关键词: 密云水库, 浮游植物群落, 中营养

Abstract: This 1998 research found that the structure of the Miyun reservoir phytoplankton community was of a diatom-green algae type, and the cell density is 358.76 ×104·L-1. The nutritive peculiarity belongs to responding type of phytoplankton. From 1988 to 1998, the total nitrogen of water body increased by 48.7% and total phosphorus of water body increased by 31.2%. Over this period the cell density of phytoplankton also increased by 41.7%. The water body of the lake has reached a medium level of nutrition and eutrophic phytoplankton, (e. g. Scenedesmus obliquus (Turp.) Kütz. , Microcystis aeruginosa Kütz. and Chroococcus limneticus Lemm. ) are now common in the lake. The water body, which supplys water for Beijing, is approaching a eutrophic condition. In order to maintain the water quality and production of Miyun reservoir, it is essential that the water environment of the valley is protected and the vegetation cover of the valley is increased.

Key words: Miyun reservoir, Phytoplankton, Middle nutrition