Dissolved Organic Matter Composition in the Deep Atlantic Ocean

由于二氧化碳(CO2)从大气中被封存，深海中溶解有机物(DOM)的转化对全球碳循环产生了深远的影响。虽然已经对这种材料的高分子量成分进行了研究，但对于低分子量DOM就不能说同样的话了，因为还没有必要的分析技术来确定其组成和反应性。近年来，伍兹霍尔海洋研究所的一个研究小组已经获得了必要的分析能力。因此，在这个项目中，他们将对西大西洋的深海DOM进行首次系统调查，以表征南向流动的北大西洋深水(NADW)、北流的南极底层水(AABW)和南极中间水(AAIW)中DOM的低分子量分数。科学家们将利用超高分辨率质谱学和多级裂解与液相色谱相结合的方法，确定DOM组成沿水团流动路径的空间变异性，并评估导致DOM组成时间变化的源水、运输和地表过程。这些结果将通过对每个水团的独特标记化合物的结构阐明和定量分析而得到加强。这些结果将为控制深海DOM动态的生物地球化学反应提供重要的见解。该提案的更广泛的影响部分已经很好地开发了。除了支持和培训一名研究生，作为他们外展努力的一部分，支持者还计划为研究生和博士后开发和教授一个关于超高分辨率质谱学的新课程。这门课将为他们提供实践经验，并教他们如何在各种质谱仪上运行样品。此外，倡导者计划设立一个基金，培训学生和博士后如何使用多元统计工具进行数据处理和解释。

Transformations of dissolved organic matter (DOM) in the deep ocean have profound impacts on the global carbon cycle due to the sequestration of carbon dioxide (CO2) away from the atmosphere. Although research has been conducted on the high molecular weight component of this material, the same cannot be said for low molecular weight DOM because the needed analytical techniques have not been available to determine its composition and reactivity. In recent years, a research team at Woods Hole Oceanographic Institution has acquired the necessary analytical capability. As such, in this project, they will carry out the first systematic survey of deep ocean DOM in the western Atlantic Ocean to characterize the low molecular weight fraction of DOM in southward flowing North Atlantic Deep Water (NADW), northward flowing Antarctic Bottom Water (AABW), and Antarctic Intermediate Water (AAIW). Using ultrahigh resolution mass spectