Co-occurrence of arsenic and fluoride in groundwater of Guide basin in China: Genesis, mobility and enrichment mechanism.

Endemic arsenic poisoning and fluorosis caused by primary high arsenic (As) and high fluoride (F-) groundwater have become one of the most serious environmental geological problems faced by the international society. High As and high F- groundwater exists in Neogene confined aquifers in Guide basin, with concentrations of 355 µg/L and 5.67 mg/L, respectively, and showing a co-occurrence phenomenon of As and F- in the groundwater. This poses a double threat to the health of tens of thousands of local residents. In this study, based on the systematic collection of groundwater and borehole sediment samples, analysis of hydrochemistry and isotope indexes, combined with laboratory tests, purpose of this study is to reveal the migration rule and co-enrichment mechanism of As and F- in aquifers, and finally establish a hydrogeochemical conceptual model of the enrichment process of As and F-. The main conclusions are as follows: hydrochemical type of unconfined and confined groundwater in Guide basin is Ca-Na-HCO3 and Na-Cl-HCO3 type, respectively. Main minerals in sediments are quartz and plagioclase. Concentrations of As and F- are lower in unconfined groundwater, but higher in confined groundwater, and which show a gradual increasing trend along the groundwater flow path. The mineralization of natural organic matter in confined aquifer causes iron and manganese oxide minerals containing As to dissolve gradually, which leads to the gradual release of As into groundwater. Large amount of HCO3- produced by mineralization of organic matter precipitate with Ca2+ in groundwater, resulting in reduction of Ca2+ content, promoting the dissolution of fluoride-containing minerals such as fluorite (CaF2), and continuously releasing F- into groundwater. Meanwhile, competitive adsorption reactions in confined aquifers causes more As and F- to be released from mineral surface into groundwater, which gradually migrate and accumulate along groundwater flow. Finally, it is established that a conceptual model for the formation of high As and F- groundwater in the confined aquifer of Guide basin. The research results not only help to improve our understanding of the formation and evolution of groundwater with high As and F- with similar geological background, but also provide scientific basis for rational development and utilization of groundwater, and prevention and control of chronic As and F- poisoning in local and similar areas.

Evaluation of non-carcinogenic causing health risks (NCHR) associated with exposure of fluoride and nitrate contaminated groundwater from a semi-arid region of south India.

Groundwater is the foremost resource for drinking water supply in arid and semi-arid regions of the world, and also intake of contaminated drinking water is the major source for creating a several health risk for humans. To estimate the groundwater suitability for drinking and also to measure the non-carcinogenic health risk for infants, children, and adults, a total of 35 groundwater samples were collected from the semi-arid region of India and analyzed major ions including fluoride and nitrate. The results revealed that the concentration of fluoride ranges from 0.6 to 3.6 mg/L and is about 2.4 times higher than the maximum allowable limit of 1.5 mg/L for drinking water purposes. And nitrate contents varied from 17 to 120 mg/L in which 54.29% of the groundwater samples exceeded the recommended limit of 50 mg/L. The estimated individual non-carcinogenic health risk (INCHR) frequency is evidently displayed that intake of higher concentration of nitrate creates the greater detrimental health effects than fluoride. The contribution of individual non-carcinogenic health risk (INCHR) of nitrate is greater detrimental health effects than the fluoride. The results of total non-carcinogenic health risk (TNCHR) reflect the infants and also children were found to be more susceptible towards fluoride and nitrate-associated health risks in the investigated region. Fluoride-bearing minerals and different anthropogenic sources such as septic tank leakages, nitrogen fertilizers, domestic, agricultural, and animal wastes played a vital role in groundwater pollution and thereby non-carcinogenic human health risks. Therefore, a proper sustainable future plan is most important to mitigate the fluoride and nitrate contamination in the groundwater of the study region.

Application of the Entropy Weighted Water Quality Index (EWQI) and the Pollution Index of Groundwater (PIG) to Assess Groundwater Quality for Drinking Purposes: A Case Study in a Rural Area of Telangana State, India.

