Measuring and Modeling the Physicochemical Properties of Organic Matter in Atmospheric Aerosols

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This project is focused on the properties of organic aerosols, which are recognized to be ubiquitous in the troposphere. The first goal is to explore, through laboratory investigations, how organic colloids in aqueous solutions can alter the basic physicochemical properties of atmospheric aerosols such as their surface composition and hygroscopicity. The second goal is to extract the required thermodynamic parameters (activity coefficients, adsorption constants, etc.) from the data in order to formulate an equilibrium aqueous solution model for pure organic aerosols as well as mixed aerosols containing both organic and inorganic components. Water uptake and surface tension of a wide range of organic-containing solutions, representative of mixtures found in atmospheric aerosols, will be measured as a function of pH and temperature. Surface composition will be probed, and the possible formation of micelles will be studied. The data will be parameterized for use in the thermodynamic model.The quantitative equilibrium solution model developed under this project for mixed solutions, including organics, should be useful to the atmospheric community for a wide variety of applications. Broader scientific impacts include an improved understanding of atmospheric aerosols and their effects on climate. Graduate students and postdoctoral researchers, including members of underrepresented groups, will be supported through this award.