Quantifying Subsurface Biodegradation
Type |
- Natural Attenuation Evaluation
- Site Characterization
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Location |
Norman Municipal Landfill, Norman, OK |
Partners |
University
of Oklahoma |
Technology |
- Integrated Geochemical and Biochemical Characterization Methods
- Alkylbenzenes Process Probes
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Contaminants |
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Description |
Environmental professionals and regulators are routinely tasked
with assessing the feasibility of natural attenuation as an alternative
to traditional remediation technologies at contaminated sites. Toxics
Program scientists are developing methods that can be used by environmental
professionals and regulators to assess the long-term potential for
biodegradation of contaminants. USGS scientists and their university
colleagues working at the Norman (Oklahoma) Municipal Landfill research
site have developed two methods to help with this assessment.
- The first method uses a novel combination of microbiological
and geochemical techniques. This method involves the detailed
mapping of overlapping biogeochemical zones in contamination plumes.
Such zone mapping is not possible when either microbiological
or geochemical methods are used in isolation. Identification of
these biogeochemical zones is key to evaluating the efficacy of
natural attenuation because organic contaminants can degrade at
different rates and to different extents depending on the dominant
microbiological process.
- The second method relies on characterizing the composition and
ratios of isomers of volatile hydrocarbons in ground water to
determine whether biodegradation is a dominant mechanism for attenuation
of ground-water contaminants. Isomers are compounds having similar
physical-chemical properties, but slightly different chemical
structures. Isomers of volatile hydrocarbons should be attenuated
in contaminated aquifers in the same manner if physical processes,
such as advection, sorption, and diffusion, control contaminant
transport. In other words the isomers migrate through the subsurface
the same distance from the source of contamination. When the isomers
show strikingly different attenuation rates or transport distances
in contaminated aquifers, it is evident that biodegradation is
the dominant process causing attenuation of these compounds. In
this instance, the hydrocarbon isomers present in the landfill
leachate serve as "process probes." USGS researchers have developed
an approach where isomeric alkylbenzenes (hydrocarbons with ring-like
chemical structures that have the same chemical formulas, but
slightly different structures) are used as probes to discover
the processes that control the migration and fate of contaminants.
This "process probe" approach has the potential to become one
of the criteria for establishing the importance of biodegradation
processes in contaminated aquifers.
USGS scientists have used these methods to demonstrate that natural
attenuation of contaminants from the Norman Landfill is taking place.
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More Information |
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Contact |
Scott Christenson, USGS, Oklahoma District, Oklahoma
City, OK, |
Publications |
- Cozzarelli, I.M., Suflita, J.M., Ulrich, G.A., Harris, S.H.,
Scholl, M.A., Schlottmann, J.L., and Christenson, S., 2000,
- Geochemical and microbiological methods for evaluating anaerobic
processes in an aquifer contaminated by landfill leachate: Environmental
Science and Technology, v. 34, no. 18, p. 4025-4033.
- Eganhouse, R.P., Cozzarelli, I.M., Scholl, M.A., and Matthews,
L.L., 2001,
- Natural
attenuation of volatile organic compounds (VOCs) in the leachate
plume of a municipal landfill-Using alkylbenzenes as process probes:
Ground Water, v. 39, no. 2, p. 192-202.
- Eganhouse, R.P., Dorsey, T.F., Phinney, C.P., and Westcott,
A.W., 1996,
- Processes affecting the fate of monoaromatic hydrocarbons in
an aquifer contaminated by crude oil: Environmental Science and
Technology, v. 30, p. 3304-3312.
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Links |
Toxics Landfill Remediation Projects
USGS Information on Natural Attenuation
Other USGS Landfill Remediation Studies
- Area 6 Landfill, Naval Air Station Whidbey Island, Island County,
Washington
- Landfill Leachate Mobilizes
Arsenic Bound in Aquifer Sediments: Saco, Maine
- Surface
Geophysical Investigation of a Chemical Waste Landfill in Northwestern
Arkansas
- Operable Unit 1 (Landfill), Naval Undersea Warfare Center,
Division Keyport, Washington
- Identification
of Potential Water-Bearing Zones by the Use of Borehole Geophysics
in the Vicinity of Keystone Sanitation Superfund Site, Adams County,
Pennsylvania, and Carroll County, Maryland: USGS WRIR 97-4104
(pdf)
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