AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Using High Complexity Analysis to Probe the Evolution of Organic Aerosol during Pollution Events in Beijing
JACQUELINE F. HAMILTON, William Dixon, Rachel E. Dunmore, Freya Squires, Stefan Swift, James D. Lee, Andrew R. Rickard, Yele Sun, Weiqi Xu, University of York
Abstract Number: 799 Working Group: Urban Aerosols
Abstract There is increasing evidence that exposure to air pollution results in significant impacts on human health. In Beijing, home to over 20 million inhabitants, particulate matter levels are very high by international standards. Changes in particle composition during pollution events will provide key information on sources and can be used to inform strategies for pollution mitigation and health benefits.
The organic fraction of PM is an extremely complex mixture reflecting the diversity of sources to the atmosphere. In this study we attempt to harness the chemical complexity of OA by developing an extensive database of over 700 mass spectra, built using literature data and sources specific tracers. Using a high throughput analysis method, involving UHPLC coupled to Orbitrap mass spectrometry, chromatograms are integrated, compared to the library and a list of identified compounds produced. Purpose built software based on R is used to automatically produce time series, alongside common aerosol metrics and data visualisation techniques, dramatically reducing analysis times.
Offline measurements of organic aerosol composition were made as part of the Sources and Emissions of Air Pollutants in Beijing project, a collaborative program between leading UK and Chinese research groups. Rather than studying only a small number samples, we collected ~250 filters at a range of time resolutions, from 30 minutes to 12 hours, depending on the time of day and PM loadings. In total 643 species were identified based on their elemental formula and retention time, with species ranging from C2-C22 and between 1-13 oxygen atoms. Here we will present preliminary results on the factors that impact the evolution of organic aerosol in Beijing, highlighting the role of biomass burning in winter and photochemistry in summer. Modern data mining and statistical analysis methods will be used to identify patterns in the OA composition.