Distribution and Pollution Assessment on Heavy Metals in Urban Soils of Guiyang

The concentrations and spatial distributions of heavy metals(Hg,Cd,As,Pb,Cr,Cu,Ni,Zn) in surface soils in different functional areas in Guiyang City were analyzed and the heavy metal pollution in urban soil was evaluated by using the method of potential ecological risk index presented by Hakanson by taking the baseline as the reference value.The results indicated that the mean concentrations of heavy metals(Hg,Cd,As,Pb,Cr,Cu,Ni,Zn) in urban soils derived mainly from activities of industries,transportation and coal burning were 0.108,0.320,20.53,22.17,35.71,64.87,48.65 and 217.90 mg/kg,respectively.Compared with environmental geochemical baseline,these elements were enriched strongly except Cr,especially in industrial areas where the concentrations of Pb and Zn were significantly higher than those in other functional areas(p0.05).Hg and Cd were the main ecological risk factors in urban soils and the degrees of their ecological risks were serious while the risks of other heavy metals were light.The ecological risks of heavy metals in surface soils in different functional areas were serious and in the following order:commercial areasindustrial areascultural and educational areasresidential areas urban green space transportation areas.