Field observations of volatile organic compound (VOC) exchange in red oaks
Volatile organic compounds (VOCs) emitted by forests strongly affect the chemical composition of the atmosphere. While the emission of isoprenoids has been largely characterized, forests also exchange many oxygenated VOCs (oVOCs), including methanol, acetone, methyl ethyl ketone (MEK), and acetaldeh...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/17/4189/2017/acp-17-4189-2017.pdf |
| Summary: | Volatile organic compounds (VOCs) emitted by forests strongly affect the
chemical composition of the atmosphere. While the emission of isoprenoids
has been largely characterized, forests also exchange many oxygenated VOCs
(oVOCs), including methanol, acetone, methyl ethyl ketone (MEK), and
acetaldehyde, which are less well understood. We monitored total
branch-level exchange of VOCs of a strong isoprene emitter (<i>Quercus rubra</i> L.) in a mixed
forest in New England, where canopy-level fluxes of VOCs had been previously
measured. We report daily exchange of several oVOCs and investigated unknown
sources and sinks, finding several novel insights. In particular, we found
that emission of MEK is linked to uptake of methyl vinyl ketone (MVK), a
product of isoprene oxidation. The link was confirmed by corollary
experiments proving in vivo detoxification of MVK, which is harmful to plants.
Comparison of MEK, MVK, and isoprene fluxes provided an indirect indication
of within-plant isoprene oxidation. Furthermore, besides confirming
bidirectional exchange of acetaldehyde, we also report for the first time
direct evidence of benzaldehyde bidirectional exchange in forest plants. Net
emission or deposition of benzaldehyde was found in different periods of
measurements, indicating an unknown foliar sink that may influence
atmospheric concentrations. Other VOCs, including methanol, acetone, and
monoterpenes, showed clear daily emission trends but no deposition.
Measured VOC emission and deposition rates were generally consistent with
their ecosystem-scale flux measurements at a nearby site. |
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| ISSN: | 1680-7316 1680-7324 |