Heavy metal accumulation and its risk assessment in greenhouse soils in Punan,Shanghai

In this study,the heavy metal contents in greenhouse soils in Punan were analyzed and the environmental risk was assessed via both single and comprehensive pollution index method. The results showed that Cu,Pb,Cd,Cr and As accumulated to different degrees. The contents of Cu,Pb,Cr,and As were below the limits of environmental quality standard except for Cd. The heavy metal contents all increased with the prolonging of planting years and reached peak values at the third planting year. Comparatively,the contents of investigated heavy metals in greenhouse soils were all higher than those in the open field. The contents of Cu,Pb,Cr,and As all decreased with the depth of soil profile. The single pollution indexes of heavy metals decreased in the order of Cd Cu Pb Cr As.For Pb,Cr and As,all samples were in the cleanlevel. While for Cu,most were clean. But,Cd contamination was obvious and its environmental risk would increase with ages.