On-line field measurements of BVOC emissions from Norway spruce (Picea abies) at the hemiboreal SMEAR-Estonia site under autumn conditions

We investigated biogenic volatile organic compound (BVOC) emissions from a Norway spruce (Picea abies) in a hemiboreal mixed forest in autumn. Measurements were performed at the SMEAR-Estonia forest station, using PTR-MS techniques and a dynamic branch enclosure system. Parallel to BVOC measurements, atmospheric (CO2, CH4, H2O, CO) and meteorological (temperature, relative humidity, global radiation, wind speed, precipitation) parameters were monitored in the ambient atmosphere and inside the enclosure (temperature, relative humidity, ozone). Prior to the measuring period, a new inlet line consisting of 19.4 m of heated and isolated glass tube was constructed. The new inlet system allowed the on-line detection and calculation of sesquiterpene (SQT) emission rates for the first time for a hemiboreal forest site. In total, 12 atmospherically relevant BVOCs were continuously monitored during the measurement campaign and the emission rates of terpenoid species and predominant oxygenated VOCs were estimated, with monoterpenes to be emitted the most, followed by acetone, acetaldehyde and sesquiterpenes.