Iron-binding Ligands in the Eastern Tropical South Pacific: Results from U.S. GEOTRACES Cruise GP16

Kristen N Buck, University of South Florida Tampa, College of Marine Science, Tampa, FL, United States, Jessica N Fitzsimmons, Texas A & M University College Station, Oceanography, College Station, TX, United States, Robert M Sherrell, Rutgers University, Marine and Coastal Sciences and Earth and Planetary Sciences, New Brunswick, NJ, United States, Bettina M Sohst, Old Dominion University, Norfolk, VA, United States, Peter Sedwick, Old Dominion University, Department of Ocean, Earth and Atmospheric Sciences, Norfolk, VA, United States and Seth John, University of South Carolina, Columbia, SC, United States
Abstract:
High-resolution depth profiles, consisting of 25-49 samples each, were collected as part of the U.S. GEOTRACES Eastern Pacific Zonal Transect (GEOTRACES cruise GP16). The organic complexation of dissolved iron in these samples, including the concentrations and conditional stability constants of iron-binding ligands, was measured by competitive ligand exchange-adsorptive cathodic stripping voltammetry using the added competitive ligand salicylaldoxime. In addition to the conventional depth profile samples for dissolved (<0.2 µm) iron-binding ligands, samples were collected for size-fractionated ligand analyses using cross flow filtration. These samples were obtained from in and around the mid-depth near-field to distal hydrothermal plume emanating from the East Pacific Rise, and allowed for iron-binding ligand analyses in the dissolved (<0.45 µm), colloidal (10 kDa to 0.45 µm) and soluble (<10 kDa) size fractions. Results from this work will be presented in the context of the few previous studies of iron-binding ligands in the South Pacific, and compared with results from the North U.S. GEOTRACES North Atlantic Transect (GEOTRACES cruise GA03).
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