北京市中心城河流表层沉积物重金属污染评价

为了解北京市中心城河流表层沉积物中重金属污染现状,采用地累积指数法、主成分分析法、潜在生态风险指数法评价和分析了沉积物中汞、砷、铅、铬、镉、锰、铜7种重金属的污染程度、污染来源及潜在生态风险。结果表明,重金属平均含量为Hg 0.670 mg/kg,As 6.01 mg/kg,Pb 31.1 mg/kg,Cr 63 mg/kg,Cd 0.29 mg/kg,Mn 277mg/kg,Cu 45mg/kg;平均地累积指数排序为Hg(1.49)Cr(0.34)Cu(0.24)Cd(0.14)Pb(-0.77)As(-1.41)Mn(-2.30),沉积物主要受Hg、Cr、Cu、Cd的污染,Hg处于中等污染程度,Cr、Cu、Cd处于轻度-中等污染程度,污染主要来源于三方面:交通、汽配(修)及供暖燃煤。重金属平均潜在生态风险系数排序为Hg(357)Cd(80)Cu(13)As(9)Pb(7)Cr(4)Mn(2),中心城沉积物潜在生态风险指数平均值为472,总体上具有较强生态危害。

Assessment on heavy metal pollution of the surface sediments from rivers in Beijing central district

To investigate the pollution status of heavy metals in the surface sediments from rivers in Beijing Central District, we used the methods of the Geoaccumulation Index, principal component analysis, and Potential Ecological Risk Index to evaluate the pollution level, pollution sources, and potential ecological risks of the heavy metals including Hg, As, Pb, Cr, Cd, Mn, and Cu, respectively. The results showed that the average contents of the heavy metals were as follows: Hg 0.670 mg?kg-1, As 6.01 mg?kg-1, Pb 31.1 mg?kg-1, Cr 63 mg?kg-1, Cd 0.29 mg?kg-1, Mn 277 mg?kg-1, Cu 45 mg?kg-1. The descending order by the average Geoaccumulation Index was Hg(1.49) > Cr(0.34) > Cu(0.24) > Cd(0.14) > Pb(-0.77) > As(-1.41) > Mn(-2.30), showing that the surface sediments were mainly polluted by Hg, Cr, Cu, and Cd elements, with Hg at moderate pollution level and Cr, Cu, Cd at mild to moderate pollution level. The pollution mainly came from three sources: traffic, vehicle repairing, and heating coal combustion. The descending order by the average Potential Ecological Risk Coefficient was Hg(357) > Cd(80) > Cu(13) > As(9) > Pb(7) > Cr(4) > Mn(2), and the average Potential Ecological Risk Index of the sediments was 472, suggesting strong ecological hazard of the sediments in general.