Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 2 1 2002 10.5194/acpd-2-147-2002 http://www.atmos-chem-phys-discuss.net/2/147/2002/ http://www.atmos-chem-phys-discuss.net/2/147/2002/acpd-2-147-2002.html http://www.atmos-chem-phys-discuss.net/2/147/2002/acpd-2-147-2002.pdf 147 172 2002-02-11 The impact of multiphase reactions of NO2 with aromatics: a modelling approach N. Lahoutifard M. Ammann L. Gutzwiller B. Ervens Ch. George Laboratoire d’Application de la Chimie à l’Environnement (LACE), CNRS-UCBL, 43, Boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex, France Paul Scherrer Institut, Laboratory for Radio- and Environmental Chemistry, CH-5232 Villigen, Switzerland Institut für Troposphärenforschung Permoserstr. 15, D-04303 Leipzig, Germany Now at the Department of Chemistry, University of Ottawa, Canada The impact of multiphase reactions involving nitrogen dioxide (NO2) and aromatic compounds was simulated in this study. A mechanism (CAPRAM 2.4, MODAC Mechanism), was applied for the aqueous phase reactions whereas RACM was applied for the gas phase chemistry. Liquid droplets were considered as monodispersed with a mean radius of 0.1 mm and a liquid water content (LWC) of 50mg m-3. The multiphase mechanism has been further extended to the chemistry of aromatics, i.e. reactions involving benzene, toluene, xylene, phenol and cresol have been added. In addition, reaction of NO2 with dissociated hydroxyl substituted aromatic compounds has also been implemented. These reactions proceed through charge exchange leading to nitrite ions and therefore to nitrous acid formation. The strength of this source was explored under urban polluted conditions. It was shown that it may significantly increase gas phase HONO levels. About one order of magnitude change of HONO concentration was observed with finally, a minor effect on subsequent gas phase daytime photochemistry because of the limited aerosol life time considered.