title: Modeling phototransformation reactions in surface water bodies: 2,4-dichloro-6-nitrophenol as a case study.
abstract: The anionic form of 2,4-dichloro-6-nitrophenol (DCNP), which prevails in surface waters over the undissociated one, has a direct photolysis quantum yield of (4.53 ± 0.78) × 10(-6) under UVA irradiation and second-order reaction rate constants of (2.8 ± 0.3) × 10(9) M(-1) s(-1) with •OH, (3.7 ± 1.4) × 10(9) M(-1) s(-1) with (1)O(2), and (1.36 ± 0.09) × 10(8) M(-1) s(-1) with the excited triplet state of anthraquinone-2-sulfonate, adopted as a proxy for the photoactive dissolved organic compounds in surface waters. DCNP also shows negligible reactivity with the carbonate radical. Insertion of the data into a model of surface water photochemistry indicates that the direct photolysis and the reactions with •OH and (1)O(2) would be the main phototransformation processes of DCNP, with •OH prevailing in organic-poor and (1)O(2) in organic-rich waters. The model results compare well with the field data of DCNP in the Rhône river delta (Southern France), where (1)O(2) would be the main reactive species for the phototransformation of the substrate.
authors.affiliation: Dipartimento di Chimica Analitica, Università degli Studi di Torino, Via Pietro Giuria 5, 10125 Torino, Italy.
authors.forename: Pratap Reddy
authors.initials: PR
authors.lastname: Maddigapu
authors.forename: Marco
authors.initials: M
authors.lastname: Minella
authors.forename: Davide
authors.initials: D
authors.lastname: Vione
authors.forename: Valter
authors.initials: V
authors.lastname: Maurino
authors.forename: Claudio
authors.initials: C
authors.lastname: Minero
mesh_terms: D002254:Carbonates / Q000737:chemistry; D004784:Environmental Monitoring; D005602:France; D005618:Fresh Water / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D009596:Nitrophenols / Q000032:analysis / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D055668:Photochemical Processes; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: C518754:2,4-dichloro-6-nitrophenol; D002254:Carbonates; D009596:Nitrophenols; D014874:Water Pollutants, Chemical; D017665:Hydroxyl Radical; D010100:Oxygen