Source Apportionment of Ambient Aerosols during a Winter Pollution Episode in Yinchuan by Using Single-Particle Mass Spectrometry

For a winter pollution episode in Yinchuan, a city in Northwestern China, ambient aerosols were characterized using a real-time single-particle aerosol mass spectrometer (SPAMS). More than 160,000 individual particles analyzed with the SPAMS were classified into eight major categories on the basis of their mass spectral patterns: traffic emissions, biomass burning, dust, coal burning, industrial emissions, secondary inorganic, cooking, and others, all of which contribute to fine particles. The results revealed that coal burning (29.6%) and traffic emissions (23.4%) were the main sources during the monitoring period. Industrial emissions and secondary inorganic aerosols accounted for 16.6% and 14.0%, respectively. The SPAMS data indicated that the number concentration of the eight types of particles was markedly different in the different pollution cases, and higher number concentrations were discovered more often during pollution episodes. The three pollution cases were mainly caused by the accumulation of fine particles, mainly from traffic emissions, industrial emissions, and increased secondary inorganic conversion.