Long-term measurements of volatile organic compounds highlight the importance of sesquiterpenes for the atmospheric chemistry of a boreal forest

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Hellen , H , Praplan , A P , Tykkä , T , Ylivinkka , I , Vakkari , V , Bäck , J , Petäjä , T , Kulmala , M & Hakola , H 2018 , ' Long-term measurements of volatile organic compounds highlight the importance of sesquiterpenes for the atmospheric chemistry of a boreal forest ' , Atmospheric Chemistry and Physics , vol. 18 , no. 19 , pp. 13839-13863 . https://doi.org/10.5194/acp-18-13839-2018

Title: Long-term measurements of volatile organic compounds highlight the importance of sesquiterpenes for the atmospheric chemistry of a boreal forest
Author: Hellen, Heidi; Praplan, Arnaud P.; Tykkä, Toni; Ylivinkka, Ilona; Vakkari, Ville; Bäck, Jaana; Petäjä, Tuukka; Kulmala, Markku; Hakola, Hannele
Contributor organization: Institute for Atmospheric and Earth System Research (INAR)
Aerosol-Cloud-Climate -Interactions (ACCI)
Department of Physics
Department of Forest Sciences
Ecosystem processes (INAR Forest Sciences)
Forest Ecology and Management
Date: 2018-10-01
Language: eng
Number of pages: 25
Belongs to series: Atmospheric Chemistry and Physics
ISSN: 1680-7316
DOI: https://doi.org/10.5194/acp-18-13839-2018
URI: http://hdl.handle.net/10138/251212
Abstract: The concentrations of terpenoids (isoprene; monoterpenes, MTs; and sesquiterpenes, SQTs) and oxygenated volatile organic compounds (OVOCs; i.e. aldehydes, alcohols, acetates and volatile organic acids, VOAs) were investigated during 2 years at a boreal forest site in Hyytiala, Finland, using in situ gas chromatograph mass spectrometers (GC-MSs). Seasonal and diurnal variations of terpenoid and OVOC concentrations as well as their relationship with meteorological factors were studied. Of the VOCs examined, C-2-C-7 unbranched VOAs showed the highest concentrations, mainly due to their low reactivity. Of the terpenoids, MTs showed the highest concentrations at the site, but seven different highly reactive SQTs were also detected. The monthly and daily mean concentrations of most terpenoids, aldehydes and VOAs were highly dependent on the temperature. The highest exponential correlation with temperature was found for a SQT (beta-caryophyllene) in summer. The diurnal variations in the concentrations could be explained by sources, sinks and vertical mixing. The diurnal variations in MT concentrations were strongly affected by vertical mixing. Based on the temperature correlations and mixing layer height (MLH), simple proxies were developed for estimating the MT and SQT concentrations. To estimate the importance of different compound groups and compounds in local atmospheric chemistry, reactivity with main oxidants (hydroxyl radical, OH; nitrate radical, NO3; and ozone, O-3) and production rates of oxidation products (OxPRs) were calculated. The MTs dominated OH and NO3 radical chemistry, but the SQTs greatly impacted O-3 chemistry, even though the concentrations of SQT were 30 times lower than the MT concentrations. SQTs were also the most important for the production of oxidation products. Since the SQTs show high secondary organic aerosol (SOA) yields, the results clearly indicate the importance of SQTs for local SOA production.
Subject: IN-SITU MEASUREMENTS
OH REACTIVITY MEASUREMENTS
BIOGENIC VOC EMISSIONS
TROPICAL RAIN-FOREST
SCOTS PINE
OXIDATION-PRODUCTS
DOPPLER LIDAR
NORWAY SPRUCE
BETA-PINENE
AMBIENT AIR
1172 Environmental sciences
114 Physical sciences
4112 Forestry
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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