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Characterization, sources and reactivity of volatile organic compounds (VOCs) in Seoul and surrounding regions during KORUS-AQ

Simpson, Isobel J. and Blake, Donald R. and Blake, Nicola J. and Meinardi, Simone and Barletta, Barbara and Hughes, Stacey C. and Fleming, Lauren T. and Crawford, James H. and Diskin, Glenn S. and Emmons, Louisa K. and Fried, Alan and Guo, Hai and Peterson, David A. and Wisthaler, Armin and Woo, Jung-Hun and Barré, Jerome and Gaubert, Benjamin and Kim, Jinseok and Kim, Michelle J. and Kim, Younha and Knote, Christoph and Mikoviny, Tomas and Pusede, Sally E. and Schroeder, Jason R. and Wang, Yu and Wennberg, Paul O. and Zeng, Lewei (2020) Characterization, sources and reactivity of volatile organic compounds (VOCs) in Seoul and surrounding regions during KORUS-AQ. Elementa: Science of the Anthropocene, 8 (1). Art. No. 37. ISSN 2325-1026. doi:10.1525/elementa.434.

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The Korea-United States Air Quality Study (KORUS-AQ) took place in spring 2016 to better understand air pollution in Korea. In support of KORUS-AQ, 2554 whole air samples (WAS) were collected aboard the NASA DC-8 research aircraft and analyzed for 82 C₁–C₁₀ volatile organic compounds (VOCs) using multi-column gas chromatography. Together with fast-response measurements from other groups, the air samples were used to characterize the VOC composition in Seoul and surrounding regions, determine which VOCs are major ozone precursors in Seoul, and identify the sources of these reactive VOCs. (1) The WAS VOCs showed distinct signatures depending on their source origins. Air collected over Seoul had abundant ethane, propane, toluene and n-butane while plumes from the Daesan petrochemical complex were rich in ethene, C₂–C₆ alkanes and benzene. Carbonyl sulfide (COS), CFC-113, CFC-114, carbon tetrachloride (CCl₄) and 1,2-dichloroethane were good tracers of air originating from China. CFC-11 was also elevated in air from China but was surprisingly more elevated in air over Seoul. (2) Methanol, isoprene, toluene, xylenes and ethene were strong individual contributors to OH reactivity in Seoul. However methanol contributed less to ozone formation based on photochemical box modeling, which better accounts for radical chemistry. (3) Positive Matrix Factorization (PMF) and other techniques indicated a mix of VOC source influences in Seoul, including solvents, traffic, biogenic, and long-range transport. The solvent and traffic sources were roughly equal using PMF, and the solvents source was stronger in the KORUS-AQ emission inventory. Based on PMF, ethene and propene were primarily associated with traffic, and toluene, ethylbenzene and xylenes with solvents, especially non-paint solvents for toluene and paint solvents for ethylbenzene and xylenes. This suggests that VOC control strategies in Seoul could continue to target vehicle exhaust and paint solvents, with additional regulations to limit the VOC content in a variety of non-paint solvents.

Item Type:Article
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Kim, Michelle J.0000-0002-4922-4334
Wennberg, Paul O.0000-0002-6126-3854
Additional Information:© 2020 University of California Press. CC BY 4.0. Submitted on 06 Dec 2019; Accepted on 23 Jun 2020; Published on 11 Aug 2020. The KORUS-AQ mission was jointly funded by NASA and the Korean National Institute of Environmental Research (NIER). We gratefully acknowledge the KORUS-AQ crew and science team, and the technicians and staff at UC-Irvine who supported the WAS effort (Barbara Chisholm, Gloria Liu Weitz, Brent Love, Nick Vizenor, Rafe Day). The NO_y and O₃ data were provided courtesy of Andrew Weinheimer and Denise Montzka (NCAR), and John Crounse provided HCN data. The PTR-ToF-MS measurements were supported by the Austrian Federal Ministry for Transport, Innovation and Technology (bmvit) through the Austrian Space Applications Programme (ASAP) of the Austrian Research Promotion Agency (FFG). The PTR-ToF-MS instrument team (P. Eichler, L. Kaser, M. Müller) is acknowledged for their support in the field and during the mission preparation phase, and Ionicon Analytik is acknowledged for instrumental support. We also thank Daniel Bon (Colorado Dept. of Public Health & Environment) for helpful discussions on PMF, Hannah Halliday (NASA Langley) and Meehye Lee (Korea University) for helpful discussions on regional source influences, Saewung Kim (UCI) for coordination during the MAPS-2015 campaign, and Yanhong Zhu (Jinan University) for providing wheat count hotspots during the KORUS-AQ timeframe. We thank the UC White Mountain Research Center for use of the Crooked Creek Station for gathering air samples for use as working standards. Finally we thank numerous colleagues for valuable discussions and feedback on the interpretation of the source apportionment results. The authors have no competing interests to declare. Author contributions: IJS interpreted the data and wrote the manuscript. DRB oversaw the WAS contribution to KORUS-AQ and performed data analysis and interpretation. NJB oversaw WAS field operations, and NJB, SCH and LTF acquired WAS data. SM oversaw WAS laboratory operations and performed data analysis. BB oversaw WAS data management. JHC and JRS performed photochemical box modeling calculations and data interpretation. GSD and SEP provided CO and CH₄ measurements. HG, DW and IZ supported the PMF analysis. DAP oversaw the meteorological analysis. AW and TM performed PTR-ToF-MS analysis. JHW, JK and YK oversaw the KORUSv5 emission inventory and provided data for the paper. AF led the CH₂O analysis. LKE, JB and BG provided CAM-chem model simulations. CK provided the FLEXPART back trajectories. POW and MJK provided HCN data. All co-authors revised the manuscript and approved the submitted version for publication. Data Accessibility Statement: All observational data from the KORUS-AQ mission, including the WAS VOC data, are archived at:
Funding AgencyGrant Number
National Institute of Environmental Research (NIER)UNSPECIFIED
Bundesministerium für Verkehr, Innovation und Technologie (BMVIT)UNSPECIFIED
Österreichische Forschungsförderungsgesellschaft (FFG)UNSPECIFIED
Subject Keywords:VOCs, Seoul, Korea, KORUS-AQ, Source apportionment, OH reactivity
Issue or Number:1
Record Number:CaltechAUTHORS:20200903-122323790
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Official Citation:Simpson, IJ, et al. 2020. Characterization, sources and reactivity of volatile organic compounds (VOCs) in Seoul and surrounding regions during KORUS-AQ. Elem Sci Anth, 8: 37. DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105240
Deposited By: Tony Diaz
Deposited On:08 Sep 2020 17:24
Last Modified:16 Nov 2021 18:41

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