Vertical Distribution Characteristics and Speciation Analysis of Heavy Metals in Topsoils around Xihe River of Shenyang

The vertical distribution of heavy metals including three kinds of hazardous elements of Cd, Hg and As in 13 soil profiles along the Xihe River in Shenyang were studied. In the meanwhile, an improved Tessier′s sequential chemical extraction technique was adopted to study the chemical speciation of seven heavy metals in five topsoil samples. The results showed that the speciation varied greatly according to heavy metals. The residual fraction was dominant for As, Cu, Cr, Zn and Pb. Cd mainly exists in exchangeable fraction and in rather low concentiation in the residual fraction, which indicates that Cd has strong mobility and is prone to migration. Hg mostly exists in the residual fraction. Except for Cd, the proportions of the exchangeable faction for all the heavy metals are in rather low concentiation and the potential migration ability of the heavy metals is in the order of Cd>Hg>Pb>Zn>Cr>Cu>As.