Groundwater Risk Assessment Research Articles

Hydrochemical assessment of groundwater quality in the Narmada River Basin (Central India)

Abstract This study details the hydrochemical characterization and human health risk assessment of groundwater in the Narmada River Basin. The study was performed based on data collected from 305 groundwater sample stations in the Narmada River Basin. Hydrochemical evaluation illustrated that cationic ions in the upper and middle Narmada Basin were dominated by Ca2+; however, in the lower basin it was dominated by Na+ ions. Similarly, anionic ions were dominated by HCO3− throughout the basin. A Chadha plot drawn from the collected data inferred that most groundwater belonged to the recharge water category (Ca-Mg-HCO3 type). Base-exchange indices of the collected data confirmed the presence of Na+-SO42− type of groundwater. Meteoric genesis indices indicated deep meteoric percolation groundwater. Further, Gibbs plots categorized groundwater samples in the rock dominated section, while chloro-alkaline indices confirmed direct as well as reverse ion-exchange reactions governing groundwater quality. Water Quality Index values showed that groundwater ranged from excellent to very poor. Human health risk of the Narmada River confirmed the non-carcinogenic risk for Nitrate (NO3−) and Fluoride (F−) ions. However, several indices justified that groundwater was ideal for irrigation. However, groundwater treatment is recommended before direct consumption such as drinking.

Human health risk assessment and pollution index of groundwater in Jammu plains of India: A geospatial approach

To examine the drinking water suitability as well as to study the influence of local lithology in controlling groundwater chemistry a study has been carried out in the Jammu plains of India by using 50 groundwater samples during the post-monsoon (POM) and pre-monsoon (PRM) seasons. The groundwater samples are found to be dominated by Mg–Ca–HCO3, and Ca–Mg–HCO3, types. Besides this, the Pollution Index of Groundwater (PIG) was also calculated to assess the overall groundwater quality of the study area. As per the PIG, the groundwater quality of the study is suitable for domestic utilization except for a few samples (2%) which need conventional treatment in order to make the groundwater resources potable. Based on rock water interaction, there is a considerable variation in the POM and PRM seasons, which indicates the role of weathering and dissolution of rock minerals. The multivariate statistical analysis reveals that the lithogenic factors, such as rock-water interactions and weathering of carbonate-bearing rocks, are predominantly controlling groundwater chemistry. Further, trace elements such as As, Cu, Cd, Fe, Mn, and Zn were also analyzed to determine the Human Health Risk Assessment (HHRA) in order to know about the carcinogenic risk in adults and children in the study area.

A groundwater risk assessment for irrigation purpose based on salinity indicators: applied to southeastern Tunisia.

Groundwater resources are increasingly under demand to support human activities and economic development. This naturally clean resource is threatened by human and natural pollutions. Protecting groundwater has become a challenge for both urban and rural communities. This work aims to develop a simple and effective approach to assess the risk of aquifer pollution and the delineation of risk zones. To do so, an aquifer risk index (ARI) was presented as an overall indicator of the risk of groundwater pollution. The ARI is calculated using the groundwater vulnerability index (GVI) and the normalized water quality index (WQI). The multi-linear regression (MLR) model was used to assign weights to each parameter. This model has been applied and validated in the Koutine area of southern Tunisia. The results revealed that the groundwater in the study area is characterized by low and moderate risk. Fifty-six percent (56%) of the total study area presents a low risk. The remaining 44% of the study area is classified as medium risk, primarily in the Wadi and Lowland plains. ARI considers the intrinsic characteristics of the aquifer and groundwater quality when assessing the risk of pollution. The approach developed for assessing groundwater risks is simple to implement, realistic, and efficient. AVI is a parametric approach that uses aquifer data without losing information. This method can assist academics and groundwater resource managers in delineating risk areas to protect groundwater resources from pollution.

