UD news:
As a 'carbon sponge,' iron-poor coastal
waters can't always do the job, Nature paper shows


Embargoed: Not for release until 2 p.m. EDT Wednesday, June 10, 1998

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Photo by Al Greening, San Francisco, Ca.

Like a sponge, the Earth's oceans store the greenhouse gas, carbon dioxide--but certain coastal waters can't perform this trick because they lack iron, says David A. Hutchins, an assistant professor in the University of Delaware's College of Marine Studies, whose work will appear in a forthcoming issue of the journal, Nature. With co-author Kenneth W. Bruland of the University of California at Santa Cruz, Hutchins has discovered that a lack of iron limits phytoplankton growth in waters along one of the nation's best-known shorelines: just off the scenic cliffs of Big Sur in the Monterey Bay National Marine Sanctuary (above). Without enough iron, Hutchins notes, phytoplankton can't use the sun's energy to draw carbon dioxide from the air.


Image by University of Delaware/David A. Hutchins

A 1997 field study, conducted by David A. Hutchins of the University of Delaware and Kenneth W. Bruland of the University of California at Santa Cruz, examined iron levels in waters along the central California coast (shown in black). Waters off Big Sur (south of Monterey Bay) and Cape Mendocino (north of San Francisco Bay) don't contain enough iron to help phytoplankton use the sun's energy to draw carbon dioxide from the atmosphere, the researchers say. This satellite image shows the temperature of the sea's surface where cold, nutrient-rich water--shown in blue and green--is being upwelled to the surface.