温榆河昌平段沉积物重金属影响因素分析及污染评价

温榆河是北京市重要的防洪排涝、拦污河道,每年接纳大量污水,面临严重的水环境问题. 为了解温榆河昌平段表层沉积物重金属含量、影响因素及污染状况,在温榆河昌平段采集沉积物样品28个,测定pH、w(OM)(OM有机质)、w(TN)、w(TP)、w(TK)等沉积物理化性状及w(Cu)、w(Zn)、w(Pb)和w(Cr). 通过相关性分析和因子分析,研究沉积物中pH、w(OM)、w(TN)、w(TP)、w(TK)与4种重金属质量分数的相关关系,并运用地累积指数法和潜在生态危害指数法对重金属污染状况进行评价. 结果表明:沉积物中w(Cu)、w(Zn)、w(Pb)和w(Cr)平均值分别为19.35、89.90、25.80、53.74mg/kg,变异系数分别为29.76%、43.39%、37.54%、20.90%,其中w(Zn)的空间变异程度最大. 沉积物中w(OM)与w(Cu)和w(Zn)的R(相关系数)分别为0.515(P<0.01)、0.599(P<0.01),w(TN)与w(Cu)、w(Zn)、w(Pb)的R分别为0.463(P<0.05)、0.713(P<0.01)和0.654(P<0.01).因子分析也显示,w(OM)、w(TN)、w(Cu)、w(Zn)和w(Pb)在第1因子上具有较高的载荷系数. 地累积指数评价结果表明,表层沉积物重金属污染程度顺序为Cr>Zn>Pb>Cu,Cr为轻度污染,Zn、Pb、Cu未达到污染. 潜在生态风险程度分析表明,各重金属潜在生态风险程度及综合生态风险程度均为轻微. 

Factor Analysis of Heavy Metals in the Sediment in Changping Section of the Wenyu River and Their Pollution Assessment

As an important flood control and drainage channel of Beijing, Wenyu River has received large amounts of sewage and thus encountered serious water environmental problems. To explore concentrations of heavy metals of the Wenyu River passing Changping Section and assess its polluted condition, 28surface sediment samples were collected and analyzed. Physiochemical properties including pH, OM, TN, TP, TK, and concentrations such as Cu, Zn, Pb and Cr were examined. Correlations of the pH, OM, TN, TP, TK with the content of heavy metals were determined by correlation analysis and factor analysis. The geo-accumulation index and potential ecological risk index were used to evaluate the contamination status of heavy metals. The analyzed results showed that the average contents of Cu, Zn, Pb and Cr were 19.35,9.90,5.80and 53.74mg/kg, respectively. The variable coefficients of Cu, Zn, Pb and Cr were 29.76%, 43.39%, 37.54% and 20.90%, respectively. The spatial variation of Zn appeared to be higher than that of other heavy metals in the surface sediments.Correlation coefficients between OM and Cu, Zn were 0.515(P<0.01) and 0.599(P<0.01) respectively, while correlation coefficients between TN and Cu, Zn, Pb were 0.463(P<0.05), 0.713(P<0.01) and 0.654(P<0.01) respectively. The factor analysis further showed that OM, TN, Cu, Zn and Pb had higher eigenvalues in Factor 1. The evaluation process of geo-accumulation index proved that the decreasing order of pollution degree of various metals was:Cr>Zn>Pb>Cu with the maximum degree of Cr and the minimum degree of Cu. The index of potential ecological risks for metals indicated that the potential ecological hazards were caused by each heavy metal and by the integrated system were both mild.