Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 4 4 2004 10.5194/acpd-4-3875-2004 http://www.atmos-chem-phys-discuss.net/4/3875/2004/ http://www.atmos-chem-phys-discuss.net/4/3875/2004/acpd-4-3875-2004.html http://www.atmos-chem-phys-discuss.net/4/3875/2004/acpd-4-3875-2004.pdf 3875 3909 2004-07-12 Evolution of organic and inorganic components of aerosol during a Saharan dust episode observed in the French Alps G. Aymoz J.-L. Jaffrezo jaffrezo@lgge.obs.ujf-grenoble.fr V. Jacob A. Colomb Ch. George Laboratoire de Glaciologie et Géophysique de l’Environnement (LGGE-CNRS), 54 rue Molière, 38402 Saint Martin D’Hères Cedex, France Groupe de Recherche en Environnement et Chimie Appliquée (GRECA) IUT de Chimie, UJF, 39–41 Bd Gambetta, 38000 Grenoble, France Laboratoire d’Application de la Chimie à l’Environnement (UCLB-CNRS), 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne, France Now at Max Planck Institut für Chemie, Postfach 3060, 55020 Mainz, Germany A Saharan dust event was observed in a rural area in the Maurienne Valley (French Alps) in summer 2000. Detailed data on PM₁₀, particle numbers, and aerosol chemistry (ionic species and Elemental Carbon (EC) and Organic Carbon (OC)) are presented. The comparative evolutions of particle numbers and chemistry (calcium, sodium, and sulfate) show that the overall period included two episodes of dust particles with very distinct chemistry, followed by an episode with a large increase of the concentrations of species with an anthropogenic origin. The overall data set does not indicate large interactions between the dust particles and compounds from anthropogenic origin (sulfate, nitrate) or with organic carbon, all of these species showing very low concentrations. Simplistic calculations indicate that these concentrations are consistent with our current knowledge of adsorption processes of gases on mineral dust in a clean air mass.