Seminar

Abstract

The atmospheric environment is rapidly changing. Climate change and a shift in anthropogenic emission profiles can alter chemical processes occurring in the atmosphere. Wildfires are expected to gain both frequency and severity as climate change proceeds. The chemical processing of short-lived climate forcers, such as atmospheric Brown Carbon (BrC) is not fully understood. On the other hand, the emission of nitrogen and sulfur from anthropogenic activities has been reduced over the past decades, which has altered the chemical environment for certain organic compounds in the atmosphere. For instance, cloud and fog water has become less acidic due to reduced emissions of acid precursors. Meanwhile, reduced NOx concentration may facilitate autoxidation of organic compounds. My presentation will highlight a few completed projects in my research group to better understand the impact of such changes on cloudwater chemistry. In the first project, we have investigated how a shift in cloudwater acidity can potentially alter the kinetics and mechanisms of photochemical reactions, with a particular focus on organic acids. In the second project, we demonstrate that autoxidation can occur in cloudwater, but it was likely neglected in some of the previous laboratory studies. Finally in the third project, the photochemistry of BrC emitted from biomass burning is investigated. We discovered an unrecognized link between the wavelength of UV light and the mechanisms through which BrC is photochemically processed.

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Ran Zhao is an Assistant Professor at the University of Alberta. He received his BSc and PhD from the University of Toronto, and then completed his postdoctoral work at the California Institute of Technology as a NSERC fellow. He then joined the faculty of the Department of Chemistry at Alberta in 2017. His research focuses on atmospheric chemical processes, including secondary organic aerosol formation, cloudwater chemistry, and indoor air quality.