Vertical Distribution and Mobility of Heavy Metals in Agricultural Soils along Jishui River Affected by Mining in Jiangxi Province, China

The vertical distribution of Cd, Cr, Cu, Pb, and Zn and their mobility (except Cr) were investigated in ten agricultural soil cores, collected near non-ferrous metal mines and smelters along Jishui River, in Jiangxi Province, China. The surface soils near mines and smelters were contaminated by Cd, Cu, Pb, and Zn, with concentrations higher than the guideline values of China. For most polluted sites, heavy metals were mainly retained in the surface soil (0-20 cm), and the contents of them became constant in deeper soil. In all soil cores, the mean content of Cr was lower than the guideline value of China. Correlation results between studied heavy metals and soil properties showed that heavy metal contents throughout the soil profile was mostly influenced by organic matter (OM), pH, and clay content. Particularly soil OM can significantly impact on transport of soil heavy metals. There were positive correlations of OM content with all studied heavy metals, and the correlations with Cr, Cu, Pb, and Zn were significant or very significant. Heavy metal mobility in the studied region were assessed using a mobility index (MI) and mobility order was Cd >> Pb > Cu approximate to Zn.