Articles | Volume 15, issue 23
Atmos. Chem. Phys., 15, 13413–13432, 2015

Special issue: Interactions between climate change and the Cryosphere: SVALI,...

Atmos. Chem. Phys., 15, 13413–13432, 2015

Research article 07 Dec 2015

Research article | 07 Dec 2015

Sources of long-lived atmospheric VOCs at the rural boreal forest site, SMEAR II

J. Patokoski1, T. M. Ruuskanen1, M. K. Kajos1, R. Taipale1, P. Rantala1, J. Aalto2, T. Ryyppö3, T. Nieminen1,4, H. Hakola5, and J. Rinne1,5,6 J. Patokoski et al.
  • 1Division of Atmospheric Sciences, Department of Physics, University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Helsinki, Finland
  • 2Department of Forest Sciences, University of Helsinki, Helsinki, Finland
  • 3Finnish Meteorological Institute, Arctic Research Centre, Tähteläntie 62, 99600 Sodankylä, Finland
  • 4Helsinki Institute of Physics, P.O. Box 64, 00014 University of Helsinki, Helsinki, Finland
  • 5Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland
  • 6Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland

Abstract. In this study a long-term volatile organic compound (VOCs) concentration data set, measured at the SMEAR II (Station for Measuring Ecosystem–Atmosphere Relations) boreal forest site in Hyytiälä, Finland during the years 2006–2011, was analyzed in order to identify source areas and profiles of the observed VOCs. VOC mixing ratios were measured using proton transfer reaction mass spectrometry. Four-day HYSPLIT 4 (Hybrid Single Particle Lagrangian Integrated Trajectory) backward trajectories and the Unmix 6.0 receptor model were used for source area and source composition analysis. Two major forest fire events in Russia took place during the measurement period. The effect of these fires was clearly visible in the trajectory analysis, lending confidence to the method employed with this data set. Elevated volume mixing ratios (VMRs) of non-biogenic VOCs related to forest fires, e.g. acetonitrile and aromatic VOCs, were observed. Ten major source areas for long-lived VOCs (methanol, acetonitrile, acetaldehyde, acetone, benzene, and toluene) observed at the SMEAR II site were identified. The main source areas for all the targeted VOCs were western Russia, northern Poland, Kaliningrad, and the Baltic countries. Industrial areas in northern continental Europe were also found to be source areas for certain VOCs. Both trajectory and receptor analysis showed that air masses from northern Fennoscandia were less polluted with respect to both the VOCs studied and other trace gases (CO, SO2 and NOx), compared to areas of eastern and western continental Europe, western Russia, and southern Fennoscandia.

Short summary
In this study, main source areas for long-lived VOCs at the boreal forest in SMEAR II were determined. Air masses arriving from eastern and western directions were more polluted than those arriving from the northern direction. The biogenic and anthropogenic influences of three different source profiles were determined. The elevated trace gas concentrations from forest fire episodes were observed clearly in the trajectory analysis.
Final-revised paper