Modelling the contribution of biogenic volatile organic compounds to new particle formation in the Jülich plant atmosphere chamber
- 1Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
- 2Division of Nuclear Physics, Lund University, P.O. Box 118, 221 00 Lund, Sweden
- 3Department of Physics, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland
- 4Institute for Energy- and Climate Research (IEK-8), Forschungszentrum Jülich, 52425 Jülich, Germany
- 5Institute of Biogeosciences (IBG-2), Forschungszentrum Jülich, 52425 Jülich, Germany
Abstract. We used the Aerosol Dynamics gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM) to simulate the contribution of BVOC plant emissions to the observed new particle formation during photooxidation experiments performed in the Jülich Plant-Atmosphere Chamber and to evaluate how well smog chamber experiments can mimic the atmospheric conditions during new particle formation events. ADCHAM couples the detailed gas-phase chemistry from Master Chemical Mechanism with a novel aerosol dynamics and particle phase chemistry module. Our model simulations reveal that the observed particle growth may have either been controlled by the formation rate of semi- and low-volatility organic compounds in the gas phase or by acid catalysed heterogeneous reactions between semi-volatility organic compounds in the particle surface layer (e.g. peroxyhemiacetal dimer formation). The contribution of extremely low-volatility organic gas-phase compounds to the particle formation and growth was suppressed because of their rapid and irreversible wall losses, which decreased their contribution to the nano-CN formation and growth compared to the atmospheric situation. The best agreement between the modelled and measured total particle number concentration (R2 > 0.95) was achieved if the nano-CN was formed by kinetic nucleation involving both sulphuric acid and organic compounds formed from OH oxidation of BVOCs.