黄河沉积物中重金属离子的形态转化及释放研究

A Study on the Transformation and Release of Heavy Metals in the Yellow River Sediments

以黄河包头段上游清洁河段的沉积物为吸附剂,以Pb2+、Cu2+、Zn2+、Cd2+等多离子溶液为吸附质,开展了重金属离子被黄河沉积物吸附后的再释放,以及吸附作用对重金属形态转化的影响等实验研究.结果表明,重金属离子被黄河沉积物吸附后,各元素均不转入残渣态,Cu2+和Zn2+主要向碳酸盐结合态及铁锰氧化物结合态转化,Pb2+主要向碳酸盐结合态和可交换态转化;Cd2+主要转入可交换态和碳酸盐结合态.吸附后的赋存形态决定了Cd2+的释放量及释放能力远远大于其它3种重金属离子,由Cd2+排放引起的污染不易消除且影响长久.

Taking the sediments from the clean reach in the Baotou Section of the Yellow River as the adsorbent, and the solutions containing Pb^(2+), Cu^(2+), Zn^(2+) and Cd^(2+) as the adsorbate, we carried out experimental research into the effect of the Yellow River Sediments on the release and form transformation of heavy metals. The result of the experiment on the form transformation of heavy metals shows that none of the heavy metals has transformed into the residual form. Instead, Cu^(2+) and Zn^(2+) have mainly transformed into the carbonate bound form and the Fe_Mn oxides bound form, Pb^(2+) mainly into the carbonate bound form and the exchangeable form, Cd^(2+) mainly into the exchangeable form and the carbonate bound form. The release experiment suggests that the release capacity of Cd^(2+) is much greater than those of the other three heavy metals. Its adsorbed forms determine the release capacity; therefore, it is difficult to eliminate Cd^(2+) pollution.