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Accueil du site > Thèmes de recherche > Atmosphère & environnement > 2.1. Dégradation des Composés Organiques Volatils et semi-volatils et formation d’aérosols secondaires > 2.1.1 Atmospheric degradation of Volatile organic Compounds (VOCs)

2.1.1 Atmospheric degradation of Volatile organic Compounds (VOCs)

The degradation of Volatile Organic Compounds (VOCs) in the troposphere leads to the production of a range of secondary pollutants such as ozone, peroxyacyl nitrate, secondary organic aerosols and other components of the photochemical smog in urban areas. VOCs are emitted directly into the atmosphere from biogenic and anthropogenic sources. The main gas phase removal process of most VOCs is the reaction with OH radical, the oxidation by O3 and NO3 being other important degradation pathways for unsaturated VOCs. In order to assess the impact of these chemical species on air quality, a detailed understanding of the kinetics and mechanisms of their atmospheric degradation is required.

The kinetics and the atmospheric oxidation mechanisms of a number of VOCs have been studied. Using absolute and relative methods, the rate coefficients for the reactions of OH and O3 with a series of esters (methyl methacrylate, ethyl propionate, ethyl isobutyrate…), alcohols (6-methyl-5-hepten-2-ol, allyl alcohol …), fluorinated (trifluoroacetaldehyde hydrate, trifluoropropene, …) and amides (N-methyl pyrrolidinone, N-formyl pyrrolidinone) have been reported (for the first time for most of the studied compounds). Mechanistic studies have also been conducted. Most compounds were found to have short atmospheric lifetimes leading mainly to carbonyls as oxidation products (e.g. ACL76, 78, 79, 80, 81). This work has been conducted within the LEFE (CNRS-INSU) and INSU-DFG programmes and Eurochamp 1 and 2 projects (FP6 and 7).