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| Titel |
Eddy covariance VOC emission and deposition fluxes above grassland using PTR-TOF |
| VerfasserIn |
T. M. Ruuskanen, M. Müller, R. Schnitzhofer, T. Karl, M. Graus, I. Bamberger, L. Hörtnagl, F. Brilli, G. Wohlfahrt, A. Hansel |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 2 ; Nr. 11, no. 2 (2011-01-20), S.611-625 |
| Datensatznummer |
250009188
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| Publikation (Nr.) |
 copernicus.org/acp-11-611-2011.pdf |
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| Zusammenfassung |
Eddy covariance (EC) is the preferable technique for flux measurements since
it is the only direct flux determination method. It requires a continuum of
high time resolution measurements (e.g. 5–20 Hz). For volatile organic
compounds (VOC) soft ionization via proton transfer reaction has proven to
be a quantitative method for real time mass spectrometry; here we use a
proton transfer reaction time of flight mass spectrometer (PTR-TOF) for 10 Hz EC measurements of full mass spectra up to m/z 315. The mass resolution
of the PTR-TOF enabled the identification of chemical formulas and
separation of oxygenated and hydrocarbon species exhibiting the same nominal
mass. We determined 481 ion mass peaks from ambient air concentration above
a managed, temperate mountain grassland in Neustift, Stubai Valley, Austria.
During harvesting we found significant fluxes of 18 compounds distributed
over 43 ions, including protonated parent compounds, as well as their
isotopes and fragments and VOC-H+ – water clusters. The dominant BVOC
fluxes were methanol, acetaldehyde, ethanol, hexenal and other C6 leaf
wound compounds, acetone, acetic acid, monoterpenes and sequiterpenes.
The smallest reliable fluxes we determined were less than
0.1 nmol m−2 s−1, as in the case of sesquiterpene emissions from freshly cut grass.
Terpenoids, including mono- and sesquiterpenes, were also deposited to the
grassland before and after the harvesting. During cutting, total VOC
emission fluxes up to 200 nmolC m−2 s−1 were measured. Methanol
emissions accounted for half of the emissions of oxygenated VOCs and a third
of the carbon of all measured VOC emissions during harvesting. |
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