Marine Chemistry & Geochemistry (MCG) Department   E-mail     Print     PDF

	Enlarge Image Figure 1: An array of sampling technologies were utilized in the VERTIGO program to follow the fate of particles sinking from sunlit surface waters through the ocean’s dimly lit twilight zone.  In particular, Ken Buesseler and engineer Jim Valdes designed a new-generation neutrally buoyant untethered vehicle called the Twilight Zone Explorer, that is swept along with the currents and surfaces periodically to relay data via satellite. (Illustration by Jack Cook, Woods Hole Oceanographic Institution) [Figure from Oceanus]
	Enlarge Image Figure 2: Recovery of a neutrally buoyant sediment trap (or “Twilight Zone Explorer”) following deployment as part of the VERTIGO program.
	Enlarge Image Figure 3: Gas-tight sampler collecting fluid at Lost City hydrothermal field. http://www.whoi.edu/sbl/liteSite.do?litesiteid=23873; Courtesy of Deborah Kelley (University of Washington), Institute for Exploration, URI-IAO, and NOAA.
	Enlarge Image Figure 4: Environmental risk assessment and fate models rely on detailed knowledge of carbon nanotube composition. The work of Desiree Plata and colleagues reported in Nanotechnology represents a first effort to provide such data. Image source, Paul Oberlander, WHOI.
	Enlarge Image Figure 5: Working in the Southern Ocean!
	Enlarge Image Figure 6: Trawl sample
	Enlarge Image Figure 7: Photograph of fossil deep-water coral

Scientists within the Marine Chemistry and Geochemistry (MC&G) Department seek to understand the processes that drive chemical cycling in the ocean, and to learn how ocean chemistry influences and responds to biological activity and climate on Earth, both today and in the past. Ocean chemists increasingly are working at the interface with other disciplines as important new questions arise at these boundaries.  For example, recent studies using novel techniques have revealed the remarkable diversity of microbes in the ocean and their powerful role in biogeochemical processes.  This topic represents a vibrant area of interaction between chemists and biologists, and Assistant Scientist Tracy Mincer – who has expertise in both natural products chemistry and molecular biology - joined the MC&G staff in 2008 to further strengthen these interactions. Several WHOI scientists from the MC&G Department, including Scott Doney, Dan Repeta and Mak Saito are also involved in a large, on-going NSF-sponsored, multi-investigator, multi-institutional program coordinated from Hawaii called “C-MORE” (Center for Microbial Oceanography: Research and Education) that seeks a more comprehensive understanding of the biological and ecological diversity of marine microbes and their role in global processes.

2008 also marked the culmination of a major research program called “VERTIGO” (VERtical Transport In the Global Ocean) spearheaded by MC&G Senior Scientist Ken Buesseler to understand biogeochemical processes taking place in the mesopelagic oceanic realm.  This region is also called the “Twilight Zone”, [Figure 1] both due to its location (i.e., immediately below the sunlit surface ocean layers and above abyssal waters, approximately between 100 and 1000 m) and because of the enigmatic biological, chemical and physical processes at work.  Yet despite its mysteries, understanding this region is critical for assessing the ocean’s ability to remove CO₂ from the atmosphere via the “biological pump” by converting CO₂ to particulate organic matter in surface waters and sequestering this carbon to the deep ocean.  Buesseler’s VERTIGO program - which used a host of innovative sampling [Figure 2] and measurement technologies developed in collaboration with WHOI engineers, and which included contributions from several MC&G scientists, including Karen Casciotti, Phoebe Lam, Carl Lamborg, and Ben Van Mooy - shed important new light on the Twilight Zone and revealed many new facets of its operation.  These findings were highlighted in a special issue of Deep-Sea Research that was published this year. [Buesseler, K. and R. Lampitt, eds (2008). Understanding the Ocean's Biological Pump:results from VERTIGO.  Deep Sea Research Part II: Topical Studies in Oceanography, 55(14-15), 1519-1521.]

