Groundwater chemistry and groundwater quality index incorporating health risk weighting in Dingbian County, Ordos basin of northwest China

Groundwater is essential to secure the safety of water supply in the Ordos basin, China. In this study, 35 groundwater samples were collected from part of the Dingbian County, a significant part of the Ordos energy base in China, and were analyzed for 17 physicochemical parameters. The health risk was quantified through the model recommended by the United States Environmental Protection Agency (USEPA). In addition, water quality index (WQI), which is incorporated with human health risk weighting, was adopted to evaluate the overall groundwater quality. The results show that groundwater in the study area is slightly alkaline water, and the hydrochemical types of groundwater is mainly HCO3-Na, HCO3-Na center dot Mg center dot Ca and mixed SO4 center dot Cl-Na types. The noncarcinogenic health risks follow the order: NO3->F->Cr6+>As>NO2->Mn, and the carcinogenic risks is mainly contributed by Cr6+. Children face higher risks than adults, and most groundwater samples are associated with unacceptable health risks for both adults and children. WQI results show that poor quality water and very poor quality water account for 11.43 % and 17.14 % of all sampled groundwater, respectively, which are not suitable for drinking. In terms of sodium hazard, nearly half of the groundwater samples are not suitable for irrigation. The results of this study will be helpful in groundwater management and protection in this area, and the health risk weighting method can be referenced by international scholars.