title: Co-occurrence of Photochemical and Microbiological Transformation Processes in Open-Water Unit Process Wetlands.
abstract: The fate of anthropogenic trace organic contaminants in surface waters can be complex due to the occurrence of multiple parallel and consecutive transformation processes. In this study, the removal of five antiviral drugs (abacavir, acyclovir, emtricitabine, lamivudine and zidovudine) via both bio- and phototransformation processes, was investigated in laboratory microcosm experiments simulating an open-water unit process wetland receiving municipal wastewater effluent. Phototransformation was the main removal mechanism for abacavir, zidovudine, and emtricitabine, with half-lives (t1/2,photo) in wetland water of 1.6, 7.6, and 25 h, respectively. In contrast, removal of acyclovir and lamivudine was mainly attributable to slower microbial processes (t1/2,bio = 74 and 120 h, respectively). Identification of transformation products revealed that bio- and phototransformation reactions took place at different moieties. For abacavir and zidovudine, rapid transformation was attributable to high reactivity of the cyclopropylamine and azido moieties, respectively. Despite substantial differences in kinetics of different antiviral drugs, biotransformation reactions mainly involved oxidation of hydroxyl groups to the corresponding carboxylic acids. Phototransformation rates of parent antiviral drugs and their biotransformation products were similar, indicating that prior exposure to microorganisms (e.g., in a wastewater treatment plant or a vegetated wetland) would not affect the rate of transformation of the part of the molecule susceptible to phototransformation. However, phototransformation strongly affected the rates of biotransformation of the hydroxyl groups, which in some cases resulted in greater persistence of phototransformation products.
authors.affiliation: ReNUWIt Engineering Research Center and Department of Civil & Environmental Engineering, University of California at Berkeley , Berkeley, California 94720, United States.|Department of Aquatic Chemistry, Federal Institute of Hydrology , D-56002 Koblenz, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Prasse
authors.affiliation: ReNUWIt Engineering Research Center and Department of Civil & Environmental Engineering, University of California at Berkeley , Berkeley, California 94720, United States.|Department of Chemical Engineering and Water Innovation & Research Centre, University of Bath , Claverton Down, Bath BA2 7AY, United Kingdom.
authors.forename: Jannis
authors.initials: J
authors.lastname: Wenk
authors.affiliation: ReNUWIt Engineering Research Center and Department of Civil & Environmental Engineering, University of California at Berkeley , Berkeley, California 94720, United States.
authors.forename: Justin T
authors.initials: JT
authors.lastname: Jasper
authors.affiliation: Department of Aquatic Chemistry, Federal Institute of Hydrology , D-56002 Koblenz, Germany.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Ternes
authors.affiliation: ReNUWIt Engineering Research Center and Department of Civil & Environmental Engineering, University of California at Berkeley , Berkeley, California 94720, United States.
authors.forename: David L
authors.initials: DL
authors.lastname: Sedlak
mesh_terms: D000212:Acyclovir; D000998:Antiviral Agents / Q000737:chemistry; D001673:Biodegradation, Environmental; D001711:Biotransformation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008827:Microbiological Phenomena; D010777:Photochemistry; D011789:Quantum Theory; D062065:Wastewater / Q000737:chemistry; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis; D053833:Wetlands
chemical_list: D000212:Acyclovir; D000998:Antiviral Agents; D062065:Wastewater; D014867:Water; D014874:Water Pollutants, Chemical