Availability of ferric iron for microbial reduction in bottom sediments of the freshwater tidal Potomac River

Journal Article · Wed Oct 01 00:00:00 EDT 1986 · Appl. Environ. Microbiol.; (United States)

OSTI ID:5008924

Lovley, D R; Phillips, E J.P.

The distribution of Fe(III), its availability for microbial reduction, and factors controlling Fe(III) availability were investigated in sediments from a freshwater site in the Potomac River Estuary. Fe(III) reduction in sediments incubated under anaerobic conditions and depth profiles of oxalate-extractable Fe(III) indicated that Fe(III) reduction was limited to depths of 4 cm or less, with the most intense Fe(III) reduction in the top 1 cm. In incubations of the upper 4 cm of the sediments, Fe(III) reduction was as important as methane production as a pathway for anaerobic electron flow because of the high rates of Fe(III) reduction in the 0- 0.5-cm interval. Most of the oxalate-extractable Fe(III) in the sediments was not reduced and persisted to a depth of at least 20 cm. The incomplete reduction was not the result of a lack of suitable electron donors. The oxalate-extractable Fe(III) that was preserved in the sediments was considered to be in a form other than amorphous Fe(III) oxyhydroxide, since synthetic amorphous Fe(III) oxyhydroxide, amorphous Fe(III) oxyhydroxide adsorbed onto clay, and amorphous Fe(III) oxyhydroxide saturated with adsorbed phosphate or fulvic acids were all readily reduced. Fe/sub 3/O/sub 4/ and the mixed Fe(III)-Fe(II) compound(s) that were produced during the reduction of amorphous Fe(III) oxyhydroxide in an enrichment culture were oxalate extractable but were not reduced, suggesting that mixed Fe(III)-Fe(II) compounds might account for the persistence of oxalate-extractable Fe(III) in the sediments.

• Research Organization: Geological Survey, Reston, VA
• OSTI ID: 5008924
• Journal Information: Appl. Environ. Microbiol.; (United States), Vol. 52:4
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
54 ENVIRONMENTAL SCIENCES
IRON
BIODEGRADATION
BIOGEOCHEMISTRY
BIOLOGICAL AVAILABILITY
REDUCTION
SPATIAL DISTRIBUTION
ESTUARIES
EXPERIMENTAL DATA
IRON COMPOUNDS
POTOMAC RIVER
SEDIMENT-WATER INTERFACES
SEDIMENTS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECOMPOSITION
DISTRIBUTION
ELEMENTS
GEOCHEMISTRY
INFORMATION
INTERFACES
METALS
NUMERICAL DATA
RIVERS
STREAMS
SURFACE WATERS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
550500* - Metabolism
520200 - Environment
Aquatic- Chemicals Monitoring & Transport- (-1989)