Wintertime Aerosol Volatility Measurements in Seoul, Korea Using a Thermodenuder (TD) Coupled with a High-Resolution Aerosol Mass Spectrometer (HR-ToF-AMS)
HWAJIN KIM, Hyun-Gu Kang, Jiwoo Jeong,
Seoul National University Abstract Number: 191
Working Group: Urban Aerosols
AbstractHere the sources and volatility properties of ambient OA in Seoul during winter time were investigated by using a thermodenuder (TD) coupled with an high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The mean submicron aerosol (PM1 = NR-PM1 + black carbon(BC)) concentrations were 26.37µg/m3, varying between 4.61 and 91.4µg/m3 dominated by organics (41%) and nitrate (30%). The concentrations and chemical composition of PM1 varied considerably depending on meteorological conditions, atmospheric processes, and influences from local and regional emission sources.
Application of positive matrix factorization (PMF) on HR data identified six distinct OA sources: Hydrocarbon-like OA (HOA; O/C = 0.13), cooking-related OA (COA; O/C 0.18), nitrogen-enriched OA (NOA; N/C = 0.22), biomass burning OA (BBOA; O/C = 0.25), low-oxidized oxygenated OA (LO-OOA; O/C =0.68), and more-oxidized OOA (MO-OOA; O/C = 1.15).
Moreover, a volatility basis set (VBS) of the OA was derived by applying a mass transfer model on the measured mass fraction remaining (MFR) varying the temperature from 30-200˚C. The volatility distributions varied considerably depending on different OA sources. HOA, COA, NOA and BBOA showed overall high volatility. LO-OOA factor detected in the winter highly consisted of low volatility organic compounds (LVOCs, effective saturation concentration (C*) of 10-3 to 0.1µg/m3). MO-OOA, however, had an uncommon feature on the relationship between O/C ratio and the volatility. Details on these features will be discussed by comparing the other seasons and previous winter studies.