Vulnerability methods in hard rock formation as a basis for groundwater risk assessment – from resource to source

Groundwater in a hard rock formation is most endangered at places where a potential source can discharge contaminants that can reach the saturated zone of an aquifer. In these circumstances, an essential tool for groundwater protection is the contamination risk map. This map is based on the integration of two maps: a hazards map, i.e., map of potential sources of contamination and a vulnerability map. The selection of a proper vulnerability method is an important task since the resulting vulnerability map can significantly impact the final risk of contamination map. The most appropriate method for groundwater vulnerability assessment was considered in the case study of Tara National park, in Western Serbia. The four commonly used methods were applied to assess the intrinsic vulnerability maps: DRASTIC, EPIK, PI and COP. All the applied methods resulted in different vulnerability maps in assessing the degree of vulnerability, consequently influencing the groundwater contamination risk maps. The applied research presents an example of how contamination risk should be assessed in a specific area. Comparison of the results obtained for the area of Tara National Park indicates the preference of the PI method as a well-balanced method, taking into account all the specifics of the study area. A detailed analysis of the assessed risks in the catchments of the existing sources was also conducted to indicate probable sources of contamination and confirm the degree of accuracy of the created vulnerability and risk maps. The conducted research emphasizes the necessity to adopt a clear conceptual hydrogeological model and to apply several methods simultaneously to determine the optimal one for each individual area.

Potential environmental pollution and human health risk assessment due to leachate contamination of groundwater from anthropogenic impacted site

One of the consequences of landfill systems is the emission of leachate, which is capable of causing contamination of the surrounding environment, including groundwater. Considering three major abandoned landfills in an urban area in Nigeria, the potential environmental pollution due to leachate generated from landfills and human health risk assessment of nearby groundwater were examined using laboratory standards (APHA 2012). The result revealed that the landfills' leachate pollution index (LPI) is 18.84, 19.57, and 19.66, indicating potential pollution of the environment, including groundwater and soil. Conformity of groundwater indicated that Arsenic (Ar-0.0001), Cadmium (Cd-0.002), Zinc (Zn-0.02), Barium (Ba-0.03), Manganese (Mn-0.05), Copper (Cu-0.02, 0.012), Chromium (Cr-0.006, 0.007), and Cobalt (Co-0.03, 0.015) are within the WHO permissible limit while Nickel (Ni-0.06) and Lead (Pb-0.05) exceeded the permissible limit. Using the USEPA model for human health risk assessment, the Total Hazard quotient (THQ) for ingestion and derma exposure indicated that the heavy metals have ≤1 across the three landfills, indicating that the exposed population experience no significant health risk. The THQ trended as Cd>Co>Zn>Ba>Mn>Cu>Cr>Ni>As>Pb for children across all the landfills. The estimation for Total Carcinogenic Risk (TCR) for carcinogenic metals (As, Cd, Cr, Ni, and Pb) from various landfill indicated no carcinogenic risk (TCR <10−6). Although the abandoned landfills showed potential environmental pollution and contamination of groundwater; however, the health risk assessment of the groundwater revealed no significant carcinogenic risk to the population exposed to it. Hence, the need for water treatment and evaluation of the soil contamination status of landfills.

Geospatial distribution and health risk assessment of groundwater contaminated within the industrial areas: an environmental sustainability perspective.

Groundwater is the second largest water source for daily consumption, only next to surface water resources. Groundwater has been extensively investigated for its pollution level in urban areas. The groundwater quality assessments in industrial areas associated with every urban landscape are still lacking. This study was carried out in two industrial areas including Okhla and Mohan cooperative in New Delhi, India. The six groundwater samples were obtained for water quality assessment for 2015 and 2018. The heavy metals investigated in water samples were Cu, As, Pb, Mn, Ni, Zn, Fe, Cr, and Mn. The water quality was assessed in the heavy metals index (MI) and heavy metal pollution index (HPI). From indexing approach, it was observed that pollution levels have increased in year 2018 as compared to the year 2015. MI<1 for Cu in 2015 and 2018 in both industrial areas. In the case of remaining metals, MI ranged from 2.5 to 8.4. When the HPI indexing approach was adopted, water was unfit for drinking in both industrial areas in 2015 and 2018, with an HPI value>100. Non-carcinogenic risk assessment (HI) ranged from 1.7 to 1.9 in 2015, increasing from 17.41 to 217 in 2018, indicating high risk in both years. Carcinogenic risk (CR) was within the acceptable range for 48% of each heavy metal analysed sample. When the Carcinogenic risk index was considered (CRI), all samples were beyond the acceptable range, and every person was prone to carcinogenic risk in 2015.

