Study Of The Form And Release Law Of Nitrogen And Phosphorus In The Sediment Of Yujia Lake

In recent years, with the rapid development of urbanization and industrialization, alarge number of municipal solid waste, household water and industrial sewage isdischarged into lakes. The exogenous pollution gradually deposited in the sediment at thebottom of lakes, and become the internal load of eutrophication. When external sourcepollution has been effectively controlled, pollutants accumulated in sediments will releaseto the overlaying water, increasing nutrient load of water body. Therefore, the study aboutthe morphology and emancipation of nitrogen and phosphorus in sediment has greatsignificance to control eutrophication.This paper surveyed the physical and chemical properties of the sediment andoverlaying water, and the speciation and distribution of sediment in the Yujia lake ofWuhan. Firstly, the paper makes the correlation analysis on the different morphology ofphosphorus. In addition, it used plexiglass column to simulate the static release ofsediment, and utilized the taper bottles oscillation to simulate the sediment releasing indifferent hydrodynamic conditions. And it maked a fitting of equation for the release lawof N and P in the sediment based on the result of the simulation experiments. Accordingto the WASP5, it establish the water quality model of N and P, applied to the study ofwater pollution of the Yujia lake，predicting the extent of eutrophication.According to the morphology analysis of phosphorus, TN and TP were high. Thesequence for different forms of P is as follows: Or-P> Fe-P> Ca-P> De-P> Ex-P> Oc-P>AI-P. TP and IP, Fe-P, Ex-P has significant correlation due to the correlation analysis.What’s more, the P load of sediment is closely related with the concentration of theoverlying water. The experiment on the static release of sediment demonstrates that thereleasing rate of N and P varies widely at beginning. As the experiment continued, thereleasing rate becomes gradually stabilized. According to the experiment on the sedimentreleasing in different hydrodynamic conditions, it indicated that the disturbance has a greatinfluence on the release of sediment. In addition, the releasing rate of different samplingpoints is different when the oscillation rate is same. The orthogonal test on the factorsinfluencing the emancipation of sediment show that the sequence for releasing strength as follows:> temperature> DO> pH. Finally, according to the WASP5, this paper establishthe water quality model of N and P, applied to the study of water pollution. It showed thatthe measured result and simulated result for NH₃-N, Or-P, COD and BOD₅are similar. Sothe applicability of the model for the Yajia Lake is high. And this paper discoved theextent of eutrophication for the Yujia Lake is serious based on the water quality model.