Aerosol composition and sources during the Chinese Spring Festival: fireworks, secondary aerosol, and holiday effects

摘要

Aerosol particles were characterized by an Aerodyne aerosol chemicalspeciation monitor along with various collocated instruments in Beijing,China, to investigate the role of fireworks (FW) and secondary aerosol inparticulate pollution during the Chinese Spring Festival of 2013. ThreeFW events, exerting significant and short-term impacts on fineparticles (PM), were observed on the days of Lunar New Year, LunarFifth Day, and Lantern Festival. The FW were shown to have a large impact onnon-refractory potassium, chloride, sulfate, and organics in submicronaerosol (PM), of which FW organics appeared to be emittedmainly in secondary, with its mass spectrum resembling that of secondaryorganic aerosol (SOA). Pollution events (PEs) and clean periods (CPs)alternated routinely throughout the study. Secondary particulate matter (SPM= SOA + sulfate + nitrate + ammonium) dominated the total PMmass on average, accounting for 63–82% during nine PEs in this study. Theelevated contributions of secondary species during PEs resulted in a highermass extinction efficiency of PM (6.4 m g) thanduring CPs (4.4 m g). The Chinese Spring Festival also providesa unique opportunity to study the impact of reduced anthropogenic emissionson aerosol chemistry in the city. Primary species showed ubiquitousreductions during the holiday period with the largest reduction being in cookingorganic aerosol (OA; 69%), in nitrogen monoxide (54%), and in coal combustion OA (28%).Secondary sulfate, however, remained only slightly changed, and the SOA and thetotal PM even slightly increased. Our results have significantimplications for controlling local primary source emissions during PEs,e.g., cooking and traffic activities. Controlling these factors might have a limited effect onimproving air quality in the megacity of Beijing, due to the dominance of SPM fromregional transport in aerosol particle composition.