Evolution origin analysis and health risk assessment of groundwater environment in a typical mining area: Insights from water-rock interaction and anthropogenic activities.

Coal mining changes groundwater environment, results in deterioration of water quality and endangering human health in the mining area. However, the comprehensive study of groundwater evolution and its potential impact in mining area is still insufficient. In this study, 95 groundwater samples were collected from 2019 to 2020 in a typical mining area of China. Ion ratio coefficients, isotopic tracing technology, Entropy-weighted water quality index (EWQI) and human health risk assessment model (HHRA) were applicated to investigate the hydrochemical variation reasons, groundwater quality and its potential health risk in the study area. Results showed that the groundwater hydrochemical types changed from HCO∙SO-Ca∙Mg type to SO-Ca∙Mg and SO∙Cl-Ca∙Mg type. Water-rock interaction, agricultural activities, manure and sewage input, precipitation and evaporation controlled the groundwater hydrochemical composition. Groundwater quality showed a trend of fluctuation with an average EWQI of 59.23, 68.92, 63.75, 58.02 and 64.92, respectively. 91.6% of the water samples was fair and acceptable for drinking. The groundwater health risk of nitrate in the study area ranged from 0.03 to 17.80. Infants had the highest health risk and nitrate concentration was the most sensitive parameter. The results will present a comprehensive research of groundwater evolution and potential impacts through a typical mining area example. Thereby offering valuable insights into the influencing factors identification, hydrochemical processes evolution, protection and utilization of groundwater in global mining areas.