Modeling phototransformation reactions in surface water bodies: 2,4-dichloro-6-nitrophenol as a case study.
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.
Maddigapu
Pratap Reddy
PR
Dipartimento di Chimica Analitica, Università degli Studi di Torino, Via Pietro Giuria 5, 10125 Torino, Italy.
Minella
Marco
M
Vione
Davide
D
Maurino
Valter
V
Minero
Claudio
C
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*
C518754:2,4-dichloro-6-nitrophenol; D002254:Carbonates; D009596:Nitrophenols; D014874:Water Pollutants, Chemical; D017665:Hydroxyl Radical; D010100:Oxygen