Morphology, composition and mixing state of individual carbonaceous aerosol in urban Shanghai
1Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
2Research Institute for the Global Environment Change, Fudan University, Shanghai 200433, China
3Environment Research Institute, Shandong University, Jinan Shandong 250100, China
4College of Environment and Life, Dalian University of Technology, Dalian Liaoning 116024, China
Abstract. 834 individual aerosol particles were collected during Octoberober and Novemberember 2010 in urban Shanghai, China. Morphologies, compositions and mixing states of carbonaceous aerosols were investigated by transmission electron microscopy (TEM) coupled with energy-dispersive X-ray (EDX). Structures of some particles were verified using selected-area electron diffraction (SAED). Among the aerosol particles observed, carbonaceous aerosols were categorized into five types: polymeric organic compound (POC), soot, tar ball, char, and biogenic particle. Based on the detailed TEM-EDX analysis, most of particles were coated with secondary organic aerosols (SOA), which commonly formed through condensation or heterogeneous reactions of precursor gases on pre-existing particles. The internally particles of sulphates, organics and soot were encountered frequently. Such internally mixed particles may be preferentially formed during a stagnated air mass which often occurred during serious pollution events, such as a haze episode on 13 Novemberember. Although relative number counts varied with different species, sulphates (38 %–71 %) and soot (11 %–22 %) constituted the most dominant species observed in the samples. With an exception of the sample collected during a dust storm on 12 Novemberember, soil-derived particles (68 %) were relatively more frequently observed. Of particular interest was the biogenic particles encountered almost as frequently as soot on the sample collected on 13 November (18 % vs. 22 %). The result from air mass back-trajectory analysis indicated that these particles were marine-originated, most likely from the Yellow Sea.