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Réactions de radicaux halogénés (chlorés, bromés) d'intérêt atmosphérique

Abstract : In this work, we have studied the kinetics and mechanisms of reactions of bromine and chlorine containing radicals of atmospheric interest: on one hand, some reactions of BrOx (Br, BrO) and ClOx (Cl, ClO) radicals with HOx (OH, HO2) radicals, in order to estimate their impact on halogenated compound partitioning in the global stratosphere, between active and sink species, in relation to stratospheric ozone depletion ; on the other hand, some reactions between these halogenated radicals and dimethylsulfoxide (DMSO), an intermediate species in the oxidation of dimethylsulphur (DMS) emitted by oceans, in order to evaluate the potential contribution of these reactions in the oxidation of DMSO. These reactions were studied at 1 torr pressure of helium, using the dicharge-flow mass spectrometric method.

For the reactions between halogenated and HOx radicals, the results obtained show these reactions are additional sources of the reservoir species HX (X = Br, Cl) in the stratosphere. However, the values of the rate constants seem to be unable to fully explain the discrepancies between observed and modeled HX concentrations in the stratosphere, and thus the partitioning of bromine and chlorine species between active species and reservoirs.

With respect to DMSO, this work confirms that reactions with chlorinated and brominated radicals do not contribute significantly to its oxidation, mainly due to the OH radical in the gas phase.
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Submitted on : Thursday, April 24, 2008 - 5:48:33 PM
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Véronique Riffault. Réactions de radicaux halogénés (chlorés, bromés) d'intérêt atmosphérique. Océan, Atmosphère. Université d'Orléans, 2002. Français. ⟨tel-00275704⟩

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