Articles | Volume 8, issue 10
Atmos. Chem. Phys., 8, 2657–2665, 2008

Special issue: Quantification of aerosol nucleation in the European boundary...

Atmos. Chem. Phys., 8, 2657–2665, 2008

  20 May 2008

20 May 2008

The role of VOC oxidation products in continental new particle formation

A. Laaksonen1,4, M. Kulmala2, C. D. O'Dowd3, J. Joutsensaari1,*, P. Vaattovaara1, S. Mikkonen1, K. E. J. Lehtinen1,4, L. Sogacheva2, M. Dal Maso2, P. Aalto2, T. Petäjä2, A. Sogachev2, Y. J. Yoon3,**, H. Lihavainen4, D. Nilsson5, M. C. Facchini6, F. Cavalli6,***, S. Fuzzi6, T. Hoffmann7, F. Arnold8, M. Hanke8, K. Sellegri8,****, B. Umann8, W. Junkermann9, H. Coe10, J. D. Allan10, M. R. Alfarra10,*****, D. R. Worsnop11, M. -L. Riekkola12, T. Hyötyläinen12, and Y. Viisanen4 A. Laaksonen et al.
  • 1University of Kuopio, Department of Physics, POB 1627, 70211 Kuopio, Finland
  • 2University of Helsinki, Department of Physical Sciences, Helsinki, Finland
  • 3National University of Ireland, Galway, Department of Physics, Ireland
  • 4Finnish Meteorological Institute, POB 503, 00101 Helsinki, Finland
  • 5Stockholm Univ., Dept. of Applied Environmental Science (ITM), Atmospheric Science Unit, 10691, Stockholm, Sweden
  • 6Istituto di Scienze dell'Atmosfera e del Clima – CNR, Italy Via Gobetti 101, 40 129 Bologna ,Italy
  • 7Johannes Gutenberg-University of Mainz, 55128, Mainz, Germany
  • 8Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany
  • 9Forschungszentrum Karlsruhe, Ins. for Meteorology and Climate Research, IMK-IFU, Garmisch-Partenkirchen, Germany
  • 10School of Atmospheric and Environmental Science, University of Manchester, PO Box 88, Manchester, M60 1QD, UK
  • 11Aerodyne Research Inc., 45 Manning Road, Billerica, Ma 01821-3976, USA
  • 12University of Helsinki, Department of Chemistry, Helsinki, Finland
  • *now at: University of Kuopio, Department of Environmental Sciences, POB 1627, 70211 Kuopio, Finland
  • **now at: Korea Polar Res. Inst., SongDo Techno Park, 7-50, Songdo-dong, Yeonsu-Gu, Incheon City, 406-840, Korea
  • ***now at: Joint Research Centre, Via E. Fermi, 1, 21020 Ispra, Italy
  • ****now at: Laboratoire de Météorologie Physique (LaMP), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), UMR 6016 CNRS, France
  • *****now at: Paul Scherrer Institut, 5232 Villigen, Switzerland

Abstract. Aerosol physical and chemical properties and trace gas concentrations were measured during the QUEST field campaign in March–April 2003, in Hyytiälä, Finland. Our aim was to understand the role of oxidation products of VOC's such as mono- and sesquiterpenes in atmospheric nucleation events. Particle chemical compositions were measured using the Aerodyne Aerosol Mass Spectrometer, and chemical compositions of aerosol samples collected with low-pressure impactors and a high volume sampler were analysed using a number of techniques. The results indicate that during and after new particle formation, all particles larger than 50 nm in diameter contained similar organic substances that are likely to be mono- and sesquiterpene oxidation products. The oxidation products identified in the high volume samples were shown to be mostly aldehydes. In order to study the composition of particles in the 10–50 nm range, we made use of Tandem Differential Mobility Analyzer results. We found that during nucleation events, both 10 and 50 nm particle growth factors due to uptake of ethanol vapour correlate strongly with gas-phase monoterpene oxidation product (MTOP) concentrations, indicating that the organic constituents of particles smaller than 50 nm in diameter are at least partly similar to those of larger particles. We furthermore showed that particle growth rates during the nucleation events are correlated with the gas-phase MTOP concentrations. This indicates that VOC oxidation products may have a key role in determining the spatial and temporal features of the nucleation events. This conclusion was supported by our aircraft measurements of new 3–10 nm particle concentrations, which showed that the nucleation event on 28 March 2003, started at the ground layer, i.e. near the VOC source, and evolved together with the mixed layer. Furthermore, no new particle formation was detected upwind away from the forest, above the frozen Gulf of Bothnia.

Final-revised paper