Claude Hillaire-Marcel
Professor of Isotope Geochemistry
Université du Québec à Montréal

My research concerns the geochemistry of various stable and radioactive isotopes used as tracers and chronometers of studied phenomena (e.g. light isotopes, U-Th series, Nd). The main project concerns the instabilities of the climate and oceans, from the scale of astronomical climate cycles to that of secular and decadal oscillations. The work addresses some mechanisms and feedback loops involved in geological climate forcing to help in the modeling and forecasting of climate change. Through isotopic analysis of drill core or deep-water corals, we can reconstruct the instabilities of deep water formation in the Labrador Sea and the thermohaline circulation of the North Atlantic, in relation to hydrographic conditions in Arctic. Climate intervals examined include the Plio-Pleistocene transition, “warm” interglacial episodes in the last 500,000 years and some climate oscillations of the last glaciation.

A second research theme couples isotopic approaches with flux measurements (water, organic and inorganic carbon) in order to better define the metabolism of carbon in natural and managed lakes in Quebec, in the St. Lawrence River and on the eastern margin of Canada. The work seeks in particular to determine the role of the Nepheloid layer along the continental slope in respect to the geochemical fluxes from the continent to the ocean, especially the transport and sequestration in the deep ocean and sediments.

Finally, the same isotopic approaches are used to support specific studies with more immediate socio-economic impact. For example, human physiology (sports metabolism, nutrition, sugar pathology), hydrogeology (geological disposal of radioactive waste) and emissions of greenhouse gas from hydroelectric reservoirs.