Trichloroethene (TCE) is the most frequently detected organic contaminant in groundwater, is
classified as a probable human carcinogen, and exhibits toxicological effects on the human
endocrine, immune, developmental, and reproductive systems. While significant research
efforts have been devoted to the development of strategies for remediating TCE-contaminated
groundwater, their advancement is currently hindered by limitations in current methodologies
for measuring in situ reductive dechlorination rates, especially for sorbing solutes. This
dissertation describes the development, evaluation, and demonstration of a method for
measuring in situ reductive dechlorination rates that utilizes single-well, "push-pull" test
technology. Initial field tests indicated that trichlorofluoroethene (TCFE) could be used as a
surrogate for TCE in push-pull tests since (a) TCE and TCFE were transported similarly and
(b) TCFE underwent reductive dechlorination by a pathway analogous to that of TCE while
retaining the fluorine label. Because TCFE and TCE experienced sorption at the selected field
site, a novel data analysis technique called "forced mass balance" (FMB) was developed to
obtain in situ transformation rates of sorbing solutes from push-pull test data. The FMB
technique was evaluated by quantifying errors in rates derived by applying FMB to push-pull
test data generated by a numerical model. Results from simulated tests indicated that an
example in situ rate for the reductive dechlorination of TCFE, which was obtained by applying
FMB to field data, was underestimated relative to the true in situ rate by 10%. The utility of
the rate-determination method presented in this dissertation was demonstrated by using it to
evaluate the effectiveness of a chemical amendment, namely fumarate, at enhancing in situ
reductive dechlorination rates in TCE-contaminated groundwater. Reductive dechlorination
rates increased following three consecutive additions of fumarate in all five of the tested wells.
The development of the rate-determination method described in this dissertation advances the
state of bioremediation technology because methods for measuring in situ transformation rates
are needed to both assess the potential for natural attenuation and to quantify the effects of
bioremediation techniques in the field. / Graduation date: 2003
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/31130 |
| Date | 14 April 2003 |
| Creators | Hageman, Kimberly J. |
| Contributors | Field, Jennifer A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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