Using highly time-resolved online mass spectrometry to examine biogenic and anthropogenic contributions to organic aerosol in Beijing

Abstract

Organic aerosols, a major constituent of fine particulate mass in megacities, can be directly emitted or formed from secondary processing of biogenic and anthropogenic volatile organic compound emissions. The complexity of volatile organic compound emission sources, speciation and oxidation pathways leads to uncertainties in the key sources and chemistry leading to formation of organic aerosol in urban areas. Historically, online measurements of organic aerosol composition have been unable to resolve specific markers of volatile organic compound oxidation, while offline analysis of markers focus on a small proportion of organic aerosol and lack the time resolution to carry out detailed statistical analysis required to study the dynamic changes in aerosol sources and chemistry. Here we use data collected as part of the joint UK–China Air Pollution and Human Health (APHH-Beijing) collaboration during a field campaign in urban Beijing in the summer of 2017 alongside laboratory measurements of secondary organic aerosol from oxidation of key aromatic precursors (1,3,5-trimethyl benzene, 1,2,4-trimethyl benzene, propyl benzene, isopropyl benzene and 1-methyl naphthalene) to study the anthropogenic and biogenic contributions to organic aerosol. For the first time in Beijing, this study applies positive matrix factorisation to online measurements of organic aerosol composition from a time-of-flight iodide chemical ionisation mass spectrometer fitted with a filter inlet for gases and aerosols (FIGAERO-ToF-I-CIMS). This approach identifies the real-time variations in sources and oxidation processes influencing aerosol composition at a near-molecular level. We identify eight factors with distinct temporal variability, highlighting episodic differences in OA composition attributed to regional influences and in situ formation. These have average carbon numbers ranging from C5–C9 and can be associated with oxidation of anthropogenic aromatic hydrocarbons alongside biogenic emissions of isoprene, α-pinene and sesquiterpenes.

Publication DOI: https://doi.org/10.1039/d0fd00080a
Divisions: College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
College of Engineering & Physical Sciences
Additional Information: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Funding: Archit Mehra is fully funded by the Natural Environment Research Council (NERC) and acknowledges his funding through the NERC EAO Doctoral Training Partnership (NE/L002469/1) and CASE partnership support from Aerodyne Research Inc. Funding for this work was provided by the UK Natural Environment Research Council as part of AIRPRO (NE/N00695X/1) and AIRPOLL (NE/N007123/1) alongside UK Natural Environment Research Council and UK Medical Research Council funding under the framework of the Newton Innovation Fund (grant NE/N006976/1).
Uncontrolled Keywords: Physical and Theoretical Chemistry
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Related URLs: https://pubs.rs ... 0A#!divAbstract (Publisher URL)
http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2021-03-01
Published Online Date: 2021-01-21
Accepted Date: 2020-09-23
Authors: Mehra, Archit
Canagaratna, Manjula
Bannan, Thomas J.
Worrall, Stephen D. (ORCID Profile 0000-0003-1969-3671)
Bacak, Asan
Priestley, Michael
Liu, Dantong
Zhao, Jian
Xu, Weiqi
Sun, Yele
Hamilton, Jacqueline F.
Squires, Freya A.
Lee, James
Bryant, Daniel J.
Hopkins, James R.
Elzein, Atallah
Budisulistiorini, Sri Hapsari
Cheng, Xi
Chen, Qi
Wang, Yuwei
Wang, Lin
Stark, Harald
Krechmer, Jordan E.
Brean, James
Slater, Eloise
Whalley, Lisa
Heard, Dwayne
Ouyang, Bin
Acton, W. Joe F.
Hewitt, C. Nicholas
Wang, Xinming
Fu, Pingqing
Jayne, John
Worsnop, Douglas
Allan, James
Percival, Carl
Coe, Hugh

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