ChE Seminar – “The oxidative evolution of organic carbon in the atmosphere” by Jesse Kroll
March 28 @ 3:30 pm - 4:30 pm
Host: Lea Hildebrandt Ruiz
Organic species in the Earth’s atmosphere play a central role in many processes important to human health, ecosystem health, and global climate: they can serve as pollutants, they influence atmospheric oxidant levels, and their oxidation products include secondary pollutants such as ozone and secondary organic aerosol. However our ability to predict these effects is limited by the immense complexity of this chemical system, which results from not only the large number of species emitted into the atmosphere, but also from the major influence of atmospheric oxidation reactions. This talk will describe laboratory studies aimed at describing the evolving composition of organic oxidation systems, over the equivalent of hours to days in the atmosphere. Organic species are oxidized within an environmental chamber, and reactants, intermediates, and products are measured using a suite of mass spectrometric instruments, providing a comprehensive picture of the chemical composition of the entire organic mixture. From these combined measurements, the organic species can be described in terms of total carbon mass as well as distributions of key ensemble properties (such as oxidation state and volatility) that can be used to inform model frameworks. Results to be discussed will include the “completeness” of the instrument suite (carbon balance), the formation and evolution of particulate matter, and the changes to key chemical properties of the organic carbon upon multigenerational oxidation.
Jesse Kroll received an A.B. in Chemistry and Earth and Planetary Sciences and a Ph.D. in Chemistry from Harvard University. Following a postdoctoral appointment at Caltech and a Senior Scientist position at Aerodyne Research, he joined the MIT’s Departments of Civil and Environmental Engineering and Chemical Engineering in 2009, where he is now an Associate Professor. His research group studies the lifecycle of atmospheric organic carbon in the Earth’s atmosphere, with a major focus on laboratory studies of the formation and oxidative aging of organic aerosol.