大明湖表层沉积物重金属污染特征及生态风险评价

Pollution characteristics and ecological risk assessment of heavy metals in the surface sediments of Daming Lake

以典型城市湖泊大明湖为研究对象,选取研究区域26个采样点,分枯、平、丰三期分析其表层沉积物的Cu、Pb、Zn、Hg、Ni、As、Cd、Cr 8种重金属含量,利用地累积指数法和潜在生态风险指数法开展污染状况评价,并且结合地理信息系统形成可视化空间展示.结果表明,研究区Hg所有点位均未检出,其他重金属含量平均值Zn>Cr>Cu>Pb>Ni>As>Cd,分别为138.71、62.06、46.73、42.89、19.37、5.18、0.24 mg·kg^-1;分别为背景值2.37、1.18、2.53、1.85、0.71、0.59、5.20倍.结合聚类分析结果,将研究区分为3个区域,重金属超标倍数空间分布为A区>B区>C区;As、Ni、Cr地累积指数分别为-1.42、-1.11、-0.36,无污染,Cu、Zn、Pb地累积指数分别为0.70、0.64、0.26,为轻度污染,Cd的地累积指数为1.62,为偏中度污染.综合潜在生态危害指数平均值为192.06,总生态风险水平为中度风险;Cd是综合生态危害指数构成的最主要的金属,对其贡献率为81.21%;通过主成分分析和相关性分析推测Zn、Cu、Cd、Pb的来源相似,可能为交通污染源.

Typical urban inner lake Daming lake was selected as the study area.Twenty six surface sediment samples were collected to analyze the contents of heavy metals(Cu,Pb,Zn,Hg,Ni,As,Cd and Cr)in three stages.The pollution situation was assessed by the methods of ground accumulation index and potential ecological risk index,and a visual spatial display was formed by combining the geographic information system.The results showed that Hg content was below the detection limit.The average contents of other heavy metals were Zn>Cr>Cu>Pb>Ni>As>Cd,which reached 138.71,62.06,46.73,42.89,19.37,5.18,0.24 mg·kg^-1 and were 2.37,1.18,2.53,1.85,0.71,0.59,5.20 times of the background values,respectively.The cluster analysis of the heavy mental content indicated that the studied area could be divided into three regions(A,B and C),and the heavy metal content was showed as A>B>C.The geo accumulation index of As,Ni,Cr were-1.42,-1.11,-0.36,respectively,which indicated no pollution.The geo accumulation index of Cu,Zn,Pb was 0.70,0.64,0.26,respectively,which showed light pollution.The geo accumulation index of Cr was 1.62,which showed moderate pollution.The average comprehensive potential ecological hazard index of the study area was 192.06,and the total ecological risk level was moderate;Cd was the most important metal in the comprehensive ecological hazard index,and its contribution rate was 81.21%.According to the results of principal component analysis and correlation analysis,the sources of Zn,Cu,Cd and Pb were similar,and might be traffic pollution sources.