Induced-polarization measurements on unconsolidated sediments from a site of active hydrocarbon biodegradation

Gamal Z.A. Abdel Aal, Lee D. Slater, Estella A. Atekwana

Research output: Contribution to journalArticlepeer-review

84 Scopus citations

Abstract

To investigate the potential role that indigenous microorganisms and microbial processes may play in altering lowfrequency electrical properties, induced-polarization (IP) measurements in the frequency range of 0.1 to 1000 Hz were acquired from sediment samples retrieved from a site contaminated by hydrocarbon undergoing intrinsic biodegradation. Increased imaginary conductivity and phase were observed for samples from the smear zone (contaminated with residual-phase hydrocarbon), exceeding values obtained for samples contaminated with dissolved-phase hydrocarbons, and in turn, exceeding values obtained for uncontaminated samples. Real conductivity, although generally elevated for samples from the smear zone, did not show a strong correlation with contamination. Controlled experiments on uncontaminated samples from the field site indicate that variations in surface area, electrolytic conductivity, and water content across the site cannot account for the high imaginary conductivity observed within the smear zone. We suggest that microbial processes may be responsible for the enhanced IP response observed at contaminated locations. Scanning electron microscopy and IP measurements during acid leaching indicate that etched pits on mineral surfaces - caused by the production of organic acids or formed during microbial colonization of these surfaces - are not the cause of the IP enhancement. Rather, we postulate that the accumulation of microbial cells (biofilms) with high surface area at the mineral-electrolyte interface generates the IP response. These findings illustrate the potential use of electrical measurements to noninvasively monitor microbial activity at sites undergoing natural hydrocarbon degradation.

Original languageEnglish (US)
Pages (from-to)H13-H24
JournalGEOPHYSICS
Volume71
Issue number2
DOIs
StatePublished - 2006

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

Keywords

  • Geochemistry
  • Microorganisms
  • Organic compounds
  • Scanning electron microscopy
  • Sediments
  • Soil pollution

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