Removal of Nitrogen and Phosphorus in Riparian Buffer Zone of Wetland

WANG Lei1,2,ZHANG Guang-xin1(1.Northeast Institute of Geography and Agricultural Ecology,Chinese Academy of Sciences,Changchun 130012,China;2.Graduate University of Chinese Academy of Sciences,Beijing 100049,China)

wetland buffer zone;nitrogen and phosphorus removal;denitrification;absorption

Wetland buffer zone,lying on interface between aquatic ecosystem and terrestrial ecosystem,plays a special function in purifying water pollution.A riparian wetland profile was chose as target in Zhalong wetland in the present investigation,because of few researches on purification of natural wetland.Conductivity was used to judge groundwater flow direction,while chlorine ion as a tracer was employed to explain the single water resources in the profile.The results showed that wetland buffer zone had obvious purification function in removing nitrogen(N) and phosphorus(P) nutrients.The removal rates of total N and total P were 74.1% and 84.6%,respectively.Plant absorption was not the main mechanism in reduction of both N and P,due to less plant biomass on wetland buffer zone.According the concentration variation of DOC and HCO,denitrification was considered as the major mechanism in decreasing N.At the end of the profile,stronger N retention capability was believed to be contributed by high groundwater level and flourishing plant.Both soil absorption and deposition were considered as major processes of P removal.Strong P retention capability was attributed by higher P concentration at the start of the profile.Therefore,it is propitious to control wetland eutrophication by utilizing and intensifying natural purification of wetland buffer zone.