The Denitrification Potential Of Minjiang Estuarine Wetland

The denitrification of estuarine wetland played an important role in reducing eutrophication. However, there is little information available on denitrification in Min River estuarine wetland. The soils of Tajiaozhou, Bianfuzhou and Shanyutan wetlands along Min River estuary were chosen as study objects in this paper. The anaerobic submerged incubation method was applied to measure the denitrification potential of soils in three wetlands, and soils in different vegetation types of marshes in Shanyutan wetland, respectively. Moreover, the effects of the salinity to the denitrification of wetlands were simulated. The results could provide basic data for further study of nitrogen cycle and the reasonable development and protection of Minjiang estuarine wetland.The results indicated that:(1) The soils denitrification potential of three wetlands which were covered by Cyperus malaccens were different. The denitrification potential of Shanyutan was much higher than Bianfuzhou and Tajiaozhou (P<0.05), and Bianfuzhou was much higher than Tajiaozhou (P<0.05)The highest denitrification potential was appeared in40～50cm soil layer of Tajiaozhou and Shanyutan, which indicated that under the premise of relatively abundant nitrogen and carbon sources, the denitrification potential of the subsoil layers in Tajiaozhou and Shanyutan should not be ignored.Through the integrated approach of principal component analysis and stepwise regression analysis, the results showed that the soil denitrification potential of Tajiaozhou, Bianfuzhou and Shanyutan wetlands at Minjiang estuary was mainly affected by soil electrical conductivity and soil particle composition. And soil organic matter had significant effects on the denitrification of wetlands.(2) There were no significant differences among the denitrification potential of the surface soils of Cyperus malaccensis marsh in Tajiaozhou wetland under the different salinity conditions, which was0,5,15and25, respectively. The order of salinity according to denitrification potential was:15>0>5>25. (3) The soils denitrification potential of Phragmites australis, Cyperus malaccensis and Spartina alterniflora marshes were not different significantly. The denitrification potential ranked from highest to lowest as:Phragmites australis>Spartina alterniflora> Cyperus malaccensis, and the variation was mainly affected by the contents of soil organic matter and moisture of the soils in different vegetation types of marshes.