In this study, the quality of groundwater was assessed in a semi-arid region of India by using an entropy weighted water quality index (EWQI) and a pollution index of groundwater (PIG). The EWQI and PIG methods were used to evaluate data on physicochemical parameters in relation to drinking water quality standards. Groundwater samples were collected from the Dubbak region, Telangana state, India, and were analyzed for pH, total hardness, electrical conductivity, total dissolved solids, bicarbonate (HCO3-), chloride (Cl-), sulfate (SO42-), nitrate (NO3-), fluoride (F-), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), and potassium (K+). The groundwater of the study region is alkaline in nature. The abundance of cations and anions based on their mean values is in the following order: Na+ > Ca2+ > Mg2+ > K+ and Cl- > HCO3- > NO3- > SO42- > F-, respectively. The calculated EWQI values ranged from 49.0 to 174.6, with an average of 93.3. Overall, EWQI data showed that only 60% of groundwater samples were of suitable quality for drinking, although only marginally, whereas the remaining 40% of samples were unsuitable for drinking purposes and would therefore require treatment. The values of PIG varied from 0.5 to 1.8, with an average of 1.0, which showed that only 63% of groundwater samples from the study area were suitable for drinking purposes.

Groundwater chemistry, distribution and potential health risk appraisal of nitrate enriched groundwater: A case study from the semi-urban region of South India.

In recent years, an elevated concentration of nitrate in groundwater has been a growing problem on a global scale. It directly shows the adverse effects on human health via various intake pathways. Herein, the aim of the present study was to evaluate the nitrate concentration in groundwater and its associated human health risk in various age groups (females, males and children) in the investigated region. For this purposes, thirty groundwater samples were collected and analyzed physico-chemical parameters including nitrate concentration. The results showed that, the concentration of nitrate ranges from 14 to 82 mg/L and about 43.3% of these groundwater samples beyond the safe level of 45 mg/L according to Indian guidelines. The higher nitrate contamination is observed in the vicinity of Sarvepalli and Timmapur villages where groundwater chemistry is majorly influenced by anthropogenic sources. Health risks were assessed through oral/ingestion and dermal contact exposure routes for females, males and children population in the study region. Oral exposure was much higher than dermal contacts. For the non-carcinogenic risk, the HITotal values of groundwater in the investigated region varied from 0.313 to 1.976 (mean of 0.941) for males, 0.370 to 2.336 (mean of 1.112) for females and 0.443 to 2.694 (mean of 1.314) for children. The health risk assessment for nitrate divulged that 60%, 57% and 50% of groundwater samples pose a non-carcinogenic health risk for children, females and males, respectively.

Geospatial Distribution and Potential Noncarcinogenic Health Risk Assessment of Nitrate Contaminated Groundwater in Southern India: A Case Study.

Groundwater nitrate pollution is a serious threat to human health in many regions of the world. The present study was performed to assess the nitrate contamination in groundwater in the region of Nirmal province, South India, where people purely depend on groundwater for drinking purposes. The associated human health risks for different age groups (male, female, and children) also were evaluated based on the United States Environmental Protection Agency model. Results indicate that nitrate concentration in groundwater is in the range of 0.8-130 mg/L with a mean of 36.51 mg/L. Furthermore, 26.47% of groundwater samples exceeded the WHO drinking water guidelines for NO3- in the study region. The contribution of oral ingestion is very higher than the dermal contact in the total hazard quotient or noncarcinogenic health risk. The total hazard quotient values ranged from 0.02 to 3.13 for adult males, 0.02 to 3.70 for adult females, and 0.03 to 4.32 for children. The health risk assessment highlights that children are more exposed to the noncarcinogenic health risks of nitrate than adult females and males in the study region. Therefore, specific groundwater quality measures should be formulated to address the health risk problems for children in the study region.

Groundwater chemistry integrating the pollution index of groundwater and evaluation of potential human health risk: A case study from hard rock terrain of south India.

