European Directory of Marine Environmental Data (EDMED)

Data set information

| Query EDMED |     

General
Data set name

International Polar Year Gas Hydrates Data Set

Data holding centreBritish Oceanographic Data Centre
CountryUnited Kingdom  United Kingdom
ProjectDynamics of gas hydrates in polar environments(IPY Gas Hydrates)
Time periodOver the course of a two legged cruise between August and September 2008
OngoingNo
Geographical area

Arctic Ocean

Observations 
Parameters

Concentration of alkanes in the atmosphere; Active seismic refraction; Horizontal spatial co-ordinates; Air pressure; Air temperature; Electrical conductivity of the water column; Wind strength and direction; Bathymetry and Elevation; Salinity of the water column; Temperature variation in the water column; Concentration of aliphatic hydrocarbons in sediment samples; Seismic reflection; Side-scan sonar; Solar Radiation; Concentration of alkanes in the water column

Instruments

Discrete air samplers; thermosalinographs; sidescan sonars; single-beam echosounders; multi-beam echosounders; discrete water samplers; 1000 Hz top-bandwidth multi-channel seismic reflection systems; seismometers; hydrophones; unconsolidated sediment corers; GI-gun; gas chromatographs; inductively-coupled plasma mass spectrometers; Differential Global Positioning System receivers; CTD

Description 
Summary

The dataset comprises concentration of gas hydrates beneath the seabed, in the water column and, atmosphere along with the topography of the sea floor. Data were collected in the Arctic Ocean off the NorthWestern coast of Svalbard across the continental margin between 78 and 80 North and 4 and 11 East. The data were collected during cruise JR211 which, over two legs, took place between 23rd August 2008 and 24th September 2008. Geophysical and geological techniques were used to detect methane hydrate beneath the seafloor and to investigate features trough which methane escapes to the seafloor. The seabed was imaged and mapped using a multibeam sonar (Simrad EM120), an echosounder (Simrad EK60), TOBI deep-towed sidescan sonar (30 kHz), widescan sidescan sonar (100 and 350 kHz). The sedimentary layers and geological structures beneath the seabed were imaged with the 7 kHz profiler in TOBI, a TOPAS sub-bottom acoustic profiler and multichannel seismic reflaction (96 channels with 6.25 m group spacing) using two air guns in true GI mode 45/105 cu.in. More accurate information on seismic velocity was obtained by deploying ocean-bottom seismometers on the seabed which contained 3 Sercel L-28 4.5 Hz geophones and a High Tech HTI-90-U hydrophone. Sediment samples were obtained using a piston corer, a gravity corer and, a box corer. Water chemistry was measured from discrete samples taken from bottles attached to the conductivity-temperature-depth (CTD) sensor package and continuously from the ship's seawater supply. Methane concentration was measured on-board using a headspace technique. Air samples were collected at 12 hour intervals. Sampling occurred on the Navigation Bridge deck and the side of the ship upwind of the ships emissions was chosen each time. Additional samples were also collected close to the ship's funnel, to check for contamination, and from the gas released by the cores when in an inert atmosphere (N2). Analysis of methane mixing ratio is performed by Gas Chromatography - Flame Ionisation Detector (GC-FID) and the stable carbon isotopic composition of methane is analysed using a continuous flow Gas Chromatography - Isotope Ratio Mass Spectrometry (GC-IRMS) system. Almost half of the Earth's carbon is stored in gas hydrates and related shallow gas deposits. Numerical models predict that this reservoir is highly mobile and that escaping gas has a significant potential to accelerate climate change releasing as much as 2000 Gt of methane over a short period of time. As methane is a potent greenhouse gas it would course further global warming. Arctic gas hydrates are most vulnerable to future climate change because (1) it is predicted that temperatures will increase faster in the Arctic than in low latitudes (2) the intercept of the gas hydrate stability zone with the seabed is within the reach of fast warming surface waters and (3) the water column above the vulnerable zone of gas hydrates is smaller than in warmer oceans facilitating more efficient transport of greenhouse gases to the atmosphere. This information will allow a detailed assessment of the mobility of Arctic gas hydrates and it will significantly decrease the uncertainties involved in climate modelling. The data were collected by the National Oceanographic Centre, Southampton with Professor Tim Minshull as the principal scientist on-board.

OriginatorsNational Oceanography Centre, Southampton
Availability 
OrganisationBritish Oceanographic Data Centre
AvailabilityLicence; academic
ContactPolly Hadžiabdić (Head of the BODC Requests Team)
Address

British Oceanographic Data Centre
Joseph Proudman Building 6 Brownlow Street
Liverpool
Merseyside
L3 5DA
United Kingdom

Emailenquires@bodc.ac.uk
Administration 
Collating centreBritish Oceanographic Data Centre
Local identifier1048IPY_GAS_HYDRATES
Global identifier4286
Last revised2011-01-25