2010 SouthernExpedition

Day 11 – One last dive
July 19, 2010

1230 hours – Northeast Santa Monica mounds
Latitude 33 degrees 47.9479 minutes N
118 degrees 38.7775 W

A short dive today because the vehicle had to be up on deck to give us time to sail for the Los Angeles harbor and be at the dock by 3 p.m. Most of the dive was turned over to MBARI’s newest postdoctoral fellow, Andreas Hofmann, so that he could collect data for his project. The ROV dove just off the crest of the mound where the MBARI instruments are deployed (see the log from July 15th). Hofmann took a series of Raman profiles in two contrasting areas in terms of clams and color of the sediment, so that he can map out the gradient of the methane, sulfide, and sulfate signals; he also plans to analyze the results using a one-dimensional numerical sediment model.

Just before returning to the surface the pilots repeated the effort to collect methane hydrate in a tube, as we had done on July 15th, and this time it went according to plan as the tube was well-sealed. As the vehicle rose to shallower depths, the gas dissociated from the hydrate because of the change in temperature and pressure. While the tube was being held by one ROV robotic arm, the pilot inserted the Raman probe using the other robotic arm, so that an in situ measurement of the gas could be taken.

The ROV is now on deck, so it’s time to pack up the lab, clean our staterooms, and get ready to disembark. Hope you enjoyed reading this log as much as I’ve enjoyed writing it.

—Nancy Barr

The Raman probe was used to measure the methane gas in this tube. The gas was collected at a seafloor vent, where it turned to hydrate due to the temperature and pressure at depth. As it was brought to shallower water, the gas dissociated from the hydrate skins. The picture shows the white hydrate skins at the top of the tube, the gas layer just below that, and seawater in the bottom layer.
During the course of the cruise, everyone gets a turn in the chief scientist’s chair. Above, Peter Brewer shows Zeng Zhigeng how to operate the chief scientist’s camera. In the picture below, Summer Intern Melissa Luna takes a turn in the chief scientist’s chair, while pilot D.J. Osborne flies the ROV.

The science and ROV teams in front of the Doc Ricketts at the end of a successful cruise. Front row, from left, Bryan Schaefer, Mark Talkovic, Xin Zhang, Peter Brewer with the Raman probe, Zeng Zhigang, Melissa Luna, and Knute Brekke. Second row, Peter Walz, Nancy Barr, Andreas Hofmann, Buzz Scott, and Ed Peltzer. D.J. Osborne is in the back.

We had some lovely evenings at sea off Southern California and the Channel Islands.

Photo by Peter Walz
Previous log

Leg 1

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 ROV Tiburon'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.


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.

CTD Rosette

A CTD rosette is a cylindrical frame holding a group of plastic water-sampling tubes. Attached to this frame are instruments for measuring water temperature and conductivity (salinity) at various depths. Also attached to the rosette are instruments for measuring parameters such as chlorophyll, nutrients, and particulate matter in the water. As the frame is lowered over the side of a ship, water samples are taken automatically at various depths. Then the frame is raised to the surface again.

 Research Team

Peter Brewer
Senior 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 instrumentation and analytical techniques to study the composition of gases in gas hydrates and deep-sea vents. He has also collaborated on the development of new instrumentation for the measurement of temperature and pH from an ROV. 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 on the relation between pH and soundspeed, the characterization of marine "dead zones", the development of a sediment model to estimate biogeochemical rates from pore-water methane profiles obtained with the group's deep sea sediment Raman Probe, and on a few other related topics. On this cruise, Andreas will be involved in experiments using the mid-water CO2 and O2 control system and the sediment Raman probe, as well as in various data processing tasks.

Melissa Luna
Summer Intern, MBARI

Melissa is an MBARI 2010 Summer Intern working in the Brewer lab. She is a graduate of College of Charleston in Charleston, South Carolina with a BS in Chemistry. This summer Melissa will be working on using laser Raman techniques to examine hydrogen sulfide and bisulfide signals as a function of pH in marine pore waters in sea floor sediments.

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.

Xin Zhang
Seafloor Hydrothermal Activity Laboratory
Key Lab of Marine Geology and Environment
Institute of Oceanology, Chinese Academy of Sciences

Xin Zhang is a former MBARI student of Peter Brewer and Bill Kirkwood. He was involved in the development of a Deep-Sea Raman Probe for the measurement of sediment pore-water geochemistry.

Zeng Zhigang
Director, Seafloor Hydrothermal Activity Laboratory
Key Laboratory of Marine Geology and Environment
Institute of Oceanology, Chinese Academy of Sciences

Zeng Zhigang's research interests are in hydrothermal vents, geochemistry, economic geology, and the exploration of geology and mineral resources. He is on this expedition to learn more about MBARI's tools and methods for study ocean chemistry.