Assessment of Groundwater Quality and Human Health Risk in the Aeolian-Sand Area of Yulin City, Northwest China

Abstract

Groundwater is an important source of drinking water in arid areas and groundwater quality can affect human health. In the present study, 42 groundwater samples were collected from the aeolian-sand area of Yulin City, Northwest China, to better understand the groundwater quality for drinking purpose. The water quality index (WQI) was employed to evaluate the groundwater quality, and the associated human health risk was assessed using the assessment models proposed by USEPA for infants, children, and adults. The results showed that the groundwater was slightly alkaline, soft, and fresh water in the study area. The main anion and cation were Ca2+ and HCO3−, respectively, and the main processes controlling the groundwater quality were the dissolution of silicate minerals and cation exchange. NO3− concentration ranged from 0.50 to 98.00 mg/L, with a mean value of 19.13 mg/L. Among the 42 samples, 15 groundwater samples had high NO3− concentration exceeding the acceptable limit (20 mg/L) prescribed by the standard for groundwater quality of China for drinking purpose. In addition, WQI ranged from 5.5 to 132.5, indicating significant variation in water quality in the study area. Most of the groundwater samples (90.5%) were in the categories of excellent to good water for drinking purpose. Moreover, the non-carcinogenic risk of Hazard Quotient (NCHQ) for infants, children, and adults ranged from 0.0136 to 2.6630, 0.0130 to 2.5548, and from 0.0125 to 2.4500, respectively. The order of the NCHQ was infants > children > adults. The areas with high WQI and NCHQ were situated in the agricultural region, where the groundwater was polluted by nitrate due to excessive use of nitrogen fertilizers and large amount of untreated excreta of animals. These results would be helpful to establish reasonable management strategies for sustainable groundwater quality protection.