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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
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Volume 15, issue 19 | Copyright
Atmos. Chem. Phys., 15, 11291-11309, 2015
https://doi.org/10.5194/acp-15-11291-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 12 Oct 2015

Research article | 12 Oct 2015

Advanced source apportionment of size-resolved trace elements at multiple sites in London during winter

S. Visser1, J. G. Slowik1, M. Furger1, P. Zotter1,a, N. Bukowiecki1, F. Canonaco1, U. Flechsig2, K. Appel3,b, D. C. Green4, A. H. Tremper4, D. E. Young5,c, P. I. Williams5,6, J. D. Allan5,6, H. Coe5, L. R. Williams7, C. Mohr8,d, L. Xu9, N. L. Ng9,10, E. Nemitz11, J. F. Barlow12, C. H. Halios12, Z. L. Fleming13, U. Baltensperger1, and A. S. H. Prévôt1 S. Visser et al.
  • 1Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland
  • 2Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
  • 3HASYLAB, DESY Photon Science, Hamburg, Germany
  • 4Analytical and Environmental Sciences, King's College London, London, UK
  • 5School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, UK
  • 6National Centre for Atmospheric Science, University of Manchester, Manchester, UK
  • 7Aerodyne Research, Inc., Billerica, MA, USA
  • 8Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
  • 9School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA
  • 10School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
  • 11Centre for Ecology and Hydrology, Penicuik, Midlothian, Scotland
  • 12Department of Meteorology, University of Reading, Reading, UK
  • 13National Centre for Atmospheric Science, Department of Chemistry, University of Leicester, Leicester, UK
  • anow at: Lucerne School of Engineering and Architecture, Bioenergy Research, Lucerne University of Applied Sciences and Arts, Horw, Switzerland
  • bnow at: European XFEL, Hamburg, Germany
  • cnow at: Department of Environmental Toxicology, University of California, Davis, CA, USA
  • dnow at: Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany

Abstract. 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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Trace element measurements in three particle size ranges (PM10-2.5, PM2.5-1.0 and PM1.0-0.3) were performed with 2h 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. A total of nine different factors were resolved from local, regional and natural origin.
Trace element measurements in three particle size ranges (PM10-2.5, PM2.5-1.0 and PM1.0-0.3)...
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