Are quality and fate of DOM linked in boreal lakes? isotopic and stoichiometric approaches

溶解有机物（DOM）在水生系统中起着至关重要的作用。DOM经常控制光线穿透、温度、流动性和微量金属和有机污染物的毒性，以及酸碱平衡，特别是在酸敏感水域。DOM也是细菌代谢的重要能量来源。饮用水中的DOM增加了消毒的需要，氯化会产生致癌化合物。不幸的是，DOM是数千种化合物的复杂混合物，它们在空间和时间上都会发生变化，甚至从一个浸出样品到下一个浸出样品也会发生变化。最近的研究表明，仅仅测量DOC（溶解有机碳）浓度并不能充分反映DOM的重要功能。需要对DOM质量进行度量。此外，DOM的最终命运决定了淡水系统向大气中温室气体（CO2）的损失。DOM既可以在湖中转化为二氧化碳，也可以储存在湖泊沉积物中。大气和沉积物之间的碳分配也可能是DOM质量的一个函数。在过去的20年里，我们在碳循环方面的工作主要集中在利用同位素方法生产和循环DOM。与此同时，我们也一直在开发新的同位素技术，用于森林和农业流域的氮循环。该提案继续发展碳和氮循环的创新方法。在下一阶段，我们将专门研究DOM质量和北风系统中命运之间的联系。我们将利用全湖平衡和河流碳和碳同位素研究，以及孵化和新的DOM质量测量方法来解决a)北方湖泊、河流和溪流中的DOC质量和循环，b)温带和北方DOM之间DOM质量的差异，以及c)湖泊中二氧化碳生产和碳储存之间的平衡。

Dissolved organic matter (DOM) plays a critical role in aquatic systems. DOM frequently controls light penetration, temperature, mobility and toxicity of trace metals and organic contaminants, and the acid-base balance particularly in acid sensitive waters. DOM is also an important energy source for bacterial metabolism. DOM in drinking water supplies increases the need for disinfection, and chlorination results in carcinogenic compounds. Unfortunately, DOM is a complex mixture of thousands of compounds that changes spatially and temporally, even from one dip sample to the next. Recent work has shown that measurements of DOC (dissolved organic carbon) concentrations alone do not adequately reflect the important functions of DOM. Measures of DOM quality are needed. In addition, the ultimate fate of DOM governs the loss of greenhouse gases (CO2) to the atmosphere from freshwater systems. DOM can be either converted to CO2 within the lake or stored in the lake sediments. The partitioning of carbon between atmosphere and sediments is likely also a function of DOM quality. In the past 20 years our work on carbon cycling has focused on the production and cycling of DOM using isotopic approaches. In parallel, we have also been developing new isotopic techniques for nitrogen cycling in forested and agricultural catchments. This proposal continues the development of innovative approaches to carbon and nitrogen cycling. In the next phase we will specifically examine the link between DOM quality and fate in boreal systems. We will use whole lake balances and stream studies of carbon and carbon isotopes in companion with incubations and new measures of DOM quality to address a) DOC quality and cycling in boreal lakes, rivers and streams, b) differences in DOM quality between temperate and boreal DOM, and c) the balance between CO2 production and carbon storage in lakes.