在往复流现象明显的蕰藻浜中下游河道选择16个采样点,分析研究沉积物性状以及Cr、Cu、Zn、Cd、Ni、Pb、Mn的含量以及分布情况.结果表明:蕰藻浜总体污染程度为中等,其中陈行桥、江杨北路桥以及淞港码头污染较严重.Cr、Cd、Pb、Ni、Cu、Zn和Mn的含量分别为24.0 ～ 357.0、0.06 ～0.69、20.0～85.4、18.2～132、14.2～136、84.6～ 685、472～1 086 mg/kg.通过分析发现,Pb、Ni、Cu、Zn和Cr总量都具有显著的相关性,很有可能来自同一外源污染,而中游河段的Mn主要来自于沉积物母质.河道两岸以往的工业与生活排污以及往复水流使得重金属污染物在沉积物中聚集是造成重金属污染的潜在原因.运用地累积指数法、潜在生态危害指数法、污染负荷指数3种风险评价法对沉积物重金属进行风险评估,总体来说,3种评价方法都表明Cu的污染程度较严重,Mn的污染较轻.其中地累积指数法结果显示,各重金属的污染顺序为Cu＞ Zn≥Cd＞ Pb≥Cr＞ Ni＞ Mn,然而由于Cd本身生物毒性较高,对沉积物生态环境危害贡献率可达到60％;污染负荷指数评价结果发现蕰藻浜下游河段部分断面沉积物达到了极强污染程度,应当受到重视.%In current study,16 sediment sampling sites were sellected from a reciprocating river-Wenzao Creek to analyse the concentration and distribution of 7 heavy metals in the sediments.The sources of heavy metals were determined by correlation analysis.In addition,the risk was evaluated by geoaccumulation index,potential ecological risk index and pollution load index.The results showed that the overall contamination degree was medium in Wenzao Creek,with three sampling points-Chenxing bridge,Jiangyangbeilu bridge,Songgang port were more seriously polluted.The concentration of Cr,Cd,Pb,Ni,Cu,Zn and Mn in surface sediments ranged from 24.0 to 357.0,0.06 to 0.69,20.0 to 85.4,18.2 to 132,14.2 to 136,84.6 to 685,472 to 1 086 mg/kg,respectively.Lead,Ni,Cu,Zn and Cr has significant correlation which implies that they may came from the same contamination sources.Manganese in the mid of Wenzao Creek mainly came from its parent material.The sediments was mostly contaminated by Cu,while Mn was relatively uncontaminated as the results from three evaluation methods.Heavy metals from previous industrial legacy and domestic sewage was likely to be accumulated at the bottom of the river as a consequence of the reciprocating flow.Based on the geoaccumulation index,the contamination can be ordered as Cu ＞ Zn≥Cd ＞ Pb≥Cr ＞ Ni ＞ Mn,the potential ecological risk index shows Cd contribute 60％ of the total risk,and the results from the pollution load index suggested that pollution was most serious in the downriver sediments.
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