Phytoplankton bloom in the South Atlantic Ocean, off the coast of ArgentinaWIKIMEDIA, NASAIn 2012, a large team of international scientists explained how algal blooms consume atmospheric carbon, which they drag to the sea floor as they sink and die. As The Scientist reported at the time, the results pointed to iron fertilization as a potential geoengineering solution to rising carbon dioxide (CO2) levels in the atmosphere. But a study published last month (November 10) in Nature Geoscience called into question whether this approach would be as effective a carbon sink as initially thought.
In it, Ian Salter from the Helmholtz Centre for Polar and Marine Research in Germany and his colleagues report on differences among sea floor sediment samples taken from within the Polar Frontal Zone around the Crozet Islands near Antarctica. Comparing sediment from sites with and without enhanced natural iron levels, the researchers found an increase in calcium carbonate in the iron-enriched samples, suggesting a more complex ecological response.
This latest work “demonstrates that natural iron fertilization stimulates sinking of calcium carbonate in particles from the upper ocean to the deep ocean,” oceanographer Dorothee Bakker of the University of East Anglia, U.K., who has worked on the Surface Ocean CO2 Atlas but was not involved in the present study, told The Scientist in an e-mail.
Salter ...
