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dc.contributor.author
Liu, Dantong
dc.contributor.author
Allan, James D.
dc.contributor.author
Young, Dominique E.
dc.contributor.author
Coe, Hugh
dc.contributor.author
Beddows, David
dc.contributor.author
Fleming, Zoe L.
dc.contributor.author
Flynn, Michael J.
dc.contributor.author
Gallagher, Martin W.
dc.contributor.author
Harrison, Roy M.
dc.contributor.author
Lee, James
dc.contributor.author
Prévôt, André S.H.
dc.contributor.author
Taylor, Jonathan W.
dc.contributor.author
Yin, J.
dc.contributor.author
Williams, P.I.
dc.contributor.author
Zotter, Peter
dc.date.accessioned
2018-09-25T09:35:49Z
dc.date.available
2017-06-11T12:43:39Z
dc.date.available
2018-03-15T17:25:39Z
dc.date.available
2018-09-25T09:35:49Z
dc.date.issued
2014
dc.identifier.issn
1680-7375
dc.identifier.issn
1680-7367
dc.identifier.other
10.5194/acp-14-10061-2014
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/89941
dc.identifier.doi
10.3929/ethz-b-000089941
dc.description.abstract
Black carbon aerosols (BC) at a London urban site were characterised in both winter- and summertime 2012 during the Clean Air for London (ClearfLo) project. Positive matrix factorisation (PMF) factors of organic aerosol mass spectra measured by a high-resolution aerosol mass spectrometer (HR-AMS) showed traffic-dominant sources in summer but in winter the influence of additional non-traffic sources became more important, mainly from solid fuel sources (SF). Measurements using a single particle soot photometer (SP2, DMT), showed the traffic-dominant BC exhibited an almost uniform BC core size (Dc) distribution with very thin coating thickness throughout the detectable range of Dc. However, the size distribution of Dc (project average mass median Dc = 149 ± 22 nm in winter, and 120 ± 6 nm in summer) and BC coating thickness varied significantly in winter. A novel methodology was developed to attribute the BC number concentrations and mass abundances from traffic (BCtr) and from SF (BCsf), by using a 2-D histogram of the particle optical properties as a function of BC core size, as measured by the SP2. The BCtr and BCsf showed distinctly different Dc distributions and coating thicknesses, with BCsf displaying larger Dc and larger coating thickness compared to BCtr. BC particles from different sources were also apportioned by applying a multiple linear regression between the total BC mass and each AMS-PMF factor (BC–AMS–PMF method), and also attributed by applying the absorption spectral dependence of carbonaceous aerosols to 7-wavelength Aethalometer measurements (Aethalometer method). Air masses that originated from westerly (W), southeasterly (SE), and easterly (E) sectors showed BCsf fractions that ranged from low to high, and whose mass median Dc values were 137 ± 10 nm, 143 ± 11 nm and 169 ± 29 nm, respectively. The corresponding bulk relative coating thickness of BC (coated particle size/BC core – Dp/Dc) for these same sectors was 1.28 ± 0.07, 1.45 ± 0.16 and 1.65 ± 0.19. For W, SE and E air masses, the number fraction of BCsf ranged from 6 ± 2% to 11 ± 5% to 18 ± 10%, respectively, but importantly the larger BC core sizes lead to an increased fraction of BCsf in terms of mass than number (for W, SE and E air masses, the BCsf mass fractions ranged from 16 ± 6%, 24 ± 10% and 39 ± 14%, respectively). An increased fraction of non-BC particles (particles that did not contain a BC core) was also observed when SF sources were more significant. The BC mass attribution by the SP2 method agreed well with the BC–AMS–PMF multiple linear regression method (BC–AMS–PMF : SP2 ratio = 1.05, r2 = 0.80) over the entire experimental period. Good agreement was found between BCsf attributed with the Aethalometer model and the SP2. However, the assumed absorption Ångström exponent (αwb) had to be changed according to the different air mass sectors to yield the best comparison with the SP2. This could be due to influences of fuel type or burn phase.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
Copernicus
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/3.0/
dc.title
Size distribution, mixing state and source apportionment of black carbon aerosol in London during wintertime
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 3.0 Unported
dc.date.published
2014-09-22
ethz.journal.title
Atmospheric Chemistry and Physics
ethz.journal.volume
14
en_US
ethz.journal.issue
18
en_US
ethz.journal.abbreviated
Atmos. chem. phys.
ethz.pages.start
10061
en_US
ethz.pages.end
10084
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.identifier.wos
ethz.identifier.nebis
004294181
ethz.publication.place
Göttingen
en_US
ethz.publication.status
published
en_US
ethz.date.deposited
2017-06-11T12:44:28Z
ethz.source
ECIT
ethz.identifier.importid
imp5936525917e1891959
ethz.ecitpid
pub:141664
ethz.eth
no
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-07-18T08:40:50Z
ethz.rosetta.lastUpdated
2018-09-25T09:35:54Z
ethz.rosetta.exportRequired
true
ethz.rosetta.versionExported
true
ethz.COinS
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