Determining the factors controlling the chemical composition of groundwater using geochemical methods and groundwater health assessment in the Qixing town, southwest China

Studies on groundwater quality and possible hazards to human health are important for improved groundwater utilization. This study explored the chemistry of groundwater in Qixing Town and the influencing factors. Statistical evaluation, ion correlation, Entropy-Weighted Water Quality Index (EWQI) assessment, and human health risk evaluation were conducted on data derived from 25 groundwater samples. The main groundwater chemistry types were HCO3-Na and HCO3-Ca. The results of ion and geological modeling analysis indicated that major ion concentrations were mainly determined by cation exchange. The study on the variation of heavy metal concentration in groundwater with depth shows that the heavy metal content in groundwater decreases first and then increases with the increase of depth. And the EWQI suggested that groundwater was suitable for drinking. The total carcinogenic health risks for Cr and As for both adults and children were higher than the highest permissible hazard value suggested by the United States Environmental Protection Agency (USEPA). The categorization of hazardous ingestion (HI) by the USEPA indicated a negligible non-carcinogenic hazard to human health by toxic metals. The results suggest the need to increase Cr and As contamination monitoring in shallow groundwater. This study can facilitate the rational development of groundwater resources.