Marine Biogeochemistry

3-D online Display of the L3 ELAC Nautik WCI-Viewer. The light colours represent a higher acoustic intensity, the straight line marks the seafloor-

SUGAR Subproject A1 Objectives

The generation of gas hydrates requires the presence of free gas. Consequently, the presence of rising gas bubbles from the seafloor or gas flares in the water column is a strong indicator for the presence of gas hydrates in the subsurface. Gas bubbles in the water column can best be detected by hydro-acoustic methods.

Very efficient tools for that purpose are multibeam echosounder. Traditionally these systems were optimized for the precise detection of the seafloor which means that signals from the water column are suppressed or disregarded.

The aim of subproject A1 is to develop data processing methods and enhanced visualisation techniques to allow for a better and faster detection and localisation of gas flares in the water column using portable multibeam systems. The newest generation of echosounder of L-3 communications ELAC-Nautik GmbH allow for a precise determination of seafloor topography as well as for a complete recording of signals from the water column.

To enable these systems for a systematic and routine prospection of gas flares, however, the following objectives have to be achieved:

  • Development of suitable algorithms to automatically select interesting parts in the data stream in space and / or time for a reasonable data reduction
  • Development of algorithms and techniques to allow for a real-time detection of reflections from gas bubbles
  • Development of algorithms for the discrimination between echoes from gas bubbles and other objects in the water column, such as fish swarms, plankton, or abrupt changes of the physical properties of the water
  • Investigation of the geological environment of vent sites
  • Transfer of the new methods to portable multibeam systems which enable a flexible use of ships of opportunity

The objectives of subproject A1 will allow for a substantially better detection and analysis of gas bubbles in the water column and thus enable an efficient exploration on gas hydrate deposits. Furthermore, these methods can also serve as a leakage-monitor-system during a prospective CO2-deposition in the sediments, as they are sensitive not just to gas bubbles but also to small droplets of fluid CO2 in the water column.

Literature

Author

Title

Year

Journal/Proceedings

Reftype

DOI/URL

Artemov, Y.G.

Acoustic observations of gas bubble streams in the NW Black Sea as a method for estimation of gas flux from vent sites

2003


Vol. 5(09421)Geophysical Research Abstracts 

conference

URL 

Best, A.I., Richardson, M.D., Boudreau, B.P., Judd, A.G., Leifer, I., Lyons, A.P., Martens, C.S., Orange, D.L. & Wheeler, S.J.

Shallow Seabed Methane Gas Could Pose Coastal Hazard

2006

EOS, TRANSACTIONS AMERICAN GEOPHYSICAL UNION
Vol. 87(22) 

article

DOI  

Brewer, P.G., Chen, B., Warzinki, R., Baggeroer, A., Peltzer, E.T., Dunk, R.M. & Walz, P.

Three-dimensional acoustic monitoring and modeling of a deep-sea CO2 droplet cloud

2006

Geophysical Research Letters
Vol. 33(L23607) 

article

DOI  

Clarke, J.E.H.

Applications of Multibeam Water Column Imaging for Hydrographic Survey

2006

The Hydrographic Journal
Vol. 120, pp. 3-15 

article

URL 

von Deimling, J.S., Brockhoff, J. & Greinert, J.

Flare imaging with multibeam systems: Data processing for bubble detection at seeps

2007

Geochemistry Geophysics Geosystems
Vol. 8, pp. 7 

article

DOI  

Greinert, J., Artemov, Y., Egorov, V., De Batist, M. & McGinnis, D.

1300-m-high rising bubbles from mud volcanoes at 2080m in the Black Sea: Hydroacoustic characteristics and temporal variability

2006

Earth and Planetary Science Letters
Vol. 244(1-2), pp. 1-15 

article

DOI  

Greinert, J. & Nutzel, B.

Hydroacoustic experiments to establish a method for the determination of methane bubble fluxes at cold seeps

2004

Geo-Marine Letters
Vol. 24(2), pp. 75-85 

article

DOI  

Haeckel, M., Suess, E., Wallmann, K. & Rickert, D.

Rising methane gas bubbles form massive hydrate layers at the seafloor

2004

Geochimica Et Cosmochimica Acta
Vol. 68(21), pp. 4335-4345 

article

DOI  

Klaucke, I., Sahling, H., Weinrebe, W., Blinova, V., Burk, D., Lursmanashvili, N. & Bohrmann, G.

Acoustic investigation of cold seeps offshore Georgia, eastern Black Sea

2006

Marine Geology
Vol. 231(1-4), pp. 51-67 

article

DOI  

Klaucke, I., Weinrebe, W., Sahling, H., Bohrmann, G. & Bürk, D.

Mapping deep-water gas emissions with sidescan sonar

2005

EOS, TRANSACTIONS AMERICAN GEOPHYSICAL UNION
Vol. 86(83) 

article

DOI  

Milkov, A.V.

Global estimates of hydrate-bound gas in marine sediments: how much is really out there?

2004

Earth-Science Reviews
Vol. 66(3-4), pp. 183-197 

article

DOI  

Pfannkuche, O.

Methane cycle at shallow gaseous sediments in the central North Sea

2005

 

techreport

 

Rehder, G., Brewer, P.W., Peltzer, E.T. & Friederich, G.

Enhanced lifetime of methane bubble streams within the deep ocean

2002

Geophysical Research Letters
Vol. 29(15) 

article

DOI  

Weber, T., Bradley, D., Culver, R.L. & Lyons, A.

Inferring the vertical turbulent diffusion coefficient from backscatter measurements with a multibeam sonar

2003

The Journal of the Acoustical Society of America
Vol. 114(4), pp. 2300-2300 

article

URL 

Koordination

Project leader A1

Dr. rer. nat. Wilhelm Weinrebe
Forschungsbereich 4: Dynamik des Ozeanbodens
FE Geodynamik
SFB 574
Office:

Room: 8/D-209
Phone: +49 431 600-2281
Fax: +49 431 600-2922
E-Mail: wweinrebe(at)geomar.de
Address:

Wischhofstrasse 1-3

L-3 Communications ELAC-Nautik GmbH
www.elac-nautik.de

Dr. Peter Gimpel
peter.gimpel(at)l-3com.com

Dr. Christian Zwanzig
Christian.zwanzig(at)l-3com.com

http://www.elac-nautik.de/