扬水曝气对峡谷分层型水库藻类控制机制研究

Mechanisms on algal bloom control in canyon stratified reservoir by water lifting and aeration

为探明扬水曝气对峡谷分层型水库中不同径向藻类生物量和结构的影响,以李家河水库为对象,对扬水曝气系统(WLAs)运行期间水体理化性质参数和藻类数量及物种进行了高频监测,采用藻类传统和功能分类法,建立了控制条件下藻类的演替规律和控制机制.结果表明,WLAs运行12d后,径向S1~S4点藻密度削减率分别为92.7%、92.9%、92.1%和89.2%;径向S1~S4点藻属结构发生演替,绿藻(珊藻)和硅藻(短缝藻和羽纹藻)转向硅藻(针杆藻,小环藻),即“高温、大型且低比表面积(S/V)藻”转向“低温、小型且高S/V藻”;水温、光可利用率(Zeu/Zmix)、营养盐的降低和混合层深度(Zmix)的增加是扬水曝气系统控藻的主要原因;径向S1~S4点Q指数升高且TLI指数降低,表明富营养化得到改善.

To explore the effects of water lifting and aeration(WLAs)on the algal biomass and structure in different radial directions in canyon stratified reservoir,the Lijiahe Reservior(LJHR)was select to obtain the succession pattern and control mechanism of algae based on the high-frequency monitoring of water physicochemical parameters and the number and species of algae during the water lifting and aerators(WLAs)operation.These results showed that the reduction rates of algal cell density in the sites from S1to S4were 92.7%,92.9%,92.1%and 89.2%,respectively,after 12 days of the WLAs operation.The algal structure in the sites from S1to S4was changed,with the shift from Chlorophyta(Scenedesmus)and Bacillariophyta(Eunotia and Pinnularia)to Bacillariophyta(Synedra and Cyclotella)(i.e.,high-temperature,large,and low surface to volume(S/V)algae"to"low-temperature,small,and high S/V ones).The reduction of water temperature,light availability(Zeu/Zmix),nutrients,and an increase in mixing depth(Zmix)were the main drivers for the algal control by WLAs.The increase of phytoplankton assemblage(Q)index and decrease of the trophic level index(TLI)in the sites from S1 to S4,indicated the eutrophic improvement.