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Barbara Sherwood Lollar,Professor,Department of GeologyContaminant Hydrogeology and Hydrocarbon GasesCurrent research in the Stable Isotope Laboratory (SIL)focuses on two main areas of stable isotope geochemistry:contaminant hydrogeology and hydrocarbon gases and theirimplications for deep subsurface microbiology. In thisarticle I will highlight some of the ongoing work in the lab.Contamination of groundwater resources with petroleumhydrocarbons and chlorinated solvents is widespread inboth rural and urban settings and represents one of the mosturgent challenges facing environmental science. The SIL atthe University of Toronto is one of the first to have successfullydeveloped and applied techniques for using compoundspecific stable carbon isotopes to investigate controls on theorigin of these priority pollutants and on their transport andfate in the subsurface. Research in the lab has provided anessential foundation for applying compound specific carbonisotope analysis (CSIA) in groundwater - characterizing theisotopic fractionation associated with dissolution, volatilizationand adsorption of a wide variety of priority pollutants– including chlorinated solvents, alkanes, aromatichydrocarbons and fuel additives such as MtBE. Ph.D.student Mike Howlett is currently conducting a microcosmstudy investigating stable carbon isotope fractionation duringaerobic and anaerobic chlorobenzene biodegradationby natural microbial flora from a site contaminated withchlorinated benzenes. In addition, he is in the midst of anovel set of experiments investigating hydrogen isotopefractionation during degradation of chlorinated ethanes.Using analytical technologies developed in the SIL, Mikeis working on the leading edge of hydrogen isotope analysis,conducting the first online hydrogen isotope microbialdegradation experiment.Also focusing on contaminant hydrogeology, M.Sc.student Tiffany Johnson is continuing work on vinylchloride degradation. Vinyl chloride (the building block ofplastics), is a known carcinogen and a ubiquitous groundwatercontaminant. Tiffany will be using carbon isotopePostdoc Ken Voglesonger collectingsubsurface samples from a base metalmine.8analysis to determine degradation mechanisms of vinylchloride under aerobic conditions, and will be working todetermine the controls on isotopic fractionation of vinylchloride under anaerobic conditions, where variability infractionation has been reported. Results from her researchare key to determining the ability of isotope analysis toquantify vinyl chloride degradation in the field.PhD student Mike Howlett analyzingchlorobenzenesIn addition to research on organic contaminants, SIL’sresearch on the origin and fate of hydrocarbon gases in
groundwater systems continues. It is generally recognizedthat the first simple organic molecules on earth andelsewhere in the solar system must have been formed byabiogenic reactions. To date it had been largely assumedthat after the evolution of life on earth, biologically mediatedreactions overprinted evidence of this pre-bioticabiogenic history. Our research is the first indication thatabiogenic reactions that contributed to the formation ofprimary organic molecules on the early earth continued toplay a significant role in the production of hydrocarbons inthe Precambrian rocks of the earth’s crust. We reported thefirst direct evidence for inorganic synthesis of methane andhigher hydrocarbons in crystalline rocks of the CanadianShield from Kidd Creek Mine (Timmins, Ontario) based onthe carbon and hydrogen isotopic values of C1-C4 alkanes(Sherwood Lollar et al. (<strong>20</strong>02)).Research in Fracture Fluid, Hydrocarbon and H2 Gases andDeep Subsurface MicrobiologyIn addition, one of the most exciting scientific discoveriesof the past decade has been the discovery that microbiallife exists in the subsurface at depths hitherto unanticipated- the so-called “deep biosphere”. Work in our lab, in collaborationthe Indiana Princeton Tennessee team sponsoredthrough the NASA Astrobiology Institute (NAI), addressesthe question of whether the abundant hydrocarbon andhydrogen gases we have documented in mines in PrecambrianShield rocks in Canada, Finland and in South Africamay serve as chemical reactants or substrates supportingmicrobial populations in the deep subsurface. This nationaland international research consortium studies the origin,evolution, distribution and future of life on Earth and in theuniverse.Over the past 5 years, our research group has focused ongeochemical reactions sustaining deep subsurface microbiologythrough both experimental work and field studiesin mines more than 3.5 Km beneath the surface in PrecambrianShield rocks. See www.indiana.edu/~deeplife formore information. Postdoctoral Fellow Ken Voglesonger’sand PhD student Steffi Tille’s research is focused on understandingthe details of the geochemical water-rock reactionsproducing substrates, understanding the cycling of carbonspecies and the transition from abiotic (geologically) dominatedfractures and those where active microbial communitiesdominate.The geologically stable Precambrian cratons of Earth maybe among the closest terrestrial analogues to single-plateplanets such as Mars. Our research demonstrates that thehabitability of the Earth’s deep crust is not restricted to sitesof localized hydrothermal activity such as mid-ocean vents.While postulated vents have been suggested as potentialsources for CH4 reported in the Martian atmosphere, andas possible targets for exploration for life on Mars, thePrecambrian Shield fracture water research suggests analternative model whereby gases such as H2 and CH4 derivedfrom alteration of the Martian crust might be sequesteredin fractures and episodically released analogous to theterrestrial Precambrian cratons. Ongoing investigation intofracture-controlled geologic energy for life in PrecambrianShield sites in the Arctic where permafrost and clathratedeposits are common will provide additional constraints onthe habitability of the Earth’s deep “cool” biosphere andimportant implications for the search for life on Mars.In other SIL news, this past summer saw the graduation ofDr.’s Jennifer McKelvie, Michelle Chartrand, Silvia Manciniand Sarah Hirschorn.9
Page 1 and 2: Alumni NEWSIssue 17 February 2008A
Page 3 and 4: on our food sources, health, and cl
Page 5 and 6: career in both the executive and te
Page 7: Reginald Aldworth Daly(1871-1957)Di
Page 11 and 12: Alumni Create a New Graduate Schola
Page 13 and 14: News of Former Students1960’s and
Page 15 and 16: Bill Sercombe B.A.Sc. 1978 (Geologi
Page 17 and 18: of my M.Sc. And Steve, if you are r
Page 19 and 20: The Explorers FundAs announced in 2

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