© 2002 - 2004
The University of Toronto
Department of Geology
All rights reserved
Revised: December 1 2004
Michelle Chartrand 416- 978-0825
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Chlorinated solvents are common ground water contaminants that can be degraded under both aerobic and anaerobic conditions. Compound specific isotope analysis (CSIA) has been used as a tool to identify biodegradation of chlorinated compounds and has the potential to be used to distinguish between different microbial degradation pathways. To date, my research has focused on stable carbon isotope analysis in two areas: verification of biodegradation at an anaerobic trichloroethene-contaminated fractured bedrock field site and the measurement of carbon fractionation factors during aerobic vinyl chloride degradation. While stable carbon isotope measurements of chlorinated compounds can provide valuable information, stable hydrogen isotope measurements can offer an additional line of evidence to verify biodegradation and to distinguish between different degradation pathways in the field. The method for stable hydrogen isotope measurements of chlorinated compounds is tedious and time consuming: the individual chlorinated compound in a sample must be first separated, the fractions collected, and quantitatively reduced to H 2 gas using off-line techniques. Currently, no on-line system exists for the measurement of hydrogen isotopes for chlorinated compounds. Current (and near future) Research Projects:
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Martin Elsner 416-978-0825 |
If Compound Specific Isotope Analysis (CSIA) is used to detect and quantify the in-situ (bio)degradation of organic contaminants, fractionation factors must be robust and characteristic of the respective (bio)transformation reaction. While such values have long been regarded as “black box parameters”, I have recently developed an evaluation procedure that allows their conversion into site-specific apparent kinetic isotope effects (AKIE). Such insight opens a range of new possibilities. By comparison with reported kinetic isotope effects (KIE) the robustness of fractionation can be established. Characteristic AKIE allow the identification of degradation pathways from isotope data. Knowledge of KIE for a certain degradation reaction allows the approximate prediction of isotope fractionation and may serve to direct research efforts for new compounds. My current research projects: |
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Sarah Hirschorn 416-978-6807
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Field of research: Stable carbon isotope fractionation during biodegradation of chlorinated aliphatic hydrocarbons. Specifically, examining the relationship between microbial enzymatic degradation pathways and isotopic fractionation during biodegradation (aerobic and anaerobic) of chlorinated ethanes such as 1,2-dichloroethane and 1,1,1-trichloroethane. | |
Dr. Georges Lacrampe-Couloume
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Field of research: Stable Isotope Geochemistry |
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Silvia Mancini 416-978-6807
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My doctoral thesis focuses on identifying the sources of petroleum hydrocarbons and determining their fate and transport in groundwater systems using carbon and hydrogen isotope analysis. Specifically, I will examine the abiotic and biotic controls on isotopic fractionation during biodegradation of petroleum hydrocarbons. Once isotopic fractionation is constrained for different microbial populations, biodegradation pathways and environmental conditions, it can be used to accurately quantify the extent of biodegradation of petroleum products and help elucidate biodegradation pathways and mechanisms in the field. This information will aid in distinguishing between biodegradation versus non-degradative physical processes of petroleum products and in determining if biodegradation can be used as a clean-up strategy to degrade pollutants to concentrations that satisfy regulators.
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Jennifer McKelvie
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My Ph.D. research aims to improve the ability of compound specific carbon and hydrogen isotope analysis to assess the contribution of biodegradation to the natural attenuation of methyl tert-butyl ether (MTBE), a common fuel oxygenate. If carbon and hydrogen isotopic values are to be used to estimate the extent of biodegradation at contaminated field sites, appropriate enrichment factors must be used. My project will first comprise of laboratory experiments that measure the isotopic enrichment occurring during MTBE biodegradation under different environmental conditions. Analysis of field samples will then take place in order to confirm the occurrence of biodegradation at two contaminated sites. | |
Penny Lea Morrill 416-978-6807
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Ph.D. Thesis: My doctoral research focused on the application of stable
carbon isotopic analysis to constrain sources and fates of chlorinated
solvent contaminants in groundwater systems. Combining techniques from
analytical organic chemistry, isotopic analysis, geochemistry,
hydrogeology, microbiology and computer modelling, I developed the use of
stable isotope analysis as a tool to investigate and verify the extent of
chlorinated ethene biodegradation in groundwater systems.
Postdoctoral Research: In the new year I will move to Washington D.C. for a postdoctoral fellowship in the Geophysical Laboratory at the Carnegie Institution of Washington with Dr. Marilyn Fogel. Once I get settled in, I propose to investigate the synthesis of, and the diagnostic isotopic indicators for, abiogenic hydrocarbons in hydrothermal systems in both laboratory and field studies. |
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| Jon Telling Post Doctoral Fellow 416-978-0825
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A number of recent studies suggest that abiotic water-rock interactions may provide energy to sustain subsurface microbial ecosystems completely separate from surface photosynthesis. These subsurface ecosystems may provide terrestrial analogues for microbial ecosystems on other planets and moons. Recent research has shown that highly saline fluids trapped in Precambrian Shield areas of the world contain substantial quantities of hydrogen, methane and higher molecular weight hydrocarbons, with their 13 C and D ratios indicating an abiotic origin (Sherwood Lollar et al., 2002). Possible abiotic mechanisms for both hydrocarbon and hydrogen formation include serpentinisation reactions and late magmatic processes. Additional abiotic hydrogen forming processes include the crushing of minerals along faults, and the radiolysis of water. Working in association with other members of the Indiana-Princeton-Tennesee Astrobiology Initiative (http://www.indiana.edu/~deeplife/), my research focuses on the origin and microbial utilization of H 2 and hydrocarbon-rich fluids trapped within the Canadian Shield. In particular, my research aims to answer the following questions: • Can abiotic rock-water reactions in the Canadian Shield provide sufficient energy (fermentable substrates, electron donors, electron acceptors) and materials (organic compounds, trace elements) to sustain subsurface microbial ecosystems completely separate from photosynthesis over long (geologic) periods of time? • Are microorganisms presently utilizing these abiotic resources? • Using these ecosystems as analogues for life on other planets, can we develop methods to detect life on other planets e.g. future drilling missions to Mars? |
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Nancy VanStone |
Field of research: Iron permeable reactive barriers ("iron walls") have grown in popularity over the years at sites where groundwaters are highly contaminated with chlorinated solvents, like PCE and TCE. Using stable carbon isotopic analysis, we are examining the details of abiotic reactions on iron walls to corroborate findings from kinetic studies, as well as highlight the power of isotopic analysis for elucidating mechanistic information.
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Min Wong wong@geology.utoronto.ca
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