Dynamic simulation study on inner source nutrient exchange between water-sediment interfaces in the Xuanwu Lake

The distributed sediment samples in the Xuanwu Lake were collected to analyze the influence on the water quality of nutrient layer distribution condition in sediments and its physical and chemical characteristics.Through the dynamic water exchange experiments,we estimate and rmdel quantitatively the releasing process of nutrient from the sediments,the influence mechanism of consequent concentration variation of T-P and T-N in above water to the interfacial material exchange correlation of the Xuanwu Lake eutmphication.The research results show that even if the pure water is used to exchange the polluted water in the lake,after a long time exposure of surface layer sediment,a great deal of organic and integrated nutrients wauld degrade into inorganic nutrient.In the early exchanging of lake water the released T-P and T-N increase continually acting as the service to inter pollution sources.This is mainly owing to the vertical distribution of T-P and T-N in the bed sediment collected during the dry period of the Xuanwu Lake.In the long run,the concentration of T-P in the above water will maintain at a high level of 0.1mg/L.The above research results provide theoretical and practical basis for relevant ecological restoration project.