Collaborative Research: Photochemical Production of Radical Oxidants and Hydroperoxides from Organic Matter and Nitrate in Sea-Salt Aerosols

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This collaborative award involves the systematic study and assessment of the importance of hydroxyl radical and hydrogen peroxide production in the interaction of sunlight with aerosols that are found in the marine boundary layer. It is recognized that the breakdown of nitrate ions and organic compounds, commonly found in these particles, by solar radiation leads to the production of oxidized compounds, but this recognition is not accompanied by quantitative understanding. This study will deploy an apparatus to make fresh marine aerosols that will be carefully characterized and exposed to sunlight. Controlling variables such as acidity, temperature, and aerosol amount will be changed systematically to help quantify and test possible mechanisms of the production of these secondary oxidized species. Then similar experiments will be performed with ambient aerosols, which will be somewhat more complicated because they will likely have undergone some transformations during their time in the atmosphere. The results of this study will be incorporated into a model designed to quantify aerosols and gas phase chemical processes in the troposphere in order to assess the importance of these processes.During the course of this research a post-doctoral fellow as well as graduate and undergraduate students will participate. This work contributes to the goals and activities of a number of national and international programs including the Surface Ocean - Lower Atmosphere Study (SOLAS), International Global Atmospheric Chemistry (IGAC) and National Aerosol-Climate Interactions Program (NACIP).