J. Phys. IV France 107 (2003) 529
DOI: 10.1051/jp4:20030357

ln field kinetic experiments to better understand chemical mechanisms involved during mercury depletion events (MDE): Preliminary results

P.-A. Gauchard¹, C.P. Ferrai^{1, 2}, A. Dommergue¹, L. Poissant³ and C.F. Boutron<sup>1, 4

1</sup>  Laboratoire de Glaciologie et Géophysique de l'Environnement du CNRS, 54 rue Molière, Domaine Universitaire, BP. 96, 38402 Saint-Martin-d'Hères, France
²  École Polytechnique Universitaire de Grenoble, Université Joseph Fourier, 28 avenue Benoît Frachon, BP. 53, 38041 Grenoble, France
³  Processus Atmosphériques des Toxiques, Service Météorologique du Canada, Environnement Canada, 105 rue McGiti, 7$^{\rm e}$ Étage (Youville), Montréal, Québec H2Y 2E7, Canada
⁴  Unités de Formation et de Recherche de Mécanique et de Physique, Université Joseph Fourier, Institut Universitaire de France, Domaine Universitaire, BP. 68, 38041 Grenoble, France

Abstract
In order to better understand MDE chemistry, which are thought to happen in the presence of halogenated (chloride and bromide) species, we have led several kinetic experiments with gaseous mercury, ozone and chlorine in Teflon bags under polar atmospheric conditions. The chlorine was expected to produce, with natural solar radiation, the reactive chloride species assumed to play a role in the MDE mechanism. The aim of the first experiment was to study the reactivity between ozone and gaseous mercury : we obtained a rate constant of  cm ³molec/s, which is roughly comparable to constants given in the literature. Conceming the second experiment, for which chlorine has been introduced, a rate constant of (  cm ³/molec/s for the reactivity of gaseous mercury was obtained. This constant is too weak to recover the atmospheric lifetime of gaseous mercury during MDE. This difference is in discussion in this paper.

© EDP Sciences 2003