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Particulate matter (PM) episodes at a suburban site in Hong Kong: Evolution of PM characteristics and role of photochemistry in secondary aerosol formation
Qin,Yi Ming1; Li,Yong Jie2; Wang,Hao3; Lee,Berto Paul Yok Long3; Huang,Dan Dan1; Chan,Chak Keung1,3,4
2016-11-15
Source PublicationAtmospheric Chemistry and Physics
ISSN1680-7316
Volume16Issue:22Pages:14131-14145
Abstract

Episodes with high concentrations of particulate matter (PM) across the seasons were investigated during four 1-month campaigns at a suburban site in Hong Kong. High-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) measurements revealed that both regional transport and secondary formation contributed to high PM levels during the episodes at this site. Based on distinct meteorological conditions, episodes were categorized into three types: liquid water content (LWC), solar irradiance (IR), and long-range transport (LRT). Despite the difference in meteorological conditions, all episodes were characterized by a high fraction of sulfate (45-56 %) and organics (23-34 %). However, aerosols in LWC episodes were less aged, consisting of the lowest fraction of secondary organic aerosol (SOA) and the highest fraction of small particles. Large particles mixed internally while freshly formed small particles mixed externally in LWC episodes. Aerosols in LRT episodes, by contrast, were the most aged and consisted of the highest proportion of low-volatility oxygenated organic aerosol (LVOOA) and the lowest proportion of small particles. Both small and large particles mixed externally in LRT episodes. The highest proportion of semi-volatile oxygenated organic aerosol (SVOOA) and a medium proportion of small particles were observed in IR episodes. Both small and large particles were likely externally mixed during IR episodes. Furthermore, aerosols experienced the most dramatic size increase and diurnal variation, with a time lag between SVOOA and LVOOA and a gradual increase in carbon oxidation state (OS ∼ 2 × O : C - H : C). Five out of 10 episodes were of the IR type, further reflecting the importance of this type of episode. The evolution of aerosol components in one particular episode of the IR type, which exhibited a clear land-sea breeze pattern, was examined in detail. Sulfate and SOA due to photochemical aging were very efficiently produced during the course of 6 h. The "less-oxidized" SOA (SVOOA) was initially formed at a higher rate than the "more-oxidized" SOA (LVOOA). The SVOOA transformed to LVOOA at the later stage of photochemical aging. This transformation was further supported by mass spectral analysis, which showed an increase in the most oxidized ion (CO2+) and decreases in moderately oxidized ones (C2H3O+, C3H3O+and C3H5O+). By measuring the physical and chemical properties of PM in a highly time-resolved manner, the current study was able to demonstrate the dynamic and complex nature of PM transformation during high-PM episodes.

DOI10.5194/acp-16-14131-2016
URLView the original
Indexed BySCI
Language英语
WOS Research AreaEnvironmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS SubjectEnvironmental Sciences ; Meteorology & Atmospheric Sciences
WOS IDWOS:000387860800006
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Cited Times [WOS]:8   [WOS Record]     [Related Records in WOS]
Document TypeJournal article
CollectionFaculty of Science and Technology
Personal research not belonging to the institution
Corresponding AuthorLi,Yong Jie; Chan,Chak Keung
Affiliation1.Department of Chemical and Biomolecular EngineeringHong Kong University of Science and Technology,Hong Kong
2.Department of Civil and Environmental EngineeringFaculty of Science and TechnologyUniversity of Macau,Taipa,Macao
3.Division of EnvironmentHong Kong University of Science and Technology,Hong Kong
4.School of Energy and EnvironmentCity University of Hong Kong,Hong Kong
Corresponding Author AffilicationFaculty of Science and Technology
Recommended Citation
GB/T 7714
Qin,Yi Ming,Li,Yong Jie,Wang,Hao,et al. Particulate matter (PM) episodes at a suburban site in Hong Kong: Evolution of PM characteristics and role of photochemistry in secondary aerosol formation[J]. Atmospheric Chemistry and Physics,2016,16(22):14131-14145.
APA Qin,Yi Ming,Li,Yong Jie,Wang,Hao,Lee,Berto Paul Yok Long,Huang,Dan Dan,&Chan,Chak Keung.(2016).Particulate matter (PM) episodes at a suburban site in Hong Kong: Evolution of PM characteristics and role of photochemistry in secondary aerosol formation.Atmospheric Chemistry and Physics,16(22),14131-14145.
MLA Qin,Yi Ming,et al."Particulate matter (PM) episodes at a suburban site in Hong Kong: Evolution of PM characteristics and role of photochemistry in secondary aerosol formation".Atmospheric Chemistry and Physics 16.22(2016):14131-14145.
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