Aquatic Sciences Meeting, Albuquerque 2001

CS39 Trace Metal Limitation of Biogeochemistry

Date: Tuesday, February 13, 2001, Time: 11:45:00 AM

Location: Dona Ana

Saito, M, A, MIT/WHOI, Woods Hole, USA, msaito@whoi.edu

Moffett, J, W, Woods Hole Oceanographic Institution, Woods Hole, USA, jmoffett@whoi.edu

Generation of Cobalt Ligands in a Synechococcus Bloom

Cobalt speciation was measured in a Synechococcus bloom at the Costa Rica Upwelling Dome with cell densities of 1e6 cells/mL. Synechococcus, a photosynthetic cyanobacterium known to have an absolute cobalt requirement, may have been profiting from high concentrations of upwelled cobalt. Total dissolved cobalt concentrations were high at depth and decreased in surface waters. Cobalt speciation as measured by competitive ligand exchange adsorptive cathodic stripping voltammetry showed that the upwelled waters contained 42% labile cobalt at 90m and became completely complexed by strong organic ligands in surface waters. Bottle incubations of these surface waters with 500pM cobalt additions showed generation of 425pM ligand, indicating that the biotic community was producing cobalt ligands in response to the addition. Issues of ligand detection windows and the possibility of competition of nickel for cobalt ligands will be discussed.

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Aquatic Sciences Meeting, Albuquerque 2001

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