三峡库区支流回水区水体分层与藻类生长

【摘要】三峡水库自2003年蓄水以来,库区支流形成了长短不一的回水河段,缓慢的水流和蓄积的营养盐导致回水河段由库区蓄水之初在短时间内出现水华,逐步发展到一年内水华可维持数月。为了研究回水区水环境与水华发生的关系,从2013年4月—12月,对库区北岸最大支流澎溪河的长年回水区——高阳平湖进行了定点监测。监测结果显示,季节性变化及三峡库区特殊的调度方式,导致高阳平湖水体在春、夏和秋季有明显分层。春季水华期间藻类群落结构单一,只出现4门9属,以蓝藻门的微囊藻(Microcystis)、绿藻门的实球藻(Pandorina)和空球藻(Eudorina)为主,秋季藻类结构组成增至7门52属,优势属逐渐被硅藻门的小环藻(Cyclotella)和针杆藻(Synedra)取代,水体各层藻类细胞密度差异消失。研究结果说明高阳平湖水体分层状况影响藻类生长和分布。

【英文摘要】Since the impoundment of the Three GorgesReservoir (TGR) in 2003，backwater areas with various extents in the tributaries have formed． Within the short period ofimpoundment，algae bloomoccurred due to low velocity of water and accumulated nutrients in thebackwater areas． Moreover，the duration of algae bloom couldvary from several days to months annually． In order to find out the relation between the water environment andalgal bloom in backwater area，sampling at multiple site were conducted from April to December in2013．The studysites are located in Gaoyang Lake，the backwater area in Pengxi River，the largest river in the north bank of Yangtze River． Results show that a clear thermalstratification was found at the vertical profile of water column in spring，summer and autumn． In late spring when algal bloomhappened，the algalcommunity consisted of 9 genera of 4 divisions，mainly composed by cyanophyta and chlorella groups，and the first dominant genus wascomposed by Microcystis，Pandorina and Eudorina． However，as the seasons altered，algae structures increased to 52 genera of 7 divisions in autumn． The first dominant genus was replacedby Cyclotella and Synedra，and the different in the average cell abundance at multiple layersdisappeared． Consequently，a conclusion that waterstratification affects the growth and distribution of algal community onGaoyang Lake is proposed．