| Causes and control of eutrophication is a hot research subject in the world. In this MasterDissertation, Microcystis aeruginosa, one of the most typical algae in euthrophic water body, waschosen as the model algae and design of experimental condition was based on water quality andso on in some reservoirs used as water supply sources. The effects of ratio of nitrogen andphosphorus(N/P), single or multiple phosphorus sources, flow disturbance and other factors onthe growth, phosynthetic activity and biochemical composition of M. aeruginosa were studied inorder to provide scientific basis of effective control over the eutrophication problem in reservoirs.The following results and conclusions were made by experimental study:1）Maintaining the nitrogen concentration in the raw water, the effection on the growth ofM.aeruginosa using the K2HPO4as phosphorus source was studied. Test groups with Pconcentration5-1,000μg/L impact greatly on algae growth, which30μg/L gradually increases inthe cell density and growth rate. Thus, low、medium and high levels are set for the subsequenttest, which are5μg/L、30μg/L and1,000μg/L.2） Three kinds of phosphorus source: K2HPO4, β-glycerophosphate and sodiumpolyphosphate are selected to study the effection on the growth of M.aeruginosa under differentconcentrations. In the test, the higher concentration the more promotional for the growth of algae,which have faster growth in the medium and high concentration. Different phosphorus sourcescause different growth rates, sodium polyphosphate are much affected but β-glycerophosphatehave little effect in the low and medium concentration. Fv/Fmdeclines rapidly in K2HPO4, whichmeans the electron transfer of M.aeruginosa was significantly inhibited. And Fv/Fmare always ata high level in medium and high β-glycerophosphate, which means the photosynthesis has awider adaption range in β-glycerophosphate. The growth rates of EEM of intracellular andextracellular descript K2HPO4is absorbed in a shorter time, and sodium polyphosphate promotethe growth in the latter. 3）Setting up the experiments of composite phosphorus sources by taking into accountM.aeruginosa may use up a variety of phosphorus source in the actual water. The cell densityand growth rate in composite phosphorus sources are bigger than what in simple sources.M.aeruginosa can absorb more phosphorus fastly and produce more protein in compositephosphorus sources of K2HPO4and β-glycerophosphate. However, composite phosphorussources have worse promotion in photosynthetic activity than simple sources.4）Disturbance environment of this study was created by using shaker in laboratory. Thedisturbance effects on M.aeruginosa growth under different phosphorus source were researched.In the four kinds of disturbance velocity, the test groups of sodium polyphosphate have thehighest cell density level in10th day. The level of cell density cultured10th day is by order of30r/min、0r/min、50r/min、70r/min, which points that flow rate would affect the growth ofM.aeruginosa exceeding a certain level.5）The effect of flow rate and phosphorus on photosynthetic quantum yield of M.aeruginosais complicated. The photosynthetic quantum yield of M.aeruginosa is improved by the30r/mindisturbance velocity in K2HPO4, which means the photosynthetic activity is promoted. Thephotosynthetic quantum yield is not significantly reduced in β-glycerophosphate, and it issignificantly reduced in sodium polyphosphate.6）As the cell density increasing, the FRI value of EEM gradually increases, where Ⅰ+Ⅱ,Ⅳ area have more obvious growth than Ⅲ,Ⅴarea. It means more aromatic substances andproteins associated with the biological activity are produced inside and outside of algal cells.7）The DOC datas at maximum cell density of all the test groups show that the more rapidgrowth of algae the less soluble organics intracellular and extracellular. A greater portion oforganisms produced by photosynthes may be used to synthesize the new algal cells. |
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