December 22, 1997
In 17 days at sea, four UW undergraduates help investigate ocean’s ability to absorb greenhouse gas
Two days after their most recent research piece appeared in the journal Nature, University of Washington oceanography professors Steve Emerson and Paul Quay set sail on the UW’s Thomas G. Thompson to seek more answers about subtropical oceans and how they absorb carbon dioxide, one of the so-called greenhouse gases.
On board with these senior scientists, graduate students and marine technicians were four UW undergraduates:
Craig Schilling of Bellevue, helping calibrate and deploy an instrument known as a CTD that gives researchers information about the salinity and temperature of water being studied.
Reina Garcia of Federal Way, studying the amounts of thorium (a radioactive chemical element) in water. This provides information about particles moving from the surface ocean to the deep sea.
Mark Woodworth of Seattle, looking at the difference in carbon dioxide content of the atmosphere and surface ocean waters.
Frank Sperling of Seattle, measuring the growth rate of bacterium using tritium-labeled organic compounds to determine the differences in bacterial activity between northern and southern regions of the subtropical oceans.
The four presented their research findings during finals week to complete requirements for Oceanography 485, a course taught by Emerson that included going to sea for 17 days in November on a cruise between Seattle and Hawaii The UW is the only U.S. institution Emerson is aware of that includes an ocean expedition as part of an undergraduate course of study. This is possible because the university provides ship time on the Thompson for up to 45 days each year explicitly for teaching. The trips give oceanography students a chance to experience life at sea. During the Hawaii trip, for example, students worked shifts of 12-hours-on and 12-hours-off and experienced some days of weather so bad that no one was allowed on deck. Hands-on research experience, Emerson says, is an enormous aid to the traditional classroom teaching process.
According to Schilling, “I learned more in two weeks at sea than I did in a whole quarter of chemistry.”
Earlier this fall students selected projects that fit with research being conducted by Emerson, Quay and other members of the UW chemical oceanography faculty whose research is funded by the National Science Foundation. The NSF also supplied a small grant to Emerson specifically for this expedition to augment the chemical analysis being done.
The scientists are interested in the carbon dioxide that is exchanged between the atmosphere and the ocean and eventually ends up in ocean waters a kilometer (0.6 of a mile) deep. Learning the extent of the flux is important in order to calculate the ocean’s ability to absorb man-made carbon dioxide from burning fossil fuels, from deforestation and other human activities, Emerson says.
The process starts in the surface 100 meters (330 feet) of water where sunlight penetrates. Tiny plants called phytoplankton absorb carbon as they grow. In turn, tiny animals called zooplankton graze on the plant material and take carbon into their bodies.
Carbon makes its way into deeper waters in various ways, for example, it can be in the droppings, empty shells or dead bodies of animals or it can simply be dissolved in the water that is carried into the depths by ocean forces. Carbon moving downward into the ocean means surface waters can absorb more carbon dioxide from the atmosphere. This is a key “transport mechanism” for lowering the carbon dioxide content of the atmosphere, Emerson says.
Subtropical oceans in the northern hemisphere are in the latitudes between Northern California and Central America. A decade ago subtropical oceans were “thought to be the marine equivalent of deserts on land, with little biomass, low overall productivity and a limited role in the carbon cycle,” according to the Oct. 30 issue of Nature. In that issue, Emerson and Quay and their collaborators from the University of Hawaii described three different field measurements showing a relatively high flux of carbon in an area near Hawaii.
“If Emerson and colleagues’ findings are representative of other subtropical regions, it seems that these nutrient-poor ecosystems account for an astonishing half of the export of organic carbon from the world’s oceans,” Nature reported in a news article about the research.
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