杭州市城郊土壤重金属含量和形态的研究

Concentrations and chemical associations of heavy metals in urban and suburban soils of the Hangzhou City, Zhejiang Province

研究了杭州市城郊文教居民区、风景旅游区、市郊农业区、市内商业区和市郊工业区等 5种土地利用背景下的 32个土样中 8个重金属元素 (Cd、Co、Cr、Cu、Ni、Pb、Zn、Mn)的含量和形态 .结果表明 ,杭州市城郊土壤已受重金属的明显污染 ,其中以Pb的污染最为严重 .污染程度为 :市郊工业区 >市内商业区 >风景旅游区 >文教居民区 >市郊农业区 .用连续提取方法对重金属分级表明 ,Cd、Co、Cr和Ni主要以残余态为主 ,平均占总量的 60 %以上 ,而Cu、Pb、Zn和Mn主要以酸可提取态、氧化物结合态和有机结合态存在 。

Thirty\|two urban and suburban soils and two background (control) soils were sampled from the Hangzhou City for the study of an optimized European Community Bureau of Reference three\|step sequential extraction procedure was applied to heavy metal fractionation of the soils. Four operationally defined fractions were identified: acid extractable, reducible, oxidizable and residual. Data indicated that the urban and suburban soil in the Hangzhou City were anthropogenically contaminated by heavy metals to a great extent. Lead was the metals most enhanced with about 65 times as the concentration in the background soil. The degree of heavy metal contamination was in the order: suburban industrial zone>urban commercial zone>tourist zone>residential and education zone>suburban agricultural zone. More than 60% of Cd, Co, Cr and Ni was associated with residual fraction, Cu was dominantly associated with oxidizable fraction followed by reducible fraction. Pb was primarily associated with the reducible fraction with a mean of 65%, Zn and Mn had only one\|third of their total concentrations in the residual fraction, but one\|third in the reducible and one\|fifth in the acid extractable.