New discoveries continue to be made concerning biogeochemical processes at work at the bottom of the ocean.  Postdoctoral investigator Giora Proskurowski, working with MC&G scientist Jeff Seewald and colleagues at the University of Washington and ETH Zurich in Switzerland, has been studying geochemical processes at the Lost City deep-sea hydrothermal vent system on the Mid-Atlantic Ridge [Figure 3]. Proskurowski and colleagues found evidence for non-biological reactions that result in the synthesis of small organic (hydrocarbon) molecules under the geochemical and thermal conditions at Lost City.  These findings, which have important implications for the origin of life on Earth, were reported in a 2008 publication in the journal Science.

Scientists within MC&G are not only concerned with chemical species (elements, organic compounds, isotopes) that are the product of, or influenced by the natural processes at work; they also seeks to investigate the types, sources, concentrations and impact of chemicals stemming from human activity. Although much research has focused on understanding the fate and impact of these chemicals upon their release into the environment, chemists at WHOI are seeking to head off adverse effects of potentially harmful chemicals before they are produced.  For example, one of the most rapidly growing areas of technological innovation is nanotechnology, and an important aspect of this involves carbon nanotubes which have been found to exhibit remarkable mechanical properties.  MIT/WHOI Joint Program student Desiree Plata, working in conjunction with MC&G scientist Chris Reddy and Dr Phil Gschwend at MIT, has been examining the chemical properties of carbon nanotubes as well as potentially harmful by-products from their manufacture.  They have found that some commercially available carbon nanotubes contain large amounts of toxic metal and carbonaceous impurities. These distinct chemical signatures may serve as 'fingerprints' to trace the sources of carbon nanotubes released to the environment [Figure 4].

In one regard 2008 was no exception:  it saw MC&G scientists travel extensively to undertake fieldwork in remote corners of the globe and under challenging conditions in pursuit of their research goals. For example, in April-May 2008, Laura Robinson and several of her colleagues participated in a research cruise on the ice breaker Nathaniel B. Palmer to study cold-water corals in the Drake Passage between Antarctica and the southernmost tip of South America - some of the most inhospitable waters in the world! [Figure 5]  Corals inhabit many areas of the World’s ocean, and can grow at depths in excess of 3 miles. The calcareous skeletons of fossil deep-water corals may hold important clues about past deep ocean variability and climate history. However, the distributions, ecology and life histories of these deep-dwelling organisms are poorly known. The cruise brought together experts in coral ecology and habitats, seafloor mapping, and paleoclimate, to start building a coherent picture of the long-term temporal and spatial distributions of deep-sea corals in the Southern Ocean. During the cruise multibeam sonar and WHOI’s TOWCAM was used to map and photograph seafloor topography in order to document cold-water coral habitats.  Research trawls [Figure 6] and dredges were used to collect living and long-dead ("fossil") corals [Figure 7]. These samples are now being dated to determine how long they have been living in the Southern ocean, and to select suitable corals for paleoclimate reconstruction. [Figure 8]

On the other side of the globe in the Arctic, MC&G scientists Elizabeth Kujawinski and Matt Charette joined JP student Maya Bhatia and scientists from WHOI’s Geology & Geophysics Department for fieldwork on the coast of Greenland in order to examine the potential biogeochemical significance of materials transported in glacial meltwater from the adjacent ice sheet.  And, in the tropics, Assistant Scientist Phoebe Lam transited the Atlantic from Barbados to the Cape Verde Islands and then onto the Canary Islands aboard the R/V Oceanus in order to explore the sources of iron emanating from the African continent, and its role on ocean biological productivity.

Finally, in addition to their activities in the field and in the laboratory, MC&G scientists were also heavily involved in helping to shape science policy and scientific programs through service on panels, in working groups and at conferences.  Overall, it was a busy and highly successful year for the Department!

Timothy, I. Eglinton
Chair, Department of Marine Chemistry and Geochemistry