UV-B辐射下叶绿素和微囊藻毒素的协同降解效应研究

Study on the Synergistic Degradation of Chlorophyll and Microcystins under UV-B Radiation

[目的]探讨水体微囊藻毒素无二次污染的高效降解方法。[方法]通过开展国内富营养化水体中常见的藻毒素异构体MC-RR、MC-LR在叶绿素的添加与否条件下,研究UV-B对富营养化水体中叶绿素和微囊藻毒素的协同降解效应。[结果]2 mW/cm^(2)的UV-B照射1 h,MC-RR、MC-LR降解率分别为29.8%和16.9%,而添加叶绿素后MC-RR、MC-LR的降解率分别高达99.8%和100.0%;2 mW/cm^(2)的UV-B照射2 h,MC-RR、MC-LR均产生大量的光降解异构体产物,异构体产物与残余MC的色谱面积比分别为28.9%和21.7%,而添加叶绿素后MC-RR、MC-LR均被完全降解,MC和异构体产物均未检出。添加叶绿素后MC呈现出高效完全光降解,避免了常规光降解产生大量潜在毒性的异构体产物的缺点;2 mW/cm^(2)的UV-B照射1 h,对Chla、Chla与MC-RR混合溶液、Chla与MC-LR混合溶液中的叶绿素a的降解率分别为86.7%、18.9%和70.3%。[结论]叶绿素能高效催化UV-B对微囊藻毒素的光降解;水体添加叶绿素后MC呈现高效完全光降解,避免了常规光降解产生大量潜在毒性的异构体产物的缺点;微囊藻毒素的添加延缓了UV-B对叶绿素的光降解,值得进一步深入研究。

[Objective]To explore the degradation method of microcystins without secondary pollution.[Method]The synergistic degradation effect of UV-B on chlorophyll and microcystin in eutrophic water was studied by carrying out the research on the common cyanotoxin isomers MC-RR and MC-LR in eutrophic water in China with or without chlorophyll.[Result]After UV-B irradiation at 2 mW/cm^(2) for 1 h,the degradation rates of MC-RR and MC-LR were 29.8%and 16.9%respectively,while the degradation rates of MC-RR and MC-LR were 99.8%and 100%after chlorophyll was added.Photodegradation isomers were found from MC-RR and MC-LR after UV-B irradiation for 1 h,the proportion of isomers and residual MC-RR and MC-LR were 28.9%and 21.7%,respectively.However,after adding chlorophyll,MC-RR and MC-LR were completely degraded,MC and isomers were not detected.After UV-B irradiation at 2 mW/cm^(2) for 1 h,the degradation rates of chlorophyll a in chlorophyll,chlorophyll and MC-RR mixed solution,chlorophyll and MC-LR mixed solution were 86.7%,18.9%and 70.3%respectively.[Conclusion]After adding chlorophyll,chlorophyll could efficiently catalyze the photodegradation of microcystin by UV-B.MC showed efficient and complete photodegradation,avoiding the shortcomings of conventional photodegradation producing potentially toxic isomers.The addition of microcystins delayed the photodegradation of chlorophyll by UV-B,which was worthy of further study.