Ian Clark




Clark and Fritz, 1997. Environmental Isotopes in Hydrogeology , CRC/Lewis  (Choice Magazine's "Outstanding Textbook of the Year", translated (2006) into Mandarin.


Clark, I.D. 2014. Groundwater Geochemistry and Isotopes. CRC Press. In Press, available in Fall, 2014.



The Advanced Research Complex and Accelerator Mass Spectrometry


In 2008, we began an initiative to build Canada’s only AMS facility at the University of Ottawa. With funding from the Canada Foundation for Innovation (CFI), from the Ontario Research Fund (ORF) and uOttawa, we have built the Advanced Research Complex which hosts the Lalonde AMS Laboratory together with our G.G. Hatch Stable Isotope Lab, our Geochemistry Lab and a new Microprobe Lab: 




The new Lalonde AMS Laboratory builds on the excellence of the IsoTrace AMS research team of Professor Ted Litherland, Dr. Liam Kieser and Dr. Xiaolei Zhao who have played central roles in establishing the Lalonde AMS Lab. We share the ARC with Professors Paul Corkum and Robert Boyd, world leaders in Photonics research, and with whom we collaborate to develop new technologies for AMS research.


Kieser, W.E., Zhao, X-L, Clark, I.D., Kotzer, T. and Litherland, A.E., 2011. Can-AMS: the new accelerator mass spectrometry facility at the University of Ottawa. Application of Accelerators in Research and Industry, AIP Conf. Proc.1336, 60-66.




Crustal brines and the deep geological disposal of nuclear waste


C.J. Mackenzie’s 1945 vision for the peaceful use of nuclear fission for electrical power production has been compromised by societal concerns over radionuclide emissions and the issue of nuclear waste disposal.  Our recent research addresses both issues. With funding support from the Nuclear Waste Management Organization and in collaboration with Geofirma Engineering Lt. of Ottawa, we have been conducting research on the porewaters of the Paleozoic formations of the Michigan Basin of southwestern Ontario which are being considered  for a Bruce Deep Geological Repository. This is Canada’s only current site for characterization and permitting a low and intermediate level nuclear waste repository.

We found evidence for ancient immobile fluids in the proposed host formation. Our dating methods relied on the Lalonde AMS Laboratory and demonstrate them to be immobile since the Paleozoic time. This work is part of a larger submission by the NWMO to the Canadian Nuclear Safety Commission for a permit to begin construction of the repository. We continue this research with an international bench-marking program and development of methods for crystalline rock porewaters.


Clark, I.D., Ilin, D., Jackson, R.E., Jensen, M., Kennell, L., Mohammadzadeh, H., Poulain, A., Xing, Y.P. and Raven K.G. 2014. Paleozoic-aged microbial methane in an Ordovician shale and carbonate aquiclude of the Michigan Basin, Southwestern Ontario. In review, Organic Geochemistry.


Clark, I.D., Al, T., Jensen, M., Kennell, L., Mazurek, M., Mohapatra, R., and Raven, K.G., 2013. Paleozoic-aged brine and authigenic helium preserved in an Ordovician shale aquiclude. Geology, 41: 951-954.



Recent research funded by the Canadian Nuclear Safety Commission focused on the origin of the ubiquitous brines found in the Canadian Shield. We collaborated with Dr. Dennis Bottomley in the application of a variety of isotope and geochemical tracers to determine the origin of these Ca-Cl brines. Our finds conclude that of all the possible origins considered in the past, the most plausible origin is an evaporated Paleozoic seawater brine.


Greene, S.,  Battye, N, Clark, I.D., Kotzer, T., Bottomley, D., 2008. Canadian Shield brine from the Con Mine, Yellowknife, NT, Canada:  noble gas evidence for an evaporated Palaeozoic seawater origin mixed with glacial meltwater and Holocene recharge. Geochimica et Cosmochimica Acta 72: 4008-4019.


Stotler, R.L., Frape, S.K., Ahonen, L., Clark, I.D., Greene, S., Hobbs, M., Johnson, E., Lemieux, J.-M., Peltier, R., Pratt, L., Sudicky, E., Tarasov, L., & Ruskeeniemi, T., 2010. Origin and stability of a permafrost methane hydrate occurrence in the Canadian Shield Earth and Planetary Science Letters 296: 384-394.  EPSL-D-09-00294R1.


Farrell, S., Bell, K. and Clark, I.D., 2010. Sulphur isotopes in carbonatites and associated silicate rocks from the Superior Province, Canada. Mineralogy and Petrology, DOI 10.1007/s00710-009-0101-2.


