Spatial Distribution and Biogeochemical Cycling of Dimethylated Sulfur Compounds and Methane in the East China Sea During Spring

Abstract

The spatial distributions of dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), dimethylsulfoxide (DMSO), and methane (CH4) were studied in the East China Sea during May 2017, and the possible controlling factors and biogeochemical cycling processes are discussed. The mean surface concentrations of DMS and CH4 were 10.66 and 9.93 nmol/L in the coastal area and 7.60 and 6.88 nmol/L in the open ocean, respectively. Horizontal and vertical profiles of the dimethylated sulfur compounds and CH4 were largely affected by different water masses, with enhancement observed in the coastal area. Significant correlations were found between CH4 and particulate DMSP (r = 0.609, p < 0.01, n = 42), and between CH4 and dissolved DMSO (r = 0.654, p < 0.01, n = 42). A dissolved DMSP (DMSPd) spike experiment revealed that the bacterial communities had potential to utilize DMSPd, meanwhile producing CH4 under oligotrophic conditions. The average mixing ratio of atmospheric DMS was 109 ± 49 pptv. Variations of marine DMS and wind speed explained 23 and 40% of the variation in the mixing ratios of atmospheric DMS, respectively. The sea‐to‐air fluxes of DMS and CH4 were estimated to be 18.64 ± 14.92 and 13.85 ± 15.03 μmol m−2 d−1, respectively.

Distribution Characteristics of Dimethylated Sulfur Compounds and Turnover of Dimethylsulfide in the Northern South China Sea During Summer

“…The DMS concentrations were generally between 1.1 and 3.5 nmol L −1 , except for two small peaks of up to 9.5 nmol L −1 in areas of phytoplankton blooms near the eastern region of Hainan and the estuarine region of the Pearl River (Figure ). Our results were in agreement with those of many previous studies (Zhai et al, ; Zhang et al, ), in which high DMS levels commonly occurred in the estuaries and were related to the high phytoplankton biomass. Overall, the DMS concentrations were high in the estuarine and coastal regions and low in the central large‐scale basin.…”

“…Many studies have demonstrated that the production and consumption of DMS are significantly affected by the complex web of ecological, physical, and biogeochemical processes (Asher et al, ; Kiene et al, ; Simó et al, ; Zhai et al, ). Oceanic DMS is mainly derived from the algal and bacterial metabolite of dimethylsulfoniopropionate (DMSP) (Keller, ; Todd et al, ), which is produced by phytoplankton.…”

“…Notably, high concentrations of chromophoric dissolved organic matter (CDOM) could also have a significant influence on the photochemical processes of DMS (Andreae & Crutzen, ). In recent years, much attention regarding the cycle of dimethylated sulfur compounds has focused on the shelf areas in eastern China (Yang et al, ; Zhai et al, ; Zhang et al, ). However, limited information on the biological and photolytic processes of marine DMS is available in the South China Sea (SCS) and most of this research has focused on the central basin of the SCS (Yang et al, ; Zhai et al, ).…”

Distribution and Release of Volatile Organic Sulfur Compounds in Yangcheng Lake

“…The vertical distribution of VOSCs in lakes differed significantly from that in the ocean, where the concentration of VOSCs decreased with depth [38]. Concentrations of DMS in the surface water of Yangcheng Lake were higher than those in the open sea (0.12 µg/L) and comparable to those in the offshore area (0.62 µg/L) [39][40][41].…”

Aerobic oxidation of methane significantly reduces global diffusive methane emissions from shallow marine waters

“…The predicted high MOx rates in near-shore environments suggest that this process could serve as an important biological sink to reduce the global diffusive methane emissions from shallow waters. Furthermore, we also predicted depth profiles of MOx rates in the ECS using this model based on the previous measurements of methane concentrations and other parameters in the ECS 43 (Supplementary Table 3). The predicted depth-integrated MOx rates (22.08 ± 7.92 µmol m −2 d −1 ) were similar to the measured values, verifying the validity of our model.…”