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| Titel |
Oxygenated products of sesquiterpenes in secondary organic aerosol |
| VerfasserIn |
A. van Eijck, C. Kampf, T. Hoffmann |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250070812
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| Zusammenfassung |
| Secondary organic aerosol (SOA) has a huge impact on air quality and climate
change. It influences the Earth radiative budget through absorbing, scattering and
reflecting radiation as well as the formation of clouds because the particulates can act
as cloud condensation nuclei (CCN). Furthermore, it plays an important role for
human health. SOA is formed from gaseous precursors which get oxidized by ozone,
OH- and NO3-radicals in the atmosphere. Due to their low vapor pressure these
degradation products can nucleate to form new particles or they can condense on existing
aerosol particles. Despite the major progress in research during the last few years the
actual chemical composition as well as the contribution of various volatile organic
compounds (VOCs) to the formation of secondary organic aerosol is still partially
unknown.
Recent studies indicate that sesquiterpenes play an important role in the formation of
SOA because of the low volatility of their oxygenated products (Lee et al., 2006). Their
emission is estimated to be about 14,8 Tg per year (Henze et al., 2008), however, these
emission rates remain highly uncertain due to the lack of quantitative emission rate
measurements. In addition, the knowledge about the actual atmospheric degradation
mechanism and the main oxidation products of sesquiterpenes is quite limited.
β-Caryophyllene, α-humulene, α-farnesene and β-farnesene are the most abundant
sequiterpenes in many sesquiterpene emission profiles. But also aromadendren,
α-bergamotene and δ-cadinene and germacrene-D can contribute significantly to some
emission profiles (Duhl et al., 2008).
To determine the major oxygenated products of sesquiterpenes in SOA, reaction chamber
experiments with different sesquiterpenes and ozone were performed in a 100 L reaction
chamber. To measure the time dependent formation of initial oxidation products, an
APCI-IT-MS was directly connected to the reaction chamber. After 2 hours the
APCI-IT-MS was replaced by a filter holder and the generated aerosol was collected for 20
hours. In case of β-caryophyllene five different acidic oxidation products were
synthesized and these acids were used for quantification. Atmospheric air samples
taken during the HUMPPA campaign summer 2010 in Finland were analyzed for
sesquiterpene oxygenated products. The major sesquiterpene oxidation products in
the ambient air samples were quantified and the correlation with temperature was
analyzed.
Duhl, T. R., Helmig, D. and Guenther, A. (2008) Biogeosciences 5, 761-777.
Henze, D.K., Seinfeld, J.H., Ng, N.L., Kroll, J.H., Fu, T.M., Jacob, D.J. and Heald, C.L.
(2008) Atmospheric Chemistry and Physics 8, 2405-2421.
Lee, A., Goldstein, A.H., Kroll, J.H., Ng, N.L., Varutbangkul, V., Flagan, R.C. and
Seinfeld, J.H. (2006) Journal of Geophysical Research 111, D17305. |
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