image: This is the location of the sediment record (ODP Site 1090), shown against the concentration of nitrate in surface waters. Nitrate is a critical building block for marine algae, but there are high concentrations of unused nitrate the surface waters of the Southern Ocean, the ocean surrounding Antarctica. It was hypothesized by the late John H. Martin that the increase input of dust to the ocean during ice ages may have fertilized the marine algae, allowing more of the Southern Ocean nitrate to be used for growth and thus drawing dawn carbon dioxide into the ocean. The nitrate concentration data are from the World Ocean Atlas 2009 and are plotted using the software Ocean Data View. This image relates to a paper that appeared in the 21 March, 2014, issue of Science, published by AAAS. The paper, by Alfredo Martínez-García at ETH Zürich in Zurich, Switzerland, and colleagues was titled, "Iron Fertilization of the Subantarctic Ocean During the Last Ice Age." view more
Credit: [Image courtesy of Alfredo Martínez-García (ETH Zurich)]