汤溪水库富营养化特征与水质管理对策

通过2003年对广东省汤溪水库水生态学进行调查,分析了该水库的富营养化特征,并从流域管理和水动力学两个方面对水库水质管理对策进行了探讨。汤溪水库为中度富营养化水体,具有明显时空分布差异,丰水期富营养程度高于枯水期,溪头河流区高于新桥河流区。蓝藻是水库浮游植物的主要优势类群,其中引发水华的铜绿微囊藻(Microcystisaeruginosa)为优势种。水库上游集水流域分布近30万居民,大量的生活排污和农业污染形成了主要的外源污染源,这些外源污染的输入是水库水体营养盐的主要来源;合理处理上游居民生活垃圾、减少生活污染中磷含量、增加流域和库区周围植被覆盖、合理使用农业化肥是降低水库表层水体中营养盐浓度的主要途径。由于该水库的蓝藻和富营养化水平直接与水体的稳定性有关,利用对水库排水的可控制性调节水库水体的稳定性,可作为控制蓝藻水华发生的有效途径。

Characteristics of eutrophication and water quality management strategies in Tangxi Reservoir

By surveying the hydrology, water quality and phytoplankton assemblage of the Tangxi reservoir in 2003, characteristics of eutrophication and water quality management strategies, which related to watershed management and hydrodynamics, were preliminarily discussed. This reservoir had a high trophic state index (TSI), ranging from mesotrophic statue to eutrophic state, and varying temporally and spatially. TSI in flood season was higher than those in dry season, and was higher in the Xitou riverine zone than in the Xinqiao riverine zone. Microcystis aeruginosa, a species causing algal blooms, dominated in spring and early summer. Nutrients input into the upper water column were mainly from land runoff, due to high population and heavy pollution in the watershed. Consequently, treatment of domestic waste and reasonable fertilization in agriculture and increasing vegetation coverage in the catchment of the reservoir are necessary for lowing nutrients loading to the water body. As strong water column stability is crucial to the occurrence of cyanobacteria bloom in this reservoir, regulating the outflow and destratifying the water column vertically, which can cause water column well-mixing, are recommended as a hydrodynamic method to control cyanobacteria blooming.