Study On The Discipline Of Algal Fluorescencc Response To Biological Toxicity Of Typical Contaminants

Algae chlorophyll fluorescence signal contains much information aboutphotosynthesis, and the signal is easy to change with the change of external environmentcondition. Chlorophyll fluorescence technique can quickly detect the change of the algalphotosynthetic activity, so as to determine toxicity of pollutants. Chlorophyll fluorescencetechnique is a good technology for water quality safety evaluation.The topic selected algae Microcystis aeruginosa and Chlorella pyrenoidosa as the testalgae in experiment, and used chlorophyll fluorescence technology to study the toxicity offive kinds of typical environmental pollutants--mercury, cadmium, zinc, atrazine andparaquat on microalgae photosynthesis, which explored the law of microalgae chlorophyllfluorescence responding on environmental stress factors. Then set up a chlorophyllfluorescence method to detect biological toxicity of pollutants, and compared withbioluminescent bacteria. Experiment determined the characteristic parameters of the testalgae: Microcystis aeruginosa chlorophyll fluorescence excitation wavelength andemission wavelength is435nm/680nm, and Chlorella pyrenoidosa chlorophyllfluorescence excitation and emission wavelengths is435nm/684nm. Diluted the algae withsterile distilled water before experiment, which maked the optical density at680nm of0.4.The time of algae chlorophyll fluorescent responding on pollutants were all within1h,and there were significant effects on algal chlorophyll fluorescence of pollutants. Theorder of several toxic effects of pollutants on Microcystis aeruginosa and Chlorellapyrenoidosa were derived through this study, the toxicity to Microcystis aeruginosa wasHg>Cd>Zn, herbicides atrazine>paraquat; and the toxicity to Chlorella pyrenoidosa wasCd>Hg>Zn, paraquat>atrazine. The tolerance ability of Microcystis aeruginosa onparaquat, Cd and Zn were stronger than Chlorella pyrenoidosa, but on atrazine and Hgwere not stronger than Chlorella pyrenoidosa.The study found that the chlorophyll fluorescence intensity of Microcystis aeruginosawas positively correlated with HgCl₂concentration. The regression equation wasy=23.944x-0.458, r=0.9902. The linear range was0.001⁰.400mg/L. Microcystisaeruginosa chlorophyll fluorescence method was built preliminary to measure thebiological toxicity of mercury. Luminescent bacteria inhibition standard curve was drawnby the bioluminescent bacteria inhibition test for mercury, the regression equation was y=14.979x-0.461. The linear range was0.030⁰.100mg/L. The median inhibitoryconcentration （IC50） was0.064mg/L. The result showed that using Microcystis aeruginosachlorophyll fluorescence method to detect toxicity of mercury was feasible.