Potential particulate pollution derived from UV-induced degradation ofodorous dimethyl sulfide

UV-induced degradation of odorous dimethyl sulfide (DMS) was carried out in a static White cell chamber with UV irradiation. Thecombination of in situ Fourier transform infrared (FT-IR) spectrometer, gas chromatograph-mass spectrometer (GC-MS), wide-rangeparticle spectrometer (WPS) technique, filter sampling and ion chromatographic (IC) analysis was used to monitor the gaseous andpotential particulate products. During 240 min of UV irradiation, the degradation e ciency of DMS attained 20.9%, and partiallyoxidized sulfur-containing gaseous products, such as sulfur dioxide (SO2), carbonyl sulfide (OCS), dimethyl sulfoxide (DMSO),dimethyl sulfone (DMSO2) and dimethyl disulfide (DMDS) were identified by in situ FT-IR and GC-MS analysis, respectively.Accompanying with the oxidation of DMS, suspended particles were directly detected to be formed by WPS techniques. Theseparticles were measured mainly in the size range of accumulation mode, and increased their count median diameter throughoutthe whole removal process. IC analysis of the filter samples revealed that methanesulfonic acid (MSA), sulfuric acid (H2SO4) andother unidentified chemicals accounted for the major non-refractory compositions of these particles. Based on products analysis andpossible intermediates formed, the degradation pathways of DMS were proposed as the combination of the O(1D)- and the OH- initiatedoxidation mechanisms. A plausible formation mechanism of the suspended particles was also analyzed. It is concluded that UV-induceddegradation of odorous DMS is potentially a source of particulate pollutants in the atmosphere.