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| Titel |
Investigating the annual behaviour of submicron secondary inorganic and organic aerosols in London |
| VerfasserIn |
D. E. Young, J. D. Allan, P. I. Williams, D. C. Green, M. J. Flynn, R. M. Harrison, J. Yin, M. W. Gallagher, H. Coe |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 11 ; Nr. 15, no. 11 (2015-06-11), S.6351-6366 |
| Datensatznummer |
250119802
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| Publikation (Nr.) |
 copernicus.org/acp-15-6351-2015.pdf |
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| Zusammenfassung |
For the first time, the behaviour of non-refractory inorganic and organic
submicron particulate through an entire annual cycle is investigated using
measurements from an Aerodyne compact time-of-flight aerosol mass
spectrometer (cToF-AMS) located at a UK urban background site in North
Kensington, London. We show that secondary aerosols account for a significant
fraction of the submicron aerosol burden and that high concentration events
are governed by different factors depending on season. Furthermore, we
demonstrate that on an annual basis there is no variability in the extent of
secondary organic aerosol (SOA) oxidation, as defined by the oxygen content,
irrespective of amount. This result is surprising given the changes in
precursor emissions and contributions as well as photochemical activity
throughout the year; however it may make the characterisation of SOA in
urban environments more straightforward than previously supposed.
Organic species, nitrate, sulphate, ammonium, and chloride were measured
during 2012 with average concentrations (±1 standard deviation) of
4.32 (±4.42), 2.74 (±5.00), 1.39 (±1.34), 1.30
(±1.52), and 0.15 (±0.24) μg m−3, contributing
44, 28, 14, 13, and 2 % to the total non-refractory
submicron mass (NR-PM1) respectively. Components of the organic
aerosol fraction are determined using positive matrix factorisation (PMF),
in which five factors are identified and attributed as hydrocarbon-like OA (HOA), cooking OA (COA), solid fuel OA (SFOA), type 1 oxygenated OA (OOA1),
and type 2 oxygenated OA (OOA2). OOA1 and OOA2 represent more and less
oxygenated OA with average concentrations of 1.27 (±1.49) and 0.14
(±0.29) μg m−3 respectively, where OOA1 dominates the
SOA fraction (90%).
Diurnal, monthly, and seasonal trends are observed in all organic and
inorganic species due to meteorological conditions, specific nature of the
aerosols, and availability of precursors. Regional and transboundary
pollution as well as other individual pollution events influence London's
total submicron aerosol burden. High concentrations of non-refractory
submicron aerosols in London are governed by particulate emissions in
winter, especially nitrate and SFOA, whereas SOA formation drives the high
concentrations during the summer. The findings from this work could have
significant implications for modelling of urban air pollution as well as for
the effects of atmospheric aerosols on health and climate. |
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