Modelling the contribution of biogenic volatile organic compounds to new particle formation in the Jülich plant atmosphere chamber

摘要

We used the Aerosol Dynamics gas- and particle-phase chemistry model forlaboratory CHAMber studies (ADCHAM) to simulate the contribution of BVOCplant emissions to the observed new particle formation during photooxidationexperiments performed in the Jülich Plant-AtmosphereChamber and to evaluate how well smog chamber experiments can mimic theatmospheric conditions during new particle formation events. ADCHAM couplesthe detailed gas-phase chemistry from Master Chemical Mechanism with a novelaerosol dynamics and particle phase chemistry module. Our model simulationsreveal that the observed particle growth may have either been controlled bythe formation rate of semi- and low-volatility organic compounds in thegas phase or by acid catalysed heterogeneous reactions betweensemi-volatility organic compounds in the particle surface layer (e.g.peroxyhemiacetal dimer formation). The contribution of extremelylow-volatility organic gas-phase compounds to the particle formation andgrowth was suppressed because of their rapid and irreversible wall losses,which decreased their contribution to the nano-CN formation and growthcompared to the atmospheric situation. The best agreement between themodelled and measured total particle number concentration (R2 > 0.95)was achieved if the nano-CN was formed by kinetic nucleation involving bothsulphuric acid and organic compounds formed from OH oxidation of BVOCs.