Potential ecological risk assessment of soil heavy metals in Hunchun basin, Northeast China

In order to evaluate soil heavy metal (As, Hg, Cu, Pb, Zn, Cr, Ni, and Cd) pollution in Hunchun basin more accurately, 310 soil samples were collected. Heavy metal pollution was assessed by the Nemerow complex pollution index (INmw), geo-accumulation index (Igeo), and potential ecological risk index (RI). Multivariate statistical methods such as hierarchical cluster analysis and principal component analysis were used for heavy metal source analysis. Results showed that the INmw across all soil samples was relatively small and was not significantly contaminated. The mean Igeo of Hg in soil samples was higher than other elements. The proportion of samples with Hg content exceeding the Chinese national standard for total samples was 32.43%. The RIs of soil samples were low in all districts of the study area, apart from Machuanzi Township. The results of multivariate statistical analysis showed that Cd, Zn, and Cu were affected by coal mining, coal gangue stacking, transportation, and the action of chemical fertilizers and pesticides in Cr and Ni farmland. Pb, As, and Hg had been subjected to atmospheric deposition such as coal combustion and automobile exhaust.