The Content Of Nutriments In The Overlying Water In Lakes Responds With The Processes Of Sediment Resuspension And Settlement

Lake Taihu and Lake Dongqianhu were selected to be investigated in this paper. Physicochemical characters of the sediment in 7 sites of the two lakes were analyzed. Processes of sediment resuspension and settlement were simulated in the lab. Changes of the content of nutriments in the overlying water, responding with the processes of sediment resuspension and settlement, have been analyzed systemically.Physicochemical characters of the sediment indicate that as follows, granularity of sediment affects the quantity of suspension. The deepness of corrasion connects with the porosity and the water content of the surface layer's sediment. The content of bio-available phosphorus of the sediment in different sites of Lake Taihu, mensurated by the method of FeO/CAM, consists with the degree of eutrophication in different sites. It shows that the phosphorus's availability is the mostly limiting factor of phytoplankton's growth in wide water areas.The corrasion depth conditioned on different stormy waves is less than 2 centimeter, normally, more strongly that the stormy waves disturb, the more nutrient matters will release from sediment to the overlying water. Except in the strong wind period, hydrophyte enhanced the stability of the sediment, and reduced the ability of sediment resuspension. Furthermore, dredging reduced the content of the suspension in the water evidently.The suspended particulate matter of Lake Taihu and Lake Dongqianhu sinks to the bottom in flocculation state. In the process of settlement, except for that the sediment of East Lake Taihu put up much stronger ability of adsorption, the sediment of other sites released more nutrient matters to the water momently, after that, the content of nutrient matters in the overlying water reduced slightly to a level of stabilization. In the processes of sediment resuspension and settlement the nutrientconcentration enhanced suddenly, which showed that dynamic function is the mostly drive function of sediment resuspension and nutrient matters releasing in shallow lake.