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| Titel |
Contribution of flowering trees to urban atmospheric biogenic volatile organic compound emissions |
| VerfasserIn |
R. Baghi, D. Helmig, A. Guenther, T. Duhl, R. Daly |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 10 ; Nr. 9, no. 10 (2012-10-05), S.3777-3785 |
| Datensatznummer |
250007319
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| Publikation (Nr.) |
 copernicus.org/bg-9-3777-2012.pdf |
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| Zusammenfassung |
| Emissions of biogenic volatile organic compounds (BVOC) from urban trees
during and after blooming were measured during spring and early summer 2009
in Boulder, Colorado. Air samples were collected onto solid adsorbent
cartridges from branch enclosures on the tree species crabapple (Malus sp.),
horse chestnut (Aesculus carnea, "Ft. McNair"), honey locust (Gleditsia
triacanthos, "Sunburst"), and hawthorn (Crataegus laevigata, "Pauls
Scarlet"). These species constitute ~ 65% of the
insect-pollinated fraction of the flowering tree canopy (excluding
catkin-producing trees) from the street area managed by the City of Boulder.
Samples were analyzed for C10–C15 BVOC by thermal desorption and
gas chromatography coupled to a flame ionization detector and a mass
spectrometer (GC/FID/MS). Identified emissions and emission rates from these
four tree species during the flowering phase were found to vary over a wide
range. Monoterpene emissions were identified for honey locust, horse chestnut
and hawthorn. Sesquiterpene emissions were observed in horse chestnut and
hawthorn samples. Crabapple flowers were found to emit significant amounts of
benzyl alcohol and benzaldehyde. Floral BVOC emissions increased with
temperature, generally exhibiting exponential temperature dependence. Changes
in BVOC speciation during and after the flowering period were observed for
every tree studied. Emission rates were significantly higher during the
blooming compared to the post-blooming state for crabapple and honey locust.
The results were scaled to the dry mass of leaves and flowers contained in
the enclosure. Only flower dry mass was accounted for crabapple emission
rates as leaves appeared at the end of the flowering period. Total normalized
(30 °C) monoterpene emissions from honey locust were higher during
flowering (5.3 μgC g−1 h−1) than after flowering
(1.2 μgC g−1 h−1). The total normalized BVOC emission
rate from crabapple (93 μgC g−1 h−1) during the
flowering period is of the same order as isoprene emissions from oak trees,
which are among the highest BVOC flowering period floral emissions observed
from plants to date. These findings illustrate that during the relatively
brief springtime flowering period, floral emissions constitute by far the
most significant contribution to the BVOC flux from these tree species, some
of which are leafless at this time. Experimental results were integrated into
the MEGAN biogenic emission model and simulations were performed to estimate
the contribution of floral BVOC emissions to the total urban BVOC flux during
the spring flowering period. The floral BVOC emitted during this
three-month simulation are equivalent to 11% of the integrated
monoterpene flux for the Boulder urban area. |
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