鄱阳湖主要入湖口重金属的分布及潜在风险评价

DISTRIBUTION AND POTENTIAL RISK ASSESSMENT OF HEAVY METALS IN THE MAIN ESTUARIES OF LAKE POYANGS TRIBUTARIES

于2011年5月在鄱阳湖的主要入湖口采集了水样和表层沉积物,测定并分析了其中Cu、Zn、Pb、Cd 4种重金属元素的含量和分布。同时采用地积累指数法、潜在生态危害指数法和生态毒性效应等评价方法对沉积物中重金属的污染状况进行了分析评价。结果显示:鄱阳湖主要入湖口水体重金属Cu、Zn、Pb、Cd含量均符合国家渔业水质标准要求,除修河的Pb和信江、饶河入湖口的Cd含量属于国家地表水Ⅱ类水质外,其它所有样地的4种重金属含量均低于国家地表水I类标准限值。沉积物中4种重金属含量均超过鄱阳湖相应背景值且呈积累富集的趋势,其中信江入湖口、饶河入湖口以及三江口已受到重金属的严重污染,潜在生态危害均为中等,而污染最轻的区域为南主湖区。揭示重金属污染程度顺序为Cu>Zn>Pb>Cd;单个重金属潜在生态风险顺序为Cd>Cu>Pb>Zn。进一步的生态毒性效应评价结果表明,虽然鄱阳湖主要入湖口沉积物已经受到重金属污染,但对多数底栖生物未产生明显毒害。

Contents of heavy metals （Cu,Zn,Pb,Cd） were measured in water and sediment collected in May 2011 from seven sampling sites in Lake Poyang. The pollution status of sediment was evaluated by the geoaccumulation index,potential ecological risk index and eco-toxicological effects.The results showed that the content of Cu, Zn,Pb, Cd in water of Lake Poyang＇s main tributary estuaries conformed the quality standard for fisheries, so it is with the environmental quality for grade I surface water except for some individual sampling sites.The contents of the analyzed heavy metals in sediment of Lake Poyang were all higher than their background values, indicating an accumulation trend. The pollution was severe in sediments of Rao River estuary, Xin River estuary and Sanjiangkou Region while mild in Main southern lake region.The pollution order of analyzed heavy metals in water and sediment were Pb^Cd^Zn^Cu and Cu^Zn~ Pb~ Cd, respectively. Pearson correlation analyses showed significant relationships among Cu, Zn, Cd in sediment, providing similar geochemical character among the elements.This meant that there was combined pollution among Cu,Zn,Cd in sediment respectively.The order of integrative pollution status of each sampling site by geoaccumulation index was as follows： Xin River Estuary^Rao River Estuary~ Sanjiangkou Region^Xiu River Estuary^Nanjishan Region~ Fu River Estuary~ Main Southern Lake Region.The potential ecological risk of the analyzed heavy metals was arranged in the following order：Cd~ Cu〉Pb〉Zn.Furthermore,there is high potential ecological risk with Cd while medium level with Cu,Zn and Pb. Our results further revealed that the most bentonic organisms were beyond obvious hazard although sediment in estuaries of Lake Poyang＇s tributaries was polluted by those four heavy metals, whereas the eco-toxicological effect of Cu was severe in Rao River Estuary and Xin River Estuary,which caused obvious hazard on bentonic organisms.