Occurrence and emissions of volatile sulfur compounds in the Changjiang estuary and the adjacent East China Sea

Volatile organic sulfur compounds (VSCs) are key components of the oceanic and atmospheric sulfur cycle. Here, we investigated the distributions of three major VSCs, such as carbon disulfide (CS2), dimethyl sulfide (DMS), and carbonyl sulfide (COS), and estimated their sea-to-air fluxes in the Changjiang Estuary and the adjacent East China Sea from July 20 to August 3, 2017. The DMS, COS, and CS2 surface water concentration ranges were 0.22-18.62, 0.06-0.77, and 0.02-0.3 nmol L-1, respectively. The distributions of VSCs were related to environmental and biological factors. In contrast to DMS, COS and CS2 concentrations generally decreased from the estuary to offshore waters. A significant correlation was observed between chlorophyll a and CS2 concentration, suggesting that CS2 production may be related to phytoplankton growth. Moreover, a positive correlation was observed between CS2 and DMS, indicating that they might share similar production pathways. COS was the most abundant VSC in the atmosphere, with an average concentration of 422.9 +/- 301.8 ppt, but its distribution was likely influenced by anthropogenic activities. The average COS, DMS, and CS2 sea-to-air fluxes were 0.98 +/- 0.98, 4.38 +/- 6.42, and 0.05 +/- 0.05 mu mol m(-2) d(-1). The Changjiang Estuary and the adjacent East China Sea are important sources of atmospheric VSCs. These results will help us to better understand global VSC cycling between the oceanic atmosphere and bodies of water.