HR: 1340h
AN: A13A-0880    [Abstracts]
TI: Influence of SO2 on Nucleation, Growth Rates and Yield of Secondary Organic Aerosol (SOA)
AU: * Metzger, A
EM: axel.metzger@psi.ch
AF: Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen PSI, Villigen, 5232, Switzerland
AU: Verheggen, B
EM: verheggen@ecn.nl
AF: Energy research Centre of the Netherlands (ECN), Department of Air Quality and Climate Change, P.O. Box 1, Petten, 1755 ZG, Netherlands
AU: Duplissy, J
EM: jonathan.duplissy@psi.ch
AF: Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen PSI, Villigen, 5232, Switzerland
AU: Dommen, J
EM: joseph.dommen@psi.ch
AF: Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen PSI, Villigen, 5232, Switzerland
AU: Prevot, A S
EM: andre.prevot@psi.ch
AF: Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen PSI, Villigen, 5232, Switzerland
AU: Baltensperger, U
EM: urs.baltensperger@psi.ch
AF: Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, Villigen PSI, Villigen, 5232, Switzerland
AB: A laboratory study was carried out to investigate the secondary organic aerosol formation of 1,3,5- trimethylbenzene (TMB) in the presence of SO2. Experiments were carried out using SO2 concentrations between 0.2 and 20 ppb for TMB concentrations of 150 to 1200 ppb, while keeping all the other parameters constant. Aerosol size distributions were measured using a twin SMPS system. The first is a nano SMPS composed of a short DMA column and a TSI UWCPC, while the second one consisted of a long DMA column and a TSI 3022CPC. This combination of instruments provided measurements of the size distributions over the size range from 4 to 700 nm diameter. VOC concentrations were measured using a Proton Transfer Reaction-Mass Spectrometer while organic acids and SO2 concentrations were measured using a wet effluent diffusion denuder/aerosol collector connected to IC-MS. The particle chemical composition was measured using an Aerosol Time Of Flight Mass Spectrometer (ATOFMS, TSI, USA). The empirical particle nucleation and growth rates were determined using only the aerosol size distribution as input, using the recently developed inverse modelling procedure PARGAN (Particle Growth and Nucleation). Growth rates were determined by regression analysis of the General Dynamic Equation. The empirical growth rates were then used to estimate the time of nucleation for particles in each size bin, defined as the time when their diameter surpassed 1 nm. Their number density at the time and size of nucleation were determined by integrating the particle losses that occurred in the time interval between nucleation and measurement. The nucleation rate was then given by the rate at which particles grow past the critical cluster size, assumed to be 1 nm. The observed nucleation and growth rates as well as the observed SOA yields will be discussed with regard to sulphuric acid and TMB concentrations.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting