments, or with more evolved bedrock groundwater where SO4 has been reduced or was recharged in pre-glacial times. High SO4 concentrations are found in areas of lower recharge and permeability, where flushing occurs more slowly. Combining the Red Deer area and province-wide analyses, we identify seven regions across Alberta with characteristic distribution and controls on SO4 occurrence in shallow groundwater.

Assessing the Arsenic Contents and Associated Risks in Groundwater of Vehari and Lodhran Districts, Pakistan

Exposure to arsenic (As) can induce numerous lethal diseases, such as cancer, cardiovascular issues, skin diseases, and diabetes in humans. The major route of human and animal exposure to As is through drinking As-rich groundwater. This study assessed As occurrence in the groundwater of two districts in the Punjab (Vehari and Lodhran) provinces of Pakistan. Groundwater analysis revealed an average As concentration of 7.7 µg/L (n = 79) in the study area, with a maximum As concentration up to 41.4 µg/L (33% of samples exceeding the WHO limit of 10 µg/L). Arsenic traces were found in animal milk (n = 15, mean: 0.79 µg/L, 17% exceeding 2.0 µg/L), human hair (n = 12, mean: 0.36 µg/g, 17% exceeding 1.0 µg/g), and human nails (n = 8, mean: 0.03 µg/g, none of the samples exceeded 1.0 µg/g). Health risk assessment indices revealed that about 33% of the hazard quotient and 54% of the cancer risk factor exceeded their thresholds. Despite the low–moderate As concentration in groundwater and the accumulation of As in a few biological samples, there is a possibility of potential As poisoning via the long-term and continuous use of groundwater for drinking. Monitoring and blanket testing of wells for As in well water can provide baseline data to minimize the threat of As-mediated arsenicosis in As-affected areas of Pakistan. Moreover, a detailed study of potential As accumulation in biological samples with a higher number of samples is recommended in the area.

Development of modified MgO/biochar composite for chemical adsorption enhancement to cleanup fluoride-contaminated groundwater

Fluoride contamination in groundwater has become a global environmental issue. Magnesium oxide (MgO) has demonstrated effectiveness as an adsorbent in treating fluoride pollution in groundwater. However, its use in powder and fine granular form often results in losses during the adsorption process, posing challenges for post-treatment recovery and potentially causing secondary environmental pollution. In this study, two novel fluoride adsorbents [rice husk (RH) and spent coffee grounds (SCG)-based magnesium oxide (MgO) biochar composites (MgO/RH and MgO/SCG)] were developed to cleanup fluoride-polluted groundwater. During the adsorbent synthesis process, RH and SCG biochar were pyrolyzed at 500 °C and modified by calcination using MgO. Both MgO/RH and MgO/SCG surfaces exhibited abundant pore structures and formed MgO crystal phases. Batch experiments results show that when the MgO/RH and MgO/SCG material dosages were 1 g/L, fluoride removal rates reached 80% and 86% respectively. The isotherms and kinetics of fluoride adsorption with MgO/RH and MgO/SCG followed the Langmuir isotherm equation and pseudo-second-order kinetic model. The maximum fluoride adsorption capacities of MgO/RH and MgO/SCG were 63.47 mg/g and 141.98 mg/g, respectively, indicating these materials used mono-layer adsorption mechanism for fluoride adsorption. The addition of MgO into the pores of porous adsorbent materials effectively increased their reactive sites and enhanced the adsorption performance of carbon materials. Particularly, SCG biochar had a richer pore structure than RH biochar, providing a larger contact surface area, facilitating the effective dispersion and doping of MgO into the pores. Therefore, MgO/SCG composite exhibited excellent fluoride adsorption properties in water, indicating the potential for developing a new type of MgO-modified SCG adsorbent material with green prospects. This composite effectively mitigated fluoride contamination, reducing the fluoride concentration in groundwater. Both RH and SCG are agricultural and food waste by-products, thus offering the opportunity to significantly reduce production, operation, and maintenance costs.

