Toxin Release Of Microcystis Aeruginosa And Investigation Of Pollution Of Microcystins In Huangpu River

In recent years,cyanobacterial blooms have become more and more frequent.Microcystins,a secondary harmful metabolite secreted and released by cyanobacteria,have brought great hidden dangers to people's health and become a widely concerned environmental problem.On the other hand,the pollution caused by the extensive use of pesticide herbicides poses a new threat to aquatic environment and ecology.At present,the studies on the growth of cyanobacteria and the secretion and release of MC-LR from cyanobacteria by herbicides in aquatic environment are insufficient.In this paper,microcystins were studied.Microcystis aeruginosa was used as the target algae,and the herbicide glyphosate was poisoned.The research was carried out from three aspects: determination method,biological toxicology and river pollution investigation.Under laboratory conditions,through a series of comparative experiments,a rapid and accurate method was found for the quantitative determination of MC-LR in microcystins by high performance liquid chromatography(HPLC)and enzyme-linked immunosorbent assay(ELISA).This method was used to study the changes of intracellular and extracellular of Microcystis aeruginosa exposed to herbicide glyphosate at different culture stages.The growth of Microcystis aeruginosa under stress,oxidative damage and the release of intracellular and extracellular algae toxins at different temperatures were evaluated effectively.On the other hand,field investigation is carried out to collect and analyze the water quality of Huangpu River in Shanghai,and the MC-LR content in water quality will be detected and investigated in several different sampling points for up to half a year.The results of this study showed that: 1)Methods comparative experiments showed that although the pretreatment of samples by HPLC was complicated,the determination error was relatively small,the instrument was precise and the recovery rate was high,and the repetition rate was relatively stable.2)Studies on the toxicity of glyphosate to Microcystis aeruginosa showed that the activities of catalase(CAT),peroxidase(POD)and superoxide dismutase(SOD)in the cells of Microcystis aeruginosa under the action of herbicide glyphosate were almost significantly activated in all concentration treatments.Furthermore,according to the significant increase of intracellular malondialdehyde(MDA),it indicated that Microcystis aeruginosa experienced exposure to glyphosate.3)The growth of cells was inhibited by oxidative damage to varying degrees.The synthesis of chlorophyll a and carotenoids was also inhibited,which led to the acceleration of apoptosis,eventually leading to cell rupture and the release of intracellular microcystins.4)Under the action of high temperature(above 30 ?)and high concentration glyphosate,most algae cells died and broke down,and MC-LR flowed out in large quantities.Moreover,under the action of high concentration glyphosate at about 30 ? single algae cells had strong toxicity-producing ability(45.8 fg/cell).5)The concentration of MC-LR in the water of Huangpu River in Shanghai is stable.With the seasonal change,the water temperature rises continuously,reaching the highest in July to August.Similarly,the concentration of MC-LR in the water of each sampling point is also the highest.Preliminary observation shows that the content of toxin released by toxin-producing algae in Huangpu River is positively correlated with the temperature.Within six months,the four sampling points showed a positive correlation between the concentration of MC-LR and the temperature.The highest concentration of MC-LR was 291.2 ng/L,and the lowest concentration was only 20.6 ng/L.The results are helpful to understand the toxicological mechanism of glyphosate on cyanobacteria and to guide the application of glyphosate in agricultural environment.Through the investigation of algae toxin detection in Huangpu River,we can make certain water body evaluation,provide certain support for the latest typical water pollution situation in Shanghai,and have important significance for environmental assessment and protection.