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

Abstract

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 ∼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 ∼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 photo-oxidation. 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 C₅-organosulfates (C₅-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.