Terpenoid and carbonyl emissions from Norway spruce in Finland during the growing season

Hannele Hakola,Jaana Bäck,Markku Kulmala,Virpi Tarvainen,Heidi Hellén,Kerneels Jaars,Arnaud P Praplan,Marja Hemmilä

doi:10.5194/acp-17-3357-2017

Abstract

Abstract. We present spring and summer volatile organic compound (VOC) emission rate measurements from Norway spruce (Picea abies L. Karst) growing in a boreal forest in southern Finland. The measurements were conducted using in situ gas chromatograph with 1 to 2 h time resolution to reveal quantitative and qualitative short-term and seasonal variability of the emissions. The measurements cover altogether 14 weeks in years 2011, 2014 and 2015. Monoterpene (MT) and sesquiterpene (SQT) emission rates were measured all the time, but isoprene only in 2014 and 2015 and acetone and C4–C10 aldehydes only in 2015. The emission rates of all the compounds were low in spring, but MT, acetone, and C4–C10 aldehyde emission rates increased as summer proceeded, reaching maximum emission rates in July. Late summer mean values (late July and August) were 29, 17, and 33 ng g(dw)−1 h−1 for MTs, acetone, and aldehydes respectively. SQT emission rates increased during the summer and highest emissions were measured in late summer (late summer mean value 84 ng g(dw)−1 h−1) concomitant with highest linalool emissions most likely due to stress effects. The between-tree variability of emission pattern was studied by measuring seven different trees during the same afternoon using adsorbent tubes. Especially the contributions of limonene, terpinolene, and camphene were found to vary between trees, whereas proportions of α-pinene (25 ± 5 %) and β-pinene (7 ± 3 %) were more stable. Our results show that it is important to measure emissions at canopy level due to irregular emission pattern, but reliable SQT emission data can be measured only from enclosures. SQT emissions contributed more than 90 % of the ozone reactivity most of the time, and about 70 % of the OH reactivity during late summer. The contribution of aldehydes to OH reactivity was comparable to that of MT during late summer, 10–30 % most of the time.

Highlights

The boreal forest is the largest terrestrial biome, forming an almost continuous belt around the Northern Hemisphere
The emission rates of all the compounds were low in spring, but MT, acetone, and C4–C10 aldehyde emission rates increased as summer proceeded, reaching maximum emission rates in July
SQT emission rates increased during the summer and highest emissions were measured in late summer (late summer mean value 84 ng g(dw)−1 h−1) concomitant with highest linalool emissions most likely due to stress effects

Summary

Introduction

The boreal forest is the largest terrestrial biome, forming an almost continuous belt around the Northern Hemisphere. The boreal forest zone is characterized by a short growing season and a limited number of tree species. The most common tree species are Scots pine, Norway spruce, and silver and downy birch and they produce and emit vast amounts of biogenic volatile organic compounds (VOCs) (Bourtsoukidis et al, 2014a, b; Bäck et al, 2012; Cojocariu et al, 2004; Grabmer et al, 2006; Hakola et al, 2001, 2006; Tarvainen et al, 2005; Yassaa et al, 2012). Abiotic stress factors have been reviewed by Loreto and Schnizler (2010).

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Results

Conclusion