Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 15545-15559, 2016
https://doi.org/10.5194/acp-16-15545-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
16 Dec 2016
Organic aerosol source apportionment in London 2013 with ME-2: exploring the solution space with annual and seasonal analysis
Ernesto Reyes-Villegas1, David C. Green2, Max Priestman2, Francesco Canonaco3, Hugh Coe1, André S. H. Prévôt3, and James D. Allan1,4 1School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, UK
2School of Biomedical and Health Sciences, King's College London, London, UK
3Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
4National Centre for Atmospheric Science, The University of Manchester, Manchester, M13 9PL, UK
Abstract. The multilinear engine (ME-2) factorization tool is being widely used following the recent development of the Source Finder (SoFi) interface at the Paul Scherrer Institute. However, the success of this tool, when using the a value approach, largely depends on the inputs (i.e. target profiles) applied as well as the experience of the user. A strategy to explore the solution space is proposed, in which the solution that best describes the organic aerosol (OA) sources is determined according to the systematic application of predefined statistical tests. This includes trilinear regression, which proves to be a useful tool for comparing different ME-2 solutions. Aerosol Chemical Speciation Monitor (ACSM) measurements were carried out at the urban background site of North Kensington, London from March to December 2013, where for the first time the behaviour of OA sources and their possible environmental implications were studied using an ACSM. Five OA sources were identified: biomass burning OA (BBOA), hydrocarbon-like OA (HOA), cooking OA (COA), semivolatile oxygenated OA (SVOOA) and low-volatility oxygenated OA (LVOOA). ME-2 analysis of the seasonal data sets (spring, summer and autumn) showed a higher variability in the OA sources that was not detected in the combined March–December data set; this variability was explored with the triangle plots f44 : f43 f44 : f60, in which a high variation of SVOOA relative to LVOOA was observed in the f44 : f43 analysis. Hence, it was possible to conclude that, when performing source apportionment to long-term measurements, important information may be lost and this analysis should be done to short periods of time, such as seasonally. Further analysis on the atmospheric implications of these OA sources was carried out, identifying evidence of the possible contribution of heavy-duty diesel vehicles to air pollution during weekdays compared to those fuelled by petrol.

Citation: Reyes-Villegas, E., Green, D. C., Priestman, M., Canonaco, F., Coe, H., Prévôt, A. S. H., and Allan, J. D.: Organic aerosol source apportionment in London 2013 with ME-2: exploring the solution space with annual and seasonal analysis, Atmos. Chem. Phys., 16, 15545-15559, https://doi.org/10.5194/acp-16-15545-2016, 2016.
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Short summary
For the first time in the UK, an Aerosol Chemical Speciation Monitor was used to measure aerosol concentrations in London in March–December 2013, with further organic aerosol (OA) source apportionment using the ME-2 factorization tool. Five OA sources were identified: biomass burning OA, hydrocarbon-like OA, cooking OA, semivolatile oxygenated OA and low-volatility oxygenated OA. This information can be used to take future action on the respective legislation in order to improve the air quality.
For the first time in the UK, an Aerosol Chemical Speciation Monitor was used to measure aerosol...
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