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This study focuses on determining significant controlling factors of chemical consequences, inverse geochemical modeling, water quality, and human health risk in the Varuna River basin of India. The study interprets that according to pH, total dissolved solids, and total hardness, the maximum number of groundwater samples are alkaline, fresh, and have substantial hardness. The abundance of major ions follows a pattern: Na > Ca > Mg > K, and HCO 3  > Cl > SO 4  > NO 3  > F. Piper diagram shows that Ca-Mg-HCO 3 facies are predominant during both seasons. Na-normalized molar ratios of HCO 3 /Na, Mg/Na, and Ca/Na are 0.62, 0.95, and 1.82 (pre-monsoon) and 0.69, 0.91, and 1.71 (post-monsoon), respectively, elucidating the coupled silicate and carbonate weathering (dolomite dissolution) sources. The Na/Cl molar ratio is 5.3 (pre-monsoon) and 3.2 (post-monsoon), indicating silicate alteration as the primary process rather than halite dissolution. The chloro-alkaline indices confirm the presence of reverse ion- exchange. Geochemical modeling using PHREEQC identifies the formation of secondary kaolinite minerals. The inverse geochemical modeling categorizes the groundwaters along the flow path from recharge area waters (Group I: Na-HCO 3 -Cl), transitional area waters (Group II: Na-Ca-HCO 3 ), and discharge area waters (Group III: Na-Mg-HCO 3 ). The model demonstrates the prepotency of water-rock interactions in pre-monsoon justified by the precipitation of Chalcedony and Ca-montmorillonite. The mixing analysis shows that in the alluvial plains, groundwater mixing is a significant hydrogeochemical process that affects groundwater quality. The Entropy Water Quality Index ranks 45% (pre-monsoon) and 50% (post-monsoon) of samples as an excellent category. However, the non-carcinogenic health risk assessment shows that children are more susceptible to fluoride and nitrate contamination., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Impact of arsenic (As) contaminated groundwater on human health, through drinking and irrigation practices, is of grave-concern worldwide. This paper present the review of various sources, processes, health effects and treatment technologies available for the removal of As from arsenic contaminated water. Groundwater with high As concentration is detrimental to human health and incidents of As contamination in groundwater had been reported from different parts of the globe. More serious known As contamination problem as well as largest population at risk are found in Bangladesh, followed by West Bengal state in India along the Indo-Gangetic plains. Large scale natural As contamination of groundwater is found in two types of environment such as strongly reducing alluvial aquifers (ex. Bangladesh, India, China and Hungary) and inland basins in arid or semi-arid areas (ex. Argentina and Mexico). The provisional guideline of 10 ppb (0.0 l mg/l) has been adopted as the drinking water standard by World Health Organization (WHO). In the aquatic environment, the release, distribution and remobilization of As depend on temperature, redox potential, speciation, and interaction between liquid solution and solid phases. As predicaments in the environment is due to its mobilization under natural geogenic conditions as well as anthropogenic activities. Arsenic mineral is not present in As contaminated alluvial aquifer but As occurs adsorbed on hydrated ferric oxide (HFO) generally coat clastic grains derived from Himalayan mountains. As is released to the groundwater mainly by bio-remediated reductive dissolution of HFO with corresponding oxidation of organic matter. The development of strongly reductive dissolution of mineral oxides (Fe and Mn) at near-neutral pH may lead to desorption and ultimately release of As into the groundwater. As release through geochemical process is more important factor in alluvial aquifers causing As contamination rather than sources of arsenic. As is a toxin that dissolves in the bloodstream, rendering the victim susceptible to disease of the skin, bones, and also cancer of liver, kidney, gall bladder and the intestines. It is necessary to adopt highly successful technology to treat As contaminated water into the acceptable limit for human consumption. Universally accepted solutions are not developed/available even after the lapse of almost forty years since slow As poisoning identification in tens of millions of people especially in Bengal delta. The issue poses scientific, technical, health and societal problems even today., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The present study assesses the pollution load of the groundwater with reference to the trace elements (i.e. As, Hg, Cd, Cr, Cu, Fe, Mn, Zn, Ni, Co and Pb) and the potential health risk by its consumption for the residents of Obra, Renukoot and Anpara industrial clusters of Southern Sonbhadra, Uttar Pradesh, India. For this, 220 groundwater samples were collected during post- and premonsoon seasons in 2015. pH varied from slightly acidic to alkaline in both the seasons. Geochemical analysis of the area showed that all the three clusters are severely contaminated with Fe, Pb, Cd, Cr, As and Hg during both the seasons. High concentration of heavy metals indicates that groundwater was contaminated with natural as well as anthropogenic sources. For all the three clusters, the mean values of heavy metal pollution index were found above the critical index in both the seasons with Anpara in lead. For the majority of groundwater samples across the clusters during both the seasons, substantial non-cancer health risk was observed due to target hazard quotient values of Cr, Cd, As, Pb and Hg higher than unity. The hazard index value for children was very high compared to adults which means that children are more susceptible to health impairment in terms of non-carcinogenic health risk. Carcinogenic risk was higher for adults than children in the entire study area.

