湘江衡阳段沉积物重金属污染特征与生态风险评价

Characteristics and Ecological Risk Assessment of Heavy Metals Pollution in the Fluvial Sediment in Hengyang Section of Xiang River

目的了解湘江衡阳段沉积物重金属污染特征及其生态风险。方法于2007年调查湘江衡阳段10个断面18个采样点的表层沉积物重金属(Cd、Hg、Pb、As、Cr、Zn、Cu)污染特征。运用Hankanson潜在生态危害指数法评价表层沉积物重金属的富集程度和潜在生态风险。结果该区段河流沉积物重金属Cd潜在生态危害系数(Er)i均值为352.1,为极强生态危害程度;Hg次之,Eri均值为272.1,属于很强生态危害;Pb和As的Eri均值分别为150.1和104.7,为强生态危害程度;Cr、Zn、Cu的Eri均值小于40,为轻度生态危害。多种重金属的综合潜在生态风险指数(RI)为913.4。结论本次调查的湘江衡阳段沉积物存在一定程度的重金属污染,且具有较为明显的复合型污染特点,具有很强的潜在生态危害。

Objective To explore the characteristics and ecological risk assessment of heavy metals pollution in the fluvial sediment in Hengyang section of Xiang river. Methods The fluvial sediments in 18 sites in 10 sections of Hengyang section of Xiang river were collected for determination of heavy metals（ Cu, Zn, As, Hg, Cd, Cr, Pb） in 2007.The accumulation levels of heavy metals in the fluvial sediment and their potential ecological risks were assessed by the Hankanson potential ecological risk （PER） factors method. Results The average potential ecological risk index of Cd in sediment of Xiang river was 352.1 with the highest ecological risk , the index of Hg was 272.1 with higher ecological risk, the index of Pb and As was 150.1 and 104.7 with high ecological risk, the index of Cr, Zn and Cu were all lower than 40 with low ecological risk . On the whole, the integrated pollution index of seven kinds of heavy metal was 913.4 .Conclusion The fluvial sediment of Hengyang section of Xiang rive has been polluted by heavy metals in a certain degree and is characterized as a complex pollution situation with a higher ecological risk.