Brewer Expedition Cruise dates: August 10th, 2006 to August 19th, 2006

Cruise location: Barkley Canyon

Chief scientist: Peter Brewer,

MBARI Ship: R/V Western Flyer

Vehicle: ROV Tiburon

Purpose and Plan:

This ten day cruise to Barkley Canyon has two major objectives: 1) Use the laser Raman spectrometer DORISS to study exposed methane clathrate hydrates on the seafloor at in situ conditions during the day 2) Use the MBARI AUV to map both the canyon region in support of the ROV science and inspect underwater cables with Neptune Canada at night More specifically, the Brewer lab group will be -looking at undisturbed hydrate specimens in situ along the ridge -observing hydrate cores at depth, both fresh and after exposure to naturally flowing seawater -studying hydrate stability and dissolution during recovery and transit through the water column -monitoring the reaction between natural hydrates and liquid carbon dioxide It will be employing a variety of newly-created equipment: -DORISS II -a miniaturized, compacted, and lighter second-generation model based on the DORISS I -is more robust and serviceable and encased single titanium pressure housing -features pressure-compensated oil-filled tubing to protect fiber optics at great depths Other equipment that will be used on this voyage:

-Heated funnel and gas sampler for collection of escaped hydrate gases
-Immersion optic with 1 L gas box and heater for gas composition analyses
-Hydrate push core sampler
-Pyrex chamber for Raman testing of contained hydrates through the glass
-Observation chamber on tripod for hydrate dissolution measurements
-DGH Can containing 3 temperature and 2 pH probes
-2 L CO2 delivery system for hydrate dissolution experiments in liquid CO2
-Heat flow probe with insertion hydraulics
-Clathrate bucket for preserving pressurized hydrate samples

Cruise History and Background:

After over a dozen successful cruises with the DORISS I (Deep Ocean Raman In Situ Spectrometer), a second generation version of the system has been developed over the past year to further facilitate the study of marine chemistry in oceanic conditions. The original DORISS system was the first spectrometer of any kind to examine the chemistry of deep-sea vents, hydrates in their natural environment, and trace chemicals at low concentrations in the deep sea. The apparatus is designed to withstand pressures of up to 40 MPa at depths of 4000 meters and temperature changes between 20oC and 2oC within an hour of diving to the sea floor. With a particular interest in underwater methane hydrates as both an energy source as well as a potential storage system for sequestered carbon dioxide, the lab group is traveling to the recently discovered Barkley Canyon hydrate ridges. The outcrops were accidentally discovered by fishing trawlers just over three years ago, and appear to comprise a highly-accessible research site (only 800 meters in depth) easily within the practical reach of the Western Flyer. The Brewer Lab Group has been highly successful in using Raman spectroscopy to analyze the structure and composition of undersea hydrates. The transparent nature of the material combined with the strong Raman scattering properties of ethane and methane have permitted detailed analyses of gas compositions and hydrate cage structures.

Science Personnel Onboard:

Brewer Lab Group: Peter Brewer – Chief Scientist, MBARI Bill Kirkwood – Chief Project Engineer, MBARI Edward Peltzer – Project Manager, MBARI Peter Walz – Senior Project Technician, MBARI Rachel Dunk – former post-doc, York University Keith Hester – future post-doc, Colorado School of Mines Jonathan Scholl – summer intern, Princeton University Dendy Sloan – guest scientist/hydrate expert, Colorado School of Mines

AUV Group: Dave Caress – AUV Mapping P.I., MBARI Hans Thomas – AUV Operations Leader, MBARI Adien Aggenbach – Neptune Canada Representative