| The dynamic change of phytoplankton community structure and biomass is amultiple result of the effects on the environmental factors in time and space. Researchon the growth of phytoplankton community structure and population dynamic is veryimportant to us to study the water ecological system and eutrophication control. Inorder to know the trend of the phytoplankton population growth dynamic and itsimpact factors, we did a long-term monitoring research on the phytoplankton in twocampus landscape waterbodies in Shanghai Normal University (Xuesi Lake and WestPond). As the two ponds are natural reaction pools, we can analyze the relationshipbetween the growth of phytoplankton and the natural factors. From July2012toAugust2013, we monitored the phytoplankton biomass and the change of the waterquality in Xuesi Lake. In the summer of2013, we monitored these indexes every dayfrom May5thto July26th. From November2012to August2013, we monitored thebiomass of Microcystis and water quality of the West pond, and we did it every dayfrom May5thto August2ndin2013. In November2012, we applied a complexmicrobial inoculum on water purification in west pond. And the main results are asfollow:1.53genus of8Phylum including91species were identified in Xuesi Lake. Themain dominant species are: Pseudoanabaena sp., Synedra acus and Euglena proxima.The biomass in this lake is2.6-40.0*107cells/L. It is higher in summer than in winter.The main environmental factors related to the phytoplankton community are: watertemperature, total nitrogen, total phosphorus, and the proportion of nitrogen andphosphorus. The biggest influence on Cyanophyta biomass is water temperature. Thebiggest influence on Bacillariophyta biomass is total phosphorus. The biggestinfluence on Dinophyta and Euglenophyta biomass is water temperature and totalnitrogen. The water temperature was the most important factor which influenced thepopulation of phytoplankton. 2. Pseudoanabaena sp. growed better with the water temperature rising when thetemperature is below30.0℃, but when the water temperature is higher than30.0℃,it is harmful to this species; Water temperature negatively correlated with the biomassof Synedra acus; The water temperature about23.3℃was suitable for Cryptomonaseros growing, and this species like wet weather with weak light. High watertemperature and high light maybe is not good for its growth; When the watertemperature is higher than28.8℃, Euglena proxima formed blooms; The growth ofScenedesmus and Tetraedron is very similar.3. The population density of Microcystis has significantly positive correlationrelationship with the water temperature in the West Pond, and the correlation index is0.84. In sunny day, when the water temperature is about28.62℃, Microcystisgrowed very fast. When the water temperature is around24.41℃, they growedsteadily. When the water temperature is higher than29.72℃, it’s difficult for thisspecies to have cell division. In the West Pond, the fastest cell division speed was5.25*108cells/L/day. The cells growth rate was138.2%than the previous day. Inhigh temperature, the division speed was influenced by water temperature, but thehigh water temperature did not affect the photosynthesis of Microcystis. When thewater temperature was below32℃, the intensity of photosynthetic became strongerwith the water temperature. There is no obvious change of the size of Microcystis indifferent layers of West Pond.4. The LH-1had obvious effect on water purifying in the Xuesi Lake and theWest Pond. After13days of the treatment in the West Lake, the COD removal ratewas79.5%; the TP removal rate was74.6%; the TN removal rate was71.3%. Thewater transparency increased from30cm to65cm, which was increased by117%.The Microcystis density dropped to7.5*106cells/L from7.8*107cells/L. Thechlorophyll-a removal rate was76.3%. This kind of complex microbial inoculum hadobvious purification effect on landscape water pollution treatment, and it had certaininhibitory effect on phytoplankton. But the effect rebounded after20days. |
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