Access of Heavy Metals Pollution of the Sewage Irrigation Region in Taiyuan,China

Distribution characteristics of soil heavy metals in the sewage irrigation area in Taiyuan were investigated and analyzed.The results showed that concentrations of nine heavy metals(Pb,Zn,Cu,Ni,Mn,Cr,As,Hg and Cd) detected in the studied soils did not exceed the National Standard for Soil Environment Quality(GB 15618—1995),but they were higher than background values of Taiyuan soil.According to the correlation analysis of various heavy metals,there was a remarkable correlation among Pb,Zn,Cu,Ni,Mn,Cr,As and Cd,which suggested they might have the same origin.Hg was considered as a dominant element causing soil heavy metal pollution in the area.The order of typical heavy metal pollution extent was HgCdPbAsCuZnCrMnNi.The mean value of single-factor indices of soil heavy metals in all soil samples has exceeded 1.Comprehensive pollution index of soil heavy metal was 2.81,the level of pollution was moderately pollution.The single-factor polluted index and the synthesis polluted index had similar spatial distribution pattern which revealed high concentration in the southeast and south-central parts of the region.Furthermore,measures,including factor analysis and in situ investigation,were taken to identify the main sources of heavy metals contamination,and it showed that Hg contamination resulted from anthropogenic effect as well as deposition of coal combustion.Cd,Zn,Pb,and Cu contamination were mainly from sewage irrigation,and atmosphere deposition also makes certain contribution.Ni,Mn,As and Cr contamination were attributed to sewage irrigation.Hg and Cd,which were the priority pollutants,should be frequently monitored and closely regulated in the sewage-irrigated soils in Taiyuan city.