氧化与还原条件下伊通河长春区段沉积物重金属形态特征的对比研究

利用改进的Tessier连续萃取法研究了伊通河长春市自由大桥处不同深度沉积物样品在氧化及还原条件下Cu,Pb,Zn和Ni的形态变化规律,同时分析了沉积物样品中酸可挥发性硫(Acid volatile sulfide,AVS)和同时提取重金属(Simultaneous extract metals,SEM)的含量. 实验结果表明，样品经干燥、研磨处理后,Cu有机/硫化物结合态比例减少40%,锰氧化物结合态的比例显著增加; Pb,Zn和Ni 3种元素有机/硫化物结合态比例均略有下降,变化幅度小于Cu,并重新分配到不同的化学相中. 通过SEM中各金属含量与有机/硫化物结合态中金属含量的对比可知,还原性沉积物中Cu除了与硫化物结合外,很大一部分是以有机物形态存在的,Pb,Zn,Ni,Fe和Mn则主要以硫化物形态存在,各元素形态分析均不同程度地受到萃取剂的影响.

Comparison of Speciation Patterns of Heavy Metals in Yitong River Sediments under Anoxic and Oxidized Conditions

Anoxic sediments could be oxidized by extraction reagent and by air in dryness pre-treatment procedure, which resulted in different impact on speciation patterns of heavy metals during the sequential extraction procedure. The speciation patterns of Cu, Pb, Zn, Ni in different depths sediments in Yitong River under Ziyou Bridge of Changchun City were investigated by the improved Tessier sequential extraction schemes under anoxic and oxidized conditions, and AVS(acid volatile sulfide)and SEM(simultaneous extract metals)were analyzed too. The experiment results demonstrate that the percentage of Cu associated with organic/sulfide phase reduced 40% and that of Mn-oxide phase increased remarkably after dryness and grind pre-treatment procedure of sediments; the percentage of Pb, Zn, Ni in organic/sulfide phase slightly descended but less than Cu, and the redistributions are different for three metals. Comparing amounts of metals in SEM with that in organic/sulfide phase, the data indicate that Cu is mainly associated with organic materials other than sulfides, but Pb, Zn, Ni, Fe, Mn are predominantly associated with sulfides in anoxic sediments, and the speciation patterns for the metals were influenced on different degrees by extraction reagents.