Groundwater risk assessment of abandoned mines based on pressure-state-response—The example of an abandoned mine in southwest China

Due to the exhaustion of coal resources, resource integration, backward production capacity elimination, and other reasons, a large number of coal mines in China have been closed or are close to closing. When a mine is closed and the drainage stops, the water level of the mining area will rise rapidly, resulting in acid mine water (AMD), which carries pollutants through mining-induced fracture faults or poorly closed boreholes into groundwater or surface water, resulting in pollution and safety risks to the water environment. Therefore, it is essential to conduct environmental risk assessments of abandoned mine groundwater for mine environment governance and protection. On this basis and employing the pressure-state-response (PSR) risk evaluation system, and considering the abandoned Chuanbei mine in northern Sichuan province, China, mine water inflow, groundwater water chemistry, and the water environment pollution situation are analyzed, considering the AMD release and its environmental impact, while identifying the drivers and sources of pollution. Considering the mine drainage conditions, three first-level indices of environmental sensitivity response and 12 second-level indices of the redox state of aquifer permeability mine were determined, such as the aquifer thickness and relative location. The results show that the groundwater environmental risk in the study area is high, and the groundwater environmental risk index in the southeast is higher than that in the northwest. Heavy metals and other toxic and harmful substances carried by AMD are found to enter the surrounding waters, posing a direct threat to the health of downstream residents. These results can provide theoretical guidance for the comprehensive remediation of mine environments in this area, and also provide a reference for environmental risk assessment of other similar current mining areas.

Geogenic contaminants and groundwater quality around Lake Victoria goldfields in northwestern Tanzania

Geogenic contamination of groundwater is frequently associated with gold mining activities and related to drinking water quality problems worldwide. In Tanzania, elevated levels of trace elements (TEs) have been reported in drinking water sources within the Lake Victoria Basin, posing a serious health risk to communities. The present study aims to assess the groundwater quality with a focus on the concentration levels of geogenic contaminants in groundwater around the Lake Victoria goldfields in Geita and Mara districts. The water samples were collected from community drinking water sources and were analysed for physiochemical parameters (pH, EC, Eh), major ions, and trace elements. The analysed major ions included Na+, K+, Ca2+, Mg2+, SO42−, HCO3− and Cl− whereas the trace elements were As, Al, Li, Ba, B, Ti, V, U, Zr, Sr, Si, Mn Mo, Fe, Ni, Zn, Cr, Pb, Cd, and V. The present study revealed that the concentration levels of the major ions were mostly within the World Health Organization (WHO) drinking water standards in the following order of their relative abundance; for cations, Ca2+∼Na+>Mg2+>K+ and for anions was HCO3− > SO42− > NO3−, Cl− > PO43−. Statistical and geochemical modelling software such as ‘R Studio’, IBM SPSS, geochemical workbench, visual MINTEQ were used to understand the groundwater chemistry and evaluate its suitability for drinking purpose. The concentration of As in groundwater sources varies between below detection limit (bdl) and 300 μg/L, with highest levels in streams followed by shallow wells and boreholes. In approximately 48% of the analysed samples, As concentration exceeded the WHO drinking water guideline and Tanzania Bureau of Standards (TBS) guideline for drinking water value of 10 μg/L. The concentration of the analyzed TEs and mean values of physicochemical parameters were below the guideline limits based on WHO and TBS standards. The Canadian Council of Ministries of the Environment Water Quality Index (CCME WQI) shows that the overall water quality is acceptable with minimum threats of deviation from natural conditions. We recommend further geochemical exploration and the periodic risk assessment of groundwater in mining areas where high levels of As were recorded.

Hydrochemical characteristics and health risk assessment of groundwater in Dingbian county of the Chinese Loess Plateau, northwest China

Hydrochemical characteristics and health risk assessment of groundwater in Dingbian county of the Chinese Loess Plateau, northwest China

Integration of Heavy Metal Pollution Indices and Health Risk Assessment of Groundwater in Semi-arid Coastal Aquifers, South Africa

