Novel pathway of SO 2 oxidation in the atmosphere: reactions with monoterpene ozonolysis intermediates and secondary organic aerosol

Ye, Jianhuai; Abbatt, Jonathan P. D.; Chan, Arthur W. H.

Ozonolysis of monoterpenes is an important source of atmospheric biogenic secondary organic aerosol (BSOA). While enhanced BSOA formation has been associated with sulfate-rich conditions, the underlying mechanisms remain poorly understood. In this work, the interactions between SO 2 and reactive intermediates from monoterpene ozonolysis were investigated under different humidity conditions (10 % vs. 50 %). Chamber experiments were conducted with ozonolysis of α-pinene or limonene in the presence of SO 2. Limonene SOA formation was enhanced in the presence of SO 2, while no significant changes in SOA yields were observed during α-pinene ozonolysis. Under dry conditions, SO 2 primarily reacted with stabilized Criegee intermediates (sCIs) produced from ozonolysis, but at 50 % RH heterogeneous uptake of SO 2 onto organic aerosol was found to be the dominant sink of SO 2, likely owing to reactions between SO 2 and organic peroxides. This SO 2 loss mechanism to organic peroxides in SOA has not previously been identified in experimental chamber studies. Organosulfates were detected and identified using an electrospray ionization–ion mobility spectrometry–high-resolution time-of-flight mass spectrometer (ESI-IMS-TOF) when SO 2 was present in the experiments. Our results demonstrate the synergistic effects between BSOA formation and SO 2 oxidation through sCI chemistry and SO 2 uptake onto organic aerosol and illustrate the importance of considering the chemistry of organic and sulfur-containing compounds holistically to properly account for their reactive sinks.



Ye, Jianhuai / Abbatt, Jonathan P. D. / Chan, Arthur W. H.: Novel pathway of SO2 oxidation in the atmosphere: reactions with monoterpene ozonolysis intermediates and secondary organic aerosol. 2018. Copernicus Publications.


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