Size distribution and mixing state of black carbon particles during a heavy air pollution episode in Shanghai
Item
Title (Dublin Core)
Size distribution and mixing state of black carbon particles during a heavy air pollution episode in Shanghai
Description (Dublin Core)
A Single Particle Aerosol Mass Spectrometer (SPAMS), a Single Particle Soot Photometer (SP2) and various meteorological instruments were employed to investigate the chemical and physical properties of black carbon (BC) aerosols during a regional air pollution episode in urban Shanghai over a 5-day period in December 2013. The refractory black carbon (rBC) mass concentrations measured by SP2 averaged 3.2 µg m<sup>−3</sup>, with the peak value of 12.1 µg m<sup>−3</sup> at 04:26 LT on 7 December. The number of BC-containing particles captured by SPAMS in the size range 200–1200 nm agreed very well with that detected by SP2 (<i>R</i><sup>2</sup> = 0.87). A cluster analysis of the single particle mass spectra allowed for the separation of BC-containing particles into five major classes: (1) Pure BC; (2) BC attributed to biomass burning (BBBC); (3) K-rich BC-containing (KBC); (4) BC internally mixed with OC and ammonium sulfate (BCOC-SO<sub><i>x</i></sub>); (5) BC internally mixed with OC and ammonium nitrate (BCOC-NO<sub><i>x</i></sub>). The size distribution of internally mixed BC particles was bimodal. Detected by SP2, the condensation mode peaked around ∼ 230 nm and droplet mode peaked around ∼ 380 nm, with a clear valley in the size distribution around ∼ 320 nm. The condensation mode mainly consisted of traffic emissions, with particles featuring a small rBC core (∼ 60–80 nm) and a relatively thin absolute coating thickness (ACT, ∼ 50–130 nm). The droplet mode included highly aged traffic emission particles and biomass burning particles. The biomass burning particles had a larger rBC core (∼ 80–130 nm) and a thick ACT (∼ 110–300 nm). The highly aged traffic emissions had a smaller core (∼ 60–80 nm) and a very thick ACT (∼ 130–300 nm), which is larger than reported in any previous literature. A fast growth rate (∼ 20 nm h<sup>−1</sup>) of rBC with small core sizes was observed during the experiment. High concentrations pollutants like NO<sub>2</sub> likely accelerated the aging process and resulted in a continuous size growth of rBC-containing particles from traffic emission.
Creator (Dublin Core)
Gong, Xianda
Zhang, Ci
Chen, Hong
Nizkorodov, Sergey A.
Chen, Jianmin
Yang, Xin
Date (Dublin Core)
2018-09-10
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-16-5399-2016
https://acp.copernicus.org/articles/16/5399/2016/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
