Heavy metals in shallow groundwater of the urban area in Suzhou, northern Anhui Province, China

Urbanization and related human activities have brought bad effects to the environment, especially shallow groundwater systems in urban areas. In this study, sixty-three shallow groundwater samples in the urban area of Suzhou, northern Anhui Province, China were collected and analyzed for the concentrations of eight heavy metals (Fe, Mn, Zn, Cr, Cd, Cu, Pb and Ni). The results indicate that some of the heavy metals (Zn, Ni, Cr, Cd and Fe) are present below the international drinking water standards but more than half of the sources sampled do not meet the requirements for Mn, Cu and Pb. Quality assessment suggests that all of the samples have heavy metal pollution indices (HPI) lower than 100, implying that they can be used for drinking directly. However, the degrees of contamination (C_d) observed suggest that about one third of the samples are classified as heavily polluted. Heavy densities of population and traffic in the old quarter of the city are considered responsible for the pollution of the groundwater system in the city. Moreover, Cd, Pb, Ni and Mn are identified as metals affected by human activities, whereas Fe, Zn, Cu and Cr are considered to originate from the natural environment, based on the comparison of spatial distributions of HPI, C_d and heavy metal concentrations, as well as factor analysis.