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

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My research team is federated around two synergetic axes: 1) a "vertical" one aiming at identifying terrigenous organic compounds and elucidating their specific geochemical reactivity in contrasted environments and 2) a "transversal" one applying that knowledge to the understanding of the dynamics of complex environmental issues. The present Discovery Grant proposal will address the first axis, representing a long-term distinctive research axis in my laboratory. Terrigenous organic matter (TOM) in terrestrial and aquatic environments is a carrier of pollutants such as heavy metals and pesticides, a trigger of geochemical reactions such as metals and nutrients complexation and a determinant factor of microbial activity. The originality of the more fundamental side of my scientific goals thus lies in opening of the TOM black box to follow the sources and fate of well identified terrigenous organic compounds in boreal and tropical terrestrial/aquatic systems impacted by recent forest clearing, commercial agriculture or impoundment of terrestrial systems upon the creation of reservoirs. Doing so, I intend to use specific signatures of ligneous compounds to reconstruct anthropogenic and pre-anthropogenic histories of entire watersheds. Applications will range from the evaluation of the extent of permafrost thawing in northern Québec to the establishment of Chagas disease risk maps in the Amazon based on palm tree lignin signatures. The generated knowledge will serve to: (i) refine our understanding of the mercury cycle in recently clear-cut areas of both the boreal and tropical regions, (ii) determine the contribution of specific TOM compounds to the sustained production of greenhouse gas through biodegradation and/or photodegradation in contrasted aquatic environments, (iii) estimate the role of specific TOM compounds present in boreal or tropical agricultural soils in holding or remobilizing herbicides such as glyphosate, (iv) establish the relationship between glyphosate usage in industrial agriculture and structural weaknesses of plants related to poor lignin metabolism.