Trace metal pollution and ecological risk assessment in agricultural soil in Dexing Pb/Zn mining area, China

Surface agricultural soil samples obtained from Dexing Pb/Zn mining area in Jiangxi province were analyzed for trace metals to assess their pollution status and potential ecological risk. The spatial distributions and the major trace metals pollution sources were described and identified with the combination of chemical measures and geographic information systems technology. The level of pollution in seven metals is decreasing in the following order: zinc (Zn 128.9 mg/kg) > chromium (Cr 64.1 mg/kg) > lead (Pb 58.4 mg/kg) > arsenic (As 45.3 mg/kg) > copper (Cu 41.9 mg/kg) > nickel (Ni 31.3 mg/kg) > cadmium (Cd 1.5 mg/kg). Trace metal spatial distribution maps established by geographic information system techniques displayed two high-pollution zones around mining sites in the study area. Multivariate statistical analyses were also applied, and the results demonstrated that Cd, As, Pb, Cu and Zn in the soils originated from mining activities, whereas Cr and Ni primarily originated from natural sources. The values of pollution index ranged from 4.79 to 71.59, and the values of modified pollution index ranged from 1.98 to 24.69. Moreover, the potential ecological risk values ranged from 264.0 to 3263.5, which indicated considerable ecological risk to very high ecological risk. The potential ecological risk values and other soil contamination indices showed similar patterns that the high-risk areas were around Dexing Pb/Zn mining site. The surface agricultural soil in study area is heavily to extremely polluted , with Cd that made the most dominant contribution.