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| Titel |
Seasonal variation in vertical volatile compounds air concentrations within a remote hemiboreal mixed forest |
| VerfasserIn |
S. M. Noe, K. Hüve, Ü. Niinemets, L. Copolovici |
| 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 ; 12, no. 9 ; Nr. 12, no. 9 (2012-05-03), S.3909-3926 |
| Datensatznummer |
250011110
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| Publikation (Nr.) |
 copernicus.org/acp-12-3909-2012.pdf |
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| Zusammenfassung |
| The vertical distribution of ambient biogenic volatile organic compounds
(BVOC) concentrations within a hemiboreal forest canopy was investigated over
a period of one year. Variability in temporal and spatial isoprene
concentrations, ranging from 0.1 to 7.5 μg m−3, can be mainly
explained by biogenic emissions from deciduous trees. Monoterpene
concentrations exceeded isoprene largely and ranged from 0.01 to
140 μg m−3 and during winter time anthropogenic contributions
are likely. Variation in monoterpene concentrations were found to be largest
right above the ground and the vertical profiles suggest a weak mixing
leading to terpene accumulation in the lower canopy. Exceptionally high
values were recorded during a heat wave in July 2010 with very high midday
temperatures above 30 °C for several weeks. During summer months,
monoterpene exceeded isoprene concentrations 6-fold and during winter
12-fold. During summer months, dominance of α-pinene in the lower and
of limonene in the upper part of the canopy was observed, both accounting for
up to 70% of the total monoterpene concentration. During wintertime,
Δ3-carene was the dominant species, accounting for 60% of total
monoterpene concentration in January. Possible biogenic monoterpene sources
beside the foliage are the leaf litter, the soil and also resins exuding from
stems. In comparison, the hemiboreal mixed forest canopy showed similar
isoprene but higher monoterpene concentrations than the boreal forest and
lower isoprene but substantially higher monoterpene concentrations than the
temperate mixed forest canopies. These results have major implications for
simulating air chemistry and secondary organic aerosol formation within and
above hemiboreal forest canopies. Possible effects of in-cartridge oxidation
reactions are discussed as our measurement technique did not include oxidant
scavenging. A comparison between measurements with and without scavenging
oxidants is presented. |
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