Effects Of Nitrogen, Phosphorus And Light Intensity On The Growth Of Cyanobacteria In Qingcaosha Reservoir

Qingcaosha reservoir as the important source of water supply in Shanghai,Its construction is the most important project to realize the strategy of "two rivers and simultaneously,the three pillar".The maintenance and protection of water quality is great significance to the sustainable development of Shanghai city.However,after 2000,the big natural lakes appear large algae bloomsan and the lake’s eutrophication area increased dramatically.In recent years,it has been found that the eutrophication has been the trend of eutrophication.In order to explore what factors plays a major role on the growth of cyanobacterial In this experiment,we take the qingcaosha reservoir as the research object,to do the AGP and light intensity effect experiments.In response to the growth of cyanobacteria by changes in chlorophyll solubility during the growth of cyanobacteria.By analysis regularity of cyanobacteria growth under different limiting conditions.It provides theoretical basis and reference for preventing eutrophication and cyanobacteria bloom.The following conclusions are:(1)The resultof AGP experiment show that P is the main limiting factor for the growth of cyanobacteria.in qingcaosha reservoirs,The addition of P has a significant effect on the growth of cyanobacteria.The resultof AGP experiment show that N is not the main limiting factor for the growth of cyanobacteria.in qingcaosha reservoirs。The concentration of P in Qingcaosha Reservoir to maintain good growth of Anabaena fishes,outside P source added to the little effect on the growth.(2)Under the conditions of P concentration in this experiment,the Ks of microcystis aeruginosa and oscillatoria was much smaller than that of the three species.That meet the microcystis aeruginosa and oscillatoria phosphorus concentration is lower,The affinity of phosphorus is higher,The change of growth rate was greatly influenced by the phosphorus,when the P nutrition is rich in qingchaosha reservoir,Pseudanabaen。(3)under the conditions of N concentration in experiment,the Ks of anabaena and oscillatoria was much smaller than that of the three species.That meet the anabaena and oscillatoria phosphorus concentration is lower,The affinity of N is higher,The change of growth rate was greatly influenced by the N,when the P nutrition is rich in qingchaosha reservoir。(4)Anabaena,oscillatoria is not exactly the same.For exemple The light intensity is conducive to the growth of Microcystis aeruginosa,but the promotion effect is not obvious;the biological capacity of Anabaena is certain on steady stage,the light intensity only affect its growth speedin different light intensity,the maximum biomass and the maximum growth rate will not change with the change of light intensity,and the growth of the oscillatoriacells is basically the same.(5)Under the influence of the illumination condition,when the three algae coexist,microcystis aeruginosa and Oscillatoria may be more likely to become the dominant species,and the growth of Anabaena can be limited.this can also be used to explain oscillatoria and microcystis aeruginosa will be relatively easy to bloom in some water bodies.