Bottomley, D., Clark, I.D., Batty, N. and Kotzer, T., 2005. Geochemical and isotopic evidence for a genetic link between Canadian Shield brines, dolomitization in the Western Canada Sedimentary Basin, and Devonian calcium-chloridic seawater. Canadian Journal of Earth Sciences, 42: 2059-2071.


Bottomley, D.J. and Clark, I.D., 2004. Potassium and boron co-depletion in Canadian Shield brines: evidence for diagenetic interactions between marine brines and basin sediments. Chemical Geology, 203: 225-236.


Bottomley, D.J., Chan, L.H., Katz, A., Starinsky, A. and Clark, I.D., 2003. Lithium isotope geochemistry and origin of Canadian Shield Brines. Groundwater, 41: 847-856.


Bottomley, D.J., Renaud, R., Kotzer, T. and Clark, I.D., 2002. Iodine-129 constraints on residence times of deep marine brines in the Canadian Shield. Geology, 30: 587-590.


Douglas, M., Clark, I.D., Raven, K. and Bottomley, D., 2000. Groundwater mixing dynamics at a Canadian Shield mine. Journal of Hydrology, 235: 88-103.


Clark, I.D., Douglas, M., Raven, K. and Bottomley, D.J., 2000. Recharge and preservation of glacial meltwater in the Canadian Shield. Ground Water, 38: 735-742.



Tracing nuclear emissions


Our current research on nuclear emissions tracking in the environment focuses on two radionuclides of greatly contrasting specific activities, yet both of great concern, T (3H) and 129I. Tritium is a highly radioactive emission product generated in the CanDU reactor design through neutron activation of 2H and that accumulates as organically-bound tritium (OBT) in the food supply. Our recent research documents that tritium as HT is preferentially partitioned into OBT. Our research is published in CNSC reports and abstract with journal publication awaiting CNSC authorization.


Canadian Nuclear Safety Commission (CNSC), 2013. Environmental fate of tritium in soil and vegetation, PWGSC catalogue number CC172-101/2013E-PDF ISBN 978-1-100-22687-3


Mihok, Clark, Wilk et al., 2014. Tritium dynamics in soils and plants at a tritium processing facility. (ICRER 2014)


The long-lived radioisotope 129I is considered to be the component of CanDU spent fuel of greatest long-term concern considering its biophilic nature and 16 million year half-life. The Lalonde AMS Facility supports our research on 129I mobility and partitioning in the environment. This research began with studies at high and low background sites in Ontario (Renaud et al. 2005. Radiochim. Acta, 93: 363-371; Alvaredo Quiroz, et al., 2002. Radiochim. Acta, 90: 469-478). Our current focus is on tracing the fate of Fukushima 129I in western Canada (HQP Matt Herod, PhD candidate) from the Arctic to the Frazer Valley. Further work involves developing a novel carrier-free method for ultra-low concentration samples by AMS using 125I as a 129I-free carrier/yield tracer.


Herod, M.N., Clark, I.D., Cornett, R.J., Kieser, W.E., St. Jean, G., 2014. Extraction of 129I and 127I via combustion from organic rich samples using 125I as a quantitative tracer. J. Environ. Radioactivity, S0265-931X(14)00037-X. doi: 10.1016/j.jenvrad.2014.02.005


Herod, M.N. Clark, I.D., Kieser, W.E., Agosta, S., Zhao, X-L., 2013. 129I dispersion and sources in northwest Canada. Nuclear Instruments and Methods in Physics Research B: Beam Interactions with Materials and Atoms, 294: 552-558.


Renaud, R., Clark, I.D., Kotzer, T.G., Milton, G.M. and Bottomley, D.J., 2005. The mobility of anthropogenic 129I in a shallow sand aquifer at Sturgeon Falls, Ontario, Canada. Radiochimica Acta, 93: 363-371.


Alvaredo Quiroz, N.G., Kotzer, T.G., Milton, G., Clark, I.D. and Bottomley, D., 2002. Partitioning of 127I and 129I in an unconfined glaciofluvial aquifer on the Canadian Shield.  Radiochimica Acta, 90: 469-478.





Groundwater flow in permafrost watersheds


We are quantifying the contribution of groundwater circulation in permafrost, both past and present, to discharge from Arctic watersheds. This research focuses on 14C work in the Lalonde AMS Lab and other isotope and geochemical tracers in Arctic rivers to resolve seasonal contributions of groundwater discharge and determine influences of climate and geology on this poorly understood component of permafrost hydrographs. This contributes to the International Atomic Energy Agency’s Co-ordinated Research Project: Global Network for Isotopes in Rivers.  Six HQP have been involved in this research over the past five years.


