Deciphering the composition and fate of dissolved organic matter in a rapidly changing Arctic Ocean

海洋溶解有机物（DOM）是当前和未来全球碳循环的核心，其储量与当前大气二氧化碳储量相当。几十年来，海洋是一个巨大的碳库，这一事实继续促使科学家们研究DOM的来源、化学成分、反应性和在海洋环境中的功能。海洋DOM来源于海洋初级生产，但只有一小部分可被识别为常见分子。 我的研究项目旨在阐明海洋生态系统中溶解有机物的组成和动态。在接下来的五年里，我计划继续我的研究计划的循环和动态DOM在高度分层的北极的加拿大盆地。具体而言，主要目标是：1）将海洋DOM的荧光特性与可识别分子联系起来。与平行因子分析（EEM-PARAFAC）相关的激发发射矩阵光谱已被应用于获得有关蛋白质样和腐殖酸样DOM的分布和动力学的见解，但仍然缺乏直接证据将PARAFAC组分与分子特征分子联系起来。同时测定荧光组分、木质素酚、碳水化合物和氨基酸，以研究特定荧光组分与可识别分子之间的关系。 2)评估DOM的难治性。在加拿大海岸警卫队的破冰船上将进行围隔实验，以评估DOM的体积和分子组成如何随着时间的推移而变化，以及细菌分类的变化。我们的研究旨在阐明暗海洋有机地球化学，这对于理解全球海洋DOM的循环至关重要。3)调查北冰洋DOM的季节动态。来自原位荧光DOM传感器的高频测量将在空间和季节上扩展我们的观测。DOM荧光的时间变化与层结、生物活动、矿化和冰盖的变化有关。 这项研究计划将有助于更好地了解海洋沃茨中DOM的组成、来源和动态。参与该计划的19名HQP也将有独特的机会在加拿大北极地区工作，那里的环境正在发生迅速的变化。在这个项目中获得的技能和知识，包括尖端的分析技术，北极经验和跨文化和领导技能将是在学术界，政府或行业的职业生涯中非常宝贵的。

Marine dissolved organic matter (DOM) is central to the current and future global carbon cycle, with a reservoir comparable in size to the current atmospheric carbon dioxide reservoir. The fact that the oceans are a huge reservoir of carbon has continued to urge scientists to investigate what DOM is in terms of its source, chemical composition, reactivity and function in marine environments for decades. Marine DOM originates from marine primary production, however only a small fraction is identifiable as common molecules. My research program aims to elucidate the composition and dynamics of dissolved organic matter in marine ecosystems. During the next five years, I plan to continue my research program on the cycling and dynamics of DOM in the highly stratified Arctic's Canada Basin. Specifically, the main objectives will be to: 1)Link fluorescence properties of marine DOM to identifiable molecules. Excitation emission matrix spectroscopy associated with Parallel Factor Analysis (EEM-PARAFAC) has been applied to gain insights about the distribution and dynamics of protein-like and humic-like DOM but there is still a lack of direct evidence linking PARAFAC components to molecularly characterized molecules. Concurrent determination of fluorescence composition, lignin phenol, carbohydrates and amino acids will be used to investigate the relationships between specific fluorescent components and identifiable molecules. 2)Assess the refractory nature of DOM. Mesocosm experiments will be conducted aboard the Canadian Coast Guard icebreaker to assess how the bulk and molecular composition of DOM changes over time, and with changes in bacteria taxonomy. Our research aims to illuminate dark-ocean organic biogeochemistry that is crucial for understanding the cycling of DOM in the global ocean. 3)Investigate the seasonal dynamics of DOM in the Arctic Ocean. High frequency measurements from in situ fluorescent DOM sensors will expand our observations spatially and seasonally. The temporal variability in DOM fluorescence will be related to the change in stratification, biological activities, mineralization and ice cover. This research program will allow to better understand the composition, source and dynamics of DOM in marine waters. The 19 HQP involved in this program would also have the unique opportunity to work in the Canadian Arctic where rapid environmental changes are occurring. The skills and knowledge gained within this project, including cutting edge analytical techniques, arctic experience and intercultural and leadership skills will be invaluable in careers in academia, government or industry.