Distributing Of Phosphorus And Release In Sediment Of Shanzai Reservoir

Shanzi reservoir is the second drinking water source for Fuzhou city. Because of erroneous management, the water quality was deteriorated, so arose the eutrophication. So in 2000. measure of protection and management were taken. But period of time after intercepting the runoff around the bank, the degree of eutrophication isn't be improved better, so the pollution of endogenesis become the focus. When the exterior input was reduced, the phosphorus in the sediment was released in favorable condition to supply the phosphorus in the water and maintain the phosphorus concentration balance in the water. So the phosphorus in the sediment is another source of eutrophication. This paper is based the reasons above, study the rule of source and transference and transform and action and limit factor of nutriment and pollution, to protect water quality, to prevent deterioration of water quality, it's purpose is to offer scientific bases for government. Through the experiment, it elicited the conclusion as follows:1. The DO is high in winter and low in summer. The DO in surface layer is high, and it is become little and little, it is very low in the bottom. The surface layer is alkalescence, the PH in summer is higher than that in winter, but it is between 6-7 as acidity in the bottom. The ratio of nitrogen and phosphorus is 10, so that the phosphorus is the limitative factor. The content of phosphorus is seasonal, it is high in summer and low in winter, it is increasing along with depth.2.The content of phosphorus in sediment of Shanzi reservoir is high, the content of TP is 493.6~984.73mg/kg, The content of TP is different in different site and depth. Inorganic phosphorus is the highest, about 75% of TP. The highest content is Fe-P, it is about 28.15~51.55%. The second is Ca-P and Al-P. Inorganic phosphorus is different in different site. 3.We find that the main factor that influences the phosphorus release is concentration of phosphorus, temperature , DO and the dominating form of phosphorus- Fe-P. When the temperature is high, the DO become low, so thatthe microbes activate fast, that can help the release of OP and inorganic phosphorus. Because Fe-P is the main form, so that when the DO is very low, Fe3+ become Fe2+, the ability of Fe2+ combine with PO43+ feebleness, so that can help phosphate release from sediment.