Comparison of the Estimated and the Measured Concentrations of Secondary Organic Aerosol Based on the Measured Concentration of Volatile Organic Compounds (VOC)

JI-WON JEON, Young-Ji Han, Sung-Won Park, Pyung-rae Kim, Hyo-Won Lee, Yun-seo Lee, Soo-Jin Jeong, Kangwon National University

     Abstract Number: 662
     Working Group: Chemicals of Emerging Concern in Aerosol: Sources, Transformations, and Impacts

Abstract
Organic compounds, one of the main components of PM_2.5, are either directly emitted from both natural and anthropogenic sources (primary organic aerosol: POA) or secondarily formed in atmosphere via (secondary organic aerosol: SOA). SOA can be formed through the oxidation of volatile organic compounds (VOCs) primarily by OH, ozone, and NO₃ radicals, generating low volatility products that are subsequently partitioned into the condensed phase. In this study, 52 VOC species were measured using on-line GC (GC 955-611/811, Synspec, NED)in Chuncheon, a medium-sized residential city of South Korea in 2023. PM_2.5 was also collected and the concentrations of its individual organic matters were measured using GC-MS in order to relate VOC to organic aerosol.

During the measurement period, the average total VOC concentration was 8.7 (± 5.5) ppbv. DHOPA, a tracer of anthropogenic SOAs (ASOAs) and 2-methylthreitol, 2-methylerythritol, 3-hydroglutaric acid, pinic acid, and pinonic acid, the tracers for biogenic SOAs (BSOA) were measured. Average concentrations of DHOPA and total BSOAs, were 3.1 (±2.3) and 23.1 (±18.8) ng/m³, respectively, indicating that BSOAs were actively produced in this city with a forest area of approximately 74%. Notably, the concentration of BSOAs increased to 50.1 ng/m³ in June (summer), and the isoprene concentration during this period was 0.56 (±0.48) ppbv, which was about twice higher than that in the metropolitan (Seoul) and industrial regions (Ulsan). In this study, SOA concentrations were also estimated based on the measurements of VOC and SOA tracers using box model, and the results will be presented at the conference.