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Journal of Oceanography

, Volume 64, Issue 2, pp 303–310 | Cite as

Dissolved inorganic carbon (DIC) and its carbon isotopic composition in sediment pore waters from the Shenhu area, northern South China Sea

  • Tao Yang
  • Shao-Yong Jiang
  • Jing-Hong Yang
  • Ge Lu
  • Neng-You Wu
  • Jian Liu
  • Dao-Hua Chen
Original Articles

Abstract

The Shenhu area is one of the most favorable places for the occurrence of gas hydrates in the northern continental slope of the South China Sea. Pore water samples were collected in two piston cores (SH-A and SH-B) from this area, and the concentrations of sulfate and dissolved inorganic carbon (DIC) and its carbon isotopic composition were measured. The data revealed large DIC variations and very negative δ 13C-DIC values. Two reaction zones, 0–3 mbsf and below 3 mbsf, are identified in the sediment system. At site SH-A, the upper zone (0–3 mbsf) shows relatively constant sulfate and DIC concentrations and δ 13C-DIC values, possibly due to bioturbation and fluid advection. The lower zone (below 3 mbsf) displays good linear gradients for sulfate and DIC concentrations, and δ 13C-DIC values. At site SH-B, both zones show linear gradients, but the decreasing gradients for δ 13C-DIC and SO4 2− in the lower zone below 3 mbsf are greater than those from the upper zone, 0–3 mbsf. The calculated sulfate-methane interface (SMI) depths of the two cores are 10.0 m and 11.1 m, respectively. The depth profiles of both DIC and δ 13C-DIC showed similar characteristics as those in other gas hydrate locations in the world oceans, such as the Blake Ridge. Overall, our results indicate an anaerobic methane oxidation (AMO) process in the sediments with large methane flux from depth in the studied area, which might be linked to the formation of gas hydrates in this area.

Keywords

Dissolved inorganic carbon (DIC) δ13C-DIC sulfate gradient gas hydrate South China Sea 

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Copyright information

© The Oceanographic Society of Japan/TERRAPUB/Springer 2008

Authors and Affiliations

  • Tao Yang
    • 1
    • 2
  • Shao-Yong Jiang
    • 1
    • 2
  • Jing-Hong Yang
    • 1
    • 2
  • Ge Lu
    • 1
    • 2
  • Neng-You Wu
    • 3
  • Jian Liu
    • 3
  • Dao-Hua Chen
    • 3
  1. 1.State Key Laboratory for Mineral Deposits Research, Department of Earth SciencesNanjing UniversityNanjingChina
  2. 2.Center for Marine Geochemistry ResearchNanjing UniversityNanjingChina
  3. 3.Guangzhou Marine Geological SurveyChina Geological SurveyGuangzhouChina

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