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| Titel |
Seasonal Variations of High Time-Resolved Chemical Compositions, Sources and
Evolution for Atmospheric Submicron Aerosols in the Megacity of Beijing |
| VerfasserIn |
Min Hu, Wei Hu, Weiwei Hu, Jing Zheng, Song Guo, Yusheng Wu, Sihua Lu, Limin Zeng |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123919
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| Publikation (Nr.) |
 EGU/EGU2016-3261.pdf |
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| Zusammenfassung |
| This study aims to investigate aerosol secondary formation and aging process in the megacity
of Beijing. Seasonal intensive campaigns were conducted from March 2012 to March 2013 at
an urban site located at the campus of Peking University (116.31˚ E, 37.99˚ N). An
Aerodyne high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) and other
relevant instrumentations for gaseous and particulate pollutants were deployed. The average
submicron aerosol (PM1) mass concentrations were 45.1 ± 45.8, 37.5 ± 31.0, 41.3 ± 42.7
and 81.7 ± 72.4 μg m−3 in spring, summer, autumn and winter, respectively. Organic
matter was the most abundant component, accounting for 31%, 33%, 44% and
36% in PM1 correspondingly, followed by sulfate and nitrate. Distinct seasonal
and diurnal patterns of the components of PM1 tracking primary sources (e.g., BC
and HOA) and secondary formation (e.g., sulfate, nitrate, ammonium, LV-OOA
and SV-OOA) were significantly influenced by primary emissions and mesoscale
meteorology.
Combining positive matrix factorization (PMF) analysis with the mass spectrometry of
organics measured by AMS, the contributions of primary and secondary sources to
submicron organic aerosols (OA) were apportioned. In spring and summer, the primary
sources were hydrocarbon-like OA (HOA) and cooking OA (COA), and the secondary
components were low volatility (LV-OOA) and semi-volatile oxygenated OA (SV-OOA). In
winter biomass burning OA (BBOA) was also resolved. In autumn, four factors were
resolved, that is, OOA, HOA, COA and BBOA. In general, OOA (sum of LV-OOA
and SV-OOA) was important in OA in four seasons, accounting for about 63%,
70%, 47% and 50%, respectively. SV-OOA dominated OA in summer (44%) due to
the fresh secondary formation from strong photochemical oxidations; whereas,
LV-OOA was dominant in OA in winter (33%), maybe because the transported air
masses were more aged in heavily polluted days. The POA (sum of HOA, COA and
BBOA) in OA was dominant in autumn because primary emissions, such as biomass
burning, strongly influenced Beijing and surrounding areas. The evolution processes
of OA in the atmosphere are illustrated according to the organic mass to organic
carbon ratio (OM/OC), the elemental ratios (O/C and H/C), the average carbon
oxidation state, as well as the van Krevelen triangle diagram in detail. Therefore, to
prevent regional PM2.5 and haze pollution effectively, further strengthening the
control of primary particulate emissions is expected; in addition the emissions of
secondary species’ precursors must be reduced, especially in adverse meteorological
conditions.
Acknowledgement
This work was supported by the National Basic Research Program of China
(2013CB228503) and the National Natural Science Foundation of China (21190052,
41121004, 91544214). |
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