Aerosol formation during photooxidation of organosulfur species

Measurements of aerosol formation during the photooxidation of dimethylsulfide (DMS) and dimethyldisulfide (DMDS) in an outdoor smog chamber are compared with predictions from a model of aerosol nucleation and growth in the chemically reacting system. The aerosol is assumed to consist of methanesulfonic acid (MSA), sulfuric acid, and water. Source rates of the two acid species are obtained from a detailed chemical mechanism for the organosulfur precursor oxidation and are used to drive the aerosol model. Good agreement between experiment and predictions was observed for DMDS and DMS oxidation in the presence of NOx, but maximum total number concentrations achieved during DMDS oxidation in the absence of NOx were somewhat underpredicted. The effect upon model predictions of variations in model input parameters is evaluated