宁波市回龙河表层沉积物重金属的形态分析及风险评价

为了解回龙河表层沉积物中重金属的污染状况,采集了表层沉积物样品,测定了重金属Zn、Cu、Pb、Cr、Cd和Ni的总量及其化学形态,并采用潜在生态风险指数法对重金属进行了生态风险评价。结果显示,回龙河表层沉积物中Zn、Cu、Pb、Cr、Cd和Ni均有一定程度的累积,总量分别为286.4～1277.9mg/kg、21.71～146.0mg/kg、10.33～44.20mg/kg、25.13～90.40mg/kg、0.07172～0.3901mg/kg、13.27～157.2mg/kg,其中Cu、Cr、Pb与Ni 4种重金属具有一定的同源特性;形态分析表明,Cu的形态分布以有机结合态为主,最容易迁移释放,Zn、Cr和Ni除残渣态外,铁锰氧化结合态和有机结合态占一定比例,具有潜在风险;潜在生态风险指数法分析表明,沉积物中重金属元素的单一潜在生态风险指数顺序为Cd〉Cu〉Ni〉Zn〉Pb〉Cr,潜在生态危害指数RI均小于150,总体上回龙河处于轻微的生态风险等级。

Pattern Analysis and Risk Assessment of Heavy Metals in Sediment of the Huilong River in Ningbo

To understand the condition of heavy metal pollution in the surface sediment of the Huilong River, some samples of surface sediment were collected, and total contents and chemical pattern of Zn, Cu, Pb, Cr, Cd and Ni were determined. The ecological risk of these elements were evaluated with the potential ecological risk index. The results showed that all the six elements in surface sediment of the Huilong River were enriched to some extent. The total contents of Zn, Cu, Pb, Cr, Cd and Ni were 286.4 ～1277.9 mg/kg, 21.71 ～146.0 mg/kg, 10.33 ～44.20 mg/kg,25.13～90.40 mg/kg, 0.07172～0.3901mg/kg, and 13.27～157.2mg/kg, respectively. The four heavy metals of Cu, Cr, Pb and Ni had a characteristic of homology. The pattern analysis showed that Cu existed mainly in organic fraction and had high transference ability. The greatest proportion of Zn, Cr and Ni was the residual fraction, followed by the Fe-Mn oxide fraction and organic fraction with potential risks. The result of the potential ecological risk index analysis indicated that the order of ecological risk was Cd〉Cu〉Ni〉Zn〉Pb〉Cr. The potential ecological risk index RI was less than 150. The Huilong River was generally at a low level of ecological risk.