Distribution and Risk Assessment of Soil Heavy Metals in Area Surrounding Taiyuan City

Using Taiyuan City as a study area, we measured the concentrations of soil heavy metals(Cu, Zn, Ni, Cr, Pb, Cd, Hg, and As),mapped the spatial distribution of heavy metals based on Kriging interpolation, evaluated the ecological risks of heavy metals by Hankson index, and explored the relationships between soil heavy metal concentrations and pollution sources based on the pollution source investigation in Taiyuan. Results showed that:mean values of Zn, Cr, Pb, Cd and Hg were higher than the background values of Taiyuan City soils,while those of Ni, Cu and As were almost equal to their background values. According to the Hankson ecological risk assessment, the soils in the studied area were at medium risk level. Mercury and Cd were the main risk factors. The 74.1% and 30.8% of samples exceeded medium risk levels of Hg and Cd, respectively. The concentrations of Pb, Hg, Cd, Cu, Zn, Ni and Cr were high in the south part of the area, and As was high in the south and northeast areas. Chemical industries and mineral industries were two major sources of soil heavy metal pollution in Taiyuan City.