Heavy Metal Contamination in Paddy Soils around a Pb-Zn Mining and Smelting Area and Its Relation with Soil Physicochemical Properties
- SUN Rui,SHU Fan,SUN Weiling,HAO Wei,LI Li
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The heavy metal (Pb, Zn, Cr, Cu, Cd, and Hg) concentrations in paddy soils, collected from the Pb-Zn mining and smelting area of Shuikoushan in Hunan, China, were investigated. Enrichment factor and potential ecological risk index were used to evaluate the pollution level and ecological risk of heavy metals in soil. Compared with the soils in surrounding area, the soils in central area (the mining and smelting area) exhibited elevated heavy metal concentrations. The maximum heavy metal contents of Pb, Zn, Cr, Cu, Cd, and Hg in paddy soils were up to 4330.63, 4451.25, 153.75, 315.69, 34.94, and 2.379 mg/kg, respectively. The contamination degree for different heavy metals were in the order of Cd > Pb > Zn> Cu > Cr = Hg, while the monomial potential ecological risk factor for different heavy metals followed the order of Cd > Hg > Pb > Cu > Zn > Cr. The potential ecological risk index demonstrated that about 50%, 22%, 17%, and 11% of the total sampling sites in the central area were low risk, moderate risk, considerable risk, and very high risk, while the corresponding percentages were 75%, 18%, 5%, and 2% in the surrounding area, respectively. The heavy metal contamination inhibited the dehydrogenase activity significantly, and the soil pH was relatively lower for soil samples with higher metal concentrations.