Joint impact of atmospheric SO2 and NH3 on the formation of nanoparticles from photo-oxidation of a typical biomass burning compound

The presence of atmospheric inorganic pollutants, such as SO2 and NH3 could affect the nanoparticles formation and their atmospheric abundance. In the present study, the joint impact of SO2 and NH3 on nanoparticles formation in the photo-oxidation of 3-methylfuran (3-MF) were investigated to simulate the atmospheric reactions. The experimental results demonstrated that both SO2 and NH3 have significant promotional effects on 3-MF-derived nanoparticles formation. Varying SO2 concentration in the range from 0 to similar to 180 ppb caused secondary organic aerosol (SOA) yields to increase by 3.8% on an average. Meanwhile, SOA yield increased approximately by 3.3% with similar to 50 ppb NH3 addition at the beginning of the experiments. Moreover, the existence of SO2 and NH3 could also obviously promote the secondary inorganic nanoparticles formation. In view of the fact that both NH3 and 3-MF are emitted into the atmosphere through agricultural activities, it is important to clarify the influence of NH3 on 3-MF photooxidation. The results indicated that NH3 has a substantial promotion effect on the formation of N-containing products, which were assigned as important brown carbon constituents according to their distinct absorbance in the visible region. Three C-5-organosulfates (C-5-OSs) with MW 196, 212, 228 were identified, which showed that 3-MF is probably one kind of precursor for the atmospheric C5-OSs. The present research provides information for understanding the joint impact of atmospheric pollutants and offers new insights into furan-derived SOA formation under heavy pollution conditions.