密云水库蓄水量激增对浮游植物结构的影响

Effect of water surge period on phytoplankton structure in Miyun Reservoir

基于蓄水量发生剧烈变化,对密云水库库区浮游植物结构变化进行探究,寻找规律。结果显示:密云水库蓄水量的大幅上升,浮游植物种属数量增加26种,蓝藻增加11种,绿藻增加8种,硅藻增加4种,其他藻类增加3种;水体环境的变化使得浮游植物种类数量增加,优势群落结构发生变化,但仍以蓝藻、绿藻、硅藻为主,蓝藻数量比例先下降后上升,绿藻数量比例下降,硅藻数量比例先大幅上升后小幅下降,密云水库由蓝-硅-金藻类型水体转变成硅藻型水体;蓄水量大幅上升,导致浮游植物细胞密度下降,由970万个/L下降至580万个/L;蓄水量上升的过程中,Shannon指数、Margalef指数和Pielou指数的变化范围分别为0.36~1.04、0.72~9.91和0.48~0.89;水温和营养盐是密云水库浮游植物群落结构的主要影响因子,蓄水量快速上升使得密云水库表层水温在不同时期和季节均略有下降,浮游植物密度下降;营养盐中氮元素含量的上升与磷元素的稳定为密云水库浮游植物群落结构的变化提供充足的支撑。分析结果能为密云水库高水位运行模式下水质水生态的变化提供参考。

This paper focuses on exploring the changes of phytoplankton structure in Miyun Reservoir area and looking for the law when the water storage changes sharply.The results showed that the warter storage of Miyun Reservoir increased significantly,the number of phytoplankton species increased by 26,cyanobacteria increased by 11,green algae increased by 8,diatom increased by 4 and other algae increased 3.The change of water environment increases the number of phytoplankton species and changes the dominant community structure,but it is still dominated by cynobacteria,green algae and diatom.The proportion of cyanobacteria fist decreases and then increases,the proportion of green algae decreases,the proportion of diatom first increase sharply and then decreases slightly. Miyun Reservoir changes from blue diatom type water body to diatom type water body, and the water storge increased significantly,resulting in the decrease of phytoplankton cell density from 9.7×10~6 drop to 5.8×10~6 PCs./L.In the process of warter storage rising, Shannon index,Margalef index and Pielou index vary from 0.36 to 1.04,0.72 to 9.91 and 0.48 to 0.89 respectively. Water temperature and nutrients are the main factors affecting the phytoplankton community structure of Miyun Reservoir.The rapid rise of water storage makes the surface water temperature of Miyun Reservoir decrease slightly in different periods and reasons, and the phytoplankton density decreases.The increase of nitrogen contend in nutrients and the stability of phosphorus provide sufficient survival support for the change of phytoplankton community structure in Miyun Reservoir. Through the analysis of this paper,we hope to provide reference for the change of water quality and warter ecology under the high water level operation mode of Miyun Reservoir.