Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 5399-5411, 2016
https://doi.org/10.5194/acp-16-5399-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
29 Apr 2016
Size distribution and mixing state of black carbon particles during a heavy air pollution episode in Shanghai
Xianda Gong1, Ci Zhang1, Hong Chen1, Sergey A. Nizkorodov2, Jianmin Chen1,3, and Xin Yang1,3 1Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
2Department of Chemistry, University of California, Irvine, California 92697, USA
3Fudan-Tyndall Center, Fudan University, Shanghai 200433, China
Abstract. 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−3, with the peak value of 12.1 µg m−3 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 (R2 = 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-SOx); (5) BC internally mixed with OC and ammonium nitrate (BCOC-NOx). 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−1) of rBC with small core sizes was observed during the experiment. High concentrations pollutants like NO2 likely accelerated the aging process and resulted in a continuous size growth of rBC-containing particles from traffic emission.

Citation: Gong, X., Zhang, C., Chen, H., Nizkorodov, S. A., Chen, J., and Yang, X.: Size distribution and mixing state of black carbon particles during a heavy air pollution episode in Shanghai, Atmos. Chem. Phys., 16, 5399-5411, https://doi.org/10.5194/acp-16-5399-2016, 2016.
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In this study, we used a Single Particle Aerosol Mass Spectrometer and a Single Particle Soot Photometer to investigate the chemical and physical properties of black carbon (BC) aerosols during a regional air pollution episode in urban Shanghai. BC containing particles were mainly attributed to biomass burning and traffic emissions. We observed a group of highly aged traffic emitted particles with a relatively small BC core (~ 60–80 nm) and a very thick absolute coating thickness (~ 130–300 nm).
In this study, we used a Single Particle Aerosol Mass Spectrometer and a Single Particle Soot...
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