Utting, N., Lauriol, B., Mochnacz, N., Aeschbach-Hertig, W. and Clark, I.D., 2013. Noble gas and isotope geochemistry in western Canadian Arctic watersheds: tracing groundwater recharge in permafrost terrain. Hydrogeology Journal, 21: 79-91, doi:10.1007/s10040-012-0913-8.


Utting, N., Clark, I.D., Lauriol, B., Wieser, M., and Aeschbach-Hertig, W., 2012. Origin and flow dynamics of perennial groundwater in continuous permafrost terrain using isotopes and noble gas: Case study on the Fishing River, northern Yukon, Canada.  Permafrost and Periglacial Processes,Volume 23, Issue 2, pages 91–106, DOI: 10.1002/ppp.1732.


Related permafrost research focusses on the occurrence and origin of buried ice bodies, and their impact on surface waters from melting and the formation of retrogressive thaw slumps. These features are some of the largest in the Arctic, with impacts on the salinity of rivers such as the Peel, well beyond the local watershed.


Inline image 5Kokelj, S.V., Lacelle, D., Lantz, T.C., Tunnicliffe, J., Malone, L., Clark, I.D. and Chin, K.S., 2013. Thawing of massive ground ice in mega slumps drives increases in stream sediment and solute flux across a range of watershed scales. Journal of Geophysical Research: Earth Surface, 118: 1-12, doi:10.1002/jgrf.20063.


Malone, L., Lacelle, D., Kokelj, S. and Clark, I.D., 2013. Impacts of hillslope thaw slumps on the geochemistry of permafrost catchments (Stony Creek watershed, NWT, Canada. Chemical Geology, 356: 38-49.

Lacelle, D., Lauriol, B., Zazula, G., Ghaleb, B., Utting, N., Clark, I.D., 2013. Timing of advance and basal condition of the Laurentide Ice Sheet during the last glacial maximum in the Richardson Mountains, NWT. Quaternary Research, 80: 274-283.



Lacelle, D., Radtke, K., Clark, ID., Fisher, D., Lauriol, B., Utting, N., Whyte, LG. 2011. Geomicrobiology and occluded O2-CO2-Ar analyses provide evidence of microbial respiration in ancient terrestrial ground ice bodies. Earth and Planetary Science Letters 306, 46-54.


St-Jean, M., Lauriol, B., Clark, I.D., Lacelle, D., Zdanowicz, C., 2011. Investigation of ice wedge infilling processes using stable oxygen and hydrogen isotopes, crystallography, and occluded gases (O2, N2, Ar). Permafrost and Periglacial Processes, 22: 49–64.


Lauriol B., Lacelle, D., St-Jean, M., Clark I.D. and Zazula, G. 2010.  Late Quaternary paleoenvironments and growth of intrusive ice in eastern Beringia (Eagle River valley, northern Yukon, Canada). Canadian Journal of Earth Sciences 47, 941-955.


Lacelle, D., St-Jean, M., Lauriol, B., Clark, I.D., Lewkowicz, A., Froese, D.G., Kuehn, S.C. and  Zazula, G., 2009. Burial and preservation of a 30,000 year old perennial snowbank in Red Creek valley, Ogilvie Mountains, central Yukon, Canada. Quaternary Science Reviews 28 :3401–3413.


Cardyn, R., Clark, I.D., Lacelle, D., Lauriol, B. Zdanowicz, C.H. & Calmels, F. 2007. Molar gas ratios of air entrapped in ice: A new tool to determine the origin of relict massive ground ice bodies in permafrost. Quaternary Research 68: 239-248.


Clark, I.D., Henderson, L., Chappellaz, J., Fisher, D.A., Koerner, R., Worthy, D.E.J., Kotzer, T., Norman, A.-L.,Barnola, J.-M., 2007. CO2 isotopes as tracers of firn air diffusion and age in an Arctic ice cap with summer melting, Devon Island, Canada. J. Geophysical Research 112, D01301, doi:10.1029/2006jD007471



Biogenic calcretes and ancient life in permafrost – endostromatolites


We discovered a new climate proxy, endostromatolites, (Clark et al. 2004, Can.J.Earth Sci. 41: 387), unusual yet ubiquitous biogenic, microlaminated calcite columns that grow across limestone fissures. Stable isotopes and radiocarbon show that these are methanogenic bacterial colonies that survive on nutrients carried into the saturated subsurface by liquid water during late Pleistocene climate improvement when solar insolation raised Arctic temperatures by 4 to 6°C. The Canadian Space Agency supported this research as an analogue for potential life on Mars. We extracted DNA from these ancient carbonate features to demonstrate their microbial origin and to understand the mechanisms for continued growth under continuous permafrost conditions.

