10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

Abstract View


Contrasting Physical Properties of Black Carbon in Urban Beijing between Winter and Summer

DANTONG LIU, Rutambhara Joshi, Chenjie Yu, James Allan, Hugh Coe, Michael Flynn, Junfeng Wang, Xinlei Ge, Yele Sun, Pingqing Fu, University of Manchester

     Abstract Number: 774
     Working Group: Aerosol Physics

Abstract
Black carbon (BC) exerts both climatic and health impacts, especially in regional hot spots with high emissions. The populated megacity represents the most complex anthropogenic BC emissions where the sources and related impacts are very uncertain. This study provides a characterization of BC in the Beijing urban environment using single particle soot photometry during the joint UK-China APHH (Air Pollution and Human Health) project, in both winter (Nov. - Dec. 2016) and summer (May - Jun. 2017). During this experiment, we successfully gathered 4 weeks of continuous measurements for each season, including several severe pollution events in Beijing. The BC was found to have contrasting physical properties between both seasons. In winter, during periods of high pollution levels, the core sizes of BC were larger and the coatings were thicker; whereas in summer at the same level of pollution, core size of BC particles showed little variation and the coatings were lower than in winter. This phenomenon may result from a more significant contribution of BC from the residential emission sector in winter, but may be also modulated by local and synoptic meteorology. By measuring the BC physical properties in single particles, we separate four modes of BC with different size-resolved mixing state. By comparing these modes of BC with source apportionment results based on chemical composition analysis using soot particle mass spectrometry, we are able to link the separated BC modes with possible emission sources. This paper will examine the behaviour and contribution of BC with contrasting physical properties in both seasons and will link this to the optical properties to evaluate the possible mass contribution and optical budgets of BC among different emission sectors in Beijing.