Groundwater is an important resource for drinking and irrigation purposes and also the significant route of human exposure in most of the arid and semi-arid regions of the world. In view of this, 43 groundwater samples were collected and analyzed for various physico-chemical parameters. Particularly, this study integrates the groundwater contamination by comparing it to national guidelines and the impact of fluoride and nitrate on health risk were quantified through the model recommended by the United States Environmental Protection Agency (USEPA). The groundwater of the investigated region is slightly alkaline in nature with hydrochemical facies of groundwater is predominantly characterized by Ca2+-Mg2+-HCO3- and Ca2+-Mg2+-Cl- water types. The results show that the concentrations of groundwater nitrate and fluoride range from 2.2 to 165 mg/L and 0.84 to 4.3 mg/L, and 55.81% and 65% of groundwater exceed the national guidelines for drinking purposes, respectively. The pollution index of the groundwater (PIG) method unveiled that low quality and moderate quality of water account for 40% and 4.65% of collected groundwater samples, respectively. The results of non-carcinogenic health risk ranged from 0.63 to 5.31 ± 2.59 for adults, 0.85 to 7.18 ± 3.50 for children and 0.98 to 8.29 ± 4.04 for infants, indicating health risk was higher in infants and children as compared to the adults in the study region.

Potentially toxic elements (PTEs) pollution in surface soils in a typical urban region of south India: An application of health risk assessment and distribution pattern.

The pollution level of potentially toxic elements (PTEs) in surface soils is detrimental to the ecosystem and human health. In this research, various indices such as an index of geo-accumulation (Igeo), contamination factor (CF), degree of contamination (DC), and principal component analysis (PCA) were implemented to identify and evaluate the soil PTEs pollution; and then human health risk assessment model used to establish the link between heavy metals pollution and human health in the urban region of south India. Results exhibited that the mean concentration of Cr, Cu, Ni and Zn were found to be 1.45-6.03 times greater than the geochemical background values. Cr and Cu were the most profuse PTEs measured in the soils. The pollution indices suggest that soil of the study region is mainly moderate to highly polluted. The non-carcinogenic health risk assessment proposed by the United States Environmental Protection Agency (USEPA) suggested the mean hazard indices (HIs) were below one which denotes no significant of non-carcinogenic risks to both children and adults. Furthermore, carcinogenic risk assessment results advised ~80% of cancer risk was caused by Cr contents, while other heavy metals indicate that neither children nor adults in the study region were of carcinogenic risks.

Spatial characteristics of heavy metal contamination and potential human health risk assessment of urban soils: A case study from an urban region of South India.

Due to the rapid development of urbanization, the contamination of heavy metals in urban soils has become one of the major concerns of environmental and risk to humans. The main objective was to determine the contamination of six heavy metals in 25 urban soils and also to evaluate the associated health risk via diverse indices for adults and children. The mean concentration of Pb (47.48 mg/kg), Cr (43.24 mg/kg), Cu (40.64 mg/kg), Zn (34.68 mg/kg), Co (16.54 mg/kg), and Ni (7.55 mg/kg) exceeded the geochemical background values. Pb and Zn were closely attributed to traffic sources. Geo-accumulation index (Igeo) showed that Pb and Co in the soils were at the moderately pollution level, while 4% of soil samples were moderately polluted to heavily pollution levels by Cu. Enrichment factor (EF) showed that soils presented minor to severe anthropogenic pollution levels in the investigated region. The heavy metals to the non-carcinogenic risk of humans in the investigated region are absolutely from Cr and Pb, while the carcinogenic risk is controlled by Cr, and the remaining metals pose no possible risk to the local people. Specially, children had larger health risks in terms of non-carcinogenic risks than adults which may be related to their behavioral and physiological characteristics.

Heavy metals contamination in urban surface soils of Medak province, India, and its risk assessment and spatial distribution.

