夏季短期调水对太湖贡湖湾湖区水质及藻类的影响

Effects of short-term water diversion in summer on water quality and algae in Gonghu Bay,Lake Taihu

贡湖湾作为"引江济太"工程长江来水进入太湖的第一站,湖湾水体生态环境的变化是对调水工程净水效果的最好响应,因此本文针对贡湖湾一次夏季短期调水展开调查研究,分别取2013年7月24日(调水前)和2013年8月18日(短期调水后)两次监测水样的水体理化指标和浮游藻类群落数据进行了对比分析,并对浮游藻类群落与环境因子做了相关性分析.结果表明:受来水影响,短期调水后监测区水体的p H略有下降,溶解氧、浊度、硝态氮、总氮、总磷以及高锰酸盐指数等水体理化指标浓度均较调水前有所升高;其中受调水影响最为显著的区域为望虞河的入湖口区、湾心区.两次监测调水前后湖区水体优势藻种属未发生变化,仍以微囊藻为主,但蓝藻种属比例有所下降,绿藻和硅藻等种属比例则有所上升.望虞河入湖口区和贡湖湾湾心区的Shannon-Wiener多样性指数和Pielou均匀度指数受调水的影响升高.同时,浮游藻类群落结构与受水水体理化参数的冗余分析结果表明,此次监测的短期调水后,太湖贡湖湾监测湖区水体p H、溶解氧、硝态氮、总氮、总磷、高锰酸盐指数等环境因子与浮游藻类的群落分布呈显著相关,是影响受水水体中藻类群落的主要环境因子.

As the first stop that"Water diversion from Yangtze River to Lake Taihu"project water flowing into,Gonghu Bay is the base place to evaluate the water ecological environment changes in response to the project. In this paper,a short-term water diversion in summer in Gonghu Bay is investigated. The physical and chemical indicators and phytoplankton community of the two monitoring water samples before( July 24,2013) and after short-term water diversion( August 18,2013) is compared and analyzed,and then the relationship between phytoplankton community and environmental factors is analyzed. Our results showed that the short-term water diversion in summer had a significant effect on the water quality in Gonghu Bay. After short-term water diversion,the p H value of the water body in the monitored area decreased slightly. The values of turbidity,dissoved oxygen( DO),nitrate nitrogen( NO-3-N),total nitrogen( TN),total phosphorus( TP) and permanganate index( CODMn) in the monitoring area during the water diversion were higher than those before water diversion. The most significant area affected by the water diversion was the entrance to Gonghu Bay of Wangyu River and the middle area of Gonghu Bay. Dominant genus of algae is still microcystis,while the proportion of cyanobacteria species decreased and non-blue algae species such as green algae and diatoms increased. Affected by the water diversion,Shannon-Wiener diversity index and Pielou evenness index in the entrance to Gonghu Bay of Wangyu River and the middle area of Gonghu Bay were increased as well. However,the short-term water diversion in summer didn't significantly affect the algal community structure in the middle area of Taihu Lake. Meanwhile,the redundancy analyses of phytoplankton community structure and environmental factors by the use of CANOCO software showed that the p H,DO,NO-3-N,TN TP and CODMn were significantly correlated with the distribution of phytoplankton community in Gonghu Bay of Lake Taihu,which were the main environmental factors influencing the phytoplankton community.