Transformation processes of biogenic dimethylated sulfur compounds in the northwestern Pacific continental sea

Abstract

Biogenic dimethylated sulfur compounds, comprising dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide, play a vital role in the physiological metabolism processes of marine algae, climate regulation, and global sulfur cycles, but the contribution of each transformation pathway and the factors that control them remain uncertain. For the first time, from 27 March 2017 to 15 April 2017, the rates of major transformation pathways of biogenic dimethylated sulfur compounds and the fluxes of DMS at the sea-air and seawater-sediment interfaces were measured simultaneously in the East China Continental Sea. Rapid biological turnover times of total DMSP (0.53 d), dissolved DMSP (0.29 d), and DMS (0.43 d) were observed, indicating that DMS and DMSP were renewed more than twice daily. Bacterial consumption contributed nearly 50% of the total DMSP loss, approximately 38% of which was converted into DMS. Microbial consumption, photolysis, and ventilation accounted for 56%, 34%, and 10% of DMS removal processes, respectively. Sediment had a small but positive flux of DMS, making the sediment-seawater interface a tiny source of DMS to the water column. Finally, although only about 10% of DMS was emitted to the atmosphere, the study region was identified as a "hotspot" for atmospheric DMS. The DMS budget model of the mixed layer developed in this study has provided a systematic and comprehensive understanding of the organosulfur cycle in continental shelf seas.

Revealing the Marine Cycles of Volatile Sulfur Compounds and Their Biogeochemical Controls: A Case of the Western North Pacific

“…UV radiation emerged as the predominant factor (>80%; Figure 2d) driving surface DMS photodegradation, aligning with previous research. 14,15 DMS photodegradation, primarily facilitated by secondary photosensitizers such as CDOM and nitrate, 51,52 occurs more rapidly in high-latitude regions abundant in photosensitizers and lowlatitude regions with intense solar radiation (e.g., Station P27), as evidenced by the rate constants (Table S2). Upon normalization to photon flux density, the KOE displayed the highest DMS photodegradation rate (Table S5), with UVB showing a significantly higher influence (UVB:UVA:PAR ratio of 463:39:1).…”

“…It is estimated that approximately 27.1 Tg of sulfur, in the form of DMS, is emitted from the ocean annually . Besides, sea surface DMS can be removed through microbial metabolism and photo-oxidation. , OCS is generally produced via reactions between ultraviolet radiation and dissolved organic sulfur, − which is an indirect process photosensitized by chromophoric dissolved organic matter (CDOM). The reaction of sulfur radicals can also produce OCS in the dark.…”

Distribution and physical–biological controls of dimethylsulfide in the western tropical Indian Ocean during winter monsoon

“…DMS-loss processes involve microbial consumption, photochemical oxidation, ventilation to the atmosphere, and vertical export by mixing in the euphotic layer. DMS consumption by bacteria is generally the major loss process, accounting for 50%-80% of the total, whereas release to the atmosphere represents only a small proportion of total DMS removal Simo, 2004;Toole et al, 2006;Vila-Costa et al, 2008;Ma et al, 2022). The amount of DMS released to the atmosphere accounts for only 3% of the total DMSP in the ocean (Kiene and Service, 1991).…”

Marine Dimethyl Sulfide Fluxes in the Yellow and East China Seas: Scenario Variation During the 1980s–2090s and Its Drivers

“…Spatially, the summertime [DMS] exhibits a patchy characteristic with higher value occurring in the Changjiang estuary and its adjacent area, and Zhejiang coastal (Ma & Yang, 2023b; Yang et al., 2011; Zhu et al., 2019) and, a significant positive correlation is found between [DMS] and total chlorophyll a concentration ([Chl a ]) in the YECS (Gao et al., 2017; Jian et al., 2018; Yang et al., 2011). Some studies have focused on the effect of seawater acidification and nutrient inputs on the DMS cycle (Gao et al., 2021; Jian et al., 2019; Ma & Yang, 2023a). Ship‐based incubation experiments revealed that the increased [DMS] was substantially ascribed to the elevated phytoplankton biomass that response to these environmental changes (Ma & Yang, 2023a).…”

“…Some studies have focused on the effect of seawater acidification and nutrient inputs on the DMS cycle (Gao et al., 2021; Jian et al., 2019; Ma & Yang, 2023a). Ship‐based incubation experiments revealed that the increased [DMS] was substantially ascribed to the elevated phytoplankton biomass that response to these environmental changes (Ma & Yang, 2023a). Totally, the response of biogenic DMS emitted from the YECS to environmental changes is still poorly understood.…”