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| Titel |
Diel and seasonal changes of biogenic volatile organic compounds within and above an Amazonian rainforest |
| VerfasserIn |
A. M. Yáñez-Serrano, A. C. Nölscher, J. Williams, S. Wolff, E. Alves, G. A. Martins, E. Bourtsoukidis, J. Brito, K. Jardine, P. Artaxo, J. Kesselmeier |
| 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 ; 15, no. 6 ; Nr. 15, no. 6 (2015-03-25), S.3359-3378 |
| Datensatznummer |
250119577
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| Publikation (Nr.) |
 copernicus.org/acp-15-3359-2015.pdf |
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| Zusammenfassung |
| The Amazonian rainforest is a large tropical ecosystem, which is one of the
last pristine continental terrains. This ecosystem is ideally located for the
study of diel and seasonal behaviour of biogenic volatile organic compounds
(BVOCs) in the absence of local human interference. In this study, we report
the first atmospheric BVOC measurements at the Amazonian Tall Tower
Observatory (ATTO) site, located in central Amazonia. A quadrupole
proton-transfer-reaction mass spectrometer (PTR-MS), with seven ambient air
inlets, positioned from near ground to about 80 m (0.05, 0.5, 4, 24, 38, 53
and 79 m above the forest floor), was deployed for BVOC monitoring. We
report diel and seasonal (February–March 2013 as wet season and September
2013 as dry season) ambient mixing ratios for isoprene, monoterpenes,
isoprene oxidation products, acetaldehyde, acetone, methyl ethyl ketone
(MEK), methanol and acetonitrile. Clear diel and seasonal patterns were
observed for all compounds. In general, lower mixing ratios were observed
during night, while maximum mixing ratios were observed during the wet season
(February–March 2013), with the peak in solar irradiation at 12:00 LT
(local time) and during the dry season (September 2013) with the peak in
temperature at 16:00 LT. Isoprene and monoterpene mixing ratios were the
highest within the canopy with a median of 7.6 and 1 ppb, respectively
(interquartile range (IQR) of 6.1 and 0.38 ppb) during the dry season (at
24 m, from 12:00 to 15:00 LT). The increased contribution of oxygenated
volatile organic compounds (OVOCs) above the canopy indicated a transition
from dominating forest emissions during the wet season (when mixing ratios
were higher than within the canopy), to a blend of biogenic emission,
photochemical production and advection during the dry season when mixing
ratios were higher above the canopy. Our observations suggest strong seasonal
interactions between environmental (insolation, temperature) and biological
(phenology) drivers of leaf BVOC emissions and atmospheric chemistry.
Considerable differences in the magnitude of BVOC mixing ratios, as compared
to other reports of Amazonian BVOC, demonstrate the need for long-term
observations at different sites and more standardized measurement procedures,
in order to better characterize the natural exchange of BVOCs between the
Amazonian rainforest and the atmosphere. |
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