A total of 834 individual aerosol particles were collected duringOctober and November 2010 in urban Shanghai, China. Particles were sampledunder different weather and air quality conditions. Morphologies,compositions and mixing states of carbonaceous aerosols were investigated bytransmission electron microscopy (TEM) coupled with energy-dispersive X-ray(EDX). Structures of some particles were verified using selected-areaelectron diffraction (SAED). Among the aerosol particles observed,carbonaceous aerosols were mainly categorized into four types: polymericorganic compound (POC), soot, tar ball, and biogenic particle. Based on thedetailed TEM-EDX analysis, most of the particles were coated with secondaryorganic aerosols (SOA), which commonly formed through condensation orheterogeneous reactions of precursor gases on pre-existing particles. Agedparticles were associated with days with low wind velocities, showed complexstructures, and were bigger in size. The internally mixed particles ofsulphates, organics and soot were encountered frequently. Such internallymixed particles may be preferentially formed during a stagnated air massduring serious pollution events, such as on 13 November. Although relativenumber counts varied with different species, sulphates (38–71%) and soot(11–22%) constituted the most dominant species observed in the samples.However, soil-derived particles (68%) were relatively more frequentlyobserved on the sample collected on 12 November during a dust storm.
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