Groundwater-surface water exchanges in an alluvial plain in southern France subjected to pumping: A coupled multitracer and modeling approach

Study regionThe study was conducted in an alluvial plain between the Rhône and the Ouvèze Rivers (in the southeast of France) extensively exploited for drinking water. The research area is characterized by significant groundwater-surface interactions influenced by groundwater pumping activities. Study focusThe aim of this study is to enhance the understanding of interactions between rivers and alluvial aquifers by combined multi-tracer and numerical modeling approaches. Over an 18-month period, groundwater temperature, piezometric levels, and river surface water levels were continuously monitored. Field campaigns focused on conductivity, stable isotopes of water, and radon-222 activity concentration in both groundwater and surface water. Radon-222 was used to quantify water exchanges between the river and the aquifer. A MODFLOW model, calibrated using piezometric data and PEST, was employed to simulate groundwater flow and reactive transport of radon-222 using MT3DMS. New hydrological insights for the regionThe study reveals that river water recharges the aquifer, with radon-222 data delineating this recharge zone. The methodology extended the interpretation of periodic groundwater temperature signals to isotopic signals, allowing the identification of dispersivity and Darcy's velocity. The Ouvèze River was found to contribute approximately 55 % of the pumping water supply, alongside the Rhône. These findings provide valuable insights for sustainable water resource management, demonstrating the relevance of using natural tracers in scenarios where artificial tracers are impractical.

Hydrological processes in multi-layered aquifers of a karst watershed with coal mining activity: Insights from hydrochemistry and isotopes

Study regionThe Laochang Karst watershed (LCKW) is located in eastern Yunnan Province, southwestern China. It is the representative karst area affected by coal-mining activities in southwestern China. Study focusIdentifying hydrological processes of multi-layered aquifers in karst watersheds is challenging due to complex natural and anthropogenic processes. This study attempts to clarify the hydrological conceptual model of the LCKW using hydrochemistry and D, O, Sr, S, and C isotopes. New hydrological insights for the regionSurface water and multi-layered groundwater have the hydrochemical types of SO4-Ca·Mg, HCO3·SO4-Ca, and HCO3-Ca. Meteoric water and condensate were the major recharge sources. The main processes dominating hydrochemical compositions consist of sulfide oxidative dissolution, carbonate dissolution, positive cation exchange, and agricultural activities. Elevated SO42− concentration in the mine water, river water and shallow coalbed water mainly originated from the oxidation of pyrite in the coal-bearing strata of the Longtan Formation. whereas the deeper layers and groundwater away from the mines were hardly contaminated by SO42− due to the presence of aquiclude. HCO3− concentrations of surface water and multi-layered groundwater were mainly derived from carbonate dissolution and soil CO2, and mine water was also influenced by atmospheric CO2. Positive cation exchange contributed to increasing Na+ concentration. Agricultural activities contributed NO3−, Cl−, and K+ ions in aquifers, especially near large karst fallout caves. A hydrological model of multi-layered aquifers in the LCKW was built based on the above results. These findings will provide valuable guidance for understanding the hydrological processes of complex karst watersheds worldwide.

Distribution of Subsurface Nitrogen and Phosphorus from Different Irrigation Methods in a Maize Field

With the advancement of agricultural technology, most crop cultivation adopts water-saving techniques to improve nutrient utilization efficiency. However, limited research has been carried out on the applicability of water-saving techniques for summer maize in the Shandong Province, and it is necessary to assess the risk of nutrient loss in farmland when applying these technologies. This study investigated the distribution of nitrogen and phosphorus under different irrigation methods and planting patterns through soil and water samples. It included sprinkler irrigation (SI), drip irrigation (DI), and subsurface irrigation (SUBI). Different planting patterns, i.e., monoculture (MP) and intercropping pattern (IP), were also selected in the SI zones. The results show variations in soil nitrogen distribution within the layers between 0.9 and 4.5 m, with a pronounced trend of NO3−-N accumulating in deeper layers in the SI zone. Under SI conditions, the IP effectively reduces the nutrient accumulation around the shallow root zone while controlling the accumulation of nitrogen in deep layers. The Olsen-P accumulation in each zone would increase after the accumulation ratio decreased. Compared with MP, the depth interval of the accumulation ratio mutation was shallower in the IP. The trend of NO3−-N accumulation in deep layers is consistent with that of nitrogen concentration in groundwater. Phosphorus that is accumulated in the deep layers is not easily leached into groundwater. In conclusion, these findings can provide basic information for irrigation management in existing cropping systems.

Nitrate source analysis of underground drinking water sources in Zhangjiakou main urban area and its health risk assessment

&lt;p style="line-height:200%;text-align:justify;text-justify:inter-ideograph;"&gt;&lt;span lang="EN-US"&gt;In order to investigate the main pollution factors of underground drinking water sources in semi-arid agricultural areas in China, and to reveal the threatening influence of pollutants on the normal water security of local society. Single-factor evaluation index, principal component analysis, basic data statistics are used to clarify the main pollution indicators of underground drinking water sources in Zhangjiakou main city and discuss the main influencing factors of the change of their pollution concentration, and evaluate the degree of health threat of its pollution to the drinking water of local residents. The results show that: the water sources of Taobeiying and Gushi are deeply affected by human activities, and nitrate, as the only exceeding substance under drinking water standards, is the most important indicator of groundwater pollution; and the nitrate con-centration of groundwater is higher in the pasture and nearby agricultural activities; nitrate contamination levels in groundwater are within the health acceptability range for the vast majority of the population, with only newborns in the Taobeiying drinking water source being exposed to a non-carcinogenic risk of nitrate. The results of the study will help to maintain a stable groundwater environment.&lt;/span&gt;&lt;/p&gt;

Differences in Nitrogen Sources and Contributions in Shallow Groundwater in Plateau Lake Area with Different Climate Types

Clarifying the concentration, major sources, and contribution differences of nitrogen in shallow groundwater in plateau lake areas with different climate types can provide a novel direction for the control of nitrate （NO3-） pollution in regional groundwater. Taking the shallow groundwater around Erhai Lake in the subtropical monsoon climate zone and Chenghai Lake in the dry-hot valley area of the Jinsha River as the research objects, using hydrochemical indexes and multi-isotope techniques （δ15N-NO3-, δ18O-NO3-, δ18O-H2O, and δ2H-H2O） combined with the stable isotope （SIAR） model； the differences in nitrogen concentration in shallow groundwater around Erhai Lake and Chenghai Lake were analyzed, the sources of NO3- were identified, and the contribution rates of each pollution source were calculated. The results showed that water quality of more than 33% and 5% of shallow groundwater sampling points around Erhai Lake and Chenghai Lake was worse than the groundwater Class Ⅲ quality requirements （GB/T 14848） of 20 mg·L-1 for nitrate nitrogen （NO3--N）, respectively. The δ18O-H2O and δ2H-H2O in shallow groundwater around Erhai Lake and Chenghai Lake were parallel to the global and Chinese atmospheric precipitation lines, and a large intercept was present, indicating that atmospheric precipitation was not the major recharge source of groundwater in the two regions. The contribution rate of different NO3- sources in shallow groundwater around Erhai Lake was the highest for soil organic nitrogen （53.77%）, followed by nitrogen fertilizer （21.75%） and manure and sewage （21.55%）, and atmospheric deposition nitrogen （2.93%） was the lowest. Denitrification occurred in the transformation process of nitrogen in groundwater. The contribution rate of different NO3- sources in shallow groundwater around Chenghai Lake was manure and sewage （44.88%） &gt; soil organic nitrogen （37.03%） &gt; nitrogen fertilizer （16.17%） &gt; atmospheric deposition nitrogen （1.92%）, and nitrification occurred in the transformation process of nitrogen in groundwater. The climate type significantly affected the shallow groundwater level, altering the migration and transformation process of nitrogen, thereby affecting the nitrogen concentration in groundwater and the contribution of NO3- as the chief source. However, the major source of NO3- was not affected by the climate type； however was more affected by land use, agricultural activities, and manure treatment methods.

Chemical Spatiotemporal Characteristics and Environmental Driving Factors of Groundwater in Hetao Irrigation Area

To explore the chemical characteristics and environmental factors of groundwater in the Hetao Irrigation Area of Inner Mongolia, five irrigation fields, including UulanBuh, Jiefangzha, Yongji, Yichang, and Wulat, were selected as the research area. From 72 groundwater observation wells, a total of 216 groundwater samples were collected throughout three typical periods： the end of freeze-thaw （March）, the middle of irrigation （July）, and the end of autumn watering （November）. Comprehensive methods were utilized, such as statistical analysis, Piper three-line diagram, Gibbs diagram, ion ratio, and principal component analysis, to explore the changes in the groundwater chemical environment and the environmental driving factors of groundwater component formation. The groundwater drinking suitability was evaluated using the water quality index （WQI）, and the irrigation suitability was analyzed using the USSL and Wilcox plots. The results indicated that the groundwater in the research areas was generally saline, and the total anion and cation concentrations in each period in ascending order were as follows： late freeze-thaw stage, late autumn irrigation stage, and mid-irrigation stage, with Na+ and Cl- being the major contributing ions. The chemical type of groundwater was dominated by Cl-Na, followed by Cl·SO4-Ca·Mg and a coexistence with SO4-Ca·Mg, HCO3·Cl-Na, HCO3-Na, and HCO3-Ca·Mg. Based on WQI values, the shallow groundwater in Hetao Irrigation District was mainly classified as Class IV and Class V, and the quality was poor in general. According to the USSL diagram and Wilcox diagram, the comprehensive evaluation results showed that the salinity and sodium concentration of shallow groundwater in the irrigation area were generally high. A total of 80.6% of the water samples during the late freeze-thaw period, 76.1% during the mid-irrigation period, and 77.6% during the late autumn irrigation period lacked irrigation suitability. Two major controlling factors of groundwater chemical characteristics were present in the study area, namely, evaporation and rock weathering, and Na+ and Cl- mainly came from the dissolution and cation exchange of salt rocks. Agricultural irrigation and drought were the chief driving factors of groundwater chemical evolution in the Hetao Irrigation Area. The study provides technical support for optimizing agricultural management measures and a theoretical reference for rational utilization of groundwater resources in the Yellow River irrigation area of Inner Mongolia.

Agricultural Contribution of Chloride to a Saturated Riparian Buffer System: A Case Study in Central Illinois

ABSTRACT Increases in chloride concentrations in surface water and groundwater from anthropogenic sources is a growing concern throughout the world. In the midwestern United States, the agriculture contribution of chloride may elevate concentrations in surface and groundwater systems. A saturated riparian buffer (SRB), installed to reduce nutrient input into an adjacent stream, and the groundwater water upgradient were investigated to identify sources of chloride and to quantify the agricultural contribution. During a 7-year period, over 2,200 water samples collected from 35 wells, a diversion box, and a stream were analyzed for major anions. Additionally, the waters from four quarterly (seasonal) samplings (n = 155) during the seventh year were analyzed for cations. A cumulative probability curve identified three populations of chloride: (1) upgradient shallow groundwater; (2) diversion box (waters drained from an agricultural field), downgradient shallow groundwater (representing the SRB), diamicton groundwater (waters collected deeper from within the unweathered parent material); and (3) stream water. A background chloride concentration was established at 3.9 mg/L. Elevated concentrations above the background level coupled with principal component analysis suggest agricultural contribution from the diverted tile-drainage waters was a source of chloride. In winter and spring, chloride concentrations were highest in the diversion box, while up-gradient wells were the lowest. Waters downgradient of the diversion tiles had chloride concentrations lower than the tile but higher than the upgradient waters due to mixing of the diverted tile water and the upgradient groundwater. For the specific site, agriculture contributes chloride, but at concentrations below the chronic threshold of 230 mg/L.

Unraveling the impact of high arsenic, fluoride and microbial population in community tubewell water around coal mines in a semiarid region: Insight from health hazards, and geographic information systems

High arsenic (As), fluoride (F-), and microbial pathogens coexist in semiarid conditions afflicting > 240 million people worldwide including Pakistan. Groundwater quality has declined due to geogenic and manmade activities providing suitable ground for ubiquity, bioavailability, and toxicity of contaminants. We tested the health hazard, distribution, and apportionment of As, F-, and microbes in groundwater around coal mines in Quetta, Pakistan. The range of As, and F- concentrations in groundwater were 0.2–16.6 µg/L, 0.4–18.5 mg/L. Both, As and F- correlate with high HCO3-, pH, Na+, SO42-, Fe, and Mn, and negatively with Ca2+ water. The coalfield showed many folds higher As 15.8–28.5 µg/L, and F- 10.8–34.5 mg/L compared to groundwater-wells. Geochemical phases revealed saturation of groundwater with calcite, dolomite, fluorite, gypsum, and undersaturation with halite-mirabilite, and arsenopyrite minerals. The positive matrix factorization (PMF) model assessed five-factor solutions: geogenic, industrial, coal mining, sulfide & fluoride-bearing mineral-dissolution, and agriculture pollution delivered As, F-, and microbial contamination. About 24.6 % and 64.4 % of groundwater samples exceeded the WHO guidelines of As 10 µg/L, F- 1.5 mg/L. The carcinogenicity, and non-carcinogenicity of As, and F- were higher in children than adults. Therefore, health hazards in children are of great concern in achieving sustainable management goals.

