贵阳市城区土壤重金属分布特征及污染评价

调查了贵阳市不同功能区表层土壤中重金属含量及其分布特征,以基线为参比值,采用Hakanson潜在生态危害指数法对重金属的潜在生态风险进行了评价。结果表明,贵阳市城区土壤重金属(Hg、Cd、As、Pb、Cr、Cu、Ni、Zn)主要来源于工业、交通以及燃煤等活动,其平均含量分别为0.108、0.320、20.53、22.17、35.71、64.87、48.65、217.90mg/kg,除Cr外,均显著高于相应基线。工矿区土壤中Pb、Zn含量显著高于其他功能区(p0.05)。Hg和Cd是主要的生态危害因子,其污染已达强生态危害水平,其余均显示为轻微生态危害水平;不同功能区土壤重金属污染均已达强生态危害水平,且污染程度依次是:商务区工矿区文教区居民区城市绿地交通区。

Distribution and pollution assessment on heavy metals in urban soils of Guiyang

The concentrations and spatial distributions of heavy metals (Hg, Cd, As, Pb, Cr, Cu, Ni, Zn) in surface soils in different functional areas in Guiyang City were analyzed and the heavy metal pollution in urban soil was evaluated by using the method of potential ecological risk index presented by Hakanson by taking the baseline as the reference value. The results indicated that the mean concentrations of heavy metals (Hg, Cd, As, Pb, Cr, Cu, Ni, Zn ) in urban soils derived mainly from activities of industries, transportation and coal burning were 0.108, 0.320, 20.53, 22.17, 35.71, 64.87, 48.65 and 217.90 mg/kg, respectively. Compared with environmental geochemical baseline, these elements were enriched strongly except Cr, especially in industrial areas where the concentrations of Pb and Zn were significantly higher than those in other functional areas (p<0.05). Hg and Cd were the main ecological risk factors in urban soils and the degrees of their ecological risks were serious while the risks of other heavy metals were light. The ecological risks of heavy metals in surface soils in different functional areas were serious and in the following order: commercial areas>industrial areas>cultural and educational areas>residential areas> urban green space > transportation areas.