Abstract

According to the total amount and morphological results of heavy metals (Cd²⁺, Cr³⁺, Cu²⁺, Pb²⁺, Zn²⁺) in cropland in Tianyuan Township, Wuxi County, Nemerow index, potential ecological risk index and geo-accumulation index method were utilized to assess the potential risks of heavy metals in soil. The consequences made clear that the average content of 5 heavy metals in the agricultural topsoil of Tianyuan Township, Wuxi County was: Zn²⁺ (85.92 mg/kg)>Cr³⁺ (73.00 mg/kg)>Pb²⁺ (31.17 mg/kg)>Cu²⁺ (31.16 mg/kg)>Cd²⁺ (1.61 mg/kg); Cr³⁺, Cu²⁺ and Zn²⁺ were mainly residuals, the average proportion was 91.61%, 84.48% and 72.30%, respectively. Pb²⁺ was mainly Fe/Mn oxide bound (38.24%) and residuals (49.22%), and Cd²⁺ was mainly exchangeable (22.25%) and Fe/Mn oxide bound (47.57%). Nemerow index, potential ecological risk index method and geo-accumulation index method all indicated that Cd²⁺ pollution was relatively serious, and Cr₃₊, Cu²⁺, Pb²⁺ and Zn²⁺ were all in a relatively clean state. Correlation analysis and principal component analysis showed that Cr³⁺ was mainly affected by natural factor soil parent material. Human pollution mainly had an effect upon Cd²⁺, Pb²⁺ and Zn²⁺, including traffic emissions and agricultural activities, and Cu²⁺ was jointly affected by two factors.