Biogeochemical Processes In Ethanol Stimulated Uranium Contaminated Subsurface Sediments

Journal Article · Sun Jun 15 04:00:00 EDT 2008 · Environmental Science & Technology, 42(12):4384-4390

DOI:https://doi.org/10.1021/es703082v· OSTI ID:936206

Mohanty, Santosh R; Kollah, Bharati; Hedrick, David B; Peacock, Aaron D; Kukkadapu, Ravi K; Roden, Eric E

A laboratory incubation experiment was conducted with uranium contaminated subsurface sediment to assess the geochemical and microbial community response to ethanol amendment. A classical sequence of TEAPs was observed in ethanol-amended slurries, with NO3- reduction, Fe(III) reduction, SO4 2- reduction, and CH4 production proceeding in sequence until all of the added 13C-ethanol (9 mM) was consumed. Approximately 60% of the U(VI) content of the sediment was reduced during the period of Fe(III) reduction. No additional U(VI) reduction took place during the sulfate-reducing and methanogenic phases of the experiment. Only gradual reduction of NO3 -, and no reduction of U(VI), took place in ethanol-free slurries. Stimulation of additional Fe(III) or SO4 2- reduction in the ethanol-amended slurries failed to promote further U(VI) reduction. Reverse transcribed 16S rRNA clone libraries revealed major increases in the abundance of organisms related to Dechloromonas, Geobacter, and Oxalobacter in the ethanolamended slurries. PLFAs indicative of Geobacter showed a distinct increase in the amended slurries, and analysis of PLFA 13C/12C ratios confirmed the incorporation of ethanol into these PLFAs. A increase in the abundance of 13C-labeled PLFAs indicative of Desulfobacter, Desulfotomaculum, and Desulfovibrio took place during the brief period of sulfate reduction which followed the Fe(III) reduction phase. Our results show that major redox processes in ethanol-amended sediments can be reliably interpreted in terms of standard conceptual models of TEAPs in sediments. However, the redox speciation of uranium is complex and cannot be explained based on simplified thermodynamic considerations.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 936206
• Report Number(s): PNNL-SA-58371; 19846; KP1704020
• Journal Information: Environmental Science & Technology, 42(12):4384-4390, Journal Name: Environmental Science & Technology, 42(12):4384-4390 Journal Issue: 12 Vol. 42
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
ADDITIVES
BENCH-SCALE EXPERIMENTS
BIOGEOCHEMISTRY
BIOREMEDIATION
ETHANOL
Environmental Molecular Sciences Laboratory
MICROORGANISMS
REDOX REACTIONS
SEDIMENTS
URANIUM