Field evidence for intrinsic aerobic chlorinated ethene cometabolism by methanotrophs expressing soluble methane monooxygenase

Ryan A. Wymore, M. Hope Lee, William K. Keener, Amber R. Miller, Frederick S. Colwell, Mary E. Watwood, Kent S. Sorenson

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Idaho National Laboratory's Test Area North is the site of a trichloroethene (TCE) plume resulting from waste injections. Previous investigations revealed that TCE was being attenuated relative to two codisposed internal tracers, tritium and tetrachloroethene, with a half-life of 9 to 21 years. Biological attenuation mechanisms were investigated using a novel suite of assays, including enzyme activity probes designed for the soluble methane monooxygenase (sMMO) enzyme. Samples were analyzed for chlorinated solvents, tritium, redox parameters, primary substrates, degradation products, bacterial community methanotrophic potential, and bacterial DNA. The enzyme probe assays, methanotrophic enrichments and isolations, and DNA analysis documented the presence and activity of indigenous methanotrophs expressing the sMMO enzyme. Three-dimensional groundwater data showed plume-wide aerobic conditions, with low levels of methane and detections of carbon monoxide, a by-product of TCE cometabolism. The TCE half-life attributed to aerobic cometabolism is 13 years relative to tritium, based on the tracer-corrected method. Similarly, a half-life of 8 years was estimated for cisdichloroethene (DCE). Although these rates are slower than most anaerobic degradation processes, they can be significant for large plumes. This investigation is believed to be the first documentation of intrinsic aerobic TCE and DCE cometabolism in an aquifer by indigenous methanotrophs.

Original languageEnglish (US)
Pages (from-to)125-139
Number of pages15
JournalBioremediation Journal
Volume11
Issue number3
DOIs
StatePublished - Dec 1 2007

Keywords

  • Activity-dependent enzyme probes
  • Cometabolism
  • Methane monooxygenase
  • Monitored natural attenuation
  • Trichloroethene

ASJC Scopus subject areas

  • Environmental Science(all)

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