Abstract
To investigate the sources and evolution of haze pollution in different seasons, long-term (from 15 August to 4 December 2015) variations in chemical composition of PM<span classCombining double low line"inline-formula were characterized in Beijing, China. Positive matrix factorization (PMF) analysis with a multi-linear engine (ME-2) resolved three primary and two secondary organic aerosol (OA) sources, including hydrocarbon-like OA (HOA), cooking OA (COA), coal combustion OA (CCOA), local secondary OA (LSOA) and regional SOA (RSOA). The sulfate source region analysis implies that sulfate was mainly transported at a large regional scale in late summer, while local and/or nearby sulfate formation may be more important in winter. Meanwhile, distinctly different correlations between sulfate and RSOA or LSOA (i.e., better correlation with RSOA in late summer, similar correlations with RSOA and LSOA in autumn, and close correlation with LSOA in early winter) confirmed the regional characteristic of RSOA and local property of LSOA. Secondary aerosol species including secondary inorganic aerosol (SIA - sulfate, nitrate, and ammonium) and SOA (LSOA and RSOA) dominated PM<span classCombining double low line"inline-formula during all three seasons. In particular, SOA contributed 46% to total PM<span classCombining double low line inline-formula (with 31% as RSOA) in late summer, whereas SIA contributed 41% and 45% to total PM<span classCombining double low line inline-formula in autumn and early winter, respectively. Enhanced contributions of secondary species (66%-76% of PM<span classCombining double low line inline-formula) were also observed in pollution episodes during all three seasons, further emphasizing the importance of secondary formation processes in haze pollution in Beijing. Combining chemical composition and meteorological data, our analyses suggest that both photochemical oxidation and aqueous-phase processing played important roles in SOA formation during all three seasons, while for sulfate formation, gas-phase photochemical oxidation was the major pathway in late summer, aqueous-phase reactions were more responsible during early winter and both processes had contributions during autumn.
Original language | English |
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Pages (from-to) | 10319-10334 |
Number of pages | 16 |
Journal | Atmospheric Chemistry and Physics |
Volume | 19 |
Issue number | 15 |
DOIs | |
Publication status | Published - 14 Aug 2019 |
Externally published | Yes |
ASJC Scopus subject areas
- Atmospheric Science