| Inland lakes are the main source of drinking water,however,as the development of the city,many inland lakes affected by human activities such as water eutrophication phenomenon.Aglae bloom seems to be "instantaneously".In fact,it is generated with the change of temperature and salinity accumulation.In this paper,we cultivate microcystis aeruginosa twice through batch culture.And measure the water quality parameters,biological parameters and optical parameters.According to the first period laboratory data,combined with observation of the growth of algal cells records and the change of chlorophyll a concentration,the gowth cycles of microcysits aeruginosa could be divided into three phases,that is logarithmic phase(0?45days),stationary phase(45?90days),decline phase(90?120 days).On this basis,we analyze the varying pattern of other parameters.In terms of water quality parameters,it is found that with the experiment proceed,particulate organic carbon concentration present a linear relationship;with algal density showed a trend of opposite changes,that is,when POC:Chla vary among 50-100 in logarithmic phase,algal density is low;When POC:Chla vary above 50,algal density remain high.In the terms of biological parameters,the cell density increased gradually in logarithmic phase and reduced in the decline phase.Growth rate is delined as the experiment carry on,which follows a exponential function,the function of fitted curve is y = 0.213 x-0.488,while the R2 reach to 0.933.Besides,the specific growth rate is above 0 in the logarithmic phase,near 0 in the stationary phase,below 0 in the decline phase.As to the optical properties,the absorption and backscattering of microcysits aeruginosa shows different characteristics in three growth phase.Influenced by chlorophyll a and the carotene,the pigment absorption present peaks at 450 nm and 620 nm of the absorption;as for the specific absorption coefficients,cells become bigger in logarithmic phase cells as chlorophyll a concentration increased,so in 440nm specific absorption coefficient of fluctuation range larger,and at 550 nm and 675 nm at logarithmic phase and stable phase of the specific absorption coefficient of fluctuation range consistent;in decline phase the chlorophyll a concentration remain stable,the difference in each band of the specific absorption coefficient of fluctuation are reduced to less than 0.01m2/mg.The backscattering in logarithmic phase is varied among the range of 0?10 m-1,within 5?25 m-1 in the stationary phase,while decline phase vary within 0?45 m-1;Remote sensing reflectance shows the differences at 709 nm,Analysis also found that different parameters such as cell density,cell diameter,chlorophyll a,influence the reflectance in different wavelength.In addition,the eigenvalue of aph(?):bb(?)was defined to distinguish the growth phase of microcystis aeruginosa.The eigenvalue is 4.868?14.601 in the logarithmic phase,2.791?6.948 in the stationary phase,1.287?3.039 in the decline phase.In the base of definition of aph(?):bb(?),the feasibility of the eigenvalue is verified through the second group of experiment data.The test results showed that eigenvalue can distinguish the logarithmic phase and the decline phase,but the verification of stationary phase is not ideal.Also,field data in Taihu Lake is used to test the avalibility of aph(?):bb(?),the 14 selected point are difined in the decline phase,where the algal density is reduced gradually and the a cell division ability is weak. |
PDF Full Text Request