Worldwide, several coastal environments are characterised by high methane concentration in surface sediments. This is due to high organic carbon contents, caused by burial of fresh plankton material and organic matter derived by rivers and surface run off. Whereas methane is produced by microbial degradation of organic matter at depth, closer to the seafloor microbial consortia life from the breakdown of methane.

METROL, funded by the fifth EU framework program 1998-2002, was exploring methane production and breakdown in the seabed, and how efficiently the sub-surface methane barrier controls the emission of this important greenhouse gas.

The research objectives and activities included microbiological studies, geophysical mapping of gas occurrences, biogeochemical profiling, process measurements, numerical modeling, and data compilation and spatial analysis by application of a Geo-Information-System (GIS).

Geodata indicative for high gas content and specific seafloor features as pockmarks and fault zones at depth were compiled. The data and thematic maps cover sediment depths down to deep tectonic structures and fault zone which might be potential conduits for the transfer of gas to the seafloor. For exploring through the resulting maps please visit our WeGIS on http://gissrv5.awi.de/margis/NorthSea-BalticSea/.