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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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Dr. Spyros Pandis
Department of Chemical Engineering
Carnegie Mellon University
“Atmospheric Evolution and Chemical Aging of Organic Particulate Matter”
The human development of our planet has a variety of negative impacts on the composition of its atmosphere at every scale – locally, regionally, and even globally. One of these dramatic changes has been the increase in the mass concentrations of sub-micrometer particles by one to sometimes two orders of magnitude over populated areas in the Northern Hemisphere. These atmospheric aerosols can cause serious health problems, reduce visibility, contribute to acidic deposition and material damage, but are also cooling the planet by reflecting sunlight back to space. The organic fraction of these particles is their least understood component.
Organic particulate material has been traditional classified as either primary or secondary with the primary component being treated as non-volatile and inert. Laboratory and field studies during the last decade, demonstrate that primary combustion aerosol is highly dynamic, consisting of mostly semi-volatile material that moves between the gas and particulate phases in the atmosphere and at the same time is oxidized forming a variety of oxygenated products. This oxidation can lead to both lower volatility material through functionalization but also to smaller lower volatility molecules through fragmentation. A unifying framework for the description of all organic components based on their volatility distribution and oxygen content (the two-dimensional volatility basis set) can be used for the treatment of a wide range of processes affecting organic aerosol loadings and composition in the atmosphere. This modeling framework is combined with emission characterization studies, laboratory smog chamber studies, and field measurements to simulate the atmospheric evolution of these organic emissions. Applications of this modeling framework to major urban areas (Paris and Mexico City), continental US and Europe, where major field campaigns have recently taken place are used to provide insights about our understanding (or lack thereof) of the corresponding physical and chemical processes.
In addition to its annual lectures, ChBE hosts a weekly seminar throughout the year with invited lecturers who are prominent in their fields. Unless otherwise noted, all seminars are held on Wednesdays in the Molecular Science and Engineering Building ("M" Building) in G011 (Cherry Logan Emerson Lecture Theater) at 4:00 p.m. Refreshments are served at 3:30 p.m. in the Emerson-Lewis Reception Salon.
