武汉地区湖泊沉积物重金属的分布及潜在生态效应评价

对武汉地区6个湖泊沉积物重金属元素Hg、Cd、Cu、Pb、Zn、As、Cr、Ni的空间分布特征及其潜在生态效应进行研究。调查区的湖泊底泥重金属含量表现出市区内湖泊沉积物的重金属含量普遍高于郊区湖泊，其中墨水湖中重金属含量最高；湖泊沉积物柱重金属元素垂向分布表现为城区受到一定程度污染的湖泊某些元素表现出表层沉积物显著高于底部沉积物含量的特征，而郊区湖泊除Cd外其它元素垂向含量变化不大，说明郊区湖泊受到人为影响较小。利用潜在生态危害指数法对湖泊沉积物进行生态危害评价，显示武汉地区湖泊元素生态危害排序为：Cd>Hg>As>Cu>Pb>Zn；墨水湖沉积物重金属潜在生态危害相对最高，其次是金银湖；其它湖泊重金属生态危害都比较轻，总体而言武汉湖泊重金属生态危害还是较小的。但参照国外沉积物基准的生态数据库阈值，市区受到人为污染较严重的湖泊沉积物可能会对生物产生负面影响。

DISTRIBUTION OF HEAVY METALS IN SEDIMENTS IN LAKES IN WUHAN WITH ASSESSMENT ON THEIR POTENTIAL ECOLOGICAL RISK

Distribution and characteristics of heavy metals(Hg、Cd、Cu、Pb、Zn、As、Cr、Ni) in sediment columns from six lakes in Wuhan were investigated. The results demonstrated that the concentrations of heavy metals in lakes in urban area are invariably higher than sediments from lakes in suburb area, and the concentration of heavy metals in top sediment of the urban polluted lakes show some degree of accumulation when compared with deeper sediments in lake sediment columns, while heavy metals show no significant change among sediment columns in suburb lakes. Potential ecological risk index and fresh water sediment quality criteria were then used to assess the heavy metals ecological risk, which leld us to conclude that the potential risk order of elements were Cd> Hg> As> Cu> Pb>Zn; Moshu Lake is of the highest potential risk, Jinying Lake ranks the second, while the others have relatively small risk. But, overall, the potential ecological risk of investigated lakes in Wuhan is light, at least not very serious. With reference to the threshold obtained by Canadian ecological databank of sediment baseline, heavy metals in sediments of some lakes of relatively higher risk index may press negative effects to biota within the lake.