Allocation and Circulation of Phosphorus in Artificial Wastewater within a Simulated Mangrove Wetland System

A greenhouse experiment was performed to research the behaviour of phosphorus in artificial wastewater within a simulated mangrove wetland system.It consisted of oneyear old seedlings of Kandelia candel,sediment and tidal water.Three treatment of artificial wastewater with different concentrations,namely C1,C5 and C10,were discharged into the system.C1 had the characteristics and strength similar to normal municipal sewage while C5 and C10 contained five and ten times of the nutrients and heavy metals as that in C1,respectively.Artifical seawater of 15‰ salinity was used as the control.The contents of total phosphorus in tidal waters,sediments,seedlings and litters were determined.Results showed that the total phosphorus in artificial wastewater discharged into the systems stagnated mainly in soil subsystem and only small amount in seedlings and litters.In wastewater treatment groups,the total phosphorus which were assimilated by seedlings retented mainly in living leaves,differing from the control group which were mainly in roots.In the control,C1,C5 and C10 groups,the circulation times of phosphorus uptaken by seedlings were about 67 years,82 years,92 years and 58 years,respectively.They were shorter than that of 20 years Kandelia community.The removal rate of phosphorus by the wetland system were 8871%,8924% and 8834%,respectively in C1,C5 and C10 groups.