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Sesquiterpenes and oxygenated sesquiterpenes dominate the VOC (C-5-C-20) emissions of downy birches

Hellen, Heidi and Praplan, Arnaud P. and Tykka, Toni and Helin, Aku and Schallhart, Simon and Schiestl-Aalto, Pauliina and Back, Jaana and Hakola, Hannele (2021). Sesquiterpenes and oxygenated sesquiterpenes dominate the VOC (C-5-C-20) emissions of downy birches. Atmospheric Chemistry and Physics. 21 , 8045-8066
[Research article]

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Abstract

Biogenic volatile organic compounds (BVOCs) emitted by the forests are known to have strong impacts in the atmosphere. However, lots of missing reactivity is found, especially in the forest air. Therefore better characterization of sources and identification/quantification of unknown reactive compounds is needed. While isoprene and monoterpene (MT) emissions of boreal needle trees have been studied quite intensively, there is much less knowledge on the emissions of boreal deciduous trees and emissions of larger terpenes and oxygenated volatile organic compounds (OVOCs). Here we quantified the downy birch (Betula pubescens) leaf emissions of terpenes, oxygenated terpenes and green leaf volatiles (GLVs) at the SMEAR II boreal forest site using in situ gas chromatographs with mass spectrometers. Sesquiterpenes (SQTs) and oxygenated sesquiterpenes (OSQTs) were the main emitted compounds. Mean emission rates of SQTs and OSQTs were significantly higher in the early growing season (510 and 650 ng g(dw)(-1) h(-1), respectively) compared to in the main (40 and 130 ng g(dw)(-1) h(-1), respectively) and late (14 and 46 ng g(dw)(-1) h(-1), respectively) periods, indicating that early leaf growth is a strong source of these compounds. The emissions had a very clear diurnal variation with afternoon maxima being on average 4 to 8 times higher than seasonal means for SQTs and OSQTs, respectively. fi Caryophyllene and fi-farnesene were the main SQTs emitted. The main emitted OSQTs were tentatively identified as 14-hydroxy-beta-caryophyllene acetate (M = 262 g mol(-1)) and 6-hydroxy-beta-caryophyllene (M D 220 g mol(-1)). Over the whole growing season, the total MT emissions were only 24% and 17% of the total SQT and OSQT emissions, respectively. A stressed tree growing in a pot was also studied, and high emissions of ff -farnesene and an unidentified SQT were detected together with high emissions of GLVs. Due to the relatively low volatility and the high reactivity of SQTs and OSQTs, downy birch emissions are expected to have strong impacts on atmospheric chemistry, especially on secondary organic aerosol (SOA) production.

Authors/Creators:Hellen, Heidi and Praplan, Arnaud P. and Tykka, Toni and Helin, Aku and Schallhart, Simon and Schiestl-Aalto, Pauliina and Back, Jaana and Hakola, Hannele
Title:Sesquiterpenes and oxygenated sesquiterpenes dominate the VOC (C-5-C-20) emissions of downy birches
Series Name/Journal:Atmospheric Chemistry and Physics
Year of publishing :2021
Volume:21
Page range:8045-8066
Number of Pages:22
Publisher:COPERNICUS GESELLSCHAFT MBH
ISSN:1680-7316
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Meteorology and Atmospheric Sciences
URN:NBN:urn:nbn:se:slu:epsilon-p-112579
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-112579
Additional ID:
Type of IDID
DOI10.5194/acp-21-8045-2021
Web of Science (WoS)000657139000002
ID Code:24793
Faculty:S - Faculty of Forest Sciences
Department:(S) > Dept. of Forest Ecology and Management
Deposited By: SLUpub Connector
Deposited On:05 Jul 2021 03:25
Metadata Last Modified:05 Jul 2021 05:01

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