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| Titel |
Towards an understanding of semi-volatile organic aerosol mixtures: gas-particle partitioning and mixing of primary and secondary organic aerosols |
| VerfasserIn |
A. Asa-Awuku, M. Miracolo, J. Kroll, N. M. Donahue, A. L. Robinson |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250029150
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| Zusammenfassung |
| Atmospheric organic matter constitutes a significant fraction of the total fine aerosol mass.
Some particulates, secondary organic aerosol (SOA), can be formed via atmospheric
reactions with organic gaseous species. However, the chemical composition and the
mechanisms from which SOA form are not well understood. In this a study, SOA formed in
the Carnegie Mellon University environmental smog chamber was mixed with different types
of primary organic aerosol (diesel exhaust and motor oil). The SOA was generated from
α-pinene in a dark ozonlysis reaction. Primary organic aerosol was injected into the chamber
after SOA nucleation had occurred and the mixture was allowed to age for roughly four
hours. A suite of instruments characterized changes in size, volatility, and chemical
composition of the aerosol mixtures. A High Resolution Time of Flight Aerodyne aerosol
mass spectrometer (AMS) measured the change in mass spectra throughout the experiment
and a thermodenuder was used to characterize changes in mixed aerosol volatility.
The AMS particle time-of-flight data was used to quantify the extent of mixing.
Our results indicate that the mixture of biogenic SOA with motor-oil produces a
weakly mixed particles, with two coexisting phases. In contrast, the SOA readily
mixes with diesel exhaust particles. The semi-volatile diesel exhaust matter rapidly
evaporates and re-condenses in the system to form a one phase aerosol mixture.
Understanding the mixing behavior of two distinct semi-volatile organic aerosol species will
help resolve the discrepancies between top-down and bottom-up SOA estimates. |
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