Groundwater Quality Assessment Using Improved Water Quality Index (WQI) and Human Health Risk (HHR) Evaluation in a Semi-arid Region of Northwest China

Abstract

To ensure the safety of drinking water, 51 groundwater samples were collected from a semi-arid area of China and various physicochemical parameters were analyzed. Groundwater quality for drinking purposes along with the associated health risks was assessed using a water quality index (WQI) which was improved using the Criteria Importance Through Inter-criteria Correlation weighting method. The results show that the groundwater was slightly alkaline and the total dissolved solids ranged from 497.26 to 2198.82 mg/L. The ionic dominance pattern was in the order of K+ + Na+ > Ca2+ > Mg2+ > NH4+ for cations, and HCO3− > SO42+ > Cl− > NO2− > NO3− > CO32− > F− for anions, respectively. In the study region, HCO3–Na and HCO3–Ca·Mg were the dominant water types, followed by the SO4·Cl–Na type, which are mainly controlled by rock weathering, leaching, and evaporation. 94.12% of the total samples are suitable for drinking; the poor and extremely poor water for human consumption are mainly located in the center and northeast of the study area. The non-carcinogenic health risk for males ranged from 0.0002 to 38.7575, for females 0.0002 to 49.2935, and for children 0.0003 to 84.3167, respectively. The health risk for children was approximately 2.18 times and 1.71 times higher than that for males and females, indicating that children are more susceptible to water contamination. The major pollutants in the study region are nitrite, nitrate, and fluoride. Therefore, the necessary steps to be taken to clean up this highly nitrite-, nitrate-, and fluorine-contaminated groundwater and health risks in this study region.