Abstract:

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.

Key words: Oxidized sediment; Anoxic sediment; Heavy metal; Speciation pattern; Acid volatile sulfide