Abstract: The five step sequential extraction procedure developed by Tessier was used to investigate speciation of the heavy metal(Zn， Cu， Mn， and Cr) in poultry litter when sodium sulfide and sodium diethyldithiocarbamate were added during shake flask test. And the immobilization effects of sulfuring agents on heavy metals had been explored. From the results， it can be seen that with the addition of sulfurizing agents， contents of heavy metals with exchangeable and bound to carbonate speciation in poultry litter were decreased obviously. Preferable immobilization effect can be achieved when sulfuring agent dosage was 2g/kg. Sodium diethyldithiocarbamate have better immobilization effect on four heavy metals than sodium sulfide. When sodium diethyldithiocarbamate was added， contents of heavy metals with exchangeable and bound to carbonate speciation were still decreased evidently in slightly acidic condition. However， better immobilization effect of heavy metals can be obtained in neutral or alkaline environment when sodium sulfide was used as immobilizing agent. Analytical chemistry and structural chemistry analysis demonstrated that， when sodium sulfide was used as immobilizing agent， precipitation reaction may occur between sulfur ion(or its hydrolysis product) and heavy metal ions. Nevertheless， sodium diethyldithiocarbamate can immobilize heavy metals by the formation of stable four-membered ring chelates.

Key words: sodium sulfide, sodium diethyldithiocarbamate, poultry litter, heavy metals, speciation