Chemistry of Pollutants at Air-Ice Interfaces

我的工作将解决一个主要的知识差距，影响大气化学在积雪覆盖的地区，这是我们缺乏基本的了解反应动力学和机制在空气-冰界面。环境模型通常将冰视为被少量液态水覆盖的固体不反应核，其中发生反应。然而，冰表面的物理性质不同于液态水表面（也不同于过冷水），我已经证明，在空气-冰界面的反应动力学和机制可以显着不同的液态水和冰内的液体区域。我将研究溶质对空气-冰界面的组成、极性和物理状态等性质的影响，并将这些性质与反应性联系起来。这将通过三个具体目标来实现：（1）在空气-冰界面的动力学和反应产物的测量;（2）含溶质的冰表面的表征与拉曼和荧光显微镜;和（3）在空气-冰界面的物理和化学过程的空间分辨调查。这项工作的结果将为我们提供冰作为化学反应器的理解，这是准确地参数化模型所必需的，并将提供可以包括在这些模型中的重要反应的速率常数。这项工作的预期影响包括更好地预测积雪覆盖地区的污染物命运和调查非均匀大气过程的新方法。拟议工作的结果可能最终提高我们对积雪覆盖地区污染物对健康影响的理解和缓解。这项工作与加拿大非常相关，因为该国大部分地区在一年中的某个时间都有积雪。

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.