云南金顶超大型铅锌矿区水系沉积物中镉的形态分析

SPECIATION OF CADMIUM OF RIVER SEDIMENTS AT JINDING PB-ZN MINE AREA IN YUNNAN

金顶矿区长期的矿业活动造成矿区水系沉积物严重污染。通过沉积物中Cd的化学形态分析发现:矿区沉积物中Cd元素形态主要以可还原态为主,其次为可氧化态Cd、残渣态Cd和弱酸提取态Cd。沉积物中Cd的形态特征受污染源的控制,当沉积物受氧化矿为主体的污染源控制时,镉的弱酸提取态和可还原态相对较高(占总金属量的90%以上),而当沉积物受硫化矿为主体污染源控制时,镉的弱酸提取态和可还原态相对较低(仅占总金属量的20%左右)。沘江水系沉积物中Cd的弱酸提取态占相当大比例(占金属总量的18.8%),在表生环境中极易释放出来并污染水体,对矿区乃至矿区下游流域生态环境构成直接的危害。

Cadmium is a toxic, non-essential trace element for human body. A long-term mining activity caused river sediment pollution in Jinding mine area. Different chemical forms take charge of different bioavailability for Cd. Through chemical speciation analysis of Cd in the sediment,it is found that Cd in the sediments around mining area is shown mainly as reduced speciation, as well as oxidation, residues and extractable speciation from weak acid. The form of Cd in the sediments is charged by source of pollution. When the oxidized ore occurred as the main source of pollution, the quantities of extraction speciation from the weak acid and reduction are relatively high （more than 90% of total metal） ; but when the primary ore appeared as the main source of pollution,the quantities of extraction state from the weak acid and reduction are relatively low （about 20% of total metal）. Cd in the sediments of Biiiang river shown as extractable speciation from the weak acid accounted for a fairly large proportion （18.8% of total metal）, which will easily discharge Cd and pollute water body, and then endanger the ecological environment of the downstream of the mine area.