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DMSP can be cleaved to dimethylsulfide (DMS), a climatologically important gas, through biological and chemical pathways (Andreae, 1990). Marine bacteria play an important role in DMSP degradation (Reisch et al., 2011). Many marine bacterial isolates can degrade

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Abstract. To better understand the production and loss processes of volatile organic sulfur compounds (VSCs) and their influence factors, VSCs including carbon disulfide (CS2), dimethyl sulfide (DMS), and carbonyl sulfide (COS) were surveyed in the seawater and atmosphere of the Bohai and Yellow Seas during spring and summer of 2018. The concentration ranges of COS, DMS, and CS2 in the surface seawater during spring were 0.14–0.42, 0.41–7.74, and 0.01–0.18 nmol L-1, respectively, and 0.32–0.61, 1.31–18.12, and 0.01–0.65 nmol L-1 during summer. COS and CS2 had high concentrations in coastal waters, which may be due to elevated photochemical production rates. High DMS concentrations occurred near the Yellow River, Laizhou Bay, and Yangtze River Estuary coinciding with high nitrate and Chl a concentrations due to river discharge during summer. The depth distributions of COS, DMS, and CS2 were characterized by high concentrations in the surface seawater that decreased with depth. The mixing ratios of COS, DMS, and CS2 in the atmosphere were 255.9–620.2 pptv, 1.3–191.2 pptv, and 5.2–698.8 pptv during spring, and 394.6–850.1 pptv, 10.3–464.3 pptv, and 15.3–672.7 pptv in summer. The mean oceanic/atmospheric concentrations of COS, DMS, and CS2 were 1.8/1.7-, 3.1/4.7-, and 3.7/1.6-fold higher in summer than spring due to the high Chl a concentrations in summer. The mean sea-to-air fluxes of COS, DMS, and CS2 were 1.3-, 2.1-, and 3.0-fold higher in summer than spring. The sea-to-air fluxes of VSCs indicated that these marginal seas are major sources of VSCs in the atmosphere. The results provide help with a better understanding of the control of VSCs distributions in marginal seas.

Dimethyl sulfide (DMS) is the main biogenic sulfur compound emitted to the atmosphere from seawater and likely affects the global climate (Andreae, 1990;Charlson et al., 1987). The oxidation products of DMS form cloud condensation nuclei, which changes the backscattering effect of sunlight and potentially affects the global environment (Charlson et al., 1987;Nguyen et al., 1992). The DMS precursor dimethylsulfoniopropionate (DMSP) is synthesized by marine phytoplankton (Keller et al., 1989) and bacteria (Curson et al., 2017(Curson et al., , 2018. DMSP is ubiquitous in the marine environment and serves numerous physiological and biological functions as an osmolyte (Kirst, 1989), a cryoprotectant (Sunda et al., 2002), and an antioxidant (Karsten et al., 1996). The DMS and DMSP sources and sinks in the ocean are closely related to marine organisms (i.e., bacteria, phytoplankton, and zooplankton) (Stefels et al., 2007). DMSP supplies sulfur and carbon to marine bacteria and zooplankton in the food web (Levasseur, 2013;Vila-Costa et al., 2006). DMSP dissolves in the water column and is catabolized by marine bacteria, mainly those from the classes α-Proteobacteria and γ-Proteobacteria (Curson et al., 2008;