title: Modelling the photochemical attenuation pathways of the fibrate drug gemfibrozil in surface waters.
abstract: Gemfibrozil (GFZ) is a relatively persistent pollutant in surface-water environments and it is rather recalcitrant to biological degradation. The GFZ photochemical lifetimes are relatively short in shallow waters with low levels of dissolved organic carbon (DOC), but they can reach the month-year range in deep and high-DOC waters. The main reason is that GFZ undergoes negligible reaction with singlet oxygen or degradation sensitised by the triplet states of chromophoric dissolved organic matter, which are the usually prevalent photochemical pathways in deep and high-DOC sunlit waters. Nitrate and nitrite scarcely affect the overall GFZ lifetimes, but they can shift photodegradation from direct photolysis to the OH process. These two pathways are the main GFZ phototransformation routes, with the direct photolysis prevailing in shallow environments during summer. Under these conditions the GFZ photochemical lifetimes are also shorter and the environmental significance of photodegradation correspondingly higher. The direct photolysis of GFZ under UVB irradiation yielded several transformation intermediates deriving from oxidation or cleavage of the aliphatic lateral chain. A quinone derivative (2,5-dimethyl-1,4-benzoquinone), a likely oxidation product of the transformation intermediate 2,5-dimethylphenol, is expected to be the most acutely and chronically toxic compound arising from GFZ direct photolysis. Interestingly, literature evidence suggests that the same toxic intermediate would be formed upon OH reaction.
authors.affiliation: Università degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino, Italy.
authors.forename: Debora
authors.initials: D
authors.lastname: Fabbri
authors.affiliation: Università degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino, Italy.
authors.forename: Valter
authors.initials: V
authors.lastname: Maurino
authors.affiliation: Università degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Minella
authors.affiliation: Università degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Minero
authors.affiliation: Università degli Studi di Torino, Dipartimento di Chimica, Via P. Giuria 5, 10125 Torino, Italy; Università degli Studi di Torino, Centro Interdipartimentale NatRisk, Via L. Da Vinci 44, 10095 Grugliasco (TO), Italy. Electronic address: davide.vione@unito.it.
authors.forename: Davide
authors.initials: D
authors.lastname: Vione
mesh_terms: D016227:Benzoquinones / Q000032:analysis*; D053138:Cyclohexenes / Q000032:analysis*; D004777:Environment; D015248:Gemfibrozil / Q000032:analysis*; D006207:Half-Life; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D008962:Models, Theoretical; D009566:Nitrates / Q000032:analysis; D009573:Nitrites / Q000032:analysis; D010100:Oxygen / Q000737:chemistry; D055668:Photochemical Processes; D010782:Photolysis; D014466:Ultraviolet Rays; D014867:Water; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D016227:Benzoquinones; D053138:Cyclohexenes; D009566:Nitrates; D009573:Nitrites; D014874:Water Pollutants, Chemical; D014867:Water; C020617:2,5-dimethyl-4-benzoquinone; D017665:Hydroxyl Radical; D015248:Gemfibrozil; D010100:Oxygen
keywords: Direct photolysis; Emerging pollutants; Environmental photochemistry; Gemfibrozil; Transformation intermediates