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| Titel |
Advanced source apportionment of size-resolved trace elements at multiple sites in London during winter |
| VerfasserIn |
S. Visser, J. G. Slowik, M. Furger, P. Zotter, N. Bukowiecki, F. Canonaco, U. Flechsig, K. Appel, D. C. Green, A. H. Tremper, D. E. Young, P. I. Williams, J. D. Allan, H. Coe, L. R. Williams, C. Mohr, L. Xu, N. L. Ng, E. Nemitz, J. F. Barlow, C. H. Halios, Z. L. Fleming, U. Baltensperger, A. S. H. Prévôt |
| 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. 19 ; Nr. 15, no. 19 (2015-10-12), S.11291-11309 |
| Datensatznummer |
250120090
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| Publikation (Nr.) |
 copernicus.org/acp-15-11291-2015.pdf |
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| Zusammenfassung |
Trace element measurements in PM10–2.5, PM2.5–1.0
and PM1.0–0.3 aerosol were performed with 2 h time resolution
at kerbside, urban background and rural sites during the ClearfLo winter 2012
campaign in London. The environment-dependent variability of emissions was
characterized using the Multilinear Engine implementation of the positive
matrix factorization model, conducted on data sets comprising all three sites
but segregated by size. Combining the sites enabled separation of sources
with high temporal covariance but significant spatial variability. Separation
of sizes improved source resolution by preventing sources occurring in only a
single size fraction from having too small a contribution for the model to
resolve. Anchor profiles were retrieved internally by analysing data subsets,
and these profiles were used in the analyses of the complete data sets of all
sites for enhanced source apportionment.
A total of nine different factors were resolved (notable elements in
brackets): in PM10–2.5, brake wear (Cu, Zr, Sb, Ba), other
traffic-related (Fe), resuspended dust (Si, Ca), sea/road salt (Cl), aged sea
salt (Na, Mg) and industrial (Cr, Ni); in PM2.5–1.0, brake wear,
other traffic-related, resuspended dust, sea/road salt, aged sea salt and
S-rich (S); and in PM1.0–0.3, traffic-related (Fe, Cu, Zr, Sb,
Ba), resuspended dust, sea/road salt, aged sea salt, reacted Cl (Cl), S-rich
and solid fuel (K, Pb). Human activities enhance the kerb-to-rural
concentration gradients of coarse aged sea salt, typically considered to have
a natural source, by 1.7–2.2. These site-dependent concentration differences
reflect the effect of local resuspension processes in London. The
anthropogenically influenced factors traffic (brake wear and other
traffic-related processes), dust and sea/road salt provide further
kerb-to-rural concentration enhancements by direct source emissions by a
factor of 3.5–12.7. The traffic and dust factors are mainly emitted in
PM10–2.5 and show strong diurnal variations with concentrations
up to 4 times higher during rush hour than during night-time.
Regionally influenced S-rich and solid fuel factors, occurring primarily in
PM1.0–0.3, have negligible resuspension influences, and
concentrations are similar throughout the day and across the regions. |
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