Surface and Bulk chemistry of metals in atmospherically-relevant systems that impact climate and health

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The overall impact of atmospherically-relevant surfaces of aerosols and buildings on climate and health remains uncertain due to their highly complex physicochemical properties. New policies and models used by regulators at the national and international levels need to be based on experimental data that take into account the surface chemistry of these systems under night- and day-time conditions. Metals and organic chromophores in these systems produce reactive oxygen species that impact the oxidative power of the atmosphere, structural integrity of buildings, and in case of inhalation, cause damage to the respiratory organs. Little is known about the importance of these reactions in degrading organics ubiquitous in these atmospheric systems, and their role in producing secondary organic matter and harmful gas phase species. Experimental and computational studies are needed on the surface chemistry of aerosols and buildings in the absence and presence of solar radiation for comparison with bulk phase chemistry of the same chemicals. The funding requested in this proposal aims at improving the parameterization of atmospherically-relevant surfaces in climate and pollutant transport models. More specifically, we will investigate key differences between surface and bulk phase reactions of metals ubiquitous in atmospherically-relevant systems with potential impacts on climate and health. In particular, our focus will be on metal-mediated reactions and their role in modifying surface properties, secondary production of organic materials, and uptake/release of gas phase organics. We will use a suite of experimental techniques that allow monitoring reactions on the surfaces of these materials under controlled environments mimicking atmospheric conditions, so that results may be extrapolated to the “real world”. The wet' experiments will be complemented with theoretical calculations of details that are hard to obtain experimentally. Results will help in shaping future policies related to aerosol impacts on climate and health due to changes in land use and industrial emissions, and improving climate and pollutant transport models. Other scientific fields for which our results will be relevant include photodynamic therapies and heterogeneous photocatalysis that use metal oxide nanoparticles.