Barbara Sherwood Lollar

University Professor, Dr. Norman Keevil Chair in Ore Deposits Geology, CC, FRS, NAE, NAS, FRSC, FRCGS
ES 3106, Department of Earth Sciences, 22 Ursula Franklin St., Toronto, ON M5S 3B1



Institut de Physique du Globe de Paris (IPGP) Université Paris Cité
Department of Chemical Engineering and Applied Chemistry
Department of Chemistry

Fields of Study

Areas of Interest


I. Research Program in Ancient Waters and Deep Subsurface Biosphere

a rock in ancient rusty orange coloured waterSherwood Lollar’s pioneering research on the geochemistry of deep crustal fluids has focused on fracture fluids 1–3 km deep in Precambrian Shield rocks across Canada, Fennoscandian and South Africa. Her 2002 paper, highlighted on the cover of Nature, demonstrated that saline groundwaters in hydrogeologically isolated fracture networks in such ancient crystalline rock were dominated by the products of water-rock interaction including both mM concentrations of hydrogen derived from radiolysis and serpentinization; and abiogenic hydrocarbon gases produced via Fischer-Tropsch synthesis and polymerization reactions (Sherwood Lollar et al., 2002). Subsequent papers provided isotopic models to deal with the difficult problem of distinguishing between abiotically generated hydrocarbons and conventional biologically-produced methane (Sherwood Lollar et al., 2006 Chemical Geology; 2008 GCAEtiope & Sherwood Lollar, 2013 Reviews of Geophysics) and are highly cited not only in hydrocarbon geochemistry but by colleagues in astrobiology and space exploration. In 2006, in Science, a scientist in a mine testing and collecting ancient groundwaterSherwood Lollar and colleagues in microbiology (Lin et al. 2006) demonstrated the role of such H2-rich fluids in sustaining chemolithotrophic microbial communities at 2.8 km below the surface in the deep gold mines of South Africa—one of the deepest microbial ecosystems yet discovered. Most recently, by incorporating conservative noble gas tracers, Sherwood Lollar’s work has demonstrated the extreme antiquity of these hydrogeologically ancient fracture waters—with residence times ranging from tens of millions of years in the Witwatersrand basin (Lippmann-Pipke et al., 2011 Chemical Geology) to billions of years in the Timmins mine in Northern Ontario Canada (Holland et al., 2013 Nature, Warr et al., 2018 GCA). Continuing work in this area seeks to determine the extent and volume of this isolated hydrosphere; to determine the relationship of the free flowing fracture waters to trapped fluid inclusions; and to determine the habitability of this exotic realm of the deep subsurface and its implications for the search for extinct or extant life on Mars and elsewhere.

Currently recruiting for new postdoctoral positions. Research Opportunities 

II. Research Program in Compound Specific Isotope Analysis Innovations in Contaminant Hydrogeology

Dr. Sherwood Lollar's research in a scientist collecting groundwater in a bucketgroundwater quality and remediation—specifically investigations of degradation of toxic organic compounds using stable isotopes—led the field of stable carbon isotope analysis in environmental geochemistry of organic contaminants in groundwater. Her research established the scientific principles involved in using compound specific stable carbon isotope signatures, rather than just concentration levels of contaminants, to determine the source of contaminants in groundwater and to track their movement, fate, and particularly, the effectiveness of proposed environmental clean-up strategies. A fundamental aspect of Dr. Sherwood Lollar's research involved recognizing the ability to develop Compound Specific Isotope Analysis (CSIA) as a novel quantitative tool. One of Sherwood Lollar's earliest papers in this field (Sherwood Lollar et al., 1999) provided the first quantification in the literature of the dramatic isotopic fractionation effects involved in biodegradation of chlorinated solvents compared and contrasted to petroleum hydrocarbons, and presented a framework of essential criteria for successful field applications. In a series of key papers to follow, her research team demonstrated that isotope fractionation during biodegradation of a host of priority organic contaminants is typically controlled by a Rayleigh distillation model. This reproducible and predictable Stable Isotope Lab scientists doing field workbehaviour is essential for the use of isotope fractionation as a means, not just to identify and monitor biodegradation, but to provide an alternative quantitative measure of the extent of biodegradation and a new basis for calculation of biodegradation rates. Dr. Sherwood Lollar is one of lead authors of the United States Environmental Protections Agency EPA Guidance Document (EPA 600/R-08/148) on the CSIA approach for evaluating environmental clean-up and risk assessment of groundwater contamination.

