河岸带重金属时空变化与土壤环境质量分析

Spatial and temporal distribution of heavy metals in riparian zone and soil environmental quality analysis

分析了南流江河岸带土壤重金属元素的时空变化规律、累积性变化特征。结合污染指数与潜在生态风险指数计算结果,评估了河岸带重金属污染状况、污染等级,以及土壤环境潜在生态风险。结果表明:各位点重金属元素浓度,在空间上沿江水流向大体呈下降趋势,大部分位点在年际变化上则呈现出上升趋势,其中以Cd、Zn最为典型;土壤中各重金属元素均有不同程度的超出《食用农产品产地环境质量评估标准》(HJ/T 332—2006)现象。内梅罗综合污染指数计算结果表明,全流域土壤污染处于重度污染水平;对单一元素而言,除Cd为重度污染外,Pb、Cu、Zn均处于轻度污染及以下水平。综合潜在生态风险指数计算结果表明,南流江河岸带土壤环境整体上存在极强等级的生态风险,而单一元素的单项潜在生态风险水平为Cd>Pb>Cu>Zn。

The present work explored spatiotemporal distribution and accumulations of heavy metals concentrations in riparian zone of Nanliujiang river. The pollution situation,pollution grade and potential ecological risk of heavy metals in soil was assessed by calculating pollution index and potential ecological risk index. The results showed that the concentrations of heavy metals of each sampling site gradually decreased along the flow direction of Nanliujiang river,while those of most sampling sites increased significantly with inter-annual variation,especially for Cd and Zn. Compared with 'Farmland environmental quality evaluation standards for edible agricultural products'( HJ/T 332-2006),the concentrations of heavy metals had higher values in various degree. The Nemerow index indicated the soil environment was heavily polluted. Cd was at heavy pollution grade,while others were at or below light pollution grade. The potential ecological risk of riparian zone soil in Nanliujiang river was severe,with corresponding ecological risk rank as Cd>Pb>Cu>Zn,which was based on the results of potential ecological risk index.