Abstract: Harmful cyanobacterial blooms are now considered to be a common global environmental problem, and the frequency and intensity of cyanobacterial harmful algal blooms are so increasing that they have posed an imminent threat to drinking water sources. In this work, we reported our recent progress in dealing with the toxic and harmful Microcystic aeruginosa using dielectric barrier discharge (DBD) non-thermal plasma. We investigated the processes of both algal cellular damage and microcystin-LR (MC-LR) degradation caused by DBD treatment. The excitation-emission matrix (EEM) fluorescence spectroscopy combined with fluorescence regional integration technique (FRI) was employed to monitor the dynamic changes of algal cell inclusion substances including phycocyanin, chlorophyll and metabolites during the treatment, which provided the quantitative evaluation as also checked and confirmed by high performance liquid chromatography (HPLC). The results showed that algal cellular inclusions were first released into the extracellular environment, and then degraded gradually during the DBD treatment; in particular, the cyanobacterial toxin MC-LR released from algae cells during DBD treatment could eventually be completely degraded and removed. This work therefore not only demonstrates that nonthermal DBD plasma can effectively inactivate algae cells with simultaneous removal of microcystins, but also suggests that EEMs as a rapid real-time analysis method can be very useful for revealing the plasma-induced processes of algae cell damage and microcystin degradation as well as their underlying mechanisms.

Key words: dielectric barrier discharge (DBD), nonthermal plasma, excitation-emission matrix fluorescence spectroscopy, microcystic aeruginosa, microcystin, oxidation and degradation