Characterization and source identification of submicron aerosol during serious haze pollution periods in Beijing

Submicron aerosol is of extensive concern not only due to its significant impact on air quality but also because it is detrimental to human health. In this study, we investigated the characteristics, sources and chemical processes of submicron aerosol based on real-time online measurements of submicron aerosols (NR-PM1) during December 2015 at an urban site in Beijing. The average mass concentration of NR-PM1 was 92.5 +/- 84.9 mu g/m(3), the hourly maximum was 459.1 mu g/m(3) during the entire observation. The organic aerosol (OA) (55%) was the largest contributor to NR-PM1. The average mass concentration of PAHs was 0.217 +/- 0.247 mu g/m(3), exhibiting the highest concentration at night and the lowest levels in the daytime. The average mass concentration of organic nitrate was 2.52 +/- 2.36 mu g/m(3) and that of inorganic nitrate was 7.62 +/- 8.22 mu g/m(3), accounting for 36% and 64%, respectively, of the total nitrate mass. Positive matrix factorization (PMF) differentiated the OA into five chemical components including LV-OOA, SV-OOA, COA, HOA and CCOA, accounting for 22%, 16%, 13%, 25% and 24% respectively, of the total OA. The average NR-PM1 mass concentration on the heavy polluted days (HPD) was 182.8 +/- 70.2 mu g/m(3), which was approximately 9 times that on clean days (CD). The enhanced secondary formation of SNA was evident on HPD, especially the rapid increase of sulfate (23%) and nitrate (19%). (C) 2021 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

This study investigated the characteristics, sources, and chemical processes of submicron aerosol in an urban site in Beijing based on real-time online measurements. The study found that organic aerosol was the largest contributor to submicron aerosol, and the concentration of submicron aerosol was nine times higher on heavily polluted days compared to clean days, with evident secondary formation of SNA.