OH-initiated oxidation of DMS/DMSO: reaction products at high NOx levels.
Dimethylsulphide (DMS) gas phase oxidation with OH radicals was investigated by long path FT-IR spectroscopy and by ion chromatography (IC) and HPLC-MS2 to quantify the reaction products and evaluate heterogeneous processes. The experiments were performed considering two different NOx (NO2+NO) levels. The initial concentration of NO2 was varied from 24 ppbV (NOx=1 ppmV) to 953 ppbV (NOx=10 ppmV). Photolysis of H2O2 was used as the OH-radical source. SO2, dimethylsulphoxide (DMSO), dimethylsulphone (DMSO2), methanesulphonic acid (MSA), methanesulphinic acid (MSIA) and methane sulphonyl peroxynitrate (MSPN) were identified as the main sulphur-containing products. The results indicate that higher NOx levels play a significant role in the chemistry of CH3S(O)x radical, influencing both the SO2/MSPN ratio and the amount of the sulphur species in the condensed phase, and that the NO2/NO ratio could influence the trends in the molar yields of the different products. For this reason the NOx content results a limiting parameter when on measure DMS in atmospheric environment.
Librando
Vito
V
Chemistry Department of the University of Catania, Viale Andrea Doria, 6, I-95127, Catania, Italy. vlibrando@unict.it
Tringali
Giuseppe
G
Hjorth
Jens
J
Coluccia
Salvatore
S
D000336:Aerosols; D000393:Air Pollutants / Q000737:chemistry*; D002852:Chromatography, Ion Exchange; D002980:Climate; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods*; D017665:Hydroxyl Radical / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry; D009585:Nitrogen Dioxide / Q000737:chemistry; D010777:Photochemistry; D019265:Spectroscopy, Near-Infrared; D013440:Sulfides / Q000737:chemistry*
D000336:Aerosols; D000393:Air Pollutants; D013440:Sulfides; D009569:Nitric Oxide; D017665:Hydroxyl Radical; C004784:dimethyl sulfide; D009585:Nitrogen Dioxide; D004121:Dimethyl Sulfoxide