武汉市湖泊汞污染现状研究

STATUS OF MERCURY CONTAINMENT OF WUHAN URBAN LAKE

对武汉市远郊区、城乡结合部和市区三种环境中6个湖泊沉积物和鲢鱼肌肉中的汞污染特征进行了调查采样,采用原子荧光光谱仪进行了汞含量的测定。结果表明:与环境背景值相比,各湖泊沉积物均不同程度地遭受了汞污染,且汞污染表现出由市区向远郊呈减弱的趋势;在沉积柱垂直方向上,市区湖泊表层汞污染严重,向深层汞含量迅速降低,郊区湖泊沉积柱的汞含量基本上变化不大;沉积物中汞的赋存形态研究表明,汞在各湖泊中主要以惰性残渣态形式出现,反映了以飘尘和悬浮物颗粒形式输入为主的特点;湖泊鲢鱼肌肉中汞含量与沉积物中汞含量的变化规律一致,城区湖泊鲢鱼肌肉中的汞含量大大高于郊区湖泊,但鲢鱼肌肉中的汞含量尚未超出国家标准,属安全范围。

Sediment core and chub were collected from East Lake,Moshui Lake,Tangxun Lake,Lu Lake,Jinyin Lake and Liangzi Lake,which are located in three different types of environment in Wuhan. The systematic analysis of content of the total mercury in sediments and fish muscle by cold vapor atomic absorption indicates that the lake sediments of Wuhan are all polluted by mercury compared with the value of environmental background concentrations of mercury in sediments.The study also reveals that the closer the lake is to the centre of Wuhan City,the heavier mercury containment is in lake sediments. In vertical profile,mercury containment in top layers of the sediments collected from urban lakes is very serious and decreases deeply with the increasing depth. While that in sediments collected from suburb lakes is not significantly varied in depth profile. The study of biding fractions of mercury in sediments with sequential extraction procedure(SEP) shows the major binding forms of mercury in every lake sediments are'bound to residual',which reveals mercury might have been released into the lake as airborne particles and suspended particulate of river. On the other hand distribution of mercury in fish muscle and sediments is identical. In other words,content of the total mercury in fish from lakes near the urban area is much higher than that from the suburbs. But content of the total mercury in fish muscle of Wuhan urban lakes has not exceeded standard yet,it is still the safe food for fish consumers.