Distribution and Risk Assessment of Soil Heavy Metals in the North Suburb of Shijiazhuang City

This study focused on the distribution and risk assessment of soil heavy metals in the north suburb of Shijiazhuang city.Total concentrations of Pb,Cr,As,Cd,Ni,Zn and Cu in 28 soil samples randomly collected were analyzed.Single pollution index,Nemerow pollution index,Hakanson potential ecological risk index and technical guidelines for risk assessment of contaminated sites etc,were used to assess ecological and human health risk of heavy metals.Average contents of some metals investigated were higher than the soil background values of both Hebei Province and China.Contents of soil Pb,Cd and Cu were 1.5~2.5 times of the soil background values,and those of Cr,Ni and Zn were 1.0 ~1.5 folds of the soil background values,showing anthropogenic contamination of these metals.The single pollution index of heavy metals in the soils was in order of CuNiCdZnCrPbAs.The Nemerow pollution index was 0.738 in the whole area,implying that the soil in this area was clean.However,the average potential ecological risk was 90.53,which indicated slightly ecological hazard;the risk was in order of CdPbCuAsCrNiZn.The cancer risk of exposure was ranked as CrAsNiCd,and the non-cancer risk of exposure as CrAsNiCuCdZn.Therefore,Cr and As were the most potentially harmful metals among heavy metals investigated,and their concentrations in soil were higher than the US EPA soil management standards of 10E-06 and 1,respectively.In conclusion,heavy metals have certain potential ecological risks in the north suburb soils of Shijiazhuang and it is therefore necessary to prevent the soils from further pollution by heavy metals in this region.