Pellerin, A., Lacelle, D., Fortin, D., Clark, I.D. and Lauriol, B., 2009. Microbial diversity in endostromatolites and the surrounding landscape, Haughton impact structure region, Devon Island, Canada. Astrobiology, 9: 807-822. DOI: 10.1089=ast.2008.0302


Lacelle, D., Pellerin, A., Clark, I.D., Lauriol, B., Fortin, D. 2009. Geochemical, isotopic and microbial (DNA) fingerprints of physico-chemical and biological mineralization in endostromatolites (cf. fissure calcretes), Haughton impact crater, Devon Island, Canada. Earth and Planetary Science Letters, 281: 202-214.


Lacelle, D., Juneau, V., Pellerin, A., Lauriol, B. Clark, I.D., 2008. Weathering regime and geochemical evolution in a polar desert environment, Haughton impact structure, Devon Island,Canada. Canadian Journal of Earth Sciences 45: 1-20.


Lacelle, D., Fisher, D., Clark, ID., Berinstain, A., 2008. Distinguishing between vapor and water-derived ground ice in the northern Martian regolith: implications regarding the preservation of biosignatures. Icarus, doi:10.1016/j.icarus.2008.05.017.


Lacelle, D., Lauriol, B. and Clark, I.D., 2008. Formation of annual ice bodies and associated cryogenic carbonates in Caverne de l’Ours, Québec, Canada: Kinetic isotope effects and pseudo-biogenic crystal structures. Journal of Cave and Karst Science. 71: 48-62


Clark, I.D., Lauriol, B., Marschner, M., Sabourin, N., Chauret, Y. and Desrochers, A., 2004. Endostromatolites from permafrost karst, Yukon, Canada: paleoclimatic proxies for the Holocene hypsithermal. Canadian Journal of Earth Sciences. 41: 387-399.




First evidence for Anammox reaction in groundwaters


The anammox reaction (3 NO3 + 5 NH4+ ® 4 N2 + 9 H2O + 2H+) has only recently been identified, yet remarkably it is now considered responsible for up to 50% of global nutrient cycling back to N2. Our research is the first to show anammox activity in groundwaters. This opens the door to new in-site treatment technologies for groundwaters impacted by septic effluents, manure and fertilizer contamination and landfill leachates. My NSERC strategic grant led to an eight year (to date) program of anammox research.


Moore, T., Xing, Y., Lazenby, B., Lynch, M., Schiff, S., Robertson, W., Timlin, R., Lanza, S., Ryan, M., Aravena, R., Fortin, D., Clark, I.D., and Neufeld, J.D. 2011. Prevalence of anaerobic ammonium-oxidizing bacteria in contaminated groundwater. Environmental Science & Technology 1;45(17):7217-25.


Robertson, W.D., Moore, T.A., Spoelstra, J., Li, L., Elgood, R.J., Clark, I.D., Schiff, S.L., Aravena, R., and Neufeld, J.D. 2012. Natural attenuation of septic system nitrogen by anammox. Ground Water, 50: 541-553. DOI: 10.1111/j.1745-6584.2011.00857.


Clark, I.D., Timlin, R., Bourbonnais, A., Jones, K., Lafleur, D. and Wickens, K. 2007. Origin and fate of industrial ammonia in municipal groundwaters – tracing anaerobic oxidation (annamox) and apportionment with 15NNH4, submitted. Ground Water Monitoring and Remediation (October 2006).




Groundwater contamination


Tracing the origin of contaminants in groundwaters and potential biodegradation that may be occurring is an important component of remediation. Landfill leachates offer insights to the dynamics of isotopes of tracers of such reactions. The biogenic processes of biodegradation and leachate generation in municipal landfills can be examined in considerable detail when stable isotopes of the organic components are considered. This research program looked at compound specific isotopes in leachates from the Trail Road landfill in Ottawa to identify reaction pathways and to establish isotope markers of landfill leachate to trace impingement on local groundwater. We are continuing this research in soils, looking at isotope tools to trace biodegradation of fuel contaminated soils in both temperate (Iowa) and arctic permafrost (Old Crow, Yukon), but adding 14C to the range of isotope tracers to identify the source of carbon.


Mohammadzadeh, H., Clark, I., 2011, Bioattenuation in groundwaters impacted by landfill leachate traced with d13C. Ground Water doi: 10.1111/j.1745-6584.2010.00790.x.


