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Southampton Marine and Maritime Institute

New tool for measuring frozen gas in ocean floor sediments

Published: 27 February 2013Origin: Engineering

Collaboration between the University of Southampton and National Oceanography Centre (NOC) is to develop an instrument capable of measuring seafloor methane gas, which if released, could contribute to climate change.

Gas Hydrate

Professors Tim Leighton and Paul White from the University of Southampton’s Institute of Sound and Vibration Research (ISVR) and Dr Angus Best of NOC, have been awarded a grant of £800,000 by the Natural Environment Research Council (NERC) to investigate methods for assessing the volume of methane gas and gas hydrate locked in seafloor sediments.

Dr Best explains: “Greenhouse gases, such as methane and carbon dioxide, are trapped in sediments beneath the seafloor on continental shelves and slopes around the world. Currently, there are only very broad estimates of the amount of seafloor methane and hydrate.”

The team plan a series of experiments on a range of sediment types, such as sand and mud. They intend to map out the acoustic and electrical properties of differing amounts of free methane gas and frozen solid methane hydrate.

The laboratory-based approach adopted by the team will involve the development of a major new Acoustic Pulse Tube instrument at NOC, capable of simulating the high pressures and low temperatures needed to create hydrate in sediment samples. Using acoustic techniques and theories developed by the ISVR team, they aim to provide improved geophysical remote sensing capabilities for better quantification of seafloor gas and hydrate deposits in the ocean floor.

Professor Leighton says: “Not much is known about the state of gas morphology – bubbles. Muddy sediments show crack-like bubbles, while sandy sediments show spherical bubbles. Only dedicated lab experiments can hope to unravel the complex interactions. By creating our own ‘cores’ of sediment material in a controlled environment where we know the concentrations of methane or carbon dioxide, we can create models to help us with in situ measurements on the seafloor.”

There is significant interest in sub-seafloor carbon-dioxide storage sites. Methane hydrates are a potential energy resource that could be exploited in future. They may contribute to geo-hazards such as seafloor landslides. It is thought that earthquakes and the release of gas hydrates caused the largest-ever landslide, the Storegga Slide, around 8,000 years ago.

Professor Leighton adds: “The three of us have collaborated in recent years in an experiment that used acoustics to take preliminary measurements of gas in the muddy sediments revealed at low tide. Those measurements, and the acoustic theory we developed to interpret the data, provided exactly the foundation we needed to undertake this critically important study that will be relevant to the seabed in somewhat deeper waters.
“As a greenhouse gas, methane is 20 times more potent per molecule than carbon dioxide. There is the potential for climate change to alter sea temperatures and cause more methane gas to be released from seabed hydrates into bubbles which reach the atmosphere. It is therefore vital that we have the tools to quantify and map the amount of methane that is down there.”

Related Staff Member

Related Staff Member

Notes for editors

 

  1. The photo shows a lump of gas hydrate extracted from the seabed. Courtesy of the National Oceanography Centre, Southampton.
  2. In 2012 NOC’s Dr Veit Huehnerbach from the DST-Marine Geosciences Group was involved in an expedition to recover a long-term seabed observatory called MAOX on the Arctic seafloor. MAOX (Motiroting Arctic Seafloor – Ocean Exchange) monitored methane flares off the west coast of Svalbard for two years between 2010 and 2012.
  3. The National Oceanography Centre (NOC) is the UK’s leading institution for integrated coastal and deep ocean research. NOC operates the Royal Research Ships James Cook and Discovery and develops technology for coastal and deep ocean research. Working with its partners NOC provides long-term marine science capability including: sustained ocean observing, mapping and surveying, data management and scientific advice.
    NOC operates at two sites, Southampton and Liverpool, with the headquarters based in Southampton.
    Among the resources that NOC provides on behalf of the UK are the British Oceanographic Data Centre (BODC), the Marine Autonomous and Robotic Systems (MARS) facility, the National Tide and Sea Level Facility (NTSLF), the Permanent Service for Mean Sea Level (PSMSL) and British Ocean Sediment Core Research Facility (BOSCORF).
    The National Oceanography Centre is wholly owned by the Natural Environment Research Council (NERC).
  4. The University of Southampton is a leading UK teaching and research institution with a global reputation for leading-edge research and scholarship across a wide range of subjects in engineering, science, social sciences, health and humanities.


With over 23,000 students, around 5,000 staff, and an annual turnover well in excess of £435 million, the University of Southampton is acknowledged as one of the country's top institutions for engineering, computer science and medicine. We combine academic excellence with an innovative and entrepreneurial approach to research, supporting a culture that engages and challenges students and staff in their pursuit of learning.

The University is also home to a number of world-leading research centres, including the National Oceanography Centre, Southampton, the Institute of Sound and Vibration Research, the Optoelectronics Research Centre, the Centre for the Developmental Origins of Health and Disease, the Mountbatten Centre for International Studies and the Southampton Statistical Sciences Research Institute

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Glenn Harris, Media Relations, University of Southampton, Tel: 023 8059 3212, email: G.Harris@soton.ac.uk

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