July 21, 2008

Plankton Changes Atlantic into Carbon Sink

A seasonal bloom of ocean plankton is pulling more carbon dioxide than previously thought from the atmosphere into the Atlantic Ocean, U.S. researchers said.

The bloom -- nurtured by the Amazon River -- may be enough to turn the tropical Atlantic from a net source of atmospheric carbon into a net carbon sink that removes carbon dioxide from the atmosphere, New Scientist reported.

Ajit Subramaniam, an oceanographer at Lamont-Doherty Earth Observatory in Palisades, N.Y., and his colleagues sampled phytoplankton in a water area extending from the Amazon's mouth into the Atlantic. They reported finding that, for much of the year, offshore waters support plankton that converts atmospheric nitrogen into biologically usable forms.

Plankton that escaped the nitrogen-poor Amazon thrived on its nutrients, especially phosphorus and silicon, researchers said. The result is a rapid increase of carbon dioxide absorbed by photosynthetic plankton.

I think the value of this work is not so much in figuring out how we can use it to humankind's advantage, but in figuring out that the major rivers of the world may be helping to balance the CO2 inventory of the planet in ways we haven't realized before, says David Karl, an oceanographer at the University of Hawaii.