Monterey Bay Aquarium Research Institute

 


Deep-sea chemistry
Day 8: Pilots rise to the challenge
August 17, 2011

Location: “Mount Saint Helens” seafloor site
Latitude: 48º 18.608 N
Longitude: 126º 3.8949 W

Today was the final dive for this leg of the Western Flyer Northern Expedition. To make our scheduled Thursday afternoon arrival time in Newport, Oregon, we were limited to a short dive day today, so we started our dive back at the Barkley Canyon site with two objectives—follow the free release of an oil droplet from the seafloor up through the water column, and collect another oil sample using the heated funnel.

Chief Scientist Peter Brewer set the bar high today when he requested the pilots fly a 4,500 kg (10,000 lbs) vehicle upwards while imaging a tiny diameter blob of oil wiggling in free ascent in the ocean with millimeter precision. This request was not as crazy as it sounds, for this team had done it before. The object was to describe how oil and gas plumes rise from the seafloor towards the surface.

The Barkley Canyon area has a rich natural reservoir of oil and hydrocarbons in addition to methane gas. These elements, along with the cold temperature and high pressure of the deep ocean, make for such interesting geochemical features on the seafloor. Past ROV dives at this site have measured the solid hydrate with Raman spectroscopy and collected gas and rock samples for laboratory analysis. Until now, nobody had attempted to follow a freely rising oil droplet and observe its behavior as it ascended to the surface through decreasing pressure and increasing temperature. To pull off this type of experiment, Peter Brewer's team designed what they call a “bubble box,” which gives the pilots a visual frame of reference so they can follow individual droplets of oil (or gas). The box is also equipped with several lights behind an opaque white panel to provide backlighting, which makes it easier to see the droplets or bubbles.

After a few trials with the ROV manipulator arm, the pilots and science team came up with a procedure to gently poke the mud near the hydrate mounds and stimulate a regular plume of oil droplets. The bubble box was then positioned directly over the rising droplets to allow several of them to enter the open bottom of the box. Once in the field of view, the pilots would skillfully match the vehicle’s rise rate to the rise rate of the oil droplet, keeping the droplet within the box. We successfully followed several oil drops over a vertical distance of several hundred meters. The final “chase” was only terminated by the upper operating limit of the ROV at 200 meters.

Chief Pilot Knute Brekke helps launch the remotely operated vehicle Doc Ricketts with the bubble box mounted on the side. Several measuring tapes are mounted in and on the bubble box to help determine the size of the oil droplets followed.
Close-up of a single droplet of oil inside the bubble box as it rises toward the surface. The measurements are in centimeters.

Our final operation of the day was another oil sample collection using the heated funnel. As with the bubble box, we gently agitated the seafloor sediment using a poker stick in the ROV’s robotic arm. However instead of following the oil drops and imaging them with the camera, we simply positioned the heated funnel over the oil plume and subsequently collected the oil into stainless steel sample cylinders.

A poker held in the robotic arm on the right is used to stir up the sediment to release some oil. As it bubbles up, the droplets are caught in the funnel, which is held in the left robotic arm. The methane hydrate outcrop in the background is stained yellow, which is a sign that oil is present.
Summer intern Liz Coward sits in the chief scientist’s chair where she directed the collection of oil samples. The mission chief scientist, Peter Brewer, gives Liz some pointers on operating the main camera, while ROV pilot Eric Martin, in the background, flies the remotely operated vehicle.

Our science mission successfully completed, we turned our attention to a bit of fun for our favorite local watering hole in Newport: The Rogue Brewery. The ROV pilots had included on our ROV tray of tools an empty glass bottle of the most recent ale release, Chatoe Rogue. The stunning exposed hydrate outcrops of Barkley Canyon provided an amazing backdrop to a few unique images, which we hope to provide to the Rogue Brewery as a professional courtesy.

