Groundwater Nitrate Contamination and Associated Health Risk for the Rural Communities in an Agricultural Area of Ningxia, Northwest China

The present study was carried out to evaluate the nitrate contamination in the shallow groundwater and to ascertain the associated health impact on the rural communities in the agricultural area of northwest China. A total of 86 groundwater samples were collected from private wells in rural areas where the groundwater is the main source of drinking water. Statistical analysis indicates that the concentrations of NO3-N in groundwater range from 0.49 to 62.20 mg/L with a mean of 12.15 +/- 12.92 mg/L. 40.7 % of groundwater samples are unfit for drinking purpose because of high nitrate concentrations that have exceeded the permissible limits recommended by the WHO and Chinese drinking water standards. Elevated NO3-N levels found in the study area may be attributed to the increased fertilizer rate, intensive irrigation, shallow groundwater depth, high permeability of soil, poor sanitation facilities, and bare infrastructures. Furthermore, non-carcinogenic risk of nitrate incurred by drinking contaminated groundwater in the area was estimated by using the USEPA human health risk assessment method. Only eight and four samples with high nitrate concentrations belong to the domains of the hazard index > 1 for infants and adults, respectively, indicating the higher health risk in these sampling sites. This study will be useful to develop effective strategies for improving rural drinking water supply and provide scientific evidence for decision and management of the groundwater.