MSA in Beijing aerosol

Methane sulphonate (MSA) and sulfate (SO_4~(2-)),the main oxidation products of dimethyl sulfide (DMS), arethe target of atmospheric chemistry study, as sulfate aerosolwould have important impact on the global climate change.It is widely believed that DMS is mainly emitted from phyto-plankton production in marine boundary layer (MBL), andMSA is usually used as the tracer of non-sea-salt sulfate (nss-SO_4~(2-)) in marine and coastal areas (MSA/SO_4~(2-)=1/18). Manyobservations of MSA were in marine and coastal aerosols. TOour surprise, MSA was frequently (>60%) detected in BeijingTSP, PM_(10), and PM_(2.5) aerosols, even in the samples collectedduring the dust storm period. The concentrations of MSAwere higher than those measured in marine aerosols. Factoranalysis, correlation analysis and meteorology analysis indi-cated that there was no obvious marine influence on Beijingaerosols. DMS from terrestrial emissions and dimethylsulphoxide (DMSO) from industrial wastes could be the twopossible precursors of MSA. Warm and low-pressure airmasses and long time radiation were beneficial to thc forma-tion of MSA. Anthropogenic pollution from regional andlocal sources might be the dominant contributor to MSA inBeijing aerosol. This was the first report of MSA in aerosolscollected in an inland site in China. This new finding wouldlead to the further study on the balance of sulfur in inlandcities and its global biogeochemical cycle.