Diel Profile of Hydroperoxymethyl Thioformate: Evidence for Surface Deposition and Multiphase Chemistry

• DOI: 10.1021/acs.est.0c04323
• Publication Date: 2020-08-31T21:19:06Z
• Authors: Michael P. Vermeuel; Gordon A. Novak; Christopher M. Je...; Timothy H. Bertram
• Keywords: Deposition; Dimethyl sulfide; Atmospheric chemistry; Trace gas; Mixing ratio; Dimethylsulfoniopropionate

Dimethyl sulfide (DMS; CH3SCH3), a biogenically produced trace gas emitted from the ocean, accounts for large fraction of natural sulfur released to marine atmosphere. The oxidation DMS in boundary layer (MBL), via hydrogen abstraction pathway, yields short-lived methylthiomethylperoxy radical (MSP; CH3SCH2OO). In remote MBL, unimolecular isomerization MSP outpaces bimolecular chemistry leading efficient formation hydroperoxymethyl thioformate (HPMTF; HOOCH2SCHO). Here, we report first ground observations and diurnal profiles HPMTF mixing ratios, vertical fluxes, deposition velocities ocean surface. Average daytime were recorded at 12.1 pptv, −0.11 pptv m s–1, 0.75 cm respectively. velocity is comparable other soluble phase compounds (e.g., HCOOH HNO3), resulting lifetime 30 h under typical windspeeds (3 s–1). A box model analysis incorporating current mechanistic understanding geostationary satellite cloud imagery data suggests that MBL this sampling location likely controlled by heterogeneous loss aerosol uptake clouds morning evening.