The main purpose of the current study is to assess the contamination status, human health risk, and spatial distribution of heavy metals in the urban soils from the Medak province in India. For this purposes, a total of 40 urban surface soil samples were collected and analyzed seven heavy metals including chromium (Cr), copper (Cu), cadmium (Cd), arsenic (As), nickel (Ni), lead (Pb), and zinc (Zn). The results of the study showed that the concentration of Cr (81-751 mg/kg), Cu (2-180 mg/kg), Zn (25-108 mg/kg), Pb (5-77 mg/kg), Ni (1-50 mg/kg), As (0.4-14 mg/kg), and Cd (0.1-4.2 mg/kg), respectively, was found above their natural background values. The geo-accumulation index analysis indicated that except Zn, all other tested heavy metals had a range of moderately to heavily polluted/contaminated in the study region. Spatial distribution pattern analysis inferred that the soil heavy metal (Cu, Cr, Zn, and Ni) pollutions in western regions of Medak were relatively larger than that in central and eastern regions. The hazard index (HI) values for Cu, Cd, Zn, As, Pb, and Ni were below 1, implying that there is no non-carcinogenic risks exposure from these heavy metals in soil for children and adults in the study region. However, HI value for Cr ranged from 3.08E-01 to 2.86E+00 for children, implying that children were relatively vulnerable population than adults in the current study region. Comparatively speaking, 67.5% and 100% total carcinogenic risks for Cr values for adults and children were larger than the acceptable threshold value of 1.0E-04, indicating chromium poses the greatest carcinogenic risk in the study region.

Heavy metals pollution assessment and its associated human health risk evaluation of urban soils from Indian cities: a review.

Urban soils of 32 Indian cities were collected from literature-based data for the period of 2001-2019 to measure the contamination levels of six heavy metals including arsenic (As), chromium (Cr), copper (Cu), zinc (Zn), nickel (Ni), and lead (Pb) and also evaluated the potential human health risk for adults and children. The results indicated that concentrations of six heavy metals in the urban soils were much higher than both geochemical background values (Grade-I) and also Canadian soil quality guideline values (Grade-II) in most of the cities in India. Higher concentration of Cr and Ni was in cities mainly located in southern (Karnataka), northern (Uttar Pradesh), and eastern (Odisha); As and Pb primarily in central (Telangana), while Zn and Cu largely in western (Maharashtra) and eastern (Jharkhand) states of India, respectively. The index of geo-accumulation (Igeo) values varied largely and showed moderately polluted to extremely polluted levels, possibly caused/influenced by anthropogenic activity in the urban regions in India. The non-carcinogenic health risk due to Cu, Zn, Ni, and Pb in most urban regions was lower than the threshold value (HI < 1), indicating no non-carcinogenic health risk for adults and children. As and Cr on children, non-carcinogenic risk was very higher than that of adults, and their risk values were also exceeded the threshold value, indicating that As and Cr in the urban soils posed considerable non-carcinogenic health risks on urban residents. The total carcinogenic/cancer risk due to Pb in most urban regions was lower than the recommended limit of 1.00E-04, while Cr and As have shown potential cancer risk for both adults and children. Therefore, As and Cr are the sole heavy metals that cause potential health risk in an urban region residents in India, which needs to be paid more attention and also controlling measures should be initiated.

Controlling factors and mechanism of groundwater quality variation in semiarid region of South India: an approach of water quality index (WQI) and health risk assessment (HRA).

The study region comprises fractured granitic, basaltic and lateritic aquifer system constituted by Precambrian rocks. Groundwater is the primary source for drinking and household needs. Its quality is a big issue in the three aquifers, which are mostly of human health concern. Many developing regions suffer from lack of safe drinking water, thereby health problems arise in many parts of the regions, and Telangana state is one of them. For this reason, 194 groundwater samples were collected and analyzed for fluoride, nitrate, chloride and other physicochemical parameters. The concentrations of fluoride (F-), nitrate (NO3-), magnesium (Mg2+), total dissolved solids and total hardness are above the acceptable limits for drinking purposes, prescribed by the World Health Organization. The higher concentrations of fluoride and nitrate in drinking water cause health hazards, and above 50% of the groundwater samples are not suitable for drinking purposes with respect to fluoride and nitrate. Weathering of rocks and dissolution of fluoride-bearing minerals can be a cause for higher fluoride concentrations, while anthropogenic sources are one of the major reasons for higher nitrate concentrations in the study area. Groundwater suitability for irrigation suggests that more than 90% of the groundwater sampling locations are suitable for irrigation. In addition, health risk assessments were evaluated by using the United States Environmental Protection Agency model, to determine the non-carcinogenic risk of fluoride and nitrate in drinking water for adults (females and males) and children. The ranges of hazard index in all sampling locations are varied from 0.133 to 8.870 for males, 0.146 to 10.293 for females and 0.419 to 29.487 for children, respectively. The health risk assessment results indicated that children were more exposed to health risk, due to the intake of high contaminated drinking water with respective of nitrate and fluoride in the study region.

Assessment of heavy metal (HM) contamination in agricultural soil lands in northern Telangana, India: an approach of spatial distribution and multivariate statistical analysis.

The contamination of heavy metals (HMs) in agricultural soil lands has attracted the environmental world due to their abundance, persistence, and toxicity. A study has been conducted to evaluate the degree of HM contamination in the agricultural soils of northern Telangana, using geo-accumulation index (Igeo), pollution index (PI), pollution load index (PLI), enrichment factor (EF), statistical analysis, and also spatial distribution. In this study, a total of 15 surface agricultural soil samples were collected and analyzed for the concentration of HMs including Cr, Cu, Co, Ba, V, As, Ni, Pb, and Zn. Their average values vary from 3.5 to 778, which show the increasing order of their abundance: As < Ni < Pb < Co < Cu < Zn < Cr < V < Ba. The concentrations of Ba, V, Zn, and Cu are significantly higher than their guideline values, while Co, Ni, Pb, Zn, and As are within prescribed limits proposed by Canadian soil quality guidelines. The highest Igeo (1.04) indicated the extreme degree of contamination due to Cu. The estimated PI and PLI specified the low to moderate soil pollution, whereas EF showed the moderate soil pollution due to Cr, Co, V, Zn, and As. According to principal component analysis with eigenvalue, more than one account for 53.020% of the total variance, indicating the major source of anthropogenic activity. Spatial distribution maps of HMs displayed four highly polluted zones found in the agricultural sites such as Oni, Yamcha, Bederelli, and Mudhol, in northern Telangana.

Groundwater quality evaluation using water quality index (WQI) for drinking purposes and human health risk (HHR) assessment in an agricultural region of Nanganur, south India.

An effort has been made to understand the groundwater quality of Nanganur region for drinking purpose utilizing water quality index (WQI). Nitrate contamination in groundwater was assessed and the associated health risks to rural populations were estimated for different age groups, infants, children and adults in the agricultural region of Nanganur, South India, where residents rely on only groundwater for drinking use. Groundwater was slightly alkaline and moderately hard. The concentration of nitrate in the groundwater ranged from 25 to 198 mg/L, with a mean of 66.14 mg/L, and 61% of groundwater samples exceeded the World Health Organization (WHO) safe limit of 50 mg/L. The WQI values ranged from 92 to 295, with an average of 153, and about 86% of groundwater samples were poor quality for drinking uses. Results showed that the non-carcinogenic health risk for adults ranged from 6.0E-01 to 4.8E+00, for children 8.1E-01 to 6.4E+00, and for infants 9.4E-01 to 7.4E+00, respectively. Health risk caused by excessive intake of nitrate contaminated groundwater for children and infants were 1.15 and 1.75 times larger than that for adults, which suggested that health risk degree of infants have greater health risk than children and adults in the study region. The order of nitrate contribution to non-carcinogenic health risk among the studied age groups was infants > children > adults. Therefore, health risk reduction measures should be implemented to reduce exposure to nitrate contaminated drinking water in the study region.