Résumé
Vegetation introduces to the atmosphere a diversity of biogenic volatile organic compounds (BVOCs) which affect atmospheric chemistry, air quality and climate. Understory emissions might contribute significantly to the total BVOCs budget. In this work, either dynamic or static solid-phase microextraction (SPME) combined with portable gas chro-matography-mass spectrometry were optimised and used for the in-situ measurement of the most abundant BVOCs at understory level. The study was performed in summer 2015 at the SMEAR II station in Hyytiala, Finland. The most abundant BVOCs measured in soil chambers and ambient air were alpha-pinene and Delta(3)-carene, and their relative concentrations were similar in every chamber. These species constituted 80%-90% of the measured monoterpenes. Aliphatic aldehydes were also measured, and their amounts were lower in soil chambers than in ambient air. Air BVOC concentrations were markedly higher when the wind direction was from SE, which was associated with transportation from nearby sawmills.