Organic matter dynamics in aquatic environments using bulk, molecular and isotopic methods

我建议继续过去5年开展的关于水生环境中定量重要形式有机物（OM）的形态、来源、反应和命运的研究。该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关于影响水生系统OM循环过程的假设。我们的项目先前以近期的海洋沉积物为中心，在上一个资助周期中，随着淡水和古海洋学成分的增加，我们的项目在空间和时间上变得多样化。未来5年将主要研究以下主题：(1)沉积物中OM与Fe/Mn（氧）氢氧化物的相互作用及其在OM循环和保存中的作用；(2)我们将采用独特的方法测量海洋DOC的d13C特征，结合体和分子水平分析，通过分子生态学、宏基因组学和基因表达方法（与David Walsh， Concordia）评估常年缺氧的圣劳伦斯河口OM组成变化与微生物动力学之间的联系；(3)研究自然和受砍伐影响的北方森林湖泊和水库中碳和氮的水循环，以更好地了解人为扰动和季节变化对这些系统温室气体排放的影响；(4)我们将重新考虑基于分子的有机生物标志物分析方法，以考虑固体样品中OM与Fe/Mn氢氧化物相互作用所引入的大偏差。水生OM的分子未表征成分是生物地球化学中最大的分析前沿之一。因此，制定新的分析策略可能是获得对湖泊、河口和海洋中有机质循环和保存机制理解的基本先决条件。我们在OM与Fe/Mn氢氧化物相互作用方面的研究尤其有前景。

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 this 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. Previously centered on recent marine sediments, our program was spatially and temporally diversified during the last funding cycle with the addition of freshwater and paleoceanography components. The following major themes will be addressed in the next 5 years: (1) we will target the interactions between OM and Fe/Mn (oxy)hydroxides in sediments, and their role in OM cycling and preservation; (2) we will use an unique method for the measurement of the d13C signature of marine DOC, in combination with bulk and molecular level analyses, to study the links between OM composition changes and microbial dynamics as assessed by molecular ecology, metagenomic and gene expression approaches (with David Walsh, Concordia) in the perennially hypoxic St. Lawrence Estuary; (3) we will study on the aquatic cycles of C and N in natural and logging-impacted lakes and reservoirs of the boreal forest to better understand the impact of human perturbations and seasonal variations on the emissions of greenhouse gases from these systems; (4) we will revisit molecular-based methods for the analysis of organic biomarkers to take into account the large bias introduced by OM interactions with Fe/Mn hydroxides in solid samples. The molecularly uncharacterized component of aquatic OM represents one of the greatest analytical frontiers remaining in biogeochemistry. Developing new analytical strategies may thus be a fundamental prerequisite for obtaining mechanistic understanding of OM cycling and preservation in lakes, estuaries and the ocean. Our work on OM interactions with Fe/Mn hydroxides, in particular, is very promising.