南运河重金属污染状况及生态风险评价

采集南运河的水样和沉积物样品,对其重金属污染状况和生态风险进行了分析评价。利用电感耦合等离子体质谱仪(ICP-MS)对水、沉积物中铅(Pb)、铬(Cr)、砷(As)、铜(Cu)和镉(Cd)浓度进行分析。结果显示南运河水样中这5种重金属浓度均低于地表水环境质量标准I类水质标准,虽然运河上游沉积物中As和Cd浓度较高,但沉积物中重金属浓度总体上均处于较低水平。地累积指数法计算显示:As和Cd在部分河段达到重度和中度污染水平,Cu、Cr、Pb均处于无污染水平。各种重金属的潜在生态风险指数(Eir)从大到小的顺序为:CdAsCuPbCr,与地累积指数法结果相似。南运河总的潜在生态风险指数(RI)均值为128.85,潜在生态风险程度为"中",沉积物中Cd和As是南运河需要优先控制的重金属污染物。

Contamination Status and Ecological Risk Assessments of Heavy Metals in the South Canal

Heavy metals contamination and their impacts on aquatic environment were studied based on eight rep-resentative samples collected from water and sediment in South Canal, China. Concentrations of five heavy metals, plumbum (Pb), chromium (Cr), arsenic (As), copper (Cu) and cadmium (Cd) of the samples were analyzed using ICP-MS. The results showed that concentrations of the detected heavy metals from water samples in South Canal-were lower than class I values of the National Surface Water Quality Standards. However, for sediment samples, As and Cd concentrations were higher than the corresponding background values of sediment in China, except for Cu, Cr and Pb. Geoaccumulation index evaluation showed that Cu, Cr, Pb were in non-contamination status, while Cd and As fell in the moderate and even severe contamination level in some segments of the river. The monomial po-tential ecological risk factor (Eir) showed that the risk potentials of the heavy metals followed an order of Cd >As> Cu > Pb > Cr, ranging from 0 to 355.29. The average value of the Hakanson potential ecological risk (RI) was 128.85, indicating that the potential ecological risk was ‘medium’ in South Canal. In conclusion, this study re-vealed that Cd and As were at relatively high level and had high ecological risks, and thus should be managed in priority in the South Canal.