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 arsing from GFZ direct photolysis. Interestingly, literature evidence suggests that the same toxic intermediate would be formed upon ·OH reaction.

Modelling the photochemical attenuation pathways of the fibrate drug gemfibrozil in surface waters

FABBRI, DEBORA;MAURINO, Valter;MINELLA, Marco;MINERO, Claudio;VIONE, Davide Vittorio
2017

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 arsing from GFZ direct photolysis. Interestingly, literature evidence suggests that the same toxic intermediate would be formed upon ·OH reaction.
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http://www.sciencedirect.com/science/article/pii/S0045653516316794
Direct photolysis; Emerging pollutants; Environmental photochemistry; Gemfibrozil; Transformation intermediates; Benzoquinones; Cyclohexenes; Environment; Gemfibrozil; Half-Life; Hydroxyl Radical; Kinetics; Models, Chemical; Models, Theoretical; Nitrates; Nitrites; Oxygen; Photochemical Processes; Photolysis; Ultraviolet Rays; Water; Water Pollutants, Chemical
Fabbri, Debora; Maurino, Valter; Minella, Marco; Minero, Claudio; Vione, Davide
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1637872
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