Decomposition Process Of Submerged Macrophyte Hydrilla Verticillata And Influence Of Biomass On Nitrogen Of High Denitrification Nitrogen Water

As a key aspect of material cycle and energy flow of lake ecosystem,decomposition of lake aquatic plants is one of the main process of maintaining the lake ecosystem functions.Currently,because of serious eutrophication of lakes and pollution situation of nitrogen,this research investigates the decomposing process of submerged macrophyte Hydrilla verticillata and environmental factors of decomposing process,with an aim to study the on influence of submerged macrophyte decomposing on the nitrogen cycle of lakes.This study involves two aspects:(1) Used common submerged macrophyte Hydrilla verticillata as experimental materials,simulated three different the temperature gradient and nutritional conditions, carried on a 64 days Hydrilla decomposition experiment.The total weight of the plant and carbon and nitrogen removal process was analyzed.The results showed that decomposition process of submerged macrophyte Hydrilla verticillata has obvious phase, C,N elements of plants body in the decomposition process performanced that the content of carbon decreased and nitrogen content increased during the experiment,It is of inseparable among change of Hydrilla verticillata biomass.The change of Hydrilla verticillata biomass was directly affected by total nitrogen and organic carbon.And its decomposition rate were significantly correlated with the surrounding environmental factors,temperature and nutritional conditions.(2) A decomposition experiment of common submerged macrophytes,Hydrilla verticillata,was carried out a period of 32 days,by introducing sediments from Taihu lake overlying the water which initialρ(NO₃^-) content was 15 mg/L.The early spring's temperature was simulated when submerged plants were decomposed in large-scale.The results showed that the impact of Hydrilla verticillata decomposition on nitrogen concentration(ρ(NO₃^-) andρ(NH₄⁺)) in water Was U-shaped.The nitrogen concentration was lowest in the experimental conditions,when biomass decomposition was to 2 g (equivalent dry weight to 0.111 kg/m² ).With the decomposition of Hydrilla verticillata, the release of organic matter and nitrogen into the water increased,but at the same time, increasedρ(TOC)/ρ(NO₃^-) ratio,lower Eh,and increased microbial activity is conducive to the occurrence of denitrification.The results would provide theoretical basis for aquatic plant management.