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MICROFRACTURE SURFACE GEOCHEMISTRY AND ADHERENT MICROBIAL POPULATION METABOLISM IN TCE-CONTAMINATED COMPETENT BEDROCK
Citation:
EIGHMY, T. T., J. C. SPEAR, J. CASE, M. MILLS, K. NEWMAN, N. KINNER, H. MARBET, J. CASAS, W. BOTHNER, J. COULBURN, L. S. TISA, M. MAJKO, E. R. SULLIVAN, AND M. E. GONSOULIN. MICROFRACTURE SURFACE GEOCHEMISTRY AND ADHERENT MICROBIAL POPULATION METABOLISM IN TCE-CONTAMINATED COMPETENT BEDROCK. GEOMICROBIOLOGY JOURNAL. Taylor & Francis, Inc., Philadelphia, PA, 24(3):307-330, (2007).
Impact/Purpose:
Journal Article
Description:
A TCE-contaminated competent bedrock site in Portsmouth, NH was used to determine if a relation existed between microfracture (MF) surface geochemistry and the ecology and metabolic activity of attached microbes relative to terminal electron accepting processes (TEAPs) and TCE biodegradation. Petrography and XRD revealed that carbonates and quartz were the dominant MF surface precipitates. Oxidized and reduced iron species were identified with XPS on the MF precipitate surfaces. SIMS mass fragment fingerprints revealed suggested that TCE, PCE and/or VC were possibly adsorbed to NOM on the MF surfaces. Sulfate was the dominant anion in the packer sample water (110-120 mg/L). No sulfide was detected. H2 was present in a number of the BBC wells at the site (2.2 – 7.3 nM). Amplification with specific primer sets of seven MFs from BBC5 showed the presence of bacteria, Archaea, anaerobic dehalorespirers (Dehalococcoides sp.), sulfate reducing bacteria, and iron reducing bacteria (Geobacteraceae). Fe was the dominant MF surface element the open fracture system based on the preponderance of primer data. The detection of Dehalococcoides by PCR on most MF surfaces and the putative presence of daughter products of dehalorespiration as well as H2 concentrations support the role of Dehalococcoides sp. in dehalorespiration in the MF networks.
