GEOTRACES: Speciation intercalibration of iron and copper in seawater

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Scavenging and biological uptake of trace metals are strongly influenced by redox state and the formation of organic complexes. For this reason, an investigator from the University of Southern California proposes to include speciation measurement of iron (Fe) and copper (Cu) into the GEOTRACES intercalibration exercise. Initially, organic complexation of Fe and Cu using cathodic stripping voltammetry methods would be determined on frozen samples collected during the 2004 SAFE cruise prior to participating in the 2009 Pacific GEOTRACES intercomparison cruise. Results for ligand binding strengths and concentrations would be compared with other investigators who are planning to participate in the intercalibration effort. In addition, redox speciation would be intercompared for iron, with several groups measuring Fe(II) on the 2009 Pacific GEOTRACES intercalibration cruise and on a cruise of opportunity in 2008 to southern Mexico in collaboration with a scientist from Scripps Institute of Oceanography. The investigator plans to measure Fe(II) concentrations in seawater using the chemiluminescence method and results would be compared with values obtained by other participants.As regards broader impacts, a User's manual detailing the protocols required to successfully collect seawater samples and make speciation measurements for iron and copper, as well as other bioactive metals, would be created and made available to the science community.