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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=691057
• 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.

我建议继续研究在过去5年中发起的形式，来源，反应和命运的定量重要形式的有机物（OM）在水生环境中。我们计划的中心主题是开发新的分析方法（散装，分子和同位素），可以应用于有机混合物，并使用这些方法来测试有关影响OM循环过程的假设在水生系统中。在上一个DG周期中，我们的工作针对活性铁氧化物和沉积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的13 C特征的方法和优化仪器，并使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年的研究计划将回答我们先前工作中提出的一些问题，并描述下一个DG周期将开展的新项目和原创项目。未来5年的主要研究内容包括：（1）研究沉积物中铁硫化物与有机质的相互作用及其在有机质循环和保存中的作用;（2）探讨溶解硫化物暴露对游离态和有机质结合态铁氧化物的影响及其机制;（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）我们将使用分子建模和单分子原子力显微镜，以更好地了解有机化合物和铁硫化物纳米颗粒表面之间的相互作用;（5）在一项新的计划中，我们将使用特定化合物的稳定同位素分析（CSIA; 13 C和D）对石油衍生的碳氢化合物，以了解风化的影响（例如，（1）我们将继续研究这些碳氢化合物的相对丰度和稳定同位素特征（包括扩散、蒸发、光氧化和生物降解），并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、河口和海湾中的这些污染物;（2）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，CSIA的应用可能是有益的。** 从机制上理解氧化还原界面处屏蔽OM的动力学是地球化学中最重要的分析前沿之一。因此，开发新的分析策略是获得OM保存在湖泊，河口和海洋的机械理解的一个基本前提。我们的工作OM与铁硫化物的相互作用，特别是，将被证明是非常有前途的。