Chemistry of Pollutants at Air-Ice Interfaces

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My work will address one of the major knowledge gaps afflicting atmospheric chemistry in snow-covered regions, which is our lack of fundamental understanding of reaction kinetics and mechanisms at air-ice interfaces. Environmental models often treat ice as a solid unreactive core covered by a small volume of liquid water in which reactions occur. However, the physical properties of ice surfaces are distinct from those of liquid water surfaces (and also distinct from supercooled water), and I have demonstrated that reaction kinetics and mechanisms at air-ice interfaces can differ significantly from those in liquid water and in liquid regions within ice. I will investigate the effects of solutes on properties such as composition, polarity, and physical state of air-ice interfaces, and will relate these properties to reactivity. This will be achieved through three specific aims: (1) measurement of kinetics and products of reactions at air-ice interfaces; (2) characterization of solute-containing ice surfaces with Raman and fluorescence microscopy; and (3) spatially-resolved investigations of physical and chemical processes at air-ice interfaces. The results of this work will provide us with the understanding of ice as a chemical reactor that is necessary to parameterize models accurately, and will provide rate constants for important reactions that can be included in these models. Anticipated impacts of this work include better predictions of pollutant fate in snow-covered regions and novel methods of investigating heterogeneous atmospheric processes. The results of the proposed work may ultimately improve our understanding - and mitigation - of the health implications of pollutants in snow-covered regions. This work is extremely relevant to Canada, as much of the country experiences snow cover for some fraction of the year.