Organic molecular markers and signature from wood combustion particles in winter ambient aerosols: aerosol mass spectrometer (AMS) and high time-resolved GC-MS measurements in Augsburg, Germany
The impact of wood combustion on ambient aerosols was investigated in
Augsburg, Germany during a winter measurement campaign of a six-week period.
Special attention was paid to the high time resolution observations of wood
combustion with different mass spectrometric methods. Here we present and
compare the results from an Aerodyne aerosol mass spectrometer (AMS) and gas
chromatographic – mass spectrometric (GC-MS) analysed PM<sub>1</sub> filters on an
hourly basis. This includes source apportionment of the AMS derived organic
matter (OM) using positive matrix factorisation (PMF) and analysis of
levoglucosan as wood combustion marker, respectively.
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During the measurement period nitrate and OM mass are the main contributors
to the defined submicron particle mass of AMS and Aethalometer with 28%
and 35%, respectively. Wood combustion organic aerosol (WCOA) contributes
to OM with 23% on average and 27% in the evening and night time.
Conclusively, wood combustion has a strong influence on the organic matter
and overall aerosol composition. Levoglucosan accounts for 14% of WCOA
mass with a higher percentage in comparison to other studies. The ratio
between the mass of levoglucosan and organic carbon amounts to 0.06.
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This study is unique in that it provides a one-hour time resolution
comparison between the wood combustion results of the AMS and the GC-MS
analysed filter method at a PM<sub>1</sub> particle size range. The comparison of
the concentration variation with time of the PMF WCOA factor, levoglucosan
estimated by the AMS data and the levoglucosan measured by GC-MS is highly
correlated (<i>R</i><sup>2</sup> = 0.84), and a detailed discussion on the contributors
to the wood combustion marker ion at mass-to-charge ratio 60 is given. At
the end, both estimations, the WCOA factor and the levoglucosan
concentration estimated by AMS data, allow to observe the variation with
time of wood combustion emissions (gradient correlation with GC-MS
levoglucosan of <i>R</i><sup>2</sup> = 0.84). In the case of WCOA, it provides the
estimated magnitude of wood combustion emission. Quantitative estimation of
the levoglucosan concentration from the AMS data is problematic due to its
overestimation in comparison to the levoglucosan measured by the GC-MS