The remotely operated vehicle pilots arranged this photo as a gift to the local Rogue Brewery, which is right by the dock where the Western Flyer ties up on port stops during this expedition. As a Brewer himself, our chief scientist was happy to make this quick stop in honor of the producers of this fine local ale.
Our collaborating scientists Laura Lapham and Michael Riedel process sediment samples collected from the seafloor during several of our remotely operated vehicle dives.

— Peter Walz



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Leg 1
 Equipment

R/V Western Flyer

The R/V Western Flyer is a small water-plane area twin hull (SWATH) oceanographic research vessel measuring 35.6 meters long and 16.2 meters wide. It was designed and constructed for MBARI to serve as the support vessel for ROV operations. Her missions include the Monterey Bay as well as extended cruises to Hawaii, Gulf of California and the Pacific Northwest.

ROV Doc Ricketts

ROV Doc Ricketts is MBARI's next generation ROV. The system breaks new ground in providing an integrated unmanned submersible research platform, with many powerful features providing efficient, reliable and precise sampling and data collection in a wide range of missions.

Laser Raman spectrometer DORISS2

By bouncing a specially tuned laser beam off of almost any object or substance—solid, liquid, or gas—a laser Raman spectrometer can provide information about that object's chemical composition and molecular structure.

Push cores

A push-core looks like a clear plastic tube with a rubber handle on one end. Just as its name implies, the push core is pushed down into loose sediment using the ROV's manipulator arm. As the sediment fills up the core, water exits out the top through one-way valves. When the core is pulled up again, these valves close, which (most of the time) keeps the sediment from sliding out of the core tube. When we bring these cores back to the surface, we typically look for living animals and organic material in the sediments.

Vibracores

Vibracoring is a common technique used to obtain samples from water-saturated sediment. These corers work by attaching a motor that induces high frequency vibrations in the core liner that in turn liquefies the sediment directly around the core cutter, enabling it to pass through the sediment with little resistance.

CO2 accumulator

Carbon dioxide is a liquid at the temperatures and pressures on the seafloor where hydrates are known to occur. Because of this, one cannot simply take down a tank of gas and expect to be able to release it at depth. Instead, the CO2 piston accumulator is used to deliver precise volumes of liquid CO,2 to experiments on the seafloor. The valves are operated hydraulically by remote control and hydraulic pressure is used to expel the liquid CO2 and deliver it to the experiments.

Heat-flow probe

MBARI's heat-flow probe is mounted on the side of the ROV Doc Ricketts inside the vertical stainless steel box. This both protects the delicate probe and provide the track so that the probe can be inserted into the sediment along a totally straight path.  The probe contains five high precision platinum sensors which are used to measure the vertical temperature gradient in the sediments. This gradient along with some knowledge of the heat capacity of the sediment allows scientists to calculate the rate of heat loss from the sediments into the ocean.

 Crew

R/V Western Flyer

Ian Young
Master


 

George Gunther
First Mate


 

Matt Noyes
Chief Engineer


 

Andrew McKee
Second Mate


 

Lance Wardle
First Engineer


 

Olin Jordan
Oiler


 

Paul Tucker
Second Engineer


 

Vincent Nunes
Bosun


 

Dan Chamberlain
Electronics Officer


 

Patrick Mitts
Steward


 

ROV Doc Ricketts

Knute Brekke
Chief ROV Pilot


 

Mark Talkovic
Senior ROV Pilot


 

Randy Prickett
Senior ROV Pilot


 

Bryan Schaefer
ROV Pilot/Technician


 

Eric Martin
ROV Pilot/Technician


 

 Research Team

Peter Brewer
Chief Scientist
MBARI

Peter has taken part in more than 30 deep-sea cruises, and has served as chief scientist on major expeditions and on more than 90 ROV dives with MBARI ships and vehicles. His research interests include the ocean geochemistry of the greenhouse gases. He has devised novel techniques both for measurement and for extracting the oceanic signatures of global change. At MBARI his current interests include the geochemistry of gas hydrates, and the evolution of the oceanic fossil fuel CO2 signal. He has developed novel techniques for deep ocean laser Raman spectroscopy, and for testing the principles and impacts of deep ocean CO2 injection.

