Pollution characteristics of heavy metals in sewage irrigated soil of Northern China

【Objective】This research aimed to investigate the pollution characteristics of heavy metals Cu,Pb,Zn,Cr,Cd,Ni,As and Hg in the surface soil of farmland in sewage irrigation area,which will provide a reference for the quality evaluation of soil environment and remediation of heavy mental pollution in sewage irrigated area.【Method】Based on the statistical data of 30sewage irrigation regions in Northern China,this article analyzed the heavy mental pollution in sewage irrigation area with statistical analysis methods,Nemerow index method and geoaccumulation index method.【Result】Contents of tested heavy metals in the surface soil in sewage irrigation area in Northern China were all lower than the secondary standards regulated in Soil Environment Standards.However,the average contents of all the heavy metals except Cr were higher than their national background values.Their variation coefficients were in a decrea-sing order of CdHgPbAsZnCuCrNi,among which Cu,Cr,and Ni had very small differences and Cd,Hg,and Pb had large differences.Significant relationships were found between Cu with Zn,Cr,Cd,As,and Hg,Zn with Ni,Cr with Pb,Ni,As,and Hg,and Cd with As,while extremely significant relationships were found between Pb with Cu,Zn,Ni and Hg,and Hg with Zn,Cd,Ni and As.The Nemerow indexes and geoaccumulation indexes of studied heavy metals were in a decreasing order of CdHgCuAsZnPbNiCr.【Conclusion】Heavy metals Cu,Pb,Zn,Cr,Cd,Ni,As and Hg were accumulated in soil of Northern China due to human activities.