AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Characterization of Organic Aerosol in Severe Haze Episodes Using FTIR during Fall 2013 in Beijing, China
Xiaoying Li, Kathryn George, Caiqing Yan, MEI ZHENG, Ann Dillner, Peking University
Abstract Number: 399 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Since January 2013, many cities in the North China Plain of China including Beijing have suffered severe fine particulate matter pollution episodes. During October 2013, PM2.5 in Beijing showed clear “sawtooth” pattern with PM2.5 concentration cycled through low to high every five days. About six sawtooth cycles were found during the study period. Previous studies indicated that organic aerosol (OA) played an important role in haze events. However, most organic aerosol studies are based on other techniques including aerosol mass spectrometry (AMS) or gas chromatography-mass spectrometry (GC/MS). To our best knowledge, this is the first study using Fourier-transform infrared transmission spectroscopy (FTIR) to characterize organic aerosol during haze episodes in China. PM2.5 samples were collected on 47 mm Teflon filter using the four-channel low-volume sampler, and then spectroscopic characterization provided information of organic functional groups (e.g. alkyl, hydroxyl, carbonyl, and aromatic groups). Preliminary analysis showed that carbonyl, carboxylic acid OH, saturated CH, unsaturated CH, and hydroxyl were present in the Beijing aerosol. All the investigated organic functional groups increased during haze events. Carbonyl and carboxylic acids account for a very small amount of the mass. However, it should be noted that concentration of aromatic CH in Beijing was much higher than that observed in samples in the U.S., where aromatic CH is rarely reported due to its low concentration. The high aromatic CH in the Beijing samples indicates the importance of anthropogenic sources in Beijing. More detailed information about chemical composition of these samples including major ions and detailed organic speciation as well as formation mechanisms of these episodes will be provided and discussed.