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

我的研究团队围绕着两个协同轴心组成：1)旨在识别陆源有机化合物并阐明其在对比环境中的特定地球化学反应的“垂直”轴心；以及2)将这些知识应用于理解复杂环境问题动力学的“横向”轴心。目前的发现资助提案将涉及第一个轴，这代表了我实验室中一个长期独特的研究轴。陆地和水环境中的陆源有机物(TOM)是重金属和农药等污染物的载体，是金属和营养盐络合等地球化学反应的触发因素，是微生物活动的决定因素。因此，我的科学目标中更基本的一面的独创性在于打开了TOM黑匣子，以追踪北方和热带陆地/水生系统中识别良好的陆源有机化合物的来源和命运，这些有机化合物受到最近森林砍伐、商业农业或建立水库后陆地系统蓄水的影响。为此，我打算使用木质化合物的特定特征来重建整个流域的人类历史和前人类历史。应用范围从魁北克北部永久冻土融化程度的评估到亚马逊地区基于棕榈树木质素签名的恰加斯病风险地图。所产生的知识将有助于：(I)加深我们对北方和热带地区最近开垦地区汞循环的理解；(Ii)确定特定TOM化合物通过在对比鲜明的水生环境中的生物降解和/或光降解对温室气体持续产生的贡献；(Iii)估计北方或热带农业土壤中存在的特定TOM化合物在保持或再动员除草剂如草甘膦方面的作用；(Iv)建立工业化农业中草甘膦使用与植物结构弱点之间的关系，这些弱点与木质素代谢不佳有关。

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.