Preprints
https://doi.org/10.5194/amt-2022-38
https://doi.org/10.5194/amt-2022-38
 
21 Feb 2022
21 Feb 2022
Status: this preprint is currently under review for the journal AMT.

Combined organic and inorganic aerosol source apportionment on yearlong ToF-ACSM dataset at a suburban station in Athens

Olga Zografou1, Maria Gini1, Manousos Ioannis Manousakas2, Gang Chen2, Athina Cerise Kalogridis1, Evangelia Diapouli1, Athina Pappa3, and Konstantinos Eleftheriadis1 Olga Zografou et al.
  • 1Environmental Radioacivity Laboratory, Institute of Nuclear and Radiological Sciences and Technology, Energy Safety, National Centre of Scientific Research “Demokritos”, Ag. Paraskevi, 15310, Greece
  • 2Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, CH-5232, Villigen PSI, Switzerland
  • 3Laboratory of Inorganic and Analytical Chemistry, Department of Chemical Engineering, National Technical University of Athens (NTUA), 9 Iroon Politechniou St., 15773 Athens, Greece

Abstract. The current improvements in aerosol mass spectrometers in resolution and sensitivity, and the analytical tools for mass spectra deconvolution, have enabled the in depth analysis of organic aerosol (OA) properties. Although OA constitutes a major fraction of ambient aerosol, the overall aerosol properties are determined by the mixing characteristics of both organic and inorganic contents of ambient aerosol. In the present study, the mass spectra of both organic and inorganic aerosol were obtained by a time–of–flight aerosol mass spectrometer (ToF-ACSM) and further merged into one input matrix for Positive Matrix Factorization (PMF) analysis. The scope of this work was to assess the sources of organic aerosol and total non–refractory species in the suburbs of Athens, check their temporal variation and the interactions between organic and inorganic species, after reaching environmentally reasonable solutions for both matrices. The results revealed five factors in the case of the organic aerosol matrix. Three of them were primary OA factors: hydrocarbon–like (HOA), cooking related (COA) and biomass burning (BBOA), and the remaining two were secondary, less and more oxidized oxygenated organic aerosol (LO-OOA and MO-OOA, respectively). The relative contributions of these factors were HOA 15 %, COA 18 %, BBOA 9 %, MO-OOA 34 % and LO-OOA 24 % (yearly averaged). In the case of the combined aerosol matrix, two additional factors were identified that were mainly composed of ammonium sulfate (83.5 %) and ammonium nitrate (73 %). Moreover, the two secondary factors with both organics and inorganics were named as more (MOA) and less oxidized aerosols (LOA). The relative contributions on a yearly average of these factors were HOA 6 %, COA 9 %, BBOA 6%, Ammonium Nitrate 4 %, Ammonium Sulfate 28 %, MOA 23 % and LOA 24 %. The results showed a variation in secondary aerosols composition of organics and inorganics, mainly in less oxidized aerosol (LOA). This factor was composed primarily of organics during winter (80 %), while both organics and inorganics contributed equally to this factor in spring and summer; and in early autumn this factor presented more sulfate (70 %) than organics. This work presents a new methodology on ACSM data analysis, provides insights on the sources of the non–refractory species of ambient aerosols and using innovative tools for applying PMF (Rolling window) enables the study of the temporal variation of these sources and also the variability of their composition.

Olga Zografou et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-38', Anonymous Referee #1, 13 Mar 2022
    • AC1: 'Reply on RC1', Olga Zografou, 30 Jun 2022
  • RC2: 'Comment on amt-2022-38', Anonymous Referee #2, 08 May 2022
    • AC2: 'Reply on RC2', Olga Zografou, 30 Jun 2022

Olga Zografou et al.

Olga Zografou et al.

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Short summary
A yearlong ToF-ACSM dataset was used to characterize ambient aerosols over a suburban Athenian site and innovative software for source apportionment was implemented in order to distinguish the sources of the total non-refractory species of PM1. The perks of using the methodology of combined organic and inorganic PMF analysis over conventional organic PMF were highlighted.