Response of distributions and emissions of volatile sulfur compounds to summer physical and biological processes in the Kuroshio Extension and Oyashio Current confluence region

Marine-derived volatile sulfur compounds (VSCs) play a critical role in global climate regulationand sulfur circulation. This study examined the significant roles of VSCs, including dimethyl sulfide (DMS), carbonyl sulfide (OCS), and carbon disulfide (CS₂), in the upper seawater layers and the overlying atmosphere in the Northwest Pacific during the summer of 2022. This region is characterized by dynamic oceanographic features, including active eddies and the convergence of the Kuroshio Extension (KE)and the Oyashio Current (OC), which collectively shape the distributions of these sulfur compounds. Elevated levels of CS₂ were observed with high chlorophyll a concentrations in the upper waters of the KE and OC regions, suggestingthe influence of phytoplankton species compositionon CS₂formation and indicating a biological component to CS₂ production. The facilitated photochemical and dark production pathwaysof OCS and CS₂in the KEregion contributed to their accumulations in the upper water column. Eddy edges were observed as hotspots for OCS and CS₂, associated with the stable habitatsfor zooplankton predationand sulfur compounds release. The warm and nutrient-depleted conditions promoted DMS production in the KE region and eddy active regions, likely due to the prevalence of DMSP-producing phytoplankton in nutrient-poor environments. The sea-to-air fluxes of DMS, OCS, and CS₂ in the Northwest Pacific during summer were strongly influenced by surface seawater concentrations and wind speeds. The interplay among oceanographic dynamics, phytoplankton communities, and zooplankton activity in the KE and OC confluence region drives the production and distribution of VSCs.