GEOC 141 |
| Martha H. Conklin1, Timothy L. Corley2, Hanna Gilbert2, Elizabeth Robbins2, and P. A. O'Day3. (1) School of Engineering, University of California Merced, Merced, CA 95344, (2) Department of Hydrology, University of Arizona, Tucson, AZ 85721, (3) School of Natural Sciences, UC Merced, Merced, CA 95344 |
| Mn oxyhydroxides occur ubiquitously in streams, easily discernible by characteristic black coatings on sediments and rocks. To unravel the role of biofilms on Mn oxyhydroxides formation, Mn oxyhydroxides and biofilms formed on a variety of substrates (plants, quartz sand, rutile, magnetite, glass slides) in a stream were characterized. Using EXAFS spectroscopy, a disordered Mn-oxide that is similar in local structure to a natural birnessite of low symmetry was determined. The formation of disordered, poorly crystalline birnessite is important, as it is an extremely efficient metal scavenger and the interlayer vacancies in the birnessite structure aids in metal sequestration. The microbial community in biofilms consisted primarily of diatoms, algae, and known Mn oxidizing bacteria, including Pseudomonas, as identified by SEM, ESEM, and CSLM. First order rate constants for the loss of Mn were comparable for all mineral and plant substrates (~5 x 10-6 s-1), suggesting oxide formation occurs primarily in biofilms. |
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Microbially Mediated Manganese and Iron Oxidation in the Biosphere
8:00 AM-12:15 PM, Wednesday, March 31, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |