Ozone Uptake by Clay Dusts under Environmental Conditions

Abstract

Clay is the most emitted type of dust in the atmosphere and offers a large surface for heterogeneous interactions with atmospheric compounds. In this study, we focus on the uptake of ozone (O3) by montmorillonite and kaolinite dust samples at atmospheric pressure in a coated-wall flow tube reactor. The influence of relevant environmental parameters, such as O3 concentration, relative humidity, and temperature, is determined. A mechanism for O3 interaction with the surface sites of clays is described, and atmospheric implications are discussed. Although the impact of O3 uptake by fresh clay dust seems limited in the atmosphere, this work highlights the need to consider relevant and thoroughly defined uptake coefficients in models. Moreover, the presence of a pressure-dependence in the mechanism of O3 uptake by dust suggested in this work helps reconciling measurements made at atmospheric pressure with those performed at low pressure in Knudsen cells.