The National Methane Hydrates R&D Program
MITAS 2009 Beaufort Sea Expedition
The project included the deployment of three different coring systems: multi-coring,
vibrocoring and piston coring. For vibro and piston core recovery, 15 out of 17 cores attempted were retrieved. Methane gas was observed in three of the cores based on visual observations and shipboard geochemical analyses. Post cruise sample analysis will focus on geochemical and microbiological parameters. Multicores were taken through the survey and will be analyzed in the laboratory.
Water column measurements were obtained from 34 locations coordinated with coring and acoustic geophysical surveys. These water column analyses confirmed elevated levels of methane in the water column and ongoing post-cruise isotope and geochemical studies will help constrain the source of the methane, subsurface, microbial, etc.
3.5 khz geophysical surveys were collected over several 100 km of transects that directly correspond to the coring and water column operations, in addition to broader surveys adjacent to the coring and water column points.
Using the multi-sensor core logging system, physical properties of the core (such as magnetic susceptibility and electrical resistivity) were collected during shipboard operations prior to splitting the core for further analysis. By splitting the core into two equal halves, visual core descriptions and geochemical pore water sub-sampling could occur simultaneously on the archive half, while sub-sampling for post-cruise microbiologic, geochemical, and sediment analyses occurred on the working half
Geochemical analyses of the sediment pore water for sulfate, methane dissolved inorganic carbon, sulfide and chloride profiles were conducted onboard as part of the core processing. Other shipboard processing included study of biogenic components and authigenic precipitates due to their potential relationship to methane flux in these systems. Further analysis of these items will occur post cruise. In addition to the visual descriptions of the cores, NETLs Methane Hydrate Field Studies Lab conducted preliminary sedimentological analyses including petrographic examination of smear slides and coarse fractions, and XRD/XRF measurements.
This expedition was supported by NRL, Office of Naval Research, DOE, NIOZ, IFM-Geomar, for ship time and science costs. The project is intended to initiate long term collaboration in future expeditions in the Beaufort Sea and other regions of the Arctic Ocean. The “Developing Long Term International Collaboration on Methane Hydrate Research and Monitoring in the Arctic Region” workshop, organized by J. Greinert, R. Coffin, I. Pecher, T. Treude and N. Langhorne, 18-20 February, 2009, has initiated conversations for international collaborative research off the coasts of Russia and Norway. Scientist from NRL, DOE-NETL, NIOZ Netherland, Herriot-Watt University Scotland, IFM-Geomar Netherlands, University of Bergen Norway and GNS New Zealand will participate in future expeditions.