Accession Number:

ADA464004

Title:

Shallow Seabed Methane Gas Could Pose Coastal Hazard

Descriptive Note:

Journal article

Corporate Author:

NAVAL RESEARCH LAB STENNIS SPACE CENTER MS SEAFLOOR SCIENCES DIRECTORATE

Report Date:

2006-05-30

Pagination or Media Count:

3.0

Abstract:

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 CH4 is generated in shallow seabed sediments on continental margins, especially in rapidly deposited muddy sediments with high organic matter content. Grassy sediments are found in river deltas, estuaries, and harbors, but also in deeper waters on continental shelves and slopes. Human activities can accelerate natural sea-floor 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 CH4. The impact of this extra CH4 could be felt within the next 100 years, assuming a one-centimeter-per-year sediment accumulation.

Subject Categories:

  • Atmospheric Physics
  • Organic Chemistry
  • Physical and Dynamic Oceanography
  • Geology, Geochemistry and Mineralogy
  • Solid Wastes and Pollution and Control

Distribution Statement:

APPROVED FOR PUBLIC RELEASE