Studying On Eutrophication Of Miytun Reservoir Water Body

The result of experiment in 2000 year and 2001 year suggests that primary productivity of Miyun Reservoir is decided by group constitution and cell density of phytoplankton. The character of nutrition is phytoplankton-responding type. The group structure belongs to Chlorophyta (51.64%) -Bacillariophyta (-28.68%) type. Cyanophyta, Pyrrophyta, Chrysophyta, Cryptophyta and Xanthophyta are 6.1%, 6.04%, 3.27%, 2.83% and 0.95%. Among the phytoplankton, the main are middle-nutrition designate kinds, such as Ceratium, Fragilaria, Cyclotella and Cosmarium. There are some eutrophicational designate kinds, such as Scenedesmus, Chlorella, Microcystis and Synedra.From the result of cell density we can see that the phenomena of vertical distribution of phytoplankton group is very obvious. The cell density of upper layer is more than that of middle layer and the cell density of middle layer is more than that of bottom layer. The cell density of phytoplankton in Miyun Reservoir is becoming more and more.The amount of Chlorofucine a (chla) changes with season and water depth. In Miyun Reservoir, the amount of chla adds up gradually in April, June, August, October and decreases with addition of water depth. The amount of chla in 2001 year is more than last few years.General tropic state index of PH, SD, TP, TN, BOD, COD and chla suggests that water body of Miyun Reservoir already belongs to middle nutrition and there is the tendency to eutrophicate.AGP test proves that the amount of phosphorus obviously affects growth and reproduction of phytoplankton. When phosphorus concentration achieves to 0.065mg/L, phytoplankton would reproduce rapidly. So the water body of Miyun Reservoir belongs to phosphorus-controlling type.Many factors affect the water- quality of Miyun Reservoir. Main polluting resources are dot polluting resources, side polluting resources and interior polluting resources. Interior polluting resources includes mainly matter in bottom earth and interior lake.Severe freshwater resource in Beijing seriously restricts people's life, development of economy and Olympic Games of 2008 year. In order to protect water quality and achieve persistent use of Miyun Reservoir, we should exert ourselves to govern dot polluting resources, cut down side polluting resourcesand interior polluting resources, regulate economic structure of vally, achieve to good cycle of ecological system.