Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Leakage on the continental margin

27.03.2017

Gas seepage off Norwegian coast spans hundreds of kilometers

Off the coast of Spitsbergen, on the upper continental margin between Bear Island and Kongsfjord, methane gas is emitted from the seafloor at more than a thousand sites. Past expeditions have reported methane gas seeps off the coast of Prins Karls Forland, presumed by some scientists to be a result of the dissociation of methane hydrates in the sediments caused by warming in recent years.


The Research Vessel HEINCKE at the pier at Ny-Ålesund.

Photo: G. Bohrman/MARUM-Center for Marine Environmental Sciences, University of Bremen


Team members sample water for methane analysis.

Photo: G. Bohrman/MARUM-Center for Marine Environmental Sciences, University of Bremen

The results of two cruises of the Research Vessel HEINCKE in 2015 have revealed, however, that methane emissions are not limited to this site, but extend across five degrees of latitude along the continental margin, and is very likely associated with the Hornsund Fracture Zone. Susan Mau has now published the results together with her colleagues at MARUM – Center for Marine Environmental Sciences at the University of Bremen, and others from the Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung in Bremerhaven and Oregon State University (USA).

The investigations of Susan Mau and her colleagues are based on data from two research cruises in the summer of 2015. The gas discharge sites were identified hydroacoustically as patterns called “flares.” “We already knew about the gas seeps off Prins Karls Forland because that site has been thoroughly studied,” explains Dr. Mau.

Their data, however, reveal the presence of numerous emission sites along the entire coast. The sites follow a fracture zone on the upper continental margin that could be the conduit for the methane rising from depths along this zone. Like air from a perforated bicycle inner tube submerged in water, the rising gas can escape along the fractures and ascend through the sea water. According to Mau, the scientists measured consistently high methane concentrations along the entire slope off the coast of Svalbard. “But they were especially high at the sites where multiple flares were seen.”

In addition, the gas seepage conspicuously occurred at bathymetrically elevated areas rather than in the troughs between them. Susan Mau presumes the reason for this is fine-grained deposits sealing the pathways that gas could otherwise escape from.

Why have so many emission sites been discovered off Prins Karls Forland? Are there even more sites off the coast of Svalbard? These were the initial questions to be addressed by the cruises led by Susan Mau and Gerhard Bohrmann. Furthermore, rock samples and seismic studies have shown that the entire coast is characterized by similar tectonic conditions and glacial history. The gas seeps verified off the coast of Svalbard are interesting primarily because scientists have thought that the methane escaping here is released from methane hydrates. Methane hydrates have a solid ice-like structure that is only stable under specific pressure conditions at rather well defined depths and relatively low temperatures. When the water becomes warmer methane hydrate is no longer stable and methane is released.

Should the water warm up – due to climate change, for example – methane hydrates can only occur in deeper sediments. The boundary zone in which gas hydrates become stable is effectively shifted downward. The gas bubble emissions observed by Mau and her colleagues, however, also occur above this boundary, and thus are not anthropogenically triggered gas released from methane hydrates.

These methane seepage sites are the result, rather, of large amounts of gas from great depths escaping along the Hornsund Fracture Zone, an extensive fault zone in the Earth’s crust, a natural geologic process. This produces high gas concentrations that the team has confirmed over a range of hundreds of kilometers along the coast. The data from the summer of 2015 also indicate that the dissolved methane is oxidized by microbes within the water column and only a small proportion escapes into the atmosphere. The microbes thus prevent an increase in greenhouse gas concentrations in the atmosphere.

From their current results, numerous new questions arise for the geologists Susan Mau and Gerhard Bohrmann: What is the precise course of the actual fracture zone? What is the character of the substratum? Where are the gas reservoirs located? And: What is the age of the escaping gas? In any case, a connection between the large number of gas seeps and human-produced warming of the oceans has not been confirmed.

Because the expeditions off the coast by Mau and her colleagues were carried out in the summer, it is not certain what happens during other colder and stormier seasons. “Our results cry out for long-term studies of the seeps,” Mau emphasizes. “We have to strive to learn the reason for high methane gas concentrations that have occurred repeatedly throughout the Earth’s history. The goal is to observe the seepage sites to find out what happens over the course of the year. Only then will it be possible to draw accurate conclusions – including, for example, whether gas emissions at these depths and at this temperate zone are climate relevant.”

Contact:
Dr. Susan Mau
Telephone: +49 (0) 421-21865059
Email: smau@marum.de

Original publication:
Susan Mau, Miriam Römer, Martha E. Torres, Ingeburg Bussmann, Thomas Pape, Ellen Damm, Patrizia Geprägs, Paul Wintersteller, Chieh-Wei Hsu, Markus Loher und Gerhard Bohrmann: Widespread methane seepage along the continental margin off Svalbard - from Bjørnøya to Kongsfjorden. Sci. Rep. 7, 42997; doi: 10.1038/srep42997 (2017)

Further information / Photo material:
Ulrike Prange
MARUM-Öffentlichkeitsarbeit
Telephone: 0421 218 65540
Email: medien@marum.de

Weitere Informationen:

http://www.marum.de/en/Leakage_on_the_continental_margin.page

Ulrike Prange | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care

nachricht Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>