黄浦江水源地沉积物重金属潜在生态风险评价

为了解黄浦江上游饮用水源地沉积物中重金属的污染特征,对黄浦江干流和主要支流15个采样点的Hg、Cd、Pb、Cu和Zn含量进行检测,并对其生态风险进行评价.相比环境背景中位值,在15个样品中5种重金属含量都存在一定比例的超标现象,其中,Cd和Hg的污染相对明显;相比背景最大值,仅有Cu和Cd含量超标.采用潜在生态风险指数法和污染负荷指数法进行评价,所得出的生态风险等级均为无污染～中等污染水平,急水港近苏沪交界处、淀峰大桥、大蒸港沪浙交界处、大蒸港泖洋河交汇处、园泄泾以及五厍东一号河交界处区域生态风险较高,Cd和Hg是研究区域生态风险的主导因子.值得注意的是,黄浦江支流大蒸港和园泄泾的生态风险整体高于黄浦江干流.总体而言,黄浦江上游水源地表层沉积物中重金属污染仍处于中等以下水平.

Potential Ecological Risk Assessment of Heavy Metals in River Sediments of Drinking Water Sources of Huangpu River.

The upper stream of the Huangpu River is an important drinking water source area for Shanghai.To better characterize heavy metal pollution of the region,samples of sediments were collected from 15 sampling points distributed in the main stream and major tributaries of the Huangpu River for analysis of Hg,Cd,Pb,Cu and Zn contents and for ecological risk assessment.It was found that all the five heavy metals,with Cd and Hg in particular,in the 15 samples exceeded the medians of their respective environment background values by a varying extent,and only Cu and Cd exceeded their respective highest background values.Ecological risk assessment using the potential ecological risk index method and the pollution load index method shows that the ecological risks of the heavy metals in the study area could be sorted as ＂no pollution＂ or ＂moderate pollution＂,and Sampling Point #1,#5,#9,#11,#12 and #13 were comparatively high in ecological risk.Cd and Hg are the two dominant ecological risk contributors in the study area.It is noteworthy that some of the tributaries,like Dazhenggang and Yuanxiejing,were,on the whole,higher than the main stream in ecological risk.Generally speaking,heavy metal pollution in river sediments of the upper streams of the Huangpu River is still lower than the ＂medium level＂.