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Poster Presentations
Day 4, June 25（Wed.）
Room P (Maesato East, Foyer, Ocean Wing)
- 4P-AM-25
Using an online GC-EI-TOF-MS for the source apportionment of an air pollution episode in March 2023 at a suburban site in Hong Kong
(1HKUST (CHEM), 2HKUST (ENVR))
oAnna Mae Vorwerk1, Wing Sze Chow1, Jian Zhen Yu1,2
Volatile organic compounds (VOCs) have adverse effects on air quality. For a fast response to air pollution, VOC monitoring with online instruments is crucial. Commonly used proton transfer reaction mass spectrometers (PTR-MS) offer high sensitivity, time and mass resolution. However, the detected isobaric ions notably complicate source apportionment. Therefore, online high-resolution mass spectrometer should be coupled with gas chromatographs to gain detailed knowledge of local VOC composition and emission sources.
With an Aerodyne 2-channel GC-MS, we have captured VOCs with a half-hour time resolution. Using one-week VOC data, we attempted source apportionment of a short-term high-VOC air pollution episode. Through source-indicating VOCs, VOC ratios and modelled 72-h air mass back trajectory cluster analysis, we revealed that the episode was associated with an increase of short-range transported industrial solvent use emissions. Through positive matrix factorization (PMF) analysis two of seven factors of the PMF solution were attributed to the episode. The factors represent non-local solvent-use and industrial emission sources. Another factor is associated with transported emissions, while the remaining factors correspond to background and local emissions. This study emphasizes the impact of transported VOC emissions on local air quality and highlights the capabilities of high-resolution online GC-MS instrumentations for VOC monitoring.