AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Aerosol Composition, Oxidative Properties, and Sources in Beijing during 2014 Asia-Pacific Economic Cooperation (APEC) Summit
WEIQI XU, Chen Chen, Wei Du, Zifa Wang, Tingting Han, Qingqing Wang, Yele Sun, Inst. of Atmospheric Physics, Chinese Academy of Sciences
Abstract Number: 166 Working Group: Source Apportionment
Abstract China implemented strict emission controls measures in Beijing and surrounding regions to ensure good air quality during the 2014 Asia-Pacific Economic Cooperation (APEC) summit. To investigate the impacts of emission controls on composition, oxidative properties, and sources of aerosol particles, a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) along with a suite of collocated instruments was deployed at an urban site in Beijing from 5 October to 12 November, 2014. The size-resolved non-refractory submicron aerosol composition (NR-PM$_1) was measured in-situ at a time resolution of 5 min. Our results showed large reductions of secondary inorganic aerosol (SIA = sulfate + nitrate + ammonium) during APEC owing to emission controls, whereas the changes of organics were much smaller. Positive matrix factorization analysis of high resolution mass spectra of OA further showed that oxygenated organic aerosol (OOA) including semi-volatile OOA and low-volatility OOA had similar reductions to SIA. However, the concentrations of primary OA from cooking and biomass burning were comparable to those before APEC. These results elucidate the dominant impacts of emission controls over regional scales on secondary aerosols. The routine circulation of mountain valley winds played another critical role in reducing fine particles and achieving “APEC Blue” that was commonly referred to the blue skies. The changes of size distributions and oxidative properties of submicron aerosols during APEC due to emission control will be also discussed.