武汉南湖沉积物的重金属污染状况评价

Assessment on Heavy Metal Pollution in Sediments of Lake Nanhu in Wuhan,China

采用原子吸收分光光度法对湖北武汉南湖柱状沉积物中的6种重金属(Cd,Cu,Cr,Mn,Pb和Zn)进行测定.结果表明,柱状沉积物中各种重金属的平均含量(w/mgkg-1,DM)分别为Cd0.155,Cu47.0,Cr147.8,Mn1026.5,Pb55.7,Zn132.1.水平分布,重金属的最大含量出现在点Ⅳ和点Ⅰ,且平均含量也高于其他的点;垂直分布,最大含量出现0～5cm或5～10cm的沉积层,随沉积深度的增加而降低.这些结果表明外源污染对沉积物的重金属负荷具有重要影响.应用地质累积指数Igeo值对重金属污染状况进行评价,结果表明,重金属的污染主要是Cr和Cd,其中Cr的最高含量(w/mgkg-1,DM)为231.9,Cd为0.348;重金属的污染程度较轻.

The contents of heavy metals （Cd, Cu, Cr, Mn, Pb and Zn） in the sediments of Lake Nanhu in Wuhan, China were determined by an air-acetylene flame atomic absorption spectrophotometer. The results showed that the average contents of Cd, Cu, Cr, Mn, Pb and Zn were 0.155, 47.0, 147.8, 1 026.5, 55.7, and 132.1 （w/mg kg-1, DM）, respectively. In horizontal distribution, there were higher contents of the heavy metals at sites IV and I. The heavy metals contents decreased with the sedimentation depth from surface to bottom, which means that the contents in surface of sediments were significantly higher than those at bottom. According tgcu values, Cr and Cd were the major pollutants in Lake Nanhu, and Cr and Cd （231.9 and 0.348 mg kgj, DM） were found with highest contents in the lake. However, the pollution level caused by heavy metals in Lake Nanhu was generally measured low. The present results reveal that municipal sewage discharge and rainwater runoff are the important factors for heavy metal pollution in Lake Nanhu and it is necessary to control the pollution sources discharged into the lake. Fig 2, Tab 1, Ref20