Geophysical Signatures of Microbial Activity at Hydrocarbon Contaminated Sites: A Review

Abstract

Microorganisms participate in a variety of geologic processes that alter the chemical and physical properties of their environment. Understanding the geophysical signatures of microbial activity in the environment has resulted in the development of a new sub-discipline in geophysics called "biogeophysics". This review focuses primarily on literature pertaining to biogeophysical signatures of sites contaminated by light non-aqueous phase liquids (LNAPL), as these sites provide ideal laboratories for investigating microbial-geophysical relationships. We discuss the spatial distribution and partitioning of LNAPL into different phases because the physical, chemical, and biological alteration of LNAPL and the subsequent impact to the contaminated environment is in large part due to its distribution. We examine the geophysical responses at contaminated sites over short time frames of weeks to several years when the alteration of the LNAPL by microbial activity has not occurred to a significant extent, and over the long-term of several years to decades, when significant microbial degradation of the LNAPL has occurred. A review of the literature suggests that microbial processes profoundly alter the contaminated environment causing marked changes in the petrophysical properties, mineralogy, solute concentration of pore fluids, and temperature. A variety of geophysical techniques such as electrical resistivity, induced polarization, electromagnetic induction, ground penetrating radar, and self potential are capable of defining the contaminated zones because of the new physical properties imparted by microbial processes. The changes in the physical properties of the contaminated environment vary spatially because microbial processes are controlled by the spatial distribution of the contaminant. Geophysical studies must consider the spatial variations in the physical properties during survey design, data analysis, and interpretation. Geophysical data interpretation from surveys conducted at LNAPL-contaminated sites without a microbial and geochemical context may lead to ambiguous conclusions.

Department(s)

Geosciences and Geological and Petroleum Engineering

Sponsor(s)

United States. Environmental Protection Agency
Petroleum Research Fund

Keywords and Phrases

Biogeophysics; Contaminated Environment; Contaminated Sites; Data Analysis; Electrical Resistivity; Geologic Process; Geophysical Data; Geophysical Methods; Geophysical Techniques; Ground Penetrating Radar; Induced Polarization; Large Parts; Light Non-aqueous Phase Liquids; Microbial Activities; Microbial Degradation; Microbial Process; Petrophysical Properties; Pore Fluids; Self Potential; Short Time Frames; Solute Concentrations; Spatial Distribution; Spatial Variations; Survey Design; Analytical Geochemistry; Bacteria; Bacteriology; Biodegradation; Contamination; Crystallography; Degradation; Electric Conductivity; Electromagnetic Induction; Geophysics; Hydrocarbons; Mineralogy; Minerals; Size Distribution; Surveys; Lead; Bacterium; Chemical Property; Data Interpretation; Geophysical Method; Microbial Activity; Microorganism; Nonaqueous Phase Liquid; Physical Property; Spatial Variation; Bacteria (microorganisms); LNAPL Contamination

International Standard Serial Number (ISSN)

0169-3298

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2010 Springer Verlag, All rights reserved.

Publication Date

01 Mar 2010

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