Cylindrospermopsin is an important cyanobacterial toxin found in water bodies worldwide. The ever-increasing and global occurrence of massive and prolonged blooms of cylindrospermopsin-producing cyanobacteria poses a potential threat to both human and ecosystem health. Its toxicity is associated with metabolic activation and may involve mechanisms that adversely affect a wide variety of targets in an organism. Cylindrospermopsin has been shown to be cytotoxic, dermatotoxic, genotoxic, hepatotoxic in vivo, developmentally toxic, and may be carcinogenic. Human exposure may occur through drinking water, during recreational activities and by consuming foods in which the toxin may have bioaccumulated. Drinking water shortages of sufficient quality coupled with growing human pressures and climate variability and change necessitate an integrated and sustainable water management program. This review presents an overview of the importance of cylindrospermopsin, its detection, toxicity, worldwide distribution, and lastly, its chemical and biological degradation and removal by natural processes and drinking water treatment processes.

Zhao, C. et al. (2013) a b s t r a c tTiO 2 photocatalyses of 6-hydroxymethyl uracil (6-HOMU) a model compound for the potent cyanotoxin, cylindrospermopsin (CYN), were carried out employing visible and UV irradiation using different non-metal doped TiO 2 materials, nitrogen and fluorine-TiO 2 (NF-TiO 2 ), phosphorus and fluorine-TiO 2 (PF-TiO 2 ) and sulfur-TiO 2 (S-TiO 2 ). The model compound was readily degraded under UV TiO 2 photocatalysis with pseudo-first-order rate constants (k) of 2.1, 1.0, and 0.44 h −1 for NF-TiO 2 , PF-TiO 2 and S-TiO 2 , respectively. Under visible light activated (VLA), NF-TiO 2 was the most active photocatalyst, PF-TiO 2 was marginally active and S-TiO 2 inactive. VLA NF-TiO 2 was effective and increased the k with increasing pH from 3 to 9. The presence of humic acid (HA), Fe 3+ and Cu 2+ can enhance the degradation. However, at 20 ppm HA significant inhibition was observed, likely due to shadowing of the catalyst, quenching of ROS or blocking active sites of TiO 2 . We probed the roles of different reactive oxygen species (ROS) using specific scavengers and the results indicate that O 2•− plays an important role in VLA TiO 2 photocatalysis. Our results demonstrate that NF-TiO 2 photocatalysis is effective under UV and visible irradiation and over a range of water qualities. VLA NF-TiO 2 photocatalysis is an attractive alternative technology for the CYN contaminated water treatment.

Aminoglycoside antibiotics are widely used in human therapy and veterinary medicine. We report herein a detailed study on the natural-organic-matter- (NOM-) photosensitized degradation of aminoglycosides in aqueous media under simulated solar irradiation. It appears that the direct reaction of the excited states of NOM ((3)NOM*) with aminoglycosides is minor. The contributions of reactive oxygen species (ROSs) in the bulk solutions are also unimportant, as determined by an assessment based on steady-state concentrations and bimolecular reaction rate constants in a homogeneous reaction model. The inhibition of the photodegradation by isopropamide is rationalized through competitive sorption with aminoglycosides on the NOM surface, whereas the addition of isopropanol negligibly affects degradation because it quenches HO(•) in the bulk solution but not HO(•) localized on the NOM surface where aminoglycosides reside. Therefore, a sorption-enhanced phototransformation mechanism is proposed. The sorption of aminoglycosides on NOM follows a dual-mode model involving Langmuir and linear isotherms. The steady-state concentration of HO(•) on the surface of NOM was calculated as 10(-14) M, 2 orders of magnitude higher than that in the bulk solution. This fundamental information is important in the assessment of the fate and transport of aminoglycosides in aqueous environments.

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