Towards a unifying model of Dissolved Organic Matter quality for reactivity and fate in arctic, boreal and temperate aquatic systems

溶解有机物(DOM)在水生生物系统中起着至关重要的作用。DOM经常控制光的穿透性、温度、痕量金属和有机污染物的流动性和毒性，以及酸性敏感水域的酸碱平衡。DOM也是细菌新陈代谢的重要能源。饮用水中的DOM增加了消毒和氯化的需要，导致产生致癌化合物。不幸的是，DOM是数千种化合物的复杂混合物，在空间和时间上都会发生变化，甚至从一个浸渍样品到下一个浸渍样品也是如此。最近的工作表明，单靠DOC(溶解有机碳)浓度的测量不能充分反映DOM的重要功能。需要衡量DOM质量。此外，DOM的最终命运决定了淡水系统向大气排放温室气体(CO2)的情况。DOM既可以在湖泊中转化为二氧化碳，也可以储存在湖泊沉积物中。然而，碳在大气和沉积物之间的分配也是DOM质量的函数。在过去的25年里，我们在碳循环方面的工作一直集中在使用新的同位素方法生产和循环DOM上。与此同时，我们还一直在为森林和农业集水区的氮循环开发新的同位素技术。这项提议继续开发碳和氮循环的创新方法。在下一阶段，我们将开发和测试一个新的DOM模型，该模型显式地与DOM的反应性和命运联系在一起。我们将结合对碳和碳同位素的实地研究，结合培养实验和DOM质量的新分析技术，解决a)地下水、湖泊、河流和溪流中DOM的质量和循环，b)城市来源DOM的来源、质量和消毒副产品形成潜力，c)加拿大北部永久冻土融化产生的DOM的质量和去向，以及d)DOM质量对二氧化碳产生和湖泊碳储存之间平衡的影响。

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 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, resulting in production of 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. However, the partitioning of carbon between atmosphere and sediments is also a function of DOM quality. In the past 25 years, our work on carbon cycling has focused on the production and cycling of DOM using novel 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 develop and test a nascent model of DOM that is explicitly linked to DOM reactivity and fate. We will use a combination of field studies of carbon and carbon isotopes in companion with incubation experiments and new analytical techniques for DOM quality to address a) DOC quality and cycling in ground waters, lakes, rivers and streams, b) the sources, quality and disinfection by-product formation potential of urban sources of DOM, and c) the quality and fate of DOM from melting of permafrost in Canada's north, and d) the effect of DOM quality on the balance between CO2 production and carbon storage in lakes.