长江铜陵段表层水中重金属含量及存在形态分布研究

INVESTIGATION ON HEAVY METAL ELEMENTS DISTRIBUTION ON SURFACE WATER OF TONGLING SECTION ALONG THE YANGTSE RIVER

通过测定长江铜陵段枯、丰水期江水中cu、Pb、Zn和cd不同形态的含量,分析了4种金属在江水中的存在形态分布,不同水期含量变化,水中悬浮物对金属吸附能力大小,以及近20年来含量的变化情况。结果表明,长江铜陵段江水中各重金属总量丰水期时大于枯水期,重金属各形态含量之间均有差异:丰水期时,各金属会被悬浮物以不同的方式携带进入水体中,cu、zn、Pb以活跃态和稳定态为主,Cd以活跃态为主;枯水期时,Zn主要以溶解态和稳定态为主,Pb以稳定态方式被携带,而80％的Cu、Cd是以溶解态形式存于水中。悬浮物(丰水期)对重金属的吸附能力大小顺序为Pb>Cu>Zn>Cd。与近20年江水中的重金属背景值比较,长江铜陵段重金属含量有普遍升高的趋势。

The present paper aims to introduce the author's investigation and analysis of the content and existing forms of heavy metal elements , such as copper (Cu) , lead (Pb), zinc (Zn) and cadium (Cd), in surface water of Tongling Section along Yangtse River. Our study results have shown that the amounts of their content are various in low-water and high-water seasons. In high-water season, the concentration of copper, lead and zinc existing in free ion form proves lower than in low-water season, but that of cadium proves just on the contrary. However, in the low-water season, about 80% of copper and cadium are free ions, with most of lead existing in its stable compounds. As to zinc, it appears to exit in two main forms: free ions and stable compounds. The ad-sorptive capacity of suspended particles in water to heavy metals is found to be arranged in the order :Pb>Cu>Zn>Cd respectively though the amounts of those metals in the suspended particles,are quite different. However, in general, the present study reveals that the content of such heavy metals in the surface water has increased slightly compared with the data gained in the middle of 1980s.