title: Mechanistic considerations of photosensitized transformation of microcystin-LR (cyanobacterial toxin) in aqueous environments.
abstract: Microcystin-LR (MC-LR), one of the most common cyanotoxins, is produced by harmful cyanobacteria. The current study focuses on the photosensitized transformation of MC-LR in dissolved organic matter (DOM) enriched solutions under solar simulated irradiation. It appears that the direct energy transfer of triplet excited state DOM with MC-LR plays a key role and leads to photosensitized isomerization of Adda side chain. Furthermore a micro-heterogeneous mechanism has been proposed. Size exclude chromatograph (SEC) has been applied to explore the adsorption of MC-LR on the DOM. The adsorption phenomenon supported the fact that the pseudo first-order photodegradation rates showed positive correlation with the adsorption. The photo-transformation rate of MC-LR increases as pH decreases which is also the result of the adsorptive interaction of MC-LR with DOM. Finally two bulk water parameters (TOC and UV350 nm) have been applied to predict the photodegradation rates of MC-LR in the varied water matrixes.
authors.affiliation: Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, PR China.
authors.forename: Shuwen
authors.initials: S
authors.lastname: Yan
authors.affiliation: Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, PR China.
authors.forename: Danny
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, PR China. Electronic address: wsong@fudan.edu.cn.
authors.forename: Weihua
authors.initials: W
authors.lastname: Song
mesh_terms: D000327:Adsorption; D001427:Bacterial Toxins / Q000032:analysis*; D000458:Cyanobacteria / Q000737:chemistry; D000087522:Cyanobacteria Toxins; D008387:Marine Toxins / Q000032:analysis*; D052998:Microcystins / Q000032:analysis*; D010782:Photolysis; D013472:Sunlight; D014867:Water / Q000737:chemistry*; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D008387:Marine Toxins; D052998:Microcystins; D014867:Water; C057862:cyanoginosin LR
keywords: Hydroxyl radical; Microcystin-LR; Photosensitized transformation; Singlet oxygen; Triplet excited state DOM