南通市河流底泥重金属污染及潜在生态风险评价

通过对南通市区5条主要河道柱状底泥样品重金属元素质量比的实验分析,探讨河道重金属污染的分布特征,并进行潜在生态风险评价。结果表明:①各重金属元素质量比均超过土壤背景值,污染较重,其中Hg污染最为严重;②重金属污染在垂直分布上分为未受干扰、正常沉积的"表层高、底层低"和受清淤治理措施影响的非正常沉积的"表层低、底层高"两种分布格局,在水平分布上具有"城市中间河流高、外围河流低"和"中上游河段高、下游河段低"的分布特征;③从重金属污染的潜在生态风险看,濠河和法伦寺河潜在生态风险强,姚港河生态风险中等,任港河和南川河生态风险轻微。各重金属元素对生态风险的影响程度大小依次为:HgCuZnCrPb。

Pollution and potential ecological risk assessment of heavy metals in river sediments of Nantong

Based on sediment samples from five urban channels in Nantong City and analysis of the heavy metal mass ratios in the sediment,the distribution characteristics of heavy metal pollution were revealed and the potential ecological risk was evaluated.The results were as follows：（1） All the heavy metal mass ratios exceeded the background soil value,and the pollution was serious,with Hg pollution being the highest.（2） The vertical distribution of heavy metal pollution was divided into two types.One was normal deposit sediment unaffected by dredging measures,wherein the heavy metal pollution was high in the upper layer and low in the lower layer;the other was abnormal deposit sediment affected by dredging measures,wherein the heavy metal pollution was lower in the upper layer and high in the lower layer.The horizontal distribution of the heavy metal pollution had the characteristics of the heavy metal pollution being high in the river of the central city,lower in surrounding rivers,higher in the upper and middle stream of rivers,and lower downstream.（3） According to the evaluation of the potential ecological risk of heavy metals,the Hao River and Falunsi River were heavily polluted,the Yaogang River was moderately polluted,and the Rengang River and Nanchuan River were lightly polluted.The influence degrees of potential ecological risk of heavy metals were as follows： Hg〉Cu〉Zn〉Cr〉Pb.