How Algae in the Ocean Could Help Clear the Air

AT a time when scientists are searching for ways to reduce carbon dioxide that contributes to global warming, algal blooms could play a role.

John Martin, an oceanographer at Moss Landing Marine Laboratories of California, in Salinas, is experimenting with stimulating the growth of marine algae by adding iron to ocean areas with little plant life.

"In 1990, we had been pursuing the notion that vast areas of ocean have very little plant life because of a deficiency of iron," Dr. Martin says. Plants grow better with iron, he says.

His theory is that new plant growth would deplete the oceans' supply of CO2. The ocean water then would absorb some of this greenhouse gas from the air.

"If [marine algae] was a plant on land, it would take CO2 from the air and change it to carbon for cells. In water, algae takes CO2 from the water. This leaves a `vacant' spot of carbon in the ocean, which is then filled through absorption from the air," says Donald Anderson, a marine biologist at the Woods Hole (Mass.) Oceanographic Institution.

Martin has proposed growing the algae around Antarctica where the water is rich in other nutrients. The theory is controversial, because the effect of inducing plant life and adding iron to the ocean is unknown, Anderson says.

For a pilot project, Martin is requesting funding from the National Science Foundation and the Office of Naval Research to test his theory in 29 square miles of ocean, 300 miles south of the Galapagos Islands.

"There wouldn't be any long-term effects from the experiment since iron doesn't stay in solution," Martin says.

"The iron would be gone within days. When the plants have used up the nitrates in the water, they would die back like any land plant."