Despite being the fourth most abundant element in soil and rock (and the most common on Earth as a whole), iron is in short supply in much of the sea. Scientists have long suspected that iron deficiencies might affect some 20 percent of the global ocean, and this idea has been tested. Results by National Science Foundation (NSF)-funded researchers, published in science journal Nature, confirm earlier experiments that indicated a strong biological response to added iron. But this time the effects lasted longer, and large changes were observed in the air-sea transfer of gases involved in climate processes.
On an oceanographic research cruise called "IronEx II," led by scientists from Moss Landing Marine Laboratories (MLML) in California, 37 scientists from 13 institutions in the U.S., England, and Mexico "fertilized" with iron a patch of ocean waters some 800 miles west of the Galapagos Islands. Nearly one-half of one ton of iron was added to the experimental patch, increasing surface water iron concentrations by 100 parts per trillion. The experiment was tracked for 18 days.
Iron-starved plant plankton, called phytoplankton, native to the region responded rapidly; the amount of plankton began to nearly double each day. Working around the clock, scientists performed continuous measurements and over-the-side sampling operations. "Within one week, about two million pounds of phytoplankton had grown, representing a thirty-fold increase," says scientist Kenneth Coale of MLML. "At the same time, the rapid growth of these plankton began to 'draw down' carbon dioxide in surface waters. After 10 days, the concentration of carbon dioxide had dropped 20 percent over the initial values."
Could we slow future climate change resulting from human activities by adding iron to under-productive oceans? Read more...
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American writer
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