Characterization, mixing state, and evolution of urban single particles in Xi'an (China) during wintertime haze days.
A Single Particle Aerosol Mass Spectrometer (SPAMS) was deployed in the urban area of Xi'an to investigate size-resolved chemical composition and mixing state of single particles during the heavy haze episode occurred from January 13 to January 27 in 2013. Nine major single particle types were resolved with ART-2a algorithm including biomass burning (BB), Potassium-Secondary (KSec), elemental and organic Carbon (ECOC), sodium-potassium-rich ECOC (NaKECOC), sodium-potassium-rich-secondary (NaKSec), EC, OC, and Dust. Daily PM2.5mass concentration was 213±122μgm-3. ~96% of the ambient particles were carbonaceous and internally mixed with secondary species such as sulfate and nitrate. The major particle types were from combustion sources, including coal burning, biomass burning, and vehicle exhaust. Mixing state analysis suggests gas-to-particle conversion was an important mechanism forming organic species during the winter haze episode. The relative abundances of the aged particle types, such as KSec and NaKSec increased with the elevated RH when RH<80%. The fraction of aged particles in terms of number concentration was prominent during high levels of PM2.5under stagnant air conditions. This study gained new knowledge on atmospheric aerosol formation and evolution in urban environment heavy winter haze condition.
Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
Yang
Y
Chen
Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China. Electronic address: cao@loess.llqg.ac.cn.
Junji
J
Cao
Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; Laboratory of Atmospheric Chemistry, Paul Scherrer Institut (PSI), CH-5232 Villigen PSI, Switzerland.
Rujin
R
Huang
Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
Fumo
F
Yang
Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
Qiyuan
Q
Wang
Key Lab of Aerosol Chemistry & Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China.
Yichen
Y
Wang
D000336:Aerosols; D000393:Air Pollutants / Q000032:analysis*; D002681:China; D002947:Cities; D004784:Environmental Monitoring / Q000379:methods*; D013058:Mass Spectrometry; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012621:Seasons; D014887:Weather
D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter
Evolution; Haze; Mixing state; Single particle