The heavy metal contaminated groundwater results in serious health issues and hence this study attempts to address its sources of contamination using integrated techniques including indexed and statistical methods and its related health hazards. Groundwater pH varied from 5.3 to 8.3 indicating acidic to alkaline in nature. The heavy metal pollution index shows that the groundwater samples vary from low to high pollution class and 21% of the samples exceed the critical limit of 100 implying that they are highly polluted with respect to heavy metals and are unfit for human consumption. The heavy metal evaluation index reveals that all the groundwater samples fall under low pollution. The synthetic pollution index reveals that 2%, 74% and 24% of the samples are suitable, slightly and moderately polluted, respectively, with heavy metals. The water quality index reveals that 19% and 2% of the groundwater samples belong to the poor and very poor water quality category and are spatially situated on the central, northern and southern parts of the study region. Correlation matrix and principal component analysis revealed that weathering of aquifer matrix and anthropogenic activities are accountable for the release of heavy metals into groundwater. Furthermore, R-mode and Q-mode cluster analysis revealed two clusters that are linked to mixed sources including weathering and anthropogenic activities. Based on the hazard quotient, the order of heavy metal impact is Co>Pb>Cd>Zn>As>Mn>Cu>Cr>Fe>Ni for both children and adults. The hazard index values varied from 0.06 to 8.16 for children and from 0.02 to 2.14 for adults. In this study, it is discovered that 43% and 26% of groundwater samples pose a non-carcinogenic health risk in children and adults, respectively. This study highly recommends treatment of contaminated groundwater before consumption in order to protect and maintain public health. The results from this study can be useful for the local municipalities and the policy makers while considering management and mitigation plan to maintain the water quality and to control its adverse effect on human health.

Delineating the controlling mechanisms of arsenic release into groundwater and its associated health risks in the Southern Loess Plateau, China

The mechanisms controlling arsenic (As) enrichment and mobilization associated with human health risk assessment of groundwater in the Longdong Basin, located in the southern part of the Loess Plateau, China, have been yet unexplained. This uncertainty is partly attributed to a poor understanding of groundwater arsenic management. To address this problem, this study investigated the occurrence and spatial distribution of As in unconfined groundwater (UG) and confined groundwater (CG) in the study area, integrated Self-Organizing Maps (SOM) and geochemical modeling to elucidate the mechanisms controlling As release and mobilization in groundwater, and conducted a health risk assessment of groundwater As. The results showed that 13.6% of UG samples (n = 66) and 22.4% of CG samples (n = 98) exceeded the WHO guideline limit of As (10 μg/L). The detailed hydrogeochemical studies showed that As-enrichment groundwater is dominated by Cl-Na type, and Gaillardet diagram indicated that evaporites weathering may contribute to As mobilization in CG. The SOM analysis combined with Spearman's correlation coefficient quantified the negative correlation between As and redox potential, dissolved oxygen, SO42−, NO3−, and the positive correlation between As and HCO3−, Mn in UG. In CG, As is positively correlated to pH and negatively to electrical conductivity, SO42−, Fe and Mn. The saturation indices of the mineral phases indicates an insignificant relationship between As and Fe. We conclude that under oxidizing conditions, evaporative controls and the desorption of Fe-oxides under alkaline and high salinity conditions are the dominant mechanisms controlling As release and mobilization in groundwater. In addition, exposure to groundwater As through drinking water posed potential risk of carcinogenic and non-carcinogenic effects on children and adults. This study contributes to groundwater As management and sustainable safe groundwater supply.

Intra aquifer variations in pesticide sorption during a field injection experiment

A field injection experiment was performed in an anoxic sandy aquifer over 6 days to assess sorption characteristics of 7 commonly applied pesticides in agriculture and 2 frequently detected metabolites. Pesticide use changed considerably in the last decades, and there is insufficient knowledge of the fate of currently used pesticides in aquifers. Injected water arrival was monitored at 6 depth intervals of 1 m ranging from 11.4 to 32.2 m-below surface level with varying organic carbon contents (0.057–0.91%d.w.) to examine intra-aquifer variations in sorption. Observed pesticide concentrations were fit using a non-linear least squares routine to an advection-dispersion equation, from which retardation factors (R) were obtained. Pesticide degradation did not significantly influence the simulated R during the experiment. We observed that bentazon and cycloxydim were most mobile with R < 1.1 at all depths. Desphenyl chloridazon, methyl desphenyl chloridazon, and imidacloprid were, on average, less mobile, with maximum R of 1.5. Boscalid, chloridazon, fluopyram, and flutolanil showed a larger range of R, and R > 2.0 were observed in the shallowest part of the aquifer. Largest R were observed at the top of the aquifer and decreased with depth. Koc values varied similarly, which indicates that sorption is not only influenced by sedimentary organic matter (SOM) content but also by its sorption reactivity. Obtained sorption parameters were substantially lower than reported in a widely used pesticide sorption database, which suggests that sorption parameters are influenced by methodological differences and variations in the sorption reactivity of SOM. The large intra-aquifer variations in pesticide sorption highlights that aquifer heterogeneity should be considered in groundwater risk assessments.

