Marine Chemistry & Geochemistry
Researchers in the Marine Chemistry and Geochemistry Department (MC&G) use field observations, laboratory experimentation, computational modeling, and state-of-the-art analytical techniques to understand processes that regulate ocean chemistry. Much of this work is directed at identifying and determining chemical fluxes, or exchanges, across ocean boundaries at the seafloor, coastal zone, and air-sea interface. This research helps establish the relationship between ocean chemistry and climate and the influence of human activity on the marine environment. The recognition that microorganisms are key players in many of these processes has led to more research programs within MC&G that straddle the borders of marine chemistry, geochemistry, geology and microbiology. The growing number of interdisciplinary researchers has led to exciting and cutting-edge research that contributes greatly to our understanding of ocean chemistry.
A study published in the journal Science by MC&G Associate Scientist Marco Coolen in 2011 reports the results of a research program positioned at the interface of marine chemistry, paleooceanography, and microbiology. In this study, Coolen used novel techniques to determine fossil genetic signatures from ancient DNA that allowed reconstruction of 7,000 years of population dynamics for marine phytoplankton and their associated viruses in the Black Sea. The study showed that shifts in viral and host populations coincided with environmental changes that affected salinity and nutrient availability.
During the past few years, MC&G has hosted an active and expanding group of scientists interested in exploring the ocean for naturally produced compounds that may have value in medicine and other areas of societal import such as biofuel development.
In 2011, Assistant Scientist Tracy Mincer initiated a project supported by a $1.2 million grant from the Flatley Discovery Lab to provide chemical extracts from marine microorganisms to be screened for effectiveness in treating the deadly disease cystic fibrosis. The goal of this research is to identify small molecules that could treat the mutated gene responsible for cystic fibrosis—a new approach that would enable treating the disease at its root cause instead of treating the symptoms. The significance of this work is not limited to medical applications. The chemical extracts prepared by Mincer will also be studied for their function in nature, providing important clues to microbial survival strategies and chemical cycling in marine environments.
The spring of 2011 was marked by the destruction and human loss that resulted from the magnitiude 9.0 Tohaku earthquake offshore Japan and subsequent tsunami. Damage to the coastal Fukashima Dai-ichi Nuclear Power Plant resulted in the largest accidental release of radioactivity to the marine environment to date. MC&G Senior Scientist Ken Buesseler, who had been instrumental in documenting the release of radioactivity to the marine environment following the 1986 Chernobyl accident, recognized the need to document the amount of radiation being released to the ocean and how subsequent transport and mixing affected its accumulation. Initial funding from an NSF RAPID grant allowed him to analyze limited water samples sent by colleagues, to determine baseline radiation levels.
Shortly thereafter, a $3.7 million grant from the Gordon and Betty Moore Foundation allowed Buesseler to organize an international field program involving collaborators from more than10 institutions from 6 different countries in early June 2011. Other WHOI PIs included Matt Charette and Steve Jayne of MC&G and Irina Rypina of the Physical Oceanography Department.
During the two-week research cruise, researchers collected water, small fish, and plankton samples at varying depths and distances from the Japanese coast. Initial results, published in the Proceedings of the National Academy of Sciences, reveal that radionuclides released from the power plant are rapidly transported away from the coast by the Kuroshio current. Radionuclide levels varied by a factor of 1000 within 20 to 400 miles of Fukushima, with highest levels associated with a near shore eddy and lowest levels farther off shore. Although radiation levels in fish were elevated, they remained below levels considered safe for human consumption.
MC&G Assistant Scientist Rachel Stanley and postdoctoral investigator Brice Loose led an expedition to the Bra D’Ors Lakes, Nova Scotia, in order to test a novel method to simultaneously measure biological production and air-sea gas exchange in melting ice zones using newly developed sea-going instruments. Melting ice zones in polar regions are extremely important locations for the exchange of carbon dioxide between the ocean and atmosphere. The researchers took their instruments to an inland sea in Nova Scotia to test the new method in an easily-accessible locale as a proxy for the Arctic.
They found that “easily accessible” doesn’t mean “easy to work in”! After waiting weeks for the ice to melt in order to start their experiments, a storm blew ice into the lake and their boat was pushed by an ice floe onto a sandbar, forcing them to evacuate in a dinghy. When the storm passed two days later, they found that the scientific equipment had survived but the boat was not easily reparable. Undaunted, they plan to return next spring to test their new method in the climatically important—but challenging—melting ice zone.
MC&G researchers were well-represented during the second leg of the US GEOTRACES North Atlantic cruise as the R/V Knorr left Woods Hole in November. This cruise completed the first "zonal transect" (full-ocean-depth sampling along a predetermined track) of the US GEOTRACES program in the North Atlantic, a large-scale research effort to determine the distribution of trace elements and their isotopes in the ocean.
Ken Buesseler, Matt Charette, Bill Jenkins, Phoebe Lam, Carl Lamborg, and Mak Saito are among 44 principal investigators in this highly coordinated effort to simultaneously measure a broad spectrum of trace metals and isotopes. Their results will allow a far richer and deeper interpretation of the data to identify the processes and quantify the fluxes that control distributions of trace elements in the ocean. Even with limited berths available on the ship, MC&G was also represented on the cruise by Joint Program students Jessica Fitzsimmons, Daniel Ohnemus, Stephanie Owens, postdoc Paul Morris, and Research Associate Steve Pike.
Other news from MC&G includes recognition of accomplishment through awards and promotion. Towards the end of 2011, Scott Doney was elected as a Fellow of the American Association for the Advancement of Science in recognition of “…fundamental contributions to our understanding of the ocean carbon cycle and its interactions with the Earth system and for his scientific leadership.” Research Associate Paul Henderson was recognized for his exceptional efforts in the lab and in the field with the 2011 Ryan C. Schrawder Award, given at the 2011 WHOI Employee Recognition celebration. The list of promotions includes Matt Charette to Senior Scientist, Mak Saito to Associate Scientist with Tenure, Phoebe Lamb to Associate Scientist without tenure, Heather Benway and Krista Longnecker to Research Specialist, Crystal Breier to Research Associate II, Kevin Cahill to Senior Research Assistant I, and Donna Mortimer and Janet Moore to Administrative Associate II.
Five new Assistant Scientists joined MC&G Department in 2011, adding substantial youth and breadth to our research portfolio:
Valier Galy is an organic geochemist who uses a variety of geochemical tools to study the global carbon cycle. He is particularly interested in the transport and fate of terrestrial carbon delivered to the ocean and the interplay between carbon cycling and climatic variability.
Amanda Spivak is a cross-disciplinary scientist who examines the relationship between biogeochemical processes and ecosystem functioning in seagrass environments and explores the cycling of carbon and other elements in coastal environments.
David Nicholson is a biogeochemist who studies the distribution of trace gases in the surface ocean to quantify aspects of ocean ventilation, marine productivity, and the carbon cycle. He uses field observations and numerical modeling to understand natural and anthropogenically-driven climate variability.
Frieder Klein is a geochemist/metamorphic petrologist who examines the effects of fluid-rock interaction within the oceanic lithosphere. His research has implications for a diverse set of topical issues that include carbon sequestration, earthquake prediction, and the origin of life.
Amy Apprill is a microbial biogeochemist focused on the interactions of microbial communities and larger host animals. She studies the influence of biogeochemical environments on microbial community composition and function and the development of ecosystem stress indicators.
—Jeffrey Seewald, Department Chair