沈阳细河沿岸土壤中重金属垂直分布特征与形态分析

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

研究了沈阳细河沿岸翟家、彰驿和黄腊坨地区13个土壤剖面样品中重金属的垂直分布特征,对土壤环境危害较大的3种重金属元素Cd、Hg、As进行了重点分析。采用改进的Tessier连续萃取法研究了5个表层土壤中7种重金属元素的形态分布。研究表明土壤重金属元素形态分布具有以下特点:As、Cu、Cr、Zn和Pb主要以残渣态存在;Cd主要以离子交换态存在,残渣态所占的比例较低,表明表层土壤中Cd的活动性较强,容易迁移进入生态食物链。大部分样品中Hg以残渣态为主。除Cd外,土壤中其余6种重金属的可交换态含量都比较低。7种重金属的潜在迁移能力顺序为:Cd>Hg>Pb>Zn>Cr>Cu>As。

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.