Geophysical Research Letters

Shallow gas accumulation in a small estuary and its implications: A case history from in and around Xiamen Bay

Authors

  • Yi Hu,

    Corresponding author
    1. College of Geosciences, Chinese Ocean University, Qingdao, China
    2. Coast and Ocean Environmental Geology Open Laboratory, Third Institute of Oceanography, State Oceanic Administration, Xiamen, China
    • Corresponding author: Y. Hu, Coast and Ocean Environmental Geology Open Laboratory, Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China. (huyiocean@gmail.com)

    Search for more papers by this author
  • Haidong Li,

    1. Coast and Ocean Environmental Geology Open Laboratory, Third Institute of Oceanography, State Oceanic Administration, Xiamen, China
    Search for more papers by this author
  • Jiang Xu

    1. Coast and Ocean Environmental Geology Open Laboratory, Third Institute of Oceanography, State Oceanic Administration, Xiamen, China
    Search for more papers by this author

Abstract

[1] Various forms of shallow gas have been observed in seafloor strata, on the seabed and in the water column during acoustic profiling investigations in 2007–2009 in Xiamen Bay and adjacent areas. Acoustically transparent zones, acoustic turbidity and gas seepage can be seen in seabed strata, pockmarks and accumulation bodies have been found on the seafloor, and hummocky features and mushroom shaped gas signatures can be identified in the water column. This evidence shows that shallow gas is widely distributed in and around Xiamen Bay, due to degradation of the organic matter transported by the Jiulong River. The area covered by such features is roughly estimated at 150 km2, and methane flux is estimated to be 150 × 106 m3 assuming the thickness of gas bearing formations to be 1 m. This study shows that even small rivers flowing out onto a continent shelf contribute to recognizable methane flux and are linked to identifiable gas reservoirs in the shallow seabed. More detailed studies are required to understand the role of such systems as a component of the global carbon cycle.

Ancillary