AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Chemical and Optical Properties of BC-containing Particles in Urban and Remote Sites of China
XINLEI GE, Junfeng Wang, Yele Sun, Dantong Liu, Nanjing University of Information Science & Technology
Abstract Number: 242 Working Group: Carbonaceous Aerosol
Abstract Refractory black carbon (rBC) aerosol is a very important climate forcer, and its impacts are greatly influenced by the species associated with rBC cores. However, relevant knowledge is lacking due to scarcity of surface observations of BC and its associated coatings. Here we present highly time-resolved measurement results of rBC core and its coating species at a high altitude remote site in central TP (4730 m a.s.l), and in urban Beijing, China, respectively, by using an Aerodyne soot particle aerosol mass spectrometer (SP-AMS), which exclusively measured rBC-containing particles only. Such two cases represent the very clean and highly polluted environments in China. We found that the rBC over TP was overall thickly coated with an average mass ratio of coating to rBC (RBC) of ~7.7, and the coating species were predominantly secondary in nature, mainly produced by photochemical reactions. Interestingly, we found that the thickly coated rBC was less oxygenated than the thinly coated rBC, mainly due to the influence of a transported biomass burning organic aerosol (BBOA). This BBOA was relatively fresh but able to form very thick coating on rBC. On the other hand, rBC-containing particles in urban Beijing were overall associated with thinner coating, and the organic coating had diverse sources including both primary and secondary origins; On average, more polluted rBC-particles appeared to have thicker coating and more secondary species. We also discussed the light absorption enhancement due to the coating under these two cases.