Articles | Volume 11, issue 4
Atmos. Chem. Phys., 11, 1367–1378, 2011
Atmos. Chem. Phys., 11, 1367–1378, 2011

Research article 16 Feb 2011

Research article | 16 Feb 2011

Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions

L. Q. Hao1, S. Romakkaniemi1, P. Yli-Pirilä2, J. Joutsensaari1, A. Kortelainen1, J. H. Kroll4,6, P. Miettinen1, P. Vaattovaara1, P. Tiitta1, A. Jaatinen1, M. K. Kajos3, J. K. Holopainen2, J. Heijari2,9, J. Rinne3, M. Kulmala3, D. R. Worsnop1,3,4,5, J. N. Smith1,7,8, and A. Laaksonen1,5 L. Q. Hao et al.
  • 1Department of Applied Physics, University of Eastern Finland, Kuopio 70211, Finland
  • 2Department of Environmental Sciences, University of Eastern Finland, Kuopio 70211, Finland
  • 3Department of Physics, University of Helsinki, Helsinki 00014, Finland
  • 4Aerodyne Research, Inc., Billerica, MA 08121-3976, USA
  • 5Finnish Meteorological Institute, Helsinki 00101, Finland
  • 6Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge MA, USA
  • 7Atmospheric Chemistry Division, National Center for Atmos.~Res., 1850 Table Mesa Dr., Boulder, CO 80305, USA
  • 8Finnish Meteorological Institute, Kuopio 70211, Finland
  • 9Kotka Maritime Research Centre, Kotka 48310, Finland

Abstract. Biogenic volatile organic compounds (VOCs) are a significant source of global secondary organic aerosol (SOA); however, quantifying their aerosol forming potential remains a challenge. This study presents smog chamber laboratory work, focusing on SOA formation via oxidation of the emissions of two dominant tree species from boreal forest area, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies), by hydroxyl radical (OH) and ozone (O3). Oxidation of α-pinene was also studied as a reference system. Tetramethylethylene (TME) and 2-butanol were added to control OH and O3 levels, thereby allowing SOA formation events to be categorized as resulting from either OH-dominated or O3-initiated chemistry. SOA mass yields from α-pinene are consistent with previous studies while the yields from the real plant emissions are generally lower than that from α-pinene, varying from 1.9% at an aerosol mass loading of 0.69 μg m−3 to 17.7% at 26.0 μg m−3. Mass yields from oxidation of real plant emissions are subject to the interactive effects of the molecular structures of plant emissions and their reaction chemistry with OH and O3, which lead to variations in condensable product volatility. SOA formation can be reproduced with a two-product gas-phase partitioning absorption model in spite of differences in the source of oxidant species and product volatility in the real plant emission experiments. Condensable products from OH-dominated chemistry showed a higher volatility than those from O3-initiated systems during aerosol growth stage. Particulate phase products became less volatile via aging process which continued after input gas-phase oxidants had been completely consumed.

Final-revised paper