Toxic effects of suspended particulate matter and microcystins complexes on Daphnia magna
In order to investigate the toxic effects of suspended particulate matter and microcystins complexes on Daphnia magna,the most frequently detected variants of microcystin,MC-LR,was selected and the suspended particulate matter(SPM)and MC-LR complexes were prepared.The acute toxicity of MC-LR adsorbed SPM(SPM-MC-LR)on Daphnia magna was also studied.The results showed that the adsorption process of MC-LR by SPM fitted well with the pseudo-second-order kinetic model and Freundlich isothermal adsorption model,and a maximum adsorption capacity of 1720µg/g was determined.This multimolecular layer adsorption dominated by chemical adsorption was relatively easy to occur.SPM-MC-LR influenced the immobilization rate(the maximum immobilization rate reached 93.77%)and the activity of antioxidant enzymes of Daphnia magna,with positively dose and time dependent manner.However,when the MC-LR content reached 73.52 and 94.53µg/g on the SPM surface,the oxidative stress triggered in the Daphnia magna would inhibit the activities of antioxidant enzymes.As a result,the activities of SOD and CAT after 48h exposure to SPM-MC-LR were decreased by 21.44%,26.51%and 6.2%,18.27%in comparison to that after 24h exposure,respectively.Compared with single MC-LR,the presence of SPM may enhance the toxicity of MC-LR toward Daphnia magna.
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维普
