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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
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Volume 10, issue 4
Atmos. Chem. Phys., 10, 1969–1988, 2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 10, 1969–1988, 2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.

  19 Feb 2010

19 Feb 2010

Simultaneous factor analysis of organic particle and gas mass spectra: AMS and PTR-MS measurements at an urban site

J. G. Slowik3,1, A. Vlasenko3,1, M. McGuire3,2, G. J. Evans3,2, and J. P. D. Abbatt3,1 J. G. Slowik et al.
  • 1Department of Chemistry, University of Toronto, Toronto, Canada
  • 2Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada
  • 3Southern Ontario Centre for Atmospheric Aerosol Research, University of Toronto, Toronto, Canada

Abstract. During the winter component of the SPORT (Seasonal Particle Observations in the Region of Toronto) field campaign, particulate non-refractory chemical composition and concentration of selected volatile organic compounds (VOCs) were measured by an Aerodyne time-of-flight aerosol mass spectrometer (AMS) and a proton transfer reaction-mass spectrometer (PTR-MS), respectively. Sampling was performed in downtown Toronto ~15 m from a major road. The mass spectra from the AMS and PTR-MS were combined into a unified dataset, which was analysed using positive matrix factorization (PMF). The two instruments were given balanced weight in the PMF analysis by the application of a scaling factor to the uncertainties of each instrument. A residual based metric, Δesc, was used to evaluate the instrument relative weight within each solution. The PMF analysis yielded a 6-factor solution that included factors characteristic of regional transport, local traffic emissions, charbroiling and oxidative processing. The unified dataset provides information on emission sources (particle and VOC) and atmospheric processing that cannot be obtained from the datasets of the individual instruments: (1) apportionment of oxygenated VOCs to either direct emission sources or secondary reaction products; (2) improved correlation of oxygenated aerosol factors with photochemical age; and (3) increased detail regarding the composition of oxygenated organic aerosol factors. This analysis represents the first application of PMF to a unified AMS/PTR-MS dataset.

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