上海河流沉积物重金属的污染特征与潜在生态风险

摘要

为了解上海市主要河流沉积物中重金属的污染特征,采用电感耦合等离子体发射光谱法(ICP-AES)分析了上海市60个河流表层沉积物中Cu、Pb、Ni、Ag、As、Cd、Zn、Sn、Sb和Hg10种重金属的含量,并对其来源及生态风险进行了评价.沉积物中10种重金属的浓度和介于113.9 ～ 494.0mg/kg之间,平均值为266.1 mg/kg.苏州河、黄浦江中下游和黄浦江上游部分采样点重金属污染比较严重.10种重金属的含量由高到低依次为:Zn＞ Cu＞ Ni＞ Pb＞ As＞ Sn＞ Sb＞ Cd＞ Hg＞ Ag.来源分析表明,上海河流沉积物中大多数重金属具有相似的来源,主要来源于工业废水和交通污染、农药和化肥污染.地积累指数(Igeo)评价表明各种重金属的污染程度顺序为:Cd＞Hg＞Ag＞Sb＞Cu＞Zn＞ Sn =As ＞Ni＞ Pb,Hg和Cd在多数采样点分别为中度污染和偏重污染.潜在生态风险系数(Eir)评价表明各重金属的潜在生态风险顺序为:Cd ＞Hg ＞As＞ Cu ＞Ni＞Pb ＞Zn,Cd和Hg对潜在生态风险指数(RI)的贡献最大,分别达到65.7％和30.6％.7种重金属的潜在生态风险指数(RI)介于563.0～1431之间,有极强生态风险.%In order to understand the pollution characteristics of heavy metals in surface sediments of main rives in Shanghai,the concentrations of 10 heavy metals including Cu, Pb, Ni, Ag, As, Cd, Zn, Sn, Sb and Hg in 60 sediment samples were analyzed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and the potential ecological risks of each heavy metals were evaluated. The total concentrations of 10 metals in the sediment samples ranged from 113.9 mg/kg to 494.0 mg/kg, with the mean concentration of 266.1 mg/kg. The sediments collected from Suzhou River, downstream and upstream of the Huangpu River were more seriously contaminated. The levels of sediment heavy metals followed the order: Zn > Cu> Ni > Pb > As > Sn > Sb> Cd > Hg > Ag. The source of most heavy metals in sediments were similar, and came mainly from industrial wastewater, vehicle pollution, and the use of pesticide and chemical fertilizer. The pollution extent of heavy metals in sediments by geo-accumulation index (Igeo) followed the order: Cd > Hg > Ag > Sb > Cu > Zn > Sn = As > Ni > Pb. The pollution extent of Cd and Hg were at class 3 (moderately to heavily polluted) and 4 (heavily polluted) at most sampling sites. The potential ecological risk of 7 heavy metals in sediments by the potential ecological risk factors (Eir) were in the following order: Cd > Hg > As > Cu > Ni > Pb > Zn, Cd and Hg contributed the most to the total potential ecological risk, accounting for 65.7% and 30.6%, respectively. The potential ecological risk indexes (RI) of 7 heavy metals at all sampling sites were between 563.0 and 1431, and posed very high potential ecological risk for rivers of Shanghai.