Ecological Risk of Heavy Metals on the Paddy Soils at a Village in Hunan

In order to investigate the soil pollution situation,15 topsoil samples were collected from agricultural soil at some villages,northeast of Hunan Province. The concentrations of 4 elements including As,Cd,Cu and Zn were determined.Results indicated that research area is seriously polluted by heavy metals,especially by Cd and Zn. The modified BCR sequential extraction method was applied to evaluate the mobility and bioavailability of the heavy metals. Among metals,Cd poses a serious threat to human health and the environment due to the calculated high percentage of mobility. Cu and Zn were distributed mainly in acid extractable fractions and Fe/Mn oxide fractions,and As was mainly associated with residual fraction. Risk assessment of soil pollution by risk assessment code and environmental risk index was also calculated.Calculated environmental risk index reveal a high ecological risk in mostly sites(86.7%). Additionally,cluster analyses suggested that metals such as As,Cd,Cu and Zn could be from the same sources probably related to acid mine drainage and the industry complexes located in the area aside from the natural source characteristics of the zone.