AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
PM2.5 Aerosol Composition and Sources in China during Extreme Haze Events
MIRIAM ELSER, Imad El Haddad, Robert Wolf, Jay Slowik, Junji Cao, Urs Baltensperger, Ru-Jin Huang, Andre Prévôt, Paul Scherrer Institute
Abstract Number: 208 Working Group: Haze in China: Sources, Formation Mechanisms, and Current Challenges
Abstract In the last decades China has been facing increasing air pollution levels in response to fast industrialization and economic growth. Large parts of the country are frequently affected by heavy smog, causing extensive environmental and health problems. The severe high pollution events occur mostly during wintertime, caused by a combination of primary emissions of gas- and particle-phase pollutants, generation of secondary aerosol, and stagnant meteorological conditions that confine the pollutants near ground level.
A High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was deployed to characterize the aerosol chemical composition and size distribution during winter 2013-2014 in two major cities of China: Xi’an and Beijing. The AMS was equipped with a recently developed aerodynamic lens, extending the measured particle size fraction to PM2.5. The contributing sources to non-refractory (NR) organic aerosols (OA) were identified by means of positive matrix factorization using the multi-linear engine.
During the measurements in Xi’an, an extreme haze covered the city for about a week. According to many broadsheet journals, Xi’an was rated those days the city with highest pollution in the world, with total NR-PM2.5 reaching peak concentrations of over 1000 micrograms per cubic meter. Source apportionment results indicate that during the haze events, secondary inorganic and organic aerosol dominates the composition. This contrasts with a larger fraction of primary OA during non-haze periods, with major contributions from traffic, coal, wood-burning, and cooking emissions. The influence of different sources and processes under haze and non-haze conditions on the particle size, composition, concentration and diurnal trends will be discussed.