Evidence of coal conversion in the Majuba underground coal gasification pilot plant, South Africa

Underground coal gasification (UCG) is a coal conversion method that permits coal resources to be exploited in situ using high-temperature conversion reactions. An understanding of the chemical, mineralogical, and petrographic properties of the coal, and resultant unburned carbon, degasified coal, and ash (minerals) in the UCG gasification zone, is fundamental to determining conversion rates, gas composition, and environmental and groundwater risk assessments. This study aims to provide a mineralogical and petrographic characterization of UCG residues obtained from the Eskom Majuba UCG pilot plant site in South Africa. Samples were selected from a verification borehole (VH3) drilled at the site following the pilot trial. The Permian-age Karoo Basin Majuba Gus Seam coal is medium rank C bituminous, inertinite-rich, with variable ash content. All the coal samples extracted from the borehole show evidence of heating and conversion. The volatile matter content is very low, and the mean random vitrinite reflectance values are above 5 (%RoVmr). It is possible to use vitrinite reflectance data to estimate the probable temperatures achieved in the UCG georeactor. The UCG samples in this study were exposed to maximum temperatures of around 1300°C. There is a very slight temperature gradient through the seam, indicative of fairly even heat distribution and release of volatile gases. Cracks within the degasified coals were filled with molten glassy material. Most of the iron sulfide mineralization is the degasified coal samples was transformed to pyrrhotite. The gasified samples show lower levels of sulfur as compared to unheated coal from this seam.

Modelling the environmental fate and behavior of biocides used in façades covered with mortars and plasters and their transformation products

Façade renders containing biocides are often used on external thermal insulation composite systems (ETICS), to avoid the growth of algae, fungi, and bacteria. The aim of this study was to model the transport of four organic parent compounds (PCs), namely carbendazim (CD), diuron (DR), octylisothiazolinone (OIT), and terbutryn (TB), as well as 10 of their transformation products (TPs) within an unsaturated soil compartment (sandy or loamy/silty/clayey soil) until they reached a point of compliance (OdB). The model was developed using van Genuchten's substance transport equation and general condition assumptions with reference to a Ground Water Risk Assessment (GRA). Factors such as soil type, percolation rate, soil organic carbon sorption coefficient (KOC), and the half-life (DT50) of TPs were found to affect not only the PC and TP peak concentrations, but also the time-to-peak at the point of compliance and the time needed for the substances to leave the unsaturated soil compartment. It was found that the model delivered concentrations of PCs at the OdB are, with exception of OIT, higher than the suggested value of 0.1 μg/L, independently if it is only sandy or loamy/silty/clayey soil according to the general conditions of the GRA. However, by including an appropriate topsoil layer with an organic content of 2% the concentrations of the PCs can be reduced significantly.

An integrated approach to explore the suitability of nitrate-contaminated groundwater for drinking purposes in a semiarid region of India

