Evaluation of groundwater quality and health risks from contamination in the north edge of the Loess Plateau, Yulin City, Northwest China

Groundwater is a vital source for domestic and irrigation purposes in the loess area of Northwest China where climate is arid. However, the quality of groundwater in this area is deteriorating due to intensive industrial and agricultural activities, and this has a great adverse impact on human health. In order to better understand the pollution status of groundwater and the health risks to local residents, comprehensive water quality index was applied to assess the quality of drinking water in Yulin City, Northwest China, and sodium adsorption ratio, sodium percentage, residual sodium carbonate and permeability index were used to evaluate the quality of irrigation water. Moreover, the health risks caused by ingestion of groundwater were evaluated using the model proposed by the Ministry of Environmental Protection of the PR China. The results show that all groundwater samples for irrigation will not induce soil salinization, but more than half of them are not suitable for drinking, and Fe, Mn, TH, Mg2+ and NO3-N are the common contaminants which are mainly from natural processes, industrial and agricultural activities. The health risk assessment indicates that children face greater non-carcinogenic risk than adults. The order of contribution of contaminants to non-carcinogenic risk is NO3- > As > F- > Fe > Mn > Ba2+ > Cr6+ > Zn > NO2-. The average carcinogenic risk of carcinogens (Cr6+ and As) is 1.17 x 10(-4) and 1.37 x 10(-4) for adults and children, respectively, which surpasses the permissible level (1 x 10(-6)) stipulated by the Ministry of Environmental Protection of the PR China. Hence, effective measures are highly demanded to manage groundwater pollution and reduce the risks to human health.