Spatio-Temporal Pattern of Groundwater Nitrate-Nitrogen and Its Potential Human Health Risk in a Severe Water Shortage Region

Groundwater nitrate-nitrogen (GNN) has been one of the most widespread pollutants. However, there is still a poor understanding of GNN pollution and its potential effects on human health. In this study, GNN in Taiyuan, a region of severe water scarcity in northern China, was tracked from 2016 to 2020; the spatio-temporal distribution characteristics of GNN were demonstrated and the potential human health risks to infants, children, and adults were assessed. The results showed that the concentration of GNN varied from 0.1 to 43.3 mg L−1; the highest mean concentration was observed in 2016 and the lowest value appeared in 2020. GNN concentration declined over time, which was closely related to the proactive environmental policies of Tiyuan city. GNN levels were considerably greater in urban areas than in rural areas (p < 0.001), and the forest had a very low level of GNN, which was significantly different from the grassland, farmland, and construction land (p < 0.001). According to the hazard quotient, the impacts of GNN on human health revealed age specificity, namely in the order of infants > children > adults. It was concluded that the interception effect of the forest could effectively alleviate groundwater pollution pressures, and more forest land is necessary for human health risk prevention in the severe water shortage areas to alleviate GNN pollution.