武汉市墨水湖沉积物重金属污染特征与防治对策

POLLUTANT CHARACTERISTICS AND POLLUTION CONTROL OF HEAVY METAL CONTAMINANTS IN SEDIMENTS OF MOSHUI LAKE,WUHAN,CHINA

武汉市墨水湖重金属污染严重,其污染特征在我国城市湖泊中具代表性。在对墨水湖不同湖区沉积物中重金属污染物空间分布特征进行分析的基础上,应用地积累指数法探讨不同重金属元素含量随深度变化的规律和原因,并对墨水湖沉积物中重金属的污染程度进行评价表明:墨水湖沉积物中重金属元素锌和汞污染最为严重,污染程度由高到低依次为:Zn>Hg>Cu>C r>Pb>A s;从整个湖区来看,分布有排污口的周边湖区污染严重,湖心污染程度较低;沉积物中主要重金属元素含量随深度增加而降低,其变化规律主要受污染状况的影响,沉积物颗粒粒径的变化和早期成岩作用的影响不大。为了改善墨水湖水质条件和重金属污染严重的现状,必须在截污、疏浚和引水工程等基本治理措施保护下,重建和恢复沉水植物系统,才能从根本上改善湖泊水质。

Moshui Lake has been seriously polluted by heavy metals. Based on the analysis of heavy metals （Cu, Cr,Pb, Zn, As and Hg） in the bottom sediments, their horizontal and vertical distribution characteristics are discussed. The change pattern ,causes and pollution degree of dif ferent heavy metals are synthetically studied by using the index of geoaecumulation（Igeo）. The results showed that the order of pollution intensity of the bottom sediments in the Moshui Lake is Zn 〉 Hg〉 Cu〉Cr〉Pb 〉As. Compared to the area near the centre of lake which are less contaminated, the lake sediments near lakeshore are contaminated heavily. The contents of major heavy metals in the bottom sediments decrease with depth ,and the changes are mainly affected by the status of pollution,not by the size of the sediment particles,remobilization or transformation of trace heavy metals during early diagenetic processes. In order to prevent Moshui Lake from heavy metal pollution, more efficient measures such as control of external pollutant sources, dredge of sediments and waters circulation by introduing river water into the lake,especially the restoration of aquatic vegetation should be taken to fundamentally improve the water quality.