HR: 08:00h
AN: B11B-01 INVITED     [Abstracts]
TI: Toward a Molecular Understanding of the Role of Manganese Oxidation in the Maintenance of the Suboxic Zone in the Black Sea
AU: * Tebo, B M
EM: btebo@ucsd.edu
AF: OGI School of Science and Engineering, Oregon Health and Science University 20000 NW Walker Rd, Beaverton, OR 97006 United States
AU: Clement, B G
EM: bgclemen@ucsd.edu
AF: Scripps Institution of Oceanography, University of California San Diego 9500 Gilman Drive, La Jolla, CA 92093-0202 United States
AU: Luther, G W
EM: luther@strauss.udel.edu
AF: College of Marine Studies, University of Delaware, Lewes, DE 19958 United States
AU: Trouwborst, R E
EM: r_trouwborst@hotmail.com
AF: College of Marine Studies, University of Delaware, Lewes, DE 19958 United States
AU: Webb, S M
EM: swebb@SSRL.SLAC.STANFORD.EDU
AF: Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator, Palo Alto, CA 94309 United States
AU: Bargar, J R
EM: bargar@SSRL.SLAC.STANFORD.EDU
AF: Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator, Palo Alto, CA 94309 United States
AU: Parker, D L
EM: doparker@ucsd.edu
AF: Scripps Institution of Oceanography, University of California San Diego 9500 Gilman Drive, La Jolla, CA 92093-0202 United States
AB: The oxic-anoxic transition zone in the permanently anoxic Black Sea water column is characterized by a layer of water with low or undetectable dissolved oxygen and undetectable hydrogen sulfide and termed the suboxic zone. The maintenance of this stable suboxic zone in the water column has been explained by either lateral input of oxidized species (oxygen or Mn oxides) or unusual reactions, perhaps microbially-mediated, between reduced Mn, N and S species and oxidized N and Mn species. Regardless of the mechanism involved, the upward flux of sulfide is ultimately capped by bacterially produced Mn oxides. Biogeochemical models suggest that Mn oxide production coupled to denitrification is required to balance the sulfide flux, however shipboard incubation experiments do not support model conclusions. Rather, kinetic studies show that rapid microbial Mn oxide production in the Black Sea is stimulated by oxygen concentrations below routine detection capabilities. Molecular biological evidence indicates the dominance, in Mn-oxide rich layers, of aerobic Pseudoalteromonas species closely related to Mn(II)-oxidizing Pseudoalteromonas isolates from the Black Sea. Physical and chemical evidence suggest that Mn oxides and oxygen are advected from the coast toward the central gyres. Additionally, recent work has demonstrated that Mn(II)-oxidizing bacteria produce dissolved Mn(III)-organic ligand complexes. Unlike particulate Mn oxides, the reactivity and redox potential(s) of soluble Mn(III) complexes are not well studied. This, combined with direct evidence of dissolved Mn(III) and Mn(III) production in the Black Sea suboxic zone, demonstrate a more complex Mn cycle than originally envisioned. Future Black Sea models should consider possible soluble Mn(III) species, lateral advection processes, and the kinetics of Mn(II) oxidation at low oxygen.
DE: 0404 Anoxic and hypoxic environments (4802, 4834)
DE: 0419 Biomineralization
DE: 0448 Geomicrobiology
DE: 0463 Microbe/mineral interactions
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
SC: Biogeosciences [B]
MN: Fall Meeting 2005