The main objective of the present study is to perform risk assessment of groundwater contaminated by nitrate (NO3−) and evaluate the suitability of groundwater for domestic purposes in the Palani region of South India. Thirty groundwater samples were collected in the study area. Various groundwater quality analysis parameters such as the pH, electrical conductivity, total dissolved solids, total hardness, major cations (Ca2+, Mg2+, Na+, and K+), and major anions (Cl−, SO42−, F−, CO32−, and HCO3−) were adopted in this study to evaluate the drinking water suitability according to 2011 World Health Organization (WHO) standards. Piper and Gibbs’s diagrams for the tested groundwater indicated that, due to the influence of rock–water interactions, evaporation, and reverse ion exchange, the chemical composition of groundwater varied. According to water quality index (WQI) mapping results, 46.67% of the sample locations was identified as contaminated zones via GIS spatial analysis. Multivariate statistical analysis methods, such as principal component analysis, cluster analysis, and the Pearson correlation matrix, were applied to better understand the relationship between water quality parameters. The results demonstrated that 40% of the samples could be identified as highly affected zones in the study region due to a high nitrate concentration. The noncarcinogenic health risks among men, women, and children reached 40, 50, and 53%, respectively. The results illustrated that children and women occurred at a higher risk than did men in the study region. The major sources of contamination included discharge from households, uncovered septic tanks, leachate from waste dump sites, and excess utilization of fertilizers in the agricultural sector. Furthermore, using the nitrate health hazard integrated method with the conventional indexing approach ensures that groundwater reliability can be guaranteed, contamination can be explored, and appropriate remedial measures can be implemented.

Valuation of ecosystem damage induced by soil-groundwater pollution in an arid climate area: Framework, method and case study

Groundwater is an important source of water, even the only source in some arid areas. However, climate changing and ecosystem damage induced by pollution aggravate water resource crisis. The “polluter pays” principle is deeply rooted in efforts to manage the polluted sites, particularly in the soil-groundwater environment. Unfortunately, there is no ecosystem damage compensation mechanism generally accepted by all stakeholders. In this study, we establish an assessment framework and valuation methods for ecosystem damage induced by soil-groundwater pollution in an arid climate area based on a “pollution source → target (soil-groundwater) → receptor (humans, animals, and plants) → damages → stakeholders (human society and ecosystem)” model that is usually applied in groundwater risk assessment research. Five economic loss are included in the valuation methods: (1) human health loss, (2) emergency disposal cost, (3) direct economic loss, (4) ecological restoration cost, and (5) ecosystem services loss. We apply the framework to a case study in an arid climate area, northwest China and calculate the total economic loss from ecosystem damage in the case study at 12.6 million yuan. The largest proportion of the total loss was the ecological restoration cost (85.6%), followed by the emergency disposal cost (11.2%), and finally ecosystem services loss (3.2%). Valuation of ecosystem damage from environmental pollution is essentially a socioeconomic issue. This study supplies a new framework and methods for valuing ecosystem damage induced by pollution, and offers suggestions for environmental management to reduce the damage caused by soil-groundwater pollution to health and ecosystems.

Hydrochemical characteristics and health risk assessment of groundwater in karst areas of southwest China: A case study of Bama, Guangxi

The southwest karst area is considered to have the most vulnerable groundwater environment in China. Groundwater quality is an important factor restricting sustainable economic development. In this study, traditional water chemistry method, water quality index (WQI), and hazard index (HI) were applied to comparatively analyze the hydrochemical characteristics of groundwater and the water quality in the exposed karst region (EKR) and buried karst region (BKR) in Bama, a typical karst area in southwest China. Generally, the main water type was Ca/Mg–HCO3. Due to the predominance of dissolution of carbonate rocks in EKR and silicate rocks in BKR, higher total dissolved solids (TDS), Ca and HCO3− concentrations, and lower H2SiO3 content were detected in groundwater in EKR compared with BKR. As affected by weathering of rocks such as lead-zinc ore, the maximum concentrations of Zn and Sr were 11.23 mg/L and 13.30 mg/L, showing that mineral water resources are widely distributed in Bama. The ion ratios and isotope abundances (δD and δ18O) in groundwater samples indicated stronger evaporation and rock-water interaction in EKR than BKR. Human activities exerted a more significant influence on the water quality in EKR compared to BKR. The mean WQI value also suggested that the groundwater quality was better in BKR (9.56) than EKR (12.17). Although 95.7% of the water samples in the study area were classified as excellent based on their WQI values, 4.3% of the water samples still had significant health risks (HI > 1) due to the high Sb, Zn, As, and Sr concentrations. It is recommended to reduce anthropogenic pollution in EKR and develop a plan for clean production of mineral water industry according to local conditions, which will help the sustainable development of the local economy.

Fluoride contamination, spatial variation, and health risk assessment of groundwater using GIS: a high-density survey sampling in Weifang City, North China.

The present study, with the aid of GIS, utilizes high-density groundwater (GW) sampling data (1398 samples) to analyze the spatial variation characteristics of GW fluoride in Weifang City (WFC), and evaluate the health risks associated with drinking water routes. The concentration of fluoride in the GW of WFC is observed to be between 0.08 and 9.16mg/L, with a mean value of 0.62mg/L. The fluoride concentration of a total of 192 GW samples exceeded the limit of China's GW quality standards (1mg/L), accounting for 14.74%. The GW fluoride concentration in most areas of WFC is less than 1mg/L. However, the relatively high-value zones are mostly concentrated in the upper reaches of Wen River, the east of Shouguang, the southeast of Anqiu, the east of Qingzhou, the east of Fangzi, and the southeast and northwest of Gaomi. The hydrochemical types of GW in WFC are mostly HCO3-Ca·Mg and SO4·Cl-Ca·Mg, while GW samples with hydrochemical types HCO3-Na and SO4·Cl-Na are characterized by high fluoride content. The hydrochemical characteristics of GW in WFC are mostly dominated by rock weathering. In addition, the northern coastal plain is evidently influenced by seawater intrusion. The concentration of fluoride in GW is affected by the dissolution of fluorine-containing minerals, cation exchange, and alkaline environmental factors. The effect of GW by seawater intrusion and very high content of Na+ will decrease the fluoride content of the GW through cation exchange. Health risk assessment demonstrated that the mean values of non-carcinogenic hazard quotient (HQ) for infants, children, teenagers, and adults were 0.52, 0.35, 0.31, and 0.30, respectively. In addition, the distribution characteristics of GW fluoride in high health risk areas (HQ > 1) in WFC are further consistent with the spatial variation of GW fluoride content. Overall, the health risk distribution area of GW fluoride in WFC is decreasing in the following order: infants > children > teenagers > adults.

Health risk assessment and hydrogeochemical modelling of groundwater due to heavy metals contaminants at Basundhara coal mining region, India

ABSTRACT The enrichment of heavy metals and mixing with groundwater resources, which makes a serious threat to human health and the environment. The present study was conducted to determine the enrichment of heavy metals in groundwater, geochemical modelling, and to estimate the probable health risks (non-carcinogenic and carcinogenic) of a coal mining region, in eastern India. The relative abundance of mean heavy metal concentration was in the order of Fe > Zn > Al > Ba > Mn > Sr > Ni > Ag > Cu > Pb > V > Cr > Co > Cd, and are within the WHO standards limits for drinking water values. Groundwater shows pH values as generally acidic to alkaline in nature, while Eh values indicate an oxidising environment. Principal component analysis indicates, metal concentration in the groundwater to be mainly derived from the geogenic sources and in-situ leaching of mine overburden materials. Hydrogeochemical modelling indicates heavy metals are in supersaturation to near neutral state in the groundwater with oxide and carbonate mineral phases. Based on (HPI), and (HEI) values, the majority of groundwater samples are low to moderately contaminated. The health risk assessment model based on hazard quotient (HQ) and hazard index (HI) values show few groundwater samples as crossing the reference limit and have non-carcinogenic health risks for both children and adults. The study identifies the chemical characterisation and potential health risks due to the presence of heavy metals in the groundwater of the coal mining region.

Groundwater Risk Assessment of a Rock Cave Type Landfill with Nontraditional Solid Waste

Rock cave landfill has the characteristics of superior geological conditions and strong risk controllability. In this study, taking the first rock cave type nontraditional solid waste landfill in a uranium mine in China as an example, combined with the hydrogeological conditions and engineering characteristics of the mining area, the solute transport model of underground water in a rock cave type nontraditional solid waste landfill was constructed, and the characteristic pollutants were identified, and the pollution migration law of total chromium in the impervious barrier with damaged holes was simulated and characterized. The results show that the leakage of pollutants will affect the groundwater environment when the impervious barrier of the landfill is damaged. The pollution plume exceeding the standard is mainly concentrated in the groundwater aquifer within the landfill area, which is less likely to spread to the off‐site environment. The vertical high concentration pollution plume is primarily distributed in the landfill layer. According to the characteristics of rock cave landfills, it is suggested that hazardous solid waste should be separated from surrounding rock. The research results can provide technical guidance for groundwater environment prediction and prevention measures for the same type of project.