HR: 1340h
AN: B33A-0842    [Abstracts]
TI: Solid-state Au/Hg Microelectrode for the Investigation of Fe and Mn Cycling in a Freshwater Wetland: implications for methane production
AU: * Ma, S
EM: sma@udel.edu
AF: University of Delaware, College of Marine and Earth Studies, 700 Pilottown Road, Lewes, DE 19958, United States
AU: Luther, G W
EM: luther@udel.edu
AF: University of Delaware, College of Marine and Earth Studies, 700 Pilottown Road, Lewes, DE 19958, United States
AU: Keller, J
AF: Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037, United States
AU: Madison, A S
AF: University of Delaware, College of Marine and Earth Studies, 700 Pilottown Road, Lewes, DE 19958, United States
AU: Metzger, E
AF: University of Delaware, College of Marine and Earth Studies, 700 Pilottown Road, Lewes, DE 19958, United States
AU: Megonigal, J P
AF: Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037, United States
AU: Emerson, D
AF: American Type Culture Collection, 10801 University Boulevard, Manassas, VA 22010, United States
AB: The solid-state voltammetric gold-amalgam microelectrode was used to measure multiple redox species (O, S, Fe and Mn) in situ at (sub)millimeter vertical resolution to elucidate rhizosphere processes in Jug Bay wetlands. In vegetated soil, a classic diagenetic redox sequence without any dissolved sulfide was observed in summer. However, the rhizosphere can be quite variable which is due to the introduction of O2 to the anoxic sediments by plants. In non-vegetated soil, the vertical concentration-depth profiles were relatively constant. The presence of Fe(II), Mn(II) and soluble Fe(III) in deeper sediments indicates the oxidation of Fe(II) as well as the non-reductive dissolution of Fe(III) and the reductive dissolution of Fe(III) and Mn(III, IV) solids. Mn(III, IV) and Fe(III) redox chemistry is important in organic matter mineralization mediated by bacteria and in suppressing methane formation. In addition, Mn(III, IV) also can oxidize Fe(II) to supply Fe(III) for bacterial Fe(III) reduction. Studying Fe and Mn cycling via voltammetric methods can give insights to methane production and loss as there is no methane sensor for sediment work at present.
DE: 0419 Biomineralization
DE: 0424 Biosignatures and proxies
DE: 0461 Metals
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 0471 Oxidation/reduction reactions (4851)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting