Dimethyl sulfide (DMS), a significant source of natural sulfur in the atmosphere, is instrumental in the formation and growth of aerosols in the marine atmosphere. Once emitted, DMS is primarily oxidized by the hydroxyl radical (OH) eventually leading to the formation of sulfur dioxide (SO2) and eventually sulfate aerosol (SO42-). Recent laboratory and field measurements have revealed that the OH-oxidation of DMS proceeds through the stable intermediate, hydroperoxymethyl thioformate (HPMTF), the fate of which dictates the production rate of SO2, SO42-, and carbonyl sulfide (OCS), with consequent effects on the production rate of cloud condensation nuclei (CCN). During the night, OH production ceases and the nitrate radical (NO3) emerges as a dominant oxidant. In coastal, urban regions the oxidation of DMS by nitrate radicals is thought to be of particular importance. Here, we report on the yield of SO2, OCS, HPMTF and subsequent oxidation products formed in the NO3 facilitated oxidation of DMS in the absence of light. The experiments were performed in a dark, dry environmental chamber using a mixture of nitrogen dioxide (NO2) and ozone (O3) as the source of NO3 under oxidative conditions representative of an urban coastal environment.

Examining the chemical mechanism of the nocturnal oxidation of dimethyl sulfide by the nitrate radical

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