Friday, April 12, 2019 - 12:00pm to 1:00pm
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100F Pierce, 29 Oxford St., Cambridge

Atmospheric & Environmental Chemistry Seminar

"Organic Nitrate Aerosols from Oxidation of Biogenic Volatile Organic Compounds" with Sally Ng, Georgia Tech.

Secondary organic aerosols (SOA) contribute a substantial fraction of ambient fine particulate matter (PM) and have important implications on climate and health. Recent results from field studies have revealed the ubiquitous presence of organic nitrates in ambient organic aerosols at different locations around the world. Organic nitrates are a major component of reactive oxidized nitrogen and play an important role in the cycling of NOx, ozone, and aerosol formation. However, their formation mechanisms and fates are largely unexplored. The oxidation of monoterpenes in the presence of NOx is an important source of organic nitrates.  This is a key mechanism in which human activities (NOx emissions) alter aerosol formation from biogenic emissions (emissions from trees) in the atmosphere. In this work, we investigate the formation and fates of organic nitrates generated from photochemical and nitrate radical oxidations of representative monoterpenes. Experiments are conducted in the Georgia Environmental Chamber facility (GTEC). A large suite of highly oxygenated gas- and particle-phase organic nitrates are formed rapidly. We investigate the properties and transformations of organic nitrates via hydrolysis, temperature perturbation, and further photochemical aging. Results from this study provide new insights into the chemical life cycles of organic nitrates, which will aid interpretation of ambient observations and provide fundamental inputs for atmospheric model developments to constrain organic nitrate chemistry and their impacts.

Bio: Dr. Nga Lee (Sally) Ng is an associate professor in the School of Chemical & Biomolecular Engineering and the School of Earth & Atmospheric Sciences at the Georgia Institute of Technology. She earned her doctorate in Chemical Engineering from the California Institute of Technology and was a postdoctoral scientist at Aerodyne Research Inc.  Dr. Ng’s research focuses on the understanding of the chemical mechanisms of aerosol formation and composition, as well as their health effects. Her group combines laboratory chamber studies and ambient field measurements to study aerosols using advanced mass spectrometry techniques. Dr. Ng serves as a co-editor of Atmospheric Chemistry and Physics and a member of the Editorial Board of Nature Scientific Reports, Journal of Aerosol Science, and ACS Earth and Space Chemistry. Dr. Ng is named among the world’s most highly cited researcher (top 1% of Geoscience). Dr. Ng’s research contribution has also been recognized by the Sheldon K. Friedlander Award and the Kenneth T. Whitby Award from the American Association for Aerosol Research, the EPA Early Career Award, the Health Effects Institute Walter A. Rosenblith New Investigator Award, and the NSF CAREER Award.

Contact Name: 

Kelvin Bates

Research Areas: 

Harvard University
Center for the Environment

Address: 26 Oxford Street, 4th Floor, Cambridge
Phone: (617) 495-0368

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