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ShareWASHINGTON: A team of scientists organised and led a team of university and government researchers on an Arctic expedition to initiate methane hydrate exploration in the Beaufort Sea and determine the spatial variation of sediment contribution to Arctic climate change.
The team was from the Marine Biogeochemistry and Geology and Geophysics sections of the Naval Research Laboratory (NRL).
Utilising the US Coast Guard Cutter Polar Sea as a research platform, three cross-shelf transects were surveyed and sampled off Alaska's North Slope at Hammerhead, Thetis Island and Halkett representing three regions of the Alaskan shelf.
The expedition integrated expertise in coastal geophysics, sediment geochemistry, dissolved and free methane fluxes through the water column and into the atmosphere, sediment and water column microbiology and biogeochemistry and detailed characterisation of the sub-sea floor geology.
"The objective of the sampling is to help determine variations in the shallow sediment and water column methane sources, methane cycling and the subsequent flux to the atmosphere," said Richard Coffin, chief scientist, NRL Chemistry Division.
The content, location and distribution of methane in hydrate is variable and controlled by geothermal gradients and biological and thermal methane production.
Large deposits of methane hydrates, frozen mixtures of hydrocarbon gas (mostly methane) and water, occur over large areas of the ocean floor.
International research has begun with a primary goal of obtaining the methane in these hydrates as an energy source.
During the 12-day expedition, Methane In The Arctic Shelf and Slope (MITAS-1), the crew conducted 34 conductivity-temperature-depth (CTD) water column casts using a rosette of Niskin bottles and collected sediment samples from 14 piston cores, three vibrocores and 20 multicores.
Regions selected for this study were based on the review of Minerals Management Service and US Geologic Survey (USGS) seismic data with specific sample locations decided onboard through review of the 3.5 Kilohertz (kHz) sub-bottom profiler data.
The MITAS-1 crew focussed on goals like, to acquire and integrate seismic, acoustic, temperature, geochemical, and lithostratigraphic data for evaluation of deep sediment hydrate distributions.
The team aimed to determine and model the transport of methane from the sediment through the water column into the atmosphere.
It also aimed to study the control of total methane emissions by microbial methane consumption in the sediment and in the water column.
