巢湖重污染汇流湾区沉积物重金属污染特征及风险评价

对巢湖重污染汇流湾区沉积物中主要重金属分布和累积特征及生态风险进行了分析评价.结果表明:受底泥分布影响,湾区沉积物重金属主要累积于距岸边约700m以上的低洼区,且表层沉积物(0~2cm)重金属含量大致随泥深增加而增大.基于地积累指数法和潜在生态风险指数法的评价结果表明,除Hg(Eri=325.5)和Cd(Eri=240.28)外,大多数重金属处于低风险状态,各金属元素污染顺序为Hg>Cd>Zn>Pb>Cu>As>Cr>Ni.其中,富集倍数最高的Hg和Cd具有同源性,污染等级均为3级.垂向分析表明,受Hg和Cd的影响,0~14cm沉积物已达严重生态风险程度(RI>525),14~34cm沉积物中Hg具有中度生态风险.建议亟须从流域角度对该汇流湾区重金属特别是Hg和Cd进行控制.

Pollution status and risk assessment of heavy metal in the sediment of the severe polluted confluence area of Lake Chaohu

Ecological risk and accumulation of heavy metals in the sediment of the severe polluted confluence area of Lake Chaohu were studied in the present research. The results indicated that heavy metal accumulated mainly in the low-lying area which is about 700m away from the bank and which was influenced greatly by sediment distribution. Levels of heavy metal increased with the increase of sediment depth in surface sediment (0~2cm). Index of geoaccumulation and potential ecological risk index were used to evaluate extent of heavy metal pollution in the studied area. The results indicated most of the metals studied, except Hg (Eri=325.5) and Cd(Eri=240.28), had low ecological risk and they followed a descending order as: Hg>Cd>Zn>Pb>Cu>As>Cr>Ni. Among these metals studied, Hg and Cd ranked high and was classified into grade three and they might originate from the same sources. Seriously, the upper 0~14cm of sediment had presented very high ecological risk (RI>525) because of Hg and Cd. In addition, Hg in the 14~34cm of sediment still had presented moderate ecological risk. Therefore, emergent measures must be taken to control pollution of Hg and Cd in the area studied.