In situ measurement of methane oxidation in groundwater by using natural-gradient tracer tests

Journal Article · Mon Jul 01 04:00:00 EDT 1991 · Applied and Environmental Microbiology; (United States)

OSTI ID:5412702

Smith, R L ^[1]; Howes, B L ^[2]; Garabedian, S P ^[3]

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1. Geological Survey, Lakewood, CO (USA)
2. Woods Hole Oceanographic Inst., MA (USA)
3. Geological Survey, Marlborough, MA (USA)

Methane oxidation was measured in an unconfined sand and gravel aquifer (Cape Cod, Mass.) by using in situ natural-gradient tracer tests at both a pristine, oxygenated site and an anoxic, sewage-contaminated site. The tracer sites were equipped with multilevel sampling devices to create target grids of sampling points; the injectate was prepared with groundwater from the tracer site to maintain the same geochemical conditions. Methane oxidation was calculated from breakthrough curves of methane relative to halide and inert gas (hexafluoroethane) tracers and was confirmed by the appearance of {sup 13}C-enriched carbon dioxide in experiments in which {sup 13}C-enriched methane was used as the tracer. A V{sub max} for methane oxidation could be calculated when the methane concentration was sufficiently high to result in zero-order kinetics throughout the entire transport interval. Methane breakthrough curves could be simulated by modifying a one-dimensional advection-dispersion transport model to include a Michaelis-Menten-based consumption term for methane oxidation. The K{sub m} values for methane oxidation that gave the best match for the breakthrough curve peaks were 6.0 and 9.0 {mu}M for the uncontaminated and contaminated sites, respectively. Natural-gradient tracer tests are a promising approach for assessing microbial processes and for testing in situ bioremediation potential in groundwater systems.

• OSTI ID: 5412702
• Journal Information: Applied and Environmental Microbiology; (United States), Journal Name: Applied and Environmental Microbiology; (United States) Vol. 57:7; ISSN 0099-2240; ISSN AEMID
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540211* -- Environment
Terrestrial-- Basic Studies-- Radiometric Techniques-- (1990-)
ALKANES
CARBON 13
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON ISOTOPES
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CLEANING
CONTAMINATION
DECONTAMINATION
EVEN-ODD NUCLEI
GROUND WATER
HYDROCARBONS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MEASURING METHODS
METHANE
MICROORGANISMS
NUCLEI
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
STABLE ISOTOPES
TRACER TECHNIQUES
WATER