GEOC 78 |
| George W. Luther III1, Robert E. Trouwborst1, Gregory K. Druschel1, Bradley M. Tebo2, Samuel M. Webb3, and Rachael S. Howard2. (1) College of Marine Studies, University of Delaware, Lewes, DE 19958, (2) Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0202, (3) Stanford Synchrotron Radiation Laboratory, P.O. Box 20450, MS 69, Stanford, CA 94309 |
| Soluble manganese(III)complexes were measured in suboxic waters (< 3μM O2; < 0.1μM H2S) of the Black Sea and Chesapeake Bay. Mn(III) is stabilized in both environments by natural organic ligands, likely produced by organisms and/or their decomposition products. Samples were handled with inert atmosphere techniques and trace metal clean techniques. Desferrioxamine (20 micromolar) was used to out compete natural binding organic ligands to form the strong complex, Mn(III)deferoxamine, which was measured by cyclic voltammetry at a potential of –1.18V. Leucoberbelin blue and a pyoverdine ligand obtained from a Mn(II)oxidizing bacterium also gave a positive test for dissolved Mn(III). Soluble Mn(III) shows a maximum in the suboxic zone but is not observed in the oxic and sulfidic zones of the water column. The existence of soluble Mn(III) has important biogeochemical implications for redox chemistry at oxic/anoxic interfaces in waters and sediments. The chemistry of Mn(III) formation from Mn(IV) reduction and Mn(II) oxidation reactions will be discussed. |
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Microbially Mediated Manganese and Iron Oxidation in the Biosphere
1:30 PM-5:05 PM, Tuesday, March 30, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |