title: Role of ultra-violet radiation, mercury and copper on the stability of dissolved glutathione in natural and artificial freshwater and saltwater.
abstract: The behavior and stability of dissolved reduced glutathione (GSH), an environmental antioxidant and metal transporter, is poorly known in natural waters. Glutathione oxidation rates were determined in both fresh- and brackish waters artificially submitted to different radiation wavebands. Photo-oxidation of GSH followed pseudo-first order kinetics, with half-lives ranging from 4 to 30h in natural freshwater, and from 1.6 to 7h in saltwater, with generally shorter persistence in UV-irradiated surface waters than in dark treatments. Chloride was shown to indirectly promote GSH photo-oxidation, probably through its role in the formation of radicals. The addition of Cu(II) to synthetic waters resulted in the rapid oxidation of GSH. The addition of Hg(II), a metal with strong affinity for thiols, protected GSH from oxidation by Cu(II) in the dark, but not under UV radiation. We conclude that UV-induced photo-oxidation is a key process altering the fate of GSH in natural waters. Also, the formation of stable GSH-Hg complexes could increase the bioavailability of Hg towards microorganisms in aquatic systems.
authors.affiliation: Groupe de Recherche Inter-Universitaire en Limnologie, Département de Sciences Biologiques, Université de Montréal, CP 6128, Succursale Centre-Ville, Pavillon Marie-Victorin, Montréal, Québec, Canada.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Moingt
authors.forename: Matthieu
authors.initials: M
authors.lastname: Bressac
authors.forename: Dominic
authors.initials: D
authors.lastname: Bélanger
authors.forename: Marc
authors.initials: M
authors.lastname: Amyot
mesh_terms: D002244:Carbon / Q000032:analysis; D002712:Chlorides / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D005618:Fresh Water / Q000737:chemistry; D005978:Glutathione / Q000032:analysis / Q000737:chemistry*; D007700:Kinetics; D008628:Mercury / Q000737:chemistry*; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D054712:Salinity; D012623:Seawater / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D002712:Chlorides; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride; D002244:Carbon; D003300:Copper; D008628:Mercury; D005978:Glutathione