Experimental carbonate geochemistry and early diagenesis

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My research focuses on the mechanisms and rates of biogeochemical processes in aquatic systems. The approach uses field studies, controlled laboratory experiments, and modeling. My research will be carried out on two fronts: carbonate geochemistry and sediment diagenesis. The two programs are intimately linked since carbonate minerals are common constituents of sediments and widely used as proxies to infer the paleo-environmental conditions and the chemistry of the solutions from which they precipitated. The surfaces of carbonate minerals are highly reactive and play an important role in determining the mobility of trace elements in a variety of aquatic environments (aquifers, sediments, mine tailings). The long-term objective is to develop a predictive model of the sorption (adsorption and co-precipitation) behavior and reactivity of carbonate minerals under various environmental conditions. In addition to reactions at "ideal" mineral surfaces, I plan to take a more pragmatic approach and investigate the influence of bacteria on carbonate mineral reaction kinetics and mineralogy. Bacteria are ubiquitous in aquatic environments and can be found on most mineral surfaces, yet, their influence on weathering rates and the mineralogy of carbonate precipitates has not been properly investigated. Particles that settle through the oceanic water column fuel, participate in, and are subjected to, a number of biogeochemical processes in the sediment. The long-term goal of this research program is to identify factors that control elemental fluxes across the sediment-water interface and better exploit the sedimentary record to infer paleo-environmental conditions. I will focus on the geochemical behaviour of selected redox-sensitive elements (e.g. Fe, Mn, Mo, U, and Re) in sediments, how and how fast they are concentrated or are depleted in sediment under various conditions of oxygenation and how their distribution in the sediment can be used to infer the conditions of past depositional environments.