Microbially catalyzed dissolution of iron and aluminum oxyhydroxide mineral surface coatings
- Georgia Institute of Technology, Atlanta, GA (United States)
This experimental study investigated the processes by which microbes interact with oxyhydroxide mineral surface coatings using an approach designed to better represent the conditions of natural subsurface environments. The interactions of Shewanella putrefaciens, a facultative anaerobe capable of dissimilatory iron reduction, with coatings of Fe{sup 3+} and Al{sup 3+} oxyhydroxides on natural quartz and silica glass surfaces were examined. Using synthetic groundwater solutions having composition that simulated a typical aquifer, bacteria were seeded onto mineral surfaces (and coatings) and incubated in parallel with abiotic controls for up to 96 h under aerobic and anaerobic conditions. Microbial-mineral surface interactions were determined using the direct observational technique, Fluid Tapping Mode{trademark} Atomic Force Microscopy (TMAFM) in combination with measurements of ferrous iron concentrations and pH of the incubating solutions. Observations of live bacteria-surface interactions exposed to aerobic conditions showed localized pitting on Fe{sup 3+} oxyhydroxide coated quartz surfaces within 72 h of incubation. These pits corresponded directly to sites of bacterial surface adhesion and the extent of pitting was accompanied by the accumulation of ferrous iron to low but steady-state concentrations. Localized pitting was not observed on any Al{sup 3+} oxyhydroxide coated surfaces. In contrast, iron coated surfaces exposed to bacteria under anaerobic conditions revealed progressive, nonlocalized Fe loss over 96 h. This correlated with a temporal increase in ferrous iron concentrations in the bacteria-exposed solutions compared to the abiotic controls. Aqueous chemical measurements combined with the Fluid TMAFM observations indicate biologically-catalyzed iron reduction under both aerobic and anaerobic incubation. 57 refs., 7 figs.
- OSTI ID:
- 585489
- Journal Information:
- Geochimica et Cosmochimica Acta, Journal Name: Geochimica et Cosmochimica Acta Journal Issue: 21 Vol. 61; ISSN 0016-7037; ISSN GCACAK
- Country of Publication:
- United States
- Language:
- English
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