Abstract:

In the July of the year 2008，the purification effects of the sphagnum wetland in Dajiuhu basin of Shennongjia mountains on metal ions Cd(Ⅱ)，Cu(Ⅱ)，Pb(Ⅱ)，Zn(Ⅱ) were studied using simulated wetland on the basis of the research in August，2007.The results indicate that the removal capacity of the sphagnum wetland was obvious for all the contaminant.In two hours，the removal effect decreased in the order：Pb>Cu>Cd>Zn.The removal rate at any time point increased with the augment of the initial concentration for all the metals.It takes longer time to reach equilibrium for the polluted solution with higher initial concentration.The dilution effect of the sphagnum wetland played an important role in the purification process.The relationship between removal rate and experiment time can be obtained by the twoconstant rate model.Both of the modified pseudofirst kinetic model and the pseudosecond kinetic model fitted the experimental data well，but the latter has a better fitness.The contribution ratio of dilution to the removal effect can be calculated using the modified pseudofirst kinetic model.The article provided scientific basis for evaluating the purification value of the sphagnum wetland，and for protecting and using it reasonably in the future.

Key words: Dajiuhu basin of Shennongjia mountains/ sphagnum wetland/ simulation test/ purification/ kinetic model