Study on Nutrients Release at Water-Substrate Interface of Constructed Wetland in Estuary Zone of Xinxue River, Nansi Lake, China

The substrate and in-situ overlying water of the riparian zones in Xinxue River were used to simulate nitrogen and phosphorus release through static incubation of sediment cores by controlling DO and diferent pH. The results showed that the wetland substrate was the sink of nitrogen and phosphorus for the overlying water, and the substrate had better characteristics in adsorption of ammonian(NH4+-N) and total phosphonts(TP) under the aerobic condition and alkaline condition. The intensity of substrate NH4+-N and TP adsorption was directly linear to the pH value. Under non-aerobic condition, the NH4+-N and TP adsorption fluxes were 52 and -0.15 mg/m(2).d (minus represents source), and after aerating, the NH4+-N and TP fluxes increased to 95 and 0.69 mg/m(2).d. The change of pH value and oxidation-reduction potential was one of the prime reasons on nitrogen and phosphorus release at water-substrate interface in Xinxue River wetland.