Hydrogeochemical characterization and geochemical modeling for the evaluation of groundwater quality and health risk assessment in the Varuna River basin,India

摘要

This study focuses on determining sig-nificant 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 dis-solved 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 HCO3＞Cl＞SO4＞NO3＞F.Piper diagram shows that Ca-Mg-HCO3 facies are predominant during both seasons.Na-normalized molar ratios of HCO3/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 andcarbonate 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 kao-linite minerals.The inverse geochemical modeling categorizes the groundwaters along the flow path from recharge area waters(Group Ⅰ:Na-HCO3-Cl),transitional area waters(Group Ⅱ:Na-Ca-HCO3),and discharge area waters(Group Ⅲ:Na-Mg-HCO3).The model demonstrates the prepotency of water-rock interactions in pre-monsoon justified by the precipitation of Chalcedony and Ca-montmoril-lonite.The mixing analysis shows that in the alluvial plains,groundwater mixing is a significant hydrogeo-chemical 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.