Secondary Organic Aerosol Formation of Ambient Intermediate Volatility Organic Compounds: Implication from Gasoline Vehicles

Intermediate volatility organic compounds (IVOCs) have been proposed to be great contributors to SOA formation. In this study, we performed comprehensive measurement of ambient IVOCs and calculated their SOA production at an urban site Peking University Urban Atmospheric Environment Monitoring Stations (PKUERS). Results showed that the campaign-average concentration IVOCs was 62.5 ± 45.2 μg·m^-3 (average ± standard deviation), which is comparable to the emission of VOCs. Only ~10% of the IVOCs could be speciated, with most of the IVOCs existing as unresolved complex mixture (UCM). Back trajectory analysis showed that clusters from near south has the highest IVOC concentration, suggesting the importance to control the IVOC emissions from the polluted regions of China. Using the OH exposure estimated by o-xylene to benzene and m/p-xylene to benzene, the estimated daily average SOA concentration was 5.8 ±3.4 μg·m^-3, in which IVOCs contributed 15 times that of single-ring aromatics. The estimated vehicular-SOA could be 1.04 ± 0.7 μg·m^-3. Considering its high SOA formation potential, this study highlights the importance to study the IVOC emissions in China.