Open AccessShallow seabed methane gas could pose coastal hazard
Author(s) -
Best Angus I.,
Richardson Michael D.,
Boudreau Bernard P.,
Judd Alan G.,
Leifer Ira,
Lyons Anthony P.,
Martens Christopher S.,
Orange Danial L.,
Wheeler Simon J.
Publication year - 2006
Publication title -
eos, transactions american geophysical union
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.316
H-Index - 86
eISSN - 2324-9250
pISSN - 0096-3941
DOI - 10.1029/2006eo220001
Subject(s) - seabed , biogeochemical cycle , seafloor spreading , methane , continental margin , oceanography , geology , sediment , continental shelf , organic matter , environmental science , phytodetritus , estuary , earth science , geomorphology , ecology , benthic zone , paleontology , tectonics , foraminifera , biology
Abnormally high levels of methane gas in seafloor sediments could pose a major hazard to coastal populations within the next 100 years through their impact on climate change and sea level rise. Marine scientists have known for many years that biogenic methane (CH 4 ) is generated in shallow seabed sediments on continental margins, especially in rapidly deposited muddy sediments with high organic matter content (see Methane Flux Control in Ocean Margin Sediments (METROL) project in Mienert et al ., [2004]). Gassy sediments are found in river deltas, estuaries, and harbors, but also in deeper waters on continental shelves and slopes. Human activities can accelerate natural seafloor gas generation by increasing the supply of sediments and organic matter from rivers through deforestation and intensive farming, and also by the disposal of human waste at sea. When this extra organic matter becomes buried to about one meter beneath the seabed, biogeochemical processes start to convert it to CH 4 [ Floodgate and Judd , 1992]. The impact of this extra CH 4 could be felt within the next 100 years, assuming a one‐centimeter‐per‐year sediment accumulation rate.