Gong, XD (Gong, Xianda)^[ 1 ] ; Zhang, C (Zhang, Ci)^[ 1 ] ; Chen, H (Chen, Hong)^[ 1 ] ; Nizkorodov, SA (Nizkorodov, Sergey A.)^[ 2 ] ; Chen, JM (Chen, Jianmin)^[ 1,3 ] ; Yang, X (Yang, Xin)^[ 1,3 ]

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 inDecember 2013. The refractory black carbon (rBC) mass concentrations measured by SP2 averaged 3.2aEuro-A mu gaEuro-m(-3), with the peak value of12.1aEuro-A mu gaEuro-m(-3) at 04:26aEuro-LT on 7 December. The number of BC-containing particles captured by SPAMS in the size range 200-1200aEuro-nm agreed very well with that detected by SP2 (R-2 = 0.87). A cluster analysis of the single particle mass spectra allowed for the separation of BC-containingparticles 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 BCparticles was bimodal. Detected by SP2, the condensation mode peaked around aEuro-230aEuro-nm and droplet mode peaked around aEuro-380aEuro-nm, with a clear valley in the size distribution around aEuro-320aEuro-nm. The condensation mode mainly consisted of traffic emissions, with particles featuring asmall rBC core ( aEuro-60-80aEuro-nm) and a relatively thin absolute coating thickness (ACT, aEuro-50-130aEuro-nm). The droplet mode included highly aged traffic emission particles and biomass burning particles. The biomass burning particles had a larger rBC core ( aEuro-80-130aEuro-nm) and a thick ACT ( aEuro-110-300aEuro-nm). The highly aged traffic emissions had a smaller core ( aEuro-60-80aEuro-nm) and a very thick ACT ( aEuro-130-300aEuro-nm), which is larger than reported in any previous literature. A fast growth rate ( aEuro-20aEuro-nmaEuro-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 particlesfrom traffic emission.

KeyWords Plus:AEROSOL MASS-SPECTROMETER; LASER-INDUCED INCANDESCENCE; SECONDARY ORGANIC AEROSOL; SOLUBLE IONIC COMPOSITION; EUROPEAN MEGACITY PARIS; SOOT PHOTOMETER; OPTICAL-PROPERTIES; LIGHT-ABSORPTION; ELEMENTAL CARBON; SOUTH CHINA

Reprint Address: Yang, X (reprint author)

Fudan Univ, Dept Environm Sci & Engn, Shanghai Key Lab Atmospher Particle Pollut & Prev, Shanghai 200433, Peoples R China.

Fudan Univ, Fudan Tyndall Ctr, Shanghai 200433, Peoples R China.

Addresses:

	[ 1 ] Fudan Univ, Dept Environm Sci & Engn, Shanghai Key Lab Atmospher Particle Pollut & Prev, Shanghai 200433, Peoples R China
	[ 2 ] Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA
	[ 3 ] Fudan Univ, Fudan Tyndall Ctr, Shanghai 200433, Peoples R China

E-mail Addresses:yangxin@fudan.edu.cn