Simulation of bench-scale CO2 injection using a coupled continuum-discrete approach

Unintended releases of CO2 from carbon capture and storage operations presents the risk of atmospheric emissions and groundwater or surface water quality impacts. Given the potential impacts, it is valuable to have tools capable of predicting groundwater concentrations and likely pathways of CO2 migration in the subsurface. Traditional multiphase flow models struggle to simulate the discontinuous flow expected at leakage sites. This work applied a coupled continuum-discrete model, ET-MIP, to simulate a bench-scale injection of CO2. Results demonstrate the capability of ET-MIP to accurately capture gas fingering behaviour, and the complexity of multicomponent mass transfer observed in the experiment. Simulations were computationally efficient, allowing for the use of multiple displacement pressure realizations. CO2 migration in the subsurface was shown to be sensitive to mass transfer, as i) increased groundwater velocity can dissolve leaked CO2 prior to reaching the surface and ii) background dissolved gases in the subsurface can impact the rate of upwards gas movement, gas distribution, and the composition and persistence of the gas phase. The sensitivity to mass transfer suggests it may be preferable to monitor for low-solubility gases in the source mixture rather than CO2. These findings are applicable to other gases in the subsurface, such as hydrogen or methane migrating from geoenergy wells.

Mobilization mechanisms and spatial distribution of arsenic in groundwater of western Bangladesh: Evaluating water quality and health risk using EWQI and Monte Carlo simulation

Arsenic (As) contamination in groundwater is emerging as a significant global concern, posing serious risks to the safety of drinking water and public health. To understand the release mechanisms, mobilization processes, spatial distribution, and probabilistic health risks of As in western Bangladesh, forty-seven samples were collected and analyzed using an atomic absorption spectrometer (AAS). The As concentrations in groundwater ranged from 1.97 to 697.4 μg L⁻1 (mean: 229.9), significantly exceeding recommended levels. The dominant hydrochemistry of As-enriched groundwater was Ca–Mg–HCO₃, with the primary sources of arsenic in groundwater being the dissolution of arsenic-bearing minerals in sediment and the recharge of aquifers from the Ganges River Basin. The assessment using the Entropy Water Quality Index revealed that the groundwater is unsuitable for drinking, with 89.36% (n = 42) of the samples surpassing the WHO's limit for arsenic. Rock-water interactions, including calcite dissolution and silicate weathering within the confined aquifer, predominantly influenced hydrochemical properties. The significant relationships among Fe, Mn, and As indicate that the reductive dissolution of FeOOH and/or MnOOH considerably contributes to the release of As from sediment into groundwater. Geochemical modeling analysis revealed that siderite and rhodochrosite precipitate into aquifer solids, suggesting a weak to moderate relationship among As, Fe, and Mn. The long residence time of groundwater, combined with the presence of a clayey aquitard, likely controls the mobilization of arsenic in the aquifer. For the first time, Monte Carlo simulations have been used in arsenic-prone areas to assess the severity of arsenic contamination in western Bangladesh. The analysis indicates that out of 100,000 people, 10 may develop cancer as a result of drinking arsenic-contaminated water, with children being more susceptible than adults.

Evaluating Groundwater Quality for Drinking and Irrigation Purposes and Health Risk Assessment in West Midnapore District of West Bengal, India

Groundwater quality in the West Midnapore district of West Bengal, India is affected by anthropogenic activities as well as by water quality of Subarnarekha and Kangsabati rivers. This study aims to assess quality of groundwater and river water for drinking and irrigation usage, and assess the health risks of the people consuming the water across the rivers. The study also explores the groundwater-river water interaction. The river water and groundwater samples were collected three times during monsoon season from 14 sites across the rivers. The samples were analyzed for 11 water quality parameters, i.e., pH, total dissolved solids (TDS), total hardness (TH), major anions and cations, and iron (Fe). The groundwater was found slightly acidic (mean pH ~ 6.71) and correlated with nitrate concentrations. Most of the water quality parameters were found within their permissible limits of drinking water. However, elevated concentrations of potassium (K), ammonium (NH4), magnesium (Mg), phosphate (PO4), sodium (Na), and Fe were detected at some places, which were likely due to use of fertilizers. Water quality index (WQI), sodium absorption ratio (SAR), and percentage Na values were computed to evaluate the groundwater quality. The mean WQI value of 37.07 showed that the majority of groundwater samples met drinking water standards. Groundwater was also found suitable for irrigation (SAR ~ 0.26 to 1.62 meq L-1 and percentage Na ~ 13.10% to 78.12%). Health risk assessments suggested minimal immediate risks, though high Na levels in certain areas raised concerns. Piper plot showed that increased calcium concentrations in groundwater were mainly due to interactions between river water and groundwater. Overall, groundwater quality did not present any harmful health hazards to the community. The findings of this study can be instrumental for groundwater managers in identifying potential areas for treating groundwater quality.