Ed Peltzer
Senior Research Specialist
MBARI

Ed is an ocean chemist who has been with MBARI since 1997. He has been involved in developing in situ laser Raman spectrometry instruments and lab based analytical techniques to study the composition of gases in gas hydrates and deep-sea vents. He has collaborated on the development of new instrumentation for the measurement of temperature and pH from ROVs and deep-sea observatories. As the group's project manager, Ed is also responsible for expedition planning and logistics.

Peter Walz
Senior Research Technician
MBARI

Peter has worked as a research technician for a variety of scientists at MBARI. Most recently he has supported the research efforts of Dr. Peter Brewer and his interests in the ocean chemistry of greenhouse gases such as methane and carbon dioxide. Peter assists with the design, testing and deployment of the ocean going science hardware and works closely with the marine operations group to integrate new equipment to work with MBARI's ROV's.

Andreas Hofmann
Postdoctoral Fellow
MBARI

Andreas is a MBARI Postdoctoral Fellow in the Brewer lab. He obtained a PhD in marine biogeochemistry in the Netherlands after his biology undergraduate and bioinformatics graduate studies in Germany. Andreas' specialty is pelagic and benthic biogeochemical modeling with a focus on pH and proton cycling. At MBARI, Andreas is working amongst others on the characterization of marine hypoxic and suboxic zones, focusing on the explicit description of physical limitations to aerobic respiration. On this cruise, Andreas will be involved in obtaining and processing Raman spectra, as well as in various other tasks supporting the objectives of the group.

Nancy Barr
Web/Print Project Manager
MBARI

Nancy manages the editing, design, and production of the MBARI annual report and participates in a variety of editorial and communication projects. She also oversees the institute website. Nancy has been to sea with several MBARI research groups, helping them to carefully remove worms from whale bones, annotate video, sift seafloor sediment, and collect and process water samples. For this expedition she will be in charge of the daily reports that will be posted to this website and will assist with other science crew tasks.

Elizabeth Coward
Summer Intern
MBARI

Elizabeth is an MBARI summer intern in the Brewer lab. She is a senior at Haverford College, PA, where she is obtaining her undergraduate joint degree in biology and chemistry. Elizabeth's prior research has been principally concerned with the bioavailability and geochemical dynamics of oil in marine sediments. Her interest in oceanic fossil fuels and greenhouse gases has brought her to the Brewer lab, where she will be using laser Raman spectroscopy to investigate methane and carbon dioxide signatures, the dynamics of gas hydrates and ocean acidification.

Michael Riedel
Research Scientist
Natural Resources Canada - Geological Survey of Canada

Michael Riedel was part of an international team of scientists supported by the Integrated Ocean Drilling Program (IODP) which completed a unique research expedition in 2005 aimed at recovering samples of gas hydrate, an ice-like substance hidden beneath the seafloor off Canada's western coast. As IODP Expedition 311's co-chief scientist, Michael explored his interest in gas hydrate; he believes such deposits have played an important role in ancient global climate change.

Laura Lapham
Postdoctoral Researcher
National Energy Technology Lab, U.S. Department of Energy

Laura's research is concentrated on studying methane cycling at cold seeps, biogeochemcial cycling of methane and sulfer in deep sea sediments, development of deep sea instrumentation to collect novel samples, stable isotope geochemistry, modeling of biogeochemical processes and temporal variability of dissolved methane concentrations. The focus of her research has been mainly on gas hydrate environments, but she is also interested in other systems that relate to the carbon cycle. Her research seeks to understand how methane is distributed between different pools, e.g. dissolved or hydrate phases, and also to understand how local biogeochemical processes affect this methane, mostly through anaerobic methane oxidation.

Jon Furlong
University of Victoria

Jon is a graduate student at the University of Victoria studying with Michael Riedel. His bachelor's degree was completed in Earth Sciences from Memorial University in Newfoundland before he moved from one coast to the other. Jon's research focuses on neo-tectonic faulting offshore Vancouver Island and its links to gas hydrate formation and fluid migration.