Spatial analysis, source identification and risk assessment of heavy metals in a coal mining area in Henan, Central China

The purpose of this study is to investigate the heavy metal (HM) concentration of the gangue and HM pollution of the soil in a coal mining area. On the basis of determination of the concentrations of cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn) and chromium (Cr) in the samples from the gangue and surface soils, the spatial distribution of toxic metals, contamination sources, potential ecological risks, potential health risks were studied. The content of Cd, Pb, Cu and Zn in the surface soils exceeded China National Standard (CNS, GB15618-1995). The spatial distributions of Cd, Pb, Cu and Zn are similar, exhibiting a declining trend from the gangue dump to the surrounding farmland. Results of Pearson correlation matrix and principal component analysis indicate that the origin of Cd, Pb, Cu and Zn elements is the gangue dump. The potential ecological risk index ranges from 97.2 to 619.5, and its spatial distribution is similar to those of Cd, Pb, Cu and Zn. Our results indicate that the HMs exceeded the corresponding CNS and posed noticeable ecological risks, which suggest that monitor and remediation measures should be taken in order to protect the health of the residents and the safety of the crops.