Terrigenous organic matter in aquatic systems: from the identification of specific compounds to the dynamics of complex environmental issues

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Opening the black box of organic matter (O.M.) and distinguishing specific organic compounds enables to get a better grasp on the complex dynamics of environmental drawbacks. Two main objectives are pursued: i) a fundamental one consisting in expanding and exploiting the know-how of my research team in the characterization of organic compounds, ii) a transversal one aiming at applying this sophisticated procedure to the understanding of the fine dynamics of environmental issues dealt with in my ongoing large interdisciplinary research. I first wish to expand our bank of recognizable organic molecules, ranging from lignocellulosic and cutin compounds to bacterial biomarkers thanks to spectrometry (MS-MS) identification of phenols issuing from the CuO digestion of O.M. On one hand of the applied axis, I intend to elucidate the nature of specific organic compounds as key-factors in triggering mercury methylation in relation with the biogeographical characteristics of the drainage basin and the trophic structure of an aquatic ecosystem. On the other hand, I shall work on the elucidation of the intensity and duration of greenhouse gas production by boreal hydroelectric reservoirs, detailing the respective contributions of the degradation of labile fractions of flooded O.M., new biological production and terrigenous inputs from the drainage basin. Finally, I propose to deepen our quest for the understanding of the environmental consequences of massive slashing and burning of the Amazon rain forest by identifying specific terrigenous organic compounds of tropical soils that could represent potential carriers of mercury-rich particles. Several outcomes are expected from this research, ranging from establishing a general Ecosystem Sensitivity Index of the various cases of mercury contamination across Canada, to making enlightened choices about future means of energy production, and to defining appropriate measures that could be proposed for slowing deforestation of tropical forests. On an annual basis, about ten graduate students are usually involved at various degrees with this research axis of identification of specific organic compounds and elucidating their dynamics in given environmental issues.