Factors Controlling DMS Emission and Atmospheric Sulfate Aerosols in the Western Pacific Continental Sea

The western Pacific continental sea significantly influences the regulation of climate-active gases budget and the burden of sulfate aerosols. An underway shipboard measurement device was used to determine the dimethyl sulfide (DMS) in the surface seawater and overlying atmosphere in the East China Continental Sea. The average concentration of DMS in atmosphere and seawater was 122.8 ± 86.2pptv and 6.47 ± 3.58 nmol L⁻¹, respectively. The variation trend of surface water DMS in the western Pacific continental sea was influenced by the abundance and composition of phytoplankton under different ocean current systems, with a significant impact from eddies on DMS production in the South China Sea. By eliminating the influence of terrestrial sources and limiting air mass transport within the marine boundary layer, strong correlations were established between atmospheric DMS and air mass exposure to chlorophyll (E_chl), as well as between aerosol methanesulfonic acid (MSA) and E_chl. During the aerosol sampling period, the atmospheric DMS levels (1,057 ± 371 ng/m³) were significantly higher than MSA levels (46.3 ± 59.8 ng/m³) in the East China Sea, where the conversion of DMS to MSA was not affected by changes in DMS concentration. The sea-to-air fluxes of DMS varied over a wide range, from 0.02 to 156.0 μmol m⁻² d⁻¹, with an average of 14.35 ± 18.58 μmol m⁻² d⁻¹. Marine DMS emissions play a critical role in the formation of sulfur aerosols on the western Pacific continental shelf, accounting for 24.6 ± 7.6% (14.8%–37.8%) of the total sulfate aerosols.