Heavy metal pollution and ecological risk assessment of the paddy soils in a smelting area in Central Hunan

The concentrations of Cd,Zn and Pb in the topsoil of paddy fields in a smelting area located in the central Hunan province were analyzed by field sampling and laboratory analysis,aiming to evaluate the pollution degrees and potential ecological risks of soil heavy metals.The assessment results from Single Factor Pollution Index showed that 100%,96.0%,99.5% of the sampling sites were at the serious pollution level for Cd,Zn,and Pb,respectively,and the pollution degree of heavy metals followed the order of CdPbZn in the paddy soils.The assessment results from Potential Ecological Risk showed that most of the sampling sites were at light ecological risk level for Zn,and all the sampling sites were at extremely high ecological risk level for Cd.There were different ecological risk levels for Pb in the sampling sites,but most of them belonged to high ecological risk level.Integrated Potential Ecological Risk Index of the three heavy metals revealed that 11.0% of the sample sites were at very high level,while 89.0% were at extremely high level.All the results indicated that the paddy soils in this smelting area were polluted seriously by heavy metals.