Reactive photoinduced species in estuarine waters. Characterization of hydroxyl radical, singlet oxygen and dissolved organic matter triplet state in natural oxidation processes

Abstract

This paper describes the reactive photo-induced species (RPS) hydroxyl radical (HO), singlet oxygen (1O2) and chromophoric dissolved organic matter triplet state (3CDOM*) in fresh water (Canal Fumemorte) and estuarine water (Vaccarès), sampled in the Camargue region, southern France. Experiments were conducted with a medium-pressure Hg lamp in a glass photoreactor (λ > 290 nm, 220 W m-2 irradiance between 290 and 400 nm). Steady-state concentration and initial production rate of RPS were determined for HO and for 1O2. HO and 1O2 were indirectly identified in the presence of benzene and furfuryl alcohol, respectively, as specific probes. The steady-state measured concentration of HOwas (1.72 ± 0.01) × 10-16 M and (9.41 ± 0.12)×10-17 M for Vaccarès and Canal waters samples, respectively, and the respective concentrations of 1O2 was (2.06 ± 0.22) × 10-13 M and (5.44 ± 0.04) × 10-14 M. The interference of 3CDOM* or other species in the determination of 1O2 with furfuryl alcohol, and of 1O 2 in the quantification of 3CDOM* with 2,4,6-trimethylphenol was also quantitatively assessed. We developed a kinetic model describing the solar photo-transformation of xenobiotic organic compounds induced by the three different photooxidants HO, 1O2 and 3CDOM*. © 2010 The Royal Society of Chemistry and Owner Societies.