The triangular area of the North Pacific bounded by Seattle, Hawaii and Northern Japan gulps so much carbon dioxide from the atmosphere that it just about counters all the CO2 given off by the Pacific at the equator, an area twice as vast.

Scientists do not really know why some of those North Pacific waters support such explosive phytoplankton growth, but the carbon dioxide going from the atmosphere to the water drops "like mad" as it is used by the tiny plants to grow into blooms that are visible from outer space, according to Steven Emerson, UW oceanography professor and co-chief scientist on an expedition this fall that involved seven scientists and 20 UW graduate and undergraduate students to study the situation.

It's important to find out so we can understand if changing conditions, perhaps caused by global warming, might one day tamp down the massive amount of carbon dioxide absorbed into that area, Emerson says. Right now, about 30 percent of the fossil fuel carbon dioxide we put into the atmosphere is absorbed by oceans around the world, including the area sampled during the expedition.

The expedition is part of a $2.5 million, three year project funded by the National Science Foundation aimed at understanding the North Pacific carbon cycle.

During the three-week expedition from Seattle to Hawaii students, working 12-hours-on and 12-hours-off shifts, conducted water sampling, began analysis of the data collected and helped deploy a sleek Seaglider and ARGO float, both built at the UW.

Students also had their own research projects to further the NSF investigation. One graduate student, for instance, was monitoring a continuous flow of sea water for oxygen-to-argon-gas ratios which help scientists separate oxygen that is generated by plant growth from oxygen that gets into the water in other ways, such as by the action of waves. Among the undergraduate projects, one student is correlating color images of the ocean from satellites with the five or six different measures of how fast plankton are growing that were being conducted by fellow students. In the future it could be part of the way to judge changing ocean conditions using color satellite images.

Led by Emerson and Paul Quay, UW professor of oceanography, the students also worked with marine technicians from the UW and the National Oceanic and Atmospheric Administration.

"No other university in the U.S. gives undergraduates ship time like this to run projects," Emerson says. "It's a unique opportunity from the School of Oceanography using the UW's 274-foot research vessel the Thomas G. Thompson."

"From a teaching perspective," Quay says, "all 14 undergrads performed extremely well and helped yield a world-class data set. We observed ocean conditions that corroborated what we thought was happening -- that is, the high biological productivity associated with low CO2 levels at the front -- using an array of instrumental methods that hadn't been used before."

The Kurishio Current is part of the dynamics making the area studied so productive. The Kurishio Current -- nearly as powerful as the Gulf Stream in the Atlantic -- carries warm water from the equator north along the coast of Japan and across the Pacific. The water cools as it is carried along, making it able to absorb more and more carbon dioxide, particularly in the winter. The area that is especially productive is where the Kurishio Current splits -- with part of it creating a huge spiral of water, called a gyre, north from the latitude of Oregon toward Alaska and part creating a gyre south toward Central California.

Emerson says scientists hypothesize that the two gyres may bring together a potent mix of subarctic water rich in nitrate and phosphate with subtropical water that, while low in nutrients, may be rich with iron that acts as a fertilizer for phytoplankton. Or the coming together of waters with such different temperatures and salinity may stir up nutrient-rich waters from deep in the ocean that powers the productivity.

Investigators along with Emerson and Quay on the NSF carbon cycle project are Charlie Eriksen, UW oceanography professor, and Richard Letliler of Oregon State University.

Students from the expedition, who are in the undergraduate course Special Topics in Chemical Oceanography, will present their findings pertinent to the project from 9:30 to 11:30 a.m. Thursday, Dec. 4 in 123 Marine Sciences.