CAREER: Characterizing Acid-Catalyzed Secondary Organic Aerosol Formation in the Atmosphere

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With this CAREER Award, the Environmental Chemical Sciences Program of the Division of Chemistry is supporting the research of Professor Christopher J. Hennigan at the University of Maryland, Baltimore County. Professor Hennigan is characterizing the effects of acid-catalyzed reactions on the atmospheric transformation of volatile organic compounds into secondary organic aerosol (SOA). SOA is a ubiquitous and highly abundant component of fine particle mass in the atmosphere, contributing to aerosol effects on human health and climate. This research bridges the apparent disagreement between laboratory and ambient studies on the role of particle acidity in forming SOA. These studies seek to achieve an improved representation of SOA formation in models and thus, may lead to improved predictive capabilities of ambient aerosol loadings. Professor Hennigan is integrating the research with educational activities that broaden access of underrepresented groups to research in environmental chemistry. This will be facilitated through the Meyerhoff Scholars Summer Bridge Program, and through the organization of outreach that connects high school students with undergraduates pursuing environmental chemistry research.In this work, new methodology is being developed for the fast, near real-time measurement of particle acidity. The result will be an automated system that provides the best combination of high time resolution and accuracy of any aerosol pH measurement or estimation method to-date. The system is being deployed to characterize the effects of acid catalysis on the gas-particle partitioning of semi-volatile organic compounds in the atmosphere. The ambient measurements will span multiple seasons to capture a diverse array of meteorological conditions and source influences. The work seeks to provide a detailed understanding of a process in which biogenic emissions are transformed by anthropogenic pollutants in the atmosphere. This has implications for understanding the broader impact of human activities on changes in air composition and quality and consequential impacts upon climate.