title: Oxidation of atmospheric humic like substances by ozone: a kinetic and structural analysis approach.
abstract: This work explores the heterogeneous reaction between HUmic-LIke Substances (so-called HULIS) and ozone. Genuine atmospheric HULIS were extracted from aerosol samples collected in Chamonix (France) in winter and used in coated flow tube experiments to evaluate heterogeneous uptake of O₃ on such mixtures. The uptake coefficient (γ) was investigated as a function of pH (from 2.5 to 10), O₃ concentration (from 8 to 33 × 10¹¹ molecules cm⁻³), relative humidity (20 to 65%) and photon flux (from 0 to 1.66 × 10¹⁵ photons cm⁻² s⁻¹). Reactive uptake was found to increase in the irradiated experiment with pH, humidity and photon flux. The extract was characterized before and after exposure to O₃ and/or UV light in the attempt to elucidate the effect of the photochemical aging. Carbon content measurements, UV-vis spectroscopy and functional groups analysis revealed a decrease of the UV absorbance as well as of the carbon mass content, while the functionalization rate (COOH and C═O) and therefore the polarity increased during the simulated photochemical exposure.
authors.affiliation: UJF-Grenoble 1/CNRS, Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE), UMR 5183, Grenoble, F-38041, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Baduel
authors.forename: Maria E
authors.initials: ME
authors.lastname: Monge
authors.forename: Didier
authors.initials: D
authors.lastname: Voisin
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Jaffrezo
authors.forename: Christian
authors.initials: C
authors.lastname: George
authors.forename: Imad El
authors.initials: IE
authors.lastname: Haddad
authors.forename: Nicolas
authors.initials: N
authors.lastname: Marchand
authors.forename: Barbara
authors.initials: B
authors.lastname: D'Anna
mesh_terms: D000042:Absorption; D001272:Atmosphere / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis*; D007700:Kinetics; D009930:Organic Chemicals / Q000032:analysis; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry*; D055668:Photochemical Processes; D012621:Seasons
chemical_list: D006812:Humic Substances; D009930:Organic Chemicals; D010126:Ozone