Organic carbon cycling and preservation in aquatic environments: Origin, forms and mechanisms using bulk, molecular and isotopic methods

水生环境中的有机碳循环和保存：使用本体、分子和同位素方法的起源、形式和机制

• 批准号: RGPIN-2018-05080
• 负责人: Gelinas, Yves
• 金额: $ 4.44万
• 依托单位: Concordia University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=748459
• 关键词: Organic; carbon; cycling; preservation; aquatic

I propose to continue research initiated in the past 5 years on the forms, sources, reactions, and fates of quantitatively important forms of organic matter (OM) in aquatic environments. The central themes of our program are to develop new analytical methods (bulk, molecular and isotopic) that can be applied to organic mixtures, and to use these methods to test hypotheses about processes affecting OM cycling in aquatic systems. During the previous DG cycle, our work targeted the interactions between reactive iron oxides and sedimentary OM and the role played by these interactions on carbon preservation in sediments. We also developed methods and optimized instrumentation for the measurement of the 13C signature of dissolved organic carbon in seawater, and used the stable isotope signature of methane to decipher its sources in ground water, and its cycle in lacustrine sediments. The research proposed in the next 5 years will answer some of the questions that were raised by our previous work, and describes new and original projects that will be undertaken during the next DG cycle.The following major themes will be addressed in the next 5 years: (1) we will now target the interactions between iron sulfides and OM in sediments, and their role in OM cycling and preservation; (2) we will probe the effect and mechanism of dissolved sulfide exposure on free and OM-bound iron oxides; (3) we will assess the reactivity of natural pore water extracted from anoxic sediments for iron sulfide particles and examine the speciation of sulfides in the corresponding solid phase; (4) we will use molecular modeling and single molecule atomic force microscopy to better understand the interactions between organic compounds and the surface of iron sulfides nanoparticles; (5) in a new initiative, we will use compound-specific stable isotope analysis (CSIA; 13C and D) on petroleum derived hydrocarbons to understand the effect of weathering (e.g., dispersion, evaporation, photooxidation and biodegradation) on the relative abundances and stable isotope signatures of these hydrocarbons, and we will build a dilution model that will allow spatially and temporally tracking these contaminants in the St. Lawrence River, Estuary and Gulf; and (6) we will keep developing our CSIA methods toolbox in a series of small projects for which the application of CSIA could be rewarding. Mechanistically understanding the dynamics of shielded OM at the redox interface represents one of the greatest analytical frontiers remaining in biogeochemistry. Developing new analytical strategies is thus a fundamental prerequisite for obtaining a mechanistic understanding of OM preservation in lakes, estuaries and the ocean. Our work on OM interactions with Fe sulfides, in particular, will prove very promising.

我建议继续过去 5 年发起的研究，研究水生环境中具有数量重要性的有机物 (OM) 的形式、来源、反应和归宿。我们计划的中心主题是开发可应用于有机混合物的新分析方法（本体、分子和同位素），并使用这些方法来检验有关影响水生系统中有机质循环的过程的假设。在之前的 DG 周期中，我们的工作针对活性铁氧化物和沉积物 OM 之间的相互作用以及这些相互作用对沉积物中碳保存的作用。我们还开发了测量海水中溶解有机碳 13C 特征的方法和优化仪器，并利用甲烷的稳定同位素特征来破译其在地下水中的来源及其在湖泊沉积物中的循环。未来 5 年提出的研究将回答我们之前工作中提出的一些问题，并描述将在下一个 DG 周期内开展的新的和原创的项目。未来 5 年将解决以下主要主题：（1）我们现在将研究沉积物中硫化铁和有机质之间的相互作用，以及它们在有机质循环和保存中的作用； (2)我们将探讨溶解的硫化物暴露对游离和OM结合的氧化铁的影响和机制； (3)我们将评估从缺氧沉积物中提取的天然孔隙水对硫化铁颗粒的反应性，并检查相应固相中硫化物的形态； （4）我们将利用分子建模和单分子原子力显微镜更好地理解有机化合物与硫化铁纳米粒子表面之间的相互作用； (5) 在一项新举措中，我们将对石油衍生的碳氢化合物使用特定化合物的稳定同位素分析（CSIA；13C 和 D），以了解风化（例如分散、蒸发、光氧化和生物降解）对相对丰度和这些碳氢化合物的稳定同位素特征，我们将建立一个稀释模型，以便在空间和时间上跟踪圣劳伦斯河、河口和海湾的这些污染物； (6) 我们将继续在一系列小型项目中开发我们的 CSIA 方法工具箱，对于这些项目，CSIA 的应用可能会带来回报。从机械角度理解氧化还原界面屏蔽 OM 的动力学代表了生物地球化学领域最伟大的分析前沿之一。因此，开发新的分析策略是获得对湖泊、河口和海洋中有机质保存机制的理解的基本先决条件。我们在有机金属与硫化铁相互作用方面的工作将被证明是非常有前途的。