AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Molecular Characterization of Brown Carbon in Fine Particulate Matter in China
CAIQING YAN, Yury Desyaterik, Jeffrey Collett, Mei Zheng, Peking University
Abstract Number: 286 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Brown carbon has been recognized as potential important contributor to climate change. High level of light-absorbing brown carbon has been found and reported in China. However, little is known about the relationship between chemical composition of brown carbon and its optical property. In this study, atmospheric brown carbon at an urban site located in Beijing and a suburban site in Hebei provinces, China were investigated. High performance liquid chromatography equipped with a UV/Vis absorbance detector and a time-of-flight (ToF) mass spectrometer (LC/DAD-ESI-HRTOFMS) was applied to determine elemental compositions of light-absorbing organic compounds, in order to better understand the light-absorbing properties of brown carbon and detailed chemical composition of individual organic compound that can absorb light. Our results showed that nitrophenols and aromatic carbonyls were major atmospheric light-absorbing organic compounds. Compounds with elemental formula such as C6H5NO3, C6H5NO4, C7H7NO3 and C7H7NO4 were major light absorbers found in almost all the ambient samples. More light absorbers (e.g. C8H6O4, C8H9NO3, C8H9NO4, C9H16O4, C10H7NO3) were found in winter samples than summer samples. Comparison of brown carbon chromophores were performed between summer and winter in Beijing, as well as urban versus suburban sites. The change of light absorbers in atmosphere and its associated potential sources will be further discussed.