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dc.contributor.authorRectanus, Heather Veithen_US
dc.date.accessioned2014-03-14T20:18:37Z
dc.date.available2014-03-14T20:18:37Z
dc.date.issued2006-10-31en_US
dc.identifier.otheretd-11162006-234852en_US
dc.identifier.urihttp://hdl.handle.net/10919/29614
dc.description.abstractReductive dechlorination is a significant natural attenuation process in chloroethene-contaminated aquifers where organic carbon combined with reducing redox conditions support active dechlorinating microorganisms. At sites where natural organic carbon (NOC) associated with the aquifer matrix provides fermentable organics, the ability to measure the NOC is needed to assess the potential for the long-term sustainability of reductive dechlorination. This study focused on developing a method to measure the potentially bioavailable organic carbon (PBOC) associated with aquifer sediment. To measure NOC and evaluate its biodegradability, liquid extraction techniques on aquifer sediment were investigated. Single extractions with different extracting solutions showed that extractable organic carbon associated with the sediment ranged from 1-38% of the total organic carbon content (TOCs). Bioassay experiments demonstrated that 30-60% of the extractable organic carbon can be utilized by a microbial consortium. Alternating between 0.1% pyrophosphate and base solutions over multiple extractions increased the rate of removal efficiency and targeted two organic carbon pools. The result of the investigation was a laboratory method to quantify organic carbon from the aquifer matrix in terms of the PBOC. In the second part, the extractable PBOC was shown to biodegrade under anaerobic conditions, to produce H2 at levels necessary to maintain reductive dechlorination, and to support reductive dechlorination in enrichment cultures. For the third part of the research, the difference in extractable organic carbon inside and outside of a chloroethene-contaminated plume was examined through the combination of PBOC laboratory data and field parameters. Supported by ground-water constituent data, the PBOC extraction and bioassay studies showed that less extractable organic carbon was present inside than outside of the chloroethene plume. The final part of the research investigated the distribution of PBOC extractions across six contaminated sites. PBOC extractions were directly correlated to the TOCs, soft carbon content, and level of reductive dechlorination activity at the sites. Based on these correlations, a range for organic carbon potentially available to subsurface microorganisms was proposed where the upper bound consisted of the soft carbon and the lower bound consisted of the PBOC.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartHVR_Finalv4.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectNatural Organic Carbonen_US
dc.subjectReductive Dechlorinationen_US
dc.subjectMonitored Natural Attenuationen_US
dc.subjectPotentially Bioavailable Organic Carbonen_US
dc.titleSustainability of reductive dechlorination at chlorinated solvent contaminated sites: Methods to evaluate biodegradable natural organic carbonen_US
dc.typeDissertationen_US
dc.contributor.departmentCivil Engineeringen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineCivil Engineeringen_US
dc.contributor.committeememberVikesland, Peter J.en_US
dc.contributor.committeememberChapelle, Francis H.en_US
dc.contributor.committeememberLoganathan, G. V.en_US
dc.contributor.committeememberBerry, Duane F.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-11162006-234852/en_US
dc.contributor.committeecochairWiddowson, Mark A.en_US
dc.contributor.committeecochairNovak, John T.en_US
dc.date.sdate2006-11-16en_US
dc.date.rdate2009-12-04
dc.date.adate2006-12-04en_US


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