Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Biogenic volatile organic compounds (BVOCs) emitted from terrestrial vegetation participate in oxidative reactions in the atmosphere, leading to the formation of secondary organic aerosols and longer lifetime of methane. Global models of BVOC emissions have assumed minimal emissions from the high latitudes. However, measurements from this region are lacking, and studies from the high arctic are yet to be published. This study aimed to obtain estimates for BVOC emissions from the high arctic, and hereby to add new knowledge to the understanding of global BVOC emissions. Measurements were conducted in four vegetation types dominated by Cassiope tetragona, Salix arctica, Vaccinium uliginosum and a mixture of Kobresia myosuroides, Dryas spp. and Poa arctica. Emissions were measured by an enclosure technique and collection of volatiles into adsorbent cartridges in August. Volatiles were analyzed by gas chromatography–mass spectrometry following thermal desorption. Isoprene showed highest emissions in S. arctica heath. Monoterpene and sesquiterpene emissions were especially associated with C. tetragona heath. Total observed emissions were comparable in magnitude to emissions previously found in the subarctic, whereas isoprene emissions were lower. This study shows that considerable amounts of BVOCs are emitted from the high arctic. The results are also of importance as the emissions from this region are expected to increase in the future as a result of the predicted climate warming in the high arctic. We suggest further studies to assess the effects of climate changes in the region in order to gain new knowledge and understanding of future global BVOC emissions.