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

打开有机物质的黑匣子(O.M.)区分特定的有机化合物能够更好地把握环境缺陷的复杂动态。主要追求两个目标：i)一个基本的目标，包括扩大和利用我的研究团队在表征有机化合物方面的专门知识；ii)一个横向目标，旨在应用这一复杂的程序来理解我正在进行的大型跨学科研究中处理的环境问题的精细动态。我首先希望扩大我们的可识别有机分子库，从木质纤维和角质化合物到细菌生物标记物，这要归功于光谱分析(MS-MS)从CuO对O.M.的消化产生的酚类物质。一方面，我打算在应用轴上阐明特定有机化合物的性质，它们是触发汞甲基化的关键因素，与流域的生物地理特征和水生生态系统的营养结构有关。另一方面，我将致力于阐明北方水电站产生温室气体的强度和持续时间，详细说明被淹有机物不稳定部分的退化、新的生物生产和来自排水盆地的陆源输入各自的贡献。最后，我建议通过确定热带土壤中可能代表富汞颗粒潜在载体的特定陆源有机化合物，来深化我们对大规模砍伐和焚烧亚马逊热带雨林的环境后果的了解。这项研究预计会产生几个成果，从建立加拿大各地汞污染各种情况的一般生态系统敏感性指数，到就未来的能源生产方式做出开明的选择，以及确定可以提出的减缓热带森林砍伐的适当措施。每年大约有10名研究生不同程度地参与到这一研究轴线中，以识别特定的有机化合物并阐明其在特定环境问题中的动态。

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.