Murphy, S., Ouellon, T., Ballard, J-M., Lefebvre, R., and Clark, I.D., 2010 Tritium-helium groundwater age used to constrain a groundwater flow model of a valley-fill aquifer contaminated with trichloroethylene (Quebec, Canada)  Hydrogeology Journal: HJ-2009-1477.R4


Mohammadzadeh, H., Clark, I., 2008. Degradation Pathways of Dissolved Carbon in Landfill Leachate traced with compound-specific 13C analysis of DOC, Journal of Isotopes in Environmental and Health Studies, 44: 1-28.



Hyperalkaline groundwaters in Jordan and Oman – an analogue for cementitious nuclear waste repository


The hyperalkaline groundwaters of northern Jordan, natural springs with pH of 12.6, offer a fascinating study on the behavior of radionuclides in a cementitious environment. The occurrence of such springs in the past in central Jordan is demonstrated by the extensive travertine deposits there, together with exposures of the metamorphosed marls that produced the high pH groundwaters. Past and recent work at these sites by a consortium of geoscientists from Canadian and European nuclear agencies (Ontario Hydro, Nagra, Nirex, SKB) began with our early collaboration with Dr. Hani Khoury and Dr. Elias Salemeh of the University of Jordan who introduced me to these waters and welcomed us to their country. We are continuing this work now with a more detailed look at the mineralogy of these metamorphosed zones, in particular to look at unusual uranium mineralization.


Khoury, H. N., Salemeh, E. and Clark, I.D., 2013. Mineralogy and origin of surficial uranium deposits hosted in travertine and calcrete from central Jordan. Applied Geochemistry, 43: 49-65.


Clark, I.D., Dayal, R. and Khoury, H.N., 1994. The Maqarin (Jordan) natural analogue for 14C attenuation in cementitious barriers. Waste Management, 14:467-477.


Clark, I.D., Fritz P., Seidlitz, H.K., Trimborn, P., Milodowski, A.E., Pearce, J.M., and Khoury, H.N., 1993. Recarbonation of metamorphosed marls in Jordan. Applied Geochemistry, 8: 473-481.


Khoury, H.N., E. Salameh, I.D. Clark, P. Fritz, W. Bajjali, A.E. Milodowski, M.R. Cave and W.R. Alexander, 1992. A natural analogue of high pH cement pore waters from the Maqarin site of northern Jordan, 1: Introduction to the site. Journal of Geochemical Exploration, 46: 117-132.






Biogenic Iron Oxides (BIOS)


Biogenic iron oxides are highly reactive substrates with potential interest in contaminant attenuation and radionuclide sequestration. This research program, led by Grant Ferris from the University of Toronto and Danielle Fortin at the uOttawa, examined natural occurrences of BIOS at the Atomic Energy of Canada Ltd. Chalk River site in eastern Ontario. The research aims were to characterize this material and to determine its sorption properties for two radionuclides of considerable interest – 90Sr and 129I.


Gault, A.G., Ibrahim, A., Langley, S., Renaud, R., Takahashi, Y., Boothman, C., Lloyd, J.R., Clark, I.D., Ferris, F.G. and Fortin, D., 2011. Microbial and geochemical features suggest iron redox cyclingwithin bacteriogenic iron oxide-rich sediments. Chemical Geology 281: 41–51.


Kennedy, C.B., Gault, A.G., Fortin, D., Clark, I.D., Pedersen, K., Scott, S.D. and Ferris, F.G., 2010. Carbon isotope fractionation by circumneutral iron-oxidizing bacteria Geology 2010; 38;1087-1090 doi: 10.1130/G30986.1.


Kennedy, C.B., Gault, A.G., Clark, I.D., Fortin, D. and Ferris, F.G., 2011. Retention of Iodide by Bacteriogenic Iron Oxides.  Geomicrobiology J. 28: 387-395.  doi.org/10.1080/01490451003653110


Langley, S., Gault, A.G., Ibrahim, A;, Takahashi, Y., Renaud, R., Fortin, D.,  Clark, I.D. and Ferris, F.G., 2009. Strontium de-sorption from bacteriogenic iron oxides (BIOS) subjected to microbial Fe(III) reduction.  Chemical Geology, 262, 217-228.


Langley, S., Gault, A.D., Ibrahim, A., Renaud, R., Fortin, D., Clark, I.D. and Ferris, F.G. (2009) A comparison of the rates of Fe(III) reduction in synthetic and bacteriogenic iron oxides by Shewanella putrefaciens CN32.  Geomicrobiol. J., 26, 57-70.