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

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。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有关影响OM循环过程的假设在水生系统。以前集中在最近的海洋沉积物，我们的计划是空间和时间多样化在最后一个资金周期与淡水和古海洋学成分的增加。 未来5年的研究重点是：（1）研究沉积物中有机质与铁锰氧合物的相互作用及其在有机质循环和保存中的作用;（2）我们将采用一种独特的方法测量海洋DOC的d13 C特征，结合整体和分子水平的分析，通过分子生态学、宏基因组学和基因表达方法，研究有机质组成变化与微生物动力学之间的联系（与大卫·沃尔什、康科迪亚一起）在常年缺氧的圣劳伦斯河口;（3）研究北方森林的天然湖泊和水库以及受伐木影响的湖泊和水库中的C和N的水循环，以更好地了解人为干扰和季节变化对这些系统的温室气体排放的影响;（4）我们将重新审视用于分析有机生物标志物的基于分子的方法，以考虑OM与固体样品中的Fe/Mn氢氧化物的相互作用所引入的大偏差。 水生有机物的分子特征不明的组成部分代表了最大的分析前沿之一，在地球化学。因此，开发新的分析策略可能是一个基本的先决条件，获得有机质循环和保存在湖泊，河口和海洋的机械理解。我们的工作OM与Fe/Mn氢氧化物的相互作用，特别是，是非常有前途的。

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.