【摘要】 三峡水库一期工程蓄水近两年(2003年7月—2005年4月)期间,库区发生过多次藻类“水华”,尤其在阳光充足、气温回升的春季。经鉴定形成水华的藻类主要有拟多甲藻(Peridiniopsissp1,sp2),新星形冠盘藻(Stephanodiscusneoastraea),里海小环藻(Cyclotella caspia),湖沼红胞藻(Rhodomonas lacustris),实球藻(Pandorina morum)和空球藻(Eudorina elegans);其中以拟多甲藻水华涉及面积最大,持续时间最久,污染程度最为严重。通过对拟多甲藻水华水及其藻细胞提取液的生物毒性测试,表明其对其他水生生物和小白鼠没有明显的生物毒性。更多还原

【Abstract】 The paper represents the phenomenon of water-blooms occurring in Three Gorges Reservoir from July 2003 to April 2005.During this period,algal water-blooms occurred for many times,especially in spring when the water temperature rised gradually and sunlight becomed abundant.The main taxa of water-blooms were Peridiniopsis sp₁,Peridiniopsis sp₂,Stephanodiscus neoastraea,Cyclotella caspia,Rhodomonas lacustris,Pandorina morum and Eudorina elegans, in which water-bloom of Peridiniopsis sp₁ was the most serious one.When water-bloom of dominant specie Peridiniopsis sp₁ emerged,Cyclotella sp.,Cryptomonas sp.and Melosira sp.supplied much primary productivity too.The peak values of cell density and biomass of Peridiniopsis sp₁ were noted at 1 meter with cell numbers of 8.71×10⁶cells/L and the wet weight of 69.65mg/L.The minimal values of two indexes were both noted at bottom layer with 4.58×10⁵cells/L and 3.67mg/L.Other algae also represented their own distribution orderliness.Contrasting cell densities and biomass of different algae,we educed that primary productivity was supplied by Peridiniopsis sp₁ due to its great cell volume and huge cell numbers.For proving up whether Peridiniopsis sp₁ water-bloom produced toxin and brought effects on human’s drinking water,we made out toxicological experiments on water-bloom water and algal distilled solution.The water sample taken in Tongzhuang River was filtered through Whatman GF/C filters（0.45μm）to remove natural particles and other organisms prior to experiment.We prepared seven testing medium,namely original water,original water+N,original water+P,original water+N+P,original water+full nutritional elements in BG11,autoclaved original water and BG11.The tested alga was Scenedesmus obliquus and the original cell density was 7.5×10⁵（cells/L.） The culture vessels was 150mL autoclaved glass flasks containing 100mL water.The flasks were incubated at 20℃ with a light intensity of 50—70μmol/m²/s.Bottom light was supplied at all times.The samples were cultured for sever days and the algal growth was examined everyday by light absorbance values(OD₆₅₀).The experiment was repeated three times and results were analysed with percentage to contrast.The Peridiniopsis sp₁ for mouce toxic bioassay was also taken in the Tongzhuang River with 25^# phytoplankton net.Zooplankton and other impurities were removed by filtering and centrifugating.Algal distilled solution was obtained by freezing and skiving repeatedly,also centrifugating with 10000r/min at 4℃.The expeiment was performed in six groups and ead each group has three mice.Different concentration of algal distilled solution（1、1/2、1/4、1/8、1/16）was injected in（mice’s） abdomen.The control group was 0.9% NaCl solution. By observing mice’s feedback symptom and it’s weight change,we judged whether mice were poisoned.According to the results about the toxic tests,the authors elicited primarily that the water-bloom of Peridiniopsis sp₁ had no obvious bio-toxicity to other aquatic organisms and small white mouse.Analysing many factors affecting water-blooms in Three Gorges Reservoir,we considered that water-blooms were caused by industrial effluents,life sewage export,slow current speed and appropriate temperature and so on.In addition,wind changed distribution state of water-bloom algae;It was that ship and water bird played a accelerated pole in algae movement.And also,temperature change and raining affected kinds of water-bloom algae and time of water-bloom lasting.We put forward primarily two ways to prevent water-bloom in Three Gorges Reservoir,namely reducing nutrients input and increasing water velocity.更多还原