Pollution characteristics and ecological risk assessment of heavy metals in farmland soils of a typical basin.

By means of field investigation and laboratory analysis,the concentrations and pollution characteristics of Hg,Cr,Cd,As,Pb,Cu,Zn and Mn in farmland surface soil from a valley which suffered serious industrial historical pollution were analyzed.The ecological risk assessment of heavy metal pollution in the farmland soil wais discussed with the methods of geoaccumulation index and potential ecological risk index.The results showed that the farmland soils in the research area were polluted by heavy metals,and their concentrations were all above the background values.The enrichment degree of heavy metals ranked as follows: Cd As Zn Cu Pb Cr Hg Mn.The potential ecological risk level in the farmland soils in the research area was relatively high.The potential ecological risk of Cd was highest among the eight studied heavy metals,which showed that industrial historical pollutants in the valley were harmful to the ecological environment of farmland soils in the research area.