The unplanned Bhalswa landfill is located in one of the most urbanized area of Delhi, and its influence on the huge population are inevitable in the capital city of India lying in flood plain of the Yamuna River, and its alluvial lithology makes it more susceptible to contamination by leaching of pollutants. The present study highlights to assess the impact of non-engineered Bhalswa landfill site on the groundwater quality and associated potential health risk by its consumption to local residents of New Delhi, by collecting four leachate and sixty groundwater samples for pre- and post-monsoon seasons in the year 2013. The contamination potential of the leachate samples and the groundwater quality were evaluated with the help of leachate pollution index (LPI) and water quality index (WQI), respectively. The value of LPI is high in both the seasons but more in pre-monsoon (31.51) as compared to post-monsoon (29.36). The Obtained results of groundwater samples showed elevated level of Electrical conductivity (EC), major cations and anions. The EC of groundwater samples display concentration as follows: (pre-monsoon, 456–10870, average 3772; post-monsoon, 465–10450, average 3747). The groundwater samples close to the Bhalswa landfill shows very high value of EC and other chemical parameters. WQI calculated (using 17 physico-chemical parameters and WHO standards) to distinguish the areas of excellent and unsuitable for drinking purposes which will be helpful for the management of water resources. Our results showed that the concentration of majority of heavy metals exceed the WHO permissible limit except Cr and Cu which may be due to redox conditions that control the mobility of these ions in aqueous solutions. The average target hazard quotient (THQ) value of heavy metals were found in the order of Cd > Mn > Pb > Cu > Ni > Fe > Zn > Cr in both the seasons. The tube wells with more than one THQ value for Cd (100%), Mn (63%) and Pb (37%) will have potential human health risks. Hazard index (HI) shows greater than one value for all the samples and the average HI values are 10.241 for pre- and 10.402 for post-monsoon season. THQ and HI values suggest that the residents are highly susceptible to ingestion pathway. A conceptual model is used to describe the dispersal of leachate pollutants with reference to various kinds of geo-environmental features which degrades the groundwater quality. The health risk associated with metals in near future can be a serious threat for this region if this groundwater is being used for long run without proper remedial measures. [ABSTRACT FROM AUTHOR]

Fluorosis is becoming a global environmental toxicological problem and is most commonly found in water-stressed regions. In order to evaluate the geochemical mechanism of fluoride enrichment in groundwater and health implications in the Padwakodari environs of eastern part of India, a total of twenty two samples were collected and analysed for physico-chemical parameters spreading across the study area. Geologically, the area mainly comprises of phyllites, granite gneiss, mica schist and sandstone. High fluoride concentrations found mainly in the granite gneisses which are situated central to northwestern parts of the study area. The concentration of fluoride in the groundwater samples ranges from 0.3 to 11 mg/l with an average of 2 mg/l. 64% of the groundwater samples containing fluoride concentration that exceed the WHO drinking water guidelines value of 1.5 mg/l. Chronic ingestion of high doses has been linked to the development of dental fluorosis, and in extreme cases, skeletal fluorosis. The dominant geochemical facies present in water are Na–Ca–Mg–HCO 3 (11 samples), Na–Mg–Ca–HCO 3 (5 samples), Ca–Na–Mg–HCO 3 (5 samples) and Ca–Mg–Na–HCO 3 (1 sample). Sodium and bicarbonate ions being major component in majority of the water types (located mostly in the granite gneiss formation) has a tendency to increase fluoride concentration in groundwater by dissolving the fluoride from fluoride bearing minerals. The oversaturation of half of the samples with respect to calcite and majority of samples undersaturation with respect to fluorite makes it feasible for fluoride to get released in to the groundwater. Decreasing Ca activity downgradient (recharge to discharge) leads to a dominance of fluorite-unsaturated conditions and consequently to mobilization of fluoride in groundwater. The results indicate that the fluoride concentration in groundwater is mainly governed by high weathering of fluoride bearing minerals (i.e. apatite and biotite) in granite gneiss contains abundant fluoride, alkaline hydrogeological environment, high temperature, low rainfall, evapotranspiration and ion exchange. [ABSTRACT FROM AUTHOR]