Appraising Groundwater Quality and Health Risks from Contamination in a Semiarid Region of Northwest China

This study assessed groundwater quality in a semiarid region of northwest China impacted by industrial and agricultural activities. The goal was to assess the quality of the water for drinking and irrigation, and the groundwater's effect on human health. Thirty-one groundwater samples were collected from monitoring and hand pumping wells. These wells were distributed over 54 km(2), with an average of 5.7 wells per 10 square kilometers. The samples were analyzed for pH, total dissolved solids (TDS), total hardness (TH), fluoride (F-), nitrate (NO3-N), nitrite (NO2-N), ammonia nitrogen (NH4-N), major ions (Na+, K+, Ca2+, Mg2+, HCO3 (-), SO4 (2-), Cl-), and heavy metals (Cu, Mn, Zn, As and Cr6+). Groundwater chemistry was described using statistical analysis, and Piper and Gibbs diagrams. An entropy-based matter element extension analysis was performed to quantify the overall groundwater quality. The sodium adsorption ratio, residual sodium carbonate, and soluble sodium percentage were used to assess irrigation water quality. Considering resident age, sex, and exposure pathways, the non-carcinogenic and carcinogenic health risks were estimated using the models recommended by the Ministry of Environmental Protection of China. Study area groundwater was found to be slightly alkaline. For cations, Na+ was most abundant followed by Ca2+, then Mg2+, and then K+. For anions, HCO3 (-) were more abundant than SO4 (2-) and Cl-. Gibbs diagrams indicate that groundwater evaporation influences the development of sulfate-type groundwater, compared to the other groundwater types (bicarbonate and non-dominant types). The groundwater in most parts of the study area is of fair quality, and is marginally acceptable for multiple uses. TDS, TH, NH4-N, NO3-N, and Mn are common contaminants in the alluvial plain. These contaminants originate mainly from industrial and agricultural activities, as well as natural processes. Land irrigated with the groundwater is not exposed to a sodium hazard. However, measures are needed to manage the salinity hazard. The health risk assessment suggests that females and children face higher non-carcinogenic risk than males. The contribution of the contaminants to non-carcinogenic risk is in the following order: NO3 (-)> F-> As > Mn > NO2 (-)> Cr > NH4 (+)> Cu > Zn. Cr contributes more than As to the carcinogenic risk.