U.S. GEOTRACES North Atlantic Section: The chemical speciation of dissolved iron and copper

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GEOTRACES is a newly initiated international oceanographic program to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the oceans and to establish an understanding of the sensitivity of these distributions to changing environmental conditions. During the GEOTRACES cruise to the North Atlantic basin in 2010, a scientist from the Bermuda Institute of Ocean Sciences will focus on characterizing the organic complexation of dissolved iron (Fe) in the water column. Iron is typically 99% complexed by strong organic ligands in the marine environment making these ligands a crucial component of the biogeochemical cycling of this element. The specific goals of the proposed work are the following: (1) determine the distributions of strong Fe-binding organic ligands and the sources of variability in the relationship between strong ligand and dissolved Fe concentrations in the proposed hydrographic regions; (2) inter-compare shipboard and laboratory-based speciation analyses with those of other analysts as well as with published field data; and (3) assess any apparent contributions of aeolian deposition to changes in dissolved Fe-binding organic ligand concentrations in surface waters. As regards broader impacts, results from this study would provide much-needed field data for future modeling endeavors. The outreach component of the study was truly impressive and includes the production of an radio segment from 'Our Ocean World' that highlight research finding from this study and the collaboration with high school teachers to develop lesson plans containing both hands-on experiments related to the project.