Abstract: Distribution of heavy metals (Fe,Mn,Cu,Zn and Pb) surficial sediments with water phase in the simulated system in a period of 45 d w as investigated via a modified sequential extraction procedure, and pH, Eh and enzymes (protease, dyhydrogenas, sucrase and phosphatase) were monitored simultaneously. The resultsindicate that exchangeable manganese was converted into carbonateassociated fractions (10.2%) and Fe/Mnoxides fraction (32.1%), respectively, 11.5% zinc was found to exist from exchangeable to Fe/Mnoxides fraction, and organic matterassociated Pb was observed to increase by 20.1%. pH was variable in the first 20 d while Eh was fluctuated during the whole experiment. The activities of protease and dyhydrogenase were raised by a factor of 88.9% and that of 71.4%, respectively. The correlation analysis shows that pH was signifi cantly positively correlated with carbonateassociated Fe,Cu. Noticeable correlation was found between protease activity and Mn of carbonateassociated Fe/Mnoxide fraction, Zn of exchangeable Fe/Mnoxide fraction as well as Pb of organic mattersassociated fraction (n=8, p=0.05), and the similarcorrelative phenomenon was obtained between dyhydrogenase and Pb of carbonateassociated fraction, implying that the enzyme is one of the most important factors in transforma tion and cycling of heavy metals in surficial sediments besides pH.

Key words: surficial sediment, fractions of heavy metal, sequential extraction, protease, dyhydrogenase