 A second important aspect and corollary of these results is that the degree of fractionation observed during transformation of a compound is controlled by the specifics of the reaction mechanisms, or which bonds are broken. This second important feature of Sherwood Lollar's research was explored in a series of impactful publications that demonstrated the ability to use CSIA to identify different reaction mechanisms at work at field sites. In situ degradation remediation schemes involving both biotic and abiotic processes are a major focus of R&D on site remediation for organic contaminants. Dr. Sherwood Lollar's research enabled CSIA to improve assessment of remediation effectiveness and to improve capacity for trouble-shooting and optimizing remedial schemes by providing an innovative natural probe for distinguishing degradation processes—a feature recognized by the prestigious 2012 Eni Prize for Protection of the Environment ( In their most recent work Sherwood Lollar's group is demonstrating that CSIA is sensitive enough to identify differences in enzymatic activity controlling degradation of key pollutants. Their work recently demonstrated that for degradation of some chlorinated ethanes via a single C-Cl cleavage, subtle differences in the details of the enzymes-substrate interactions can have profound effects on the observed fractionation compared to abiotic and theoretical KIE. This was shown both in systems where the same enzyme acts upon two different substrates (1,1,1-TCA and CF; Chan et al., 2012) and where two distinct yet similar enzymes act on two similar substrates (1,1,1-TCA and 1,1-DCA) (Sherwood Lollar et al., 2010). Novel applications at contaminated fields sites include high resolution CSIA to derive in situ biodegradation rates (Passeport et al., 2014; 2016) and applications of CSIA to investigate environmental fate of HCH compounds (Chartrand et al., 2015) and CFCs (Horst et al., 2015; 2016).

Currently recruiting for new postdoctoral positions. Research Opportunities 



Barbara Sherwood Lollar CC FRS NAE FRSC FRCGS - University Professor in Earth Sciences, University of Toronto is a Fellow of the American Geophysical Union (2015), the Geochemical Society (2019) and European Association of Geochemistry (2019). She is Co-Director of the Canadian Institute for Advanced Studies (CIFAR) program Earth 4D – Subsurface Science and Exploration.  She is currently a member of the Eni Prize Commission (2013-2021), the American Geophysical Union Honors and Recognition Committee, the United States National Academy of Sciences Space Studies Board, the U.S. National Academy Decadal Survey Steering Committee for Planetary Sciences and Astrobiology, the Fellows Selection Committee for the Royal Society London UK, the International Continental Drilling Program Science Advisory Committee, among others.
Sherwood Lollar’s pioneering work establishing the principles for using isotopic tracers to identify, and most importantly quantify, microbial and chemical transformation of groundwater contaminants has had a global impact in the field of drinking water remediation. Deeper in the Earth’s crust, her work coupling investigations of the deep subsurface carbon, hydrogen, and sulfur cycles with noble gas isotopic tracers elucidates water-rock reactions producing hydrogen and methane rich environments in the terrestrial subsurface, contributing to a transformed understanding of global habitability, and the sustainability of subsurface microbial communities.
Recent awards and recognition include:

  • 2022   International Fellow of the U.S. National Academy of Sciences (NAS)
  • 2021   International Fellow of the U.S. National Academy of Engineering (NAE)
  • ​2021   Royal Canadian Geographic Society Massey Medal
  • 2020   Canada Council for the Arts- Killam Prize for Natural Sciences
  • 2020   Royal Society of Canada Willet G. Miller Medal in Earth Sciences
  • 2019   Fellow of the Royal Canadian Geographical Society
  • ​2019   NSERC Gerhard Herzberg Gold Medal
  • 2019   Fellow of the Royal Society of London
  • 2019   C.C. Patterson Award in Environmental Geochemistry from the Geochemical Society
  • 2019   Fellow of the Geochemical Society and the European Association of Geochemistry
  • 2019   CIFAR Fellow and Co-Director of research program "Earth 4D - Subsurface Science and Exploration"
  • 2018   Geological Association of Canada Logan Medal
  • 2016   Appointed Companion of the Order of Canada
  • 2016   NSERC John C. Polanyi Award 
  • 2016   Royal Society of Canada Bancroft Medal
  • 2015   Fellow of American Geophysical Union
  • 2014   Canada Research Chair Tier 1- Isotopes of the Earth and Environment - Renewal
  • 2014   Helmholtz International Fellow Award
  • 2012   Eni Award
  • 2012   GSA Geobiology & Geomicrobiology Division Award
  • 2007   Canada Research Chair Tier 1- Isotopes of the Earth and Environment 
  • 2004   Fellow of Royal Society of Canada


PhD, University of Waterloo
BA (Honours - Geological Sciences), Harvard University, summa cum laude