Distributions of arsenic and other heavy metals, and health risk assessments for groundwater in the Guanzhong Plain region of China

The aim of this study was to evaluate the quality of shallow groundwater and deep groundwater in the Guanzhong Plain region of China, as well as the related health risk to humans. In total, 130 groundwater samples were collected comprising 116 from shallow groundwater (dug wells) and 14 from deep groundwater (drilled wells). The water samples were analyzed to determine the levels of As and 12 other heavy metals (Al, Cd, Mn, Cr, V, Fe, Ni, Cu, Zn, Co, Pb, and Mo). The results showed that the concentrations of As and other heavy metals in the deep groundwater samples were lower than the safe limits, but the Cr concentrations in some shallow groundwater samples exceeded the safe limits. The heavy metal pollution index and heavy metal evaluation index both showed that As and other heavy metals were pollutants at low levels in all of the shallow and deep groundwater sample. Health risk assessments showed that the deep groundwater samples had no associated non-carcinogenic health risks, whereas the shallow groundwater samples had non-carcinogenic health risks due to contamination with Cr and As. Some shallow groundwater samples had associated carcinogenic health risks due to contamination with Cr and As, whereas the deep groundwater samples only had carcinogenic health risks because of contamination with Cr. These results suggest that local residents and government departments should be made aware of Cr and As pollution in shallow groundwater.