In situ observations of methane dynamics in an active cold seep of the Formosa Ridge, the South China Sea

Lei Cao; Chao Lian; Xiangbin Ran; Huan Zhang; Hao Wang; Li Zhou; Hao Chen; Zhaoshan Zhong; Minxiao Wang; Chaolun Li

doi:10.59717/j.xinn-geo.2026.100192

The Innovation Geoscience > 2026 Vol. 4 > No. 1 > 100192

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In situ observations of methane dynamics in an active cold seep of the Formosa Ridge, the South China Sea

1.
Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
2.
Marine Ecology Research Center, First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China
3.
Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
4.
Laoshan Laboratory, Qingdao 266237, China
5.
South China Sea Institute of Oceanology, Chinese Academy of Science, Guangzhou 510320, China
6.
University of Chinese Academy of Sciences, Beijing 101408, China

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Corresponding authors: wmx@qdio.ac.cn (M.W.); lcl@qdio.ac.cn (C.L.)
Received Date: April 16, 2025

Accepted Date: December 23, 2025

Published Online: January 01, 2026

The Innovation Geoscience 4(1), https://doi.org/10.59717/j.xinn-geo.2026.100192 | Cite this article

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GRAPHICAL ABSTRACT

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PUBLIC SUMMARY

PUBLIC SUMMARY
1. Methane released by cold seep profoundly affects the marine environment and contributes to climate change.
  
  In situ observations coupled with steady-state model are employed to quantify methane fluxes from cold seep.
  
  Horizontal advection is the primary migration mechanism for released methane in the active cold seep.
  
  The contribution of methane from deep sea cold seeps to the global methane budget have been underestimated.

ABSTRACT

ABSTRACT

Methane eruptions from active cold seeps profoundly impacts the marine environment and contributes to climate change. However, in situ measurements available to constrain the efflux of methane from active seeps are scarce. In this study, in situ observations coupled with steady-state model were initially used to evaluate the flux and fate of methane released into the hydrosphere at the cold seep site F. Findings from three years of data indicated that horizontal advection is the primary migration and removal mechanism for released methane, followed by vertical diffusion and microbial oxidation. Methane flux in the active seepage (0.53-3.23 mol m^-2 d^-1) estimated by the in-situ approach was several orders of magnitude greater than that from the sediment-water interface. This would result in 0.70 - 4.22 Gmol yr^-1 methane being released into the South China Sea (SCS) continental margins. Methane flux estimated based on the in situ observation here was significantly higher than that in the previously studied seeps. The regional methane fluxes from cold seeps in the SCS further suggest that dissolved methane discharge substantially contributes to the oceanic methane budget. Extrapolating the methane flux to active seeps worldwide would result in approximately 126 Tg C emitted into the hydrosphere annually as dissolved methane, indicating that the contribution of methane from deep-sea cold seeps to the global methane budget might have been underestimated. Our study emphasizes the deep-sea cold seeps as a significant methane source to the ocean and provides valuable insights into the quantitative assessment of the oceanic methane budget.
- Cold seep /
- Overlying water /
- In situ observation /
- Dissolved methane /
- Methane flux

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Cao L., Lian C., Ran X., et al. (2026). In situ observations of methane dynamics in an active cold seep of the Formosa Ridge, the South China Sea. The Innovation Geoscience 4:100192. https://doi.org/10.59717/j.xinn-geo.2026.100192

Cao L., Lian C., Ran X., et al. (2026). In situ observations of methane dynamics in an active cold seep of the Formosa Ridge, the South China Sea. The Innovation Geoscience 4:100192. https://doi.org/10.59717/j.xinn-geo.2026.100192

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In situ observations of methane dynamics in an active cold seep of the Formosa Ridge, the South China Sea

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In situ observations of methane dynamics in an active cold seep of the Formosa Ridge, the South China Sea

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