Abstract View
Photochemical Uptake of Ozone by Organic-Coated TiO2 Particles: Influence of Atmospheric Transport on Mineral Dust Photochemistry
MAYA ABOU-GHANEM, Sarah Styler, University of Alberta
Abstract Number: 586
Working Group: Aerosol Chemistry
Abstract
Mineral dust is one of the most abundant types of aerosols in our atmosphere, with an estimated 1600 Tg emitted annually. Since the atmospheric residence time of mineral dust ranges from days to weeks, it can travel thousands of kilometers before settling. During its transport, mineral dust provides a surface for reaction of gas-phase pollutant species, with many of these reactions promoted by light. These interactions can influence not only the chemical composition of the atmosphere but also that of mineral dust itself; for example, field observations have shown the presence of organic and inorganic coatings at the surface of mineral dust upon mixing with pollutant species. Organic coatings have been found to influence cloud condensation nuclei activity and optical properties of mineral dust; however, the implications of organic coatings for mineral dust photoreactivity are still poorly understood.
Here, we use a custom-built aerosol flow tube coupled to an ozone analyzer and a scanning mobility particle sizer to investigate the influence of organic coatings on the photochemical uptake of ozone by TiO2, which we use as a simple photoactive model for mineral dust. In particular, we explore ozone photodecomposition at the surface of TiO2 coated with a suite of anthropogenic alkanes of differing viscosities and find that the uptake of ozone is suppressed in comparison to uncoated TiO2. This work provides new insights on the influence of organic coatings on mineral dust photochemistry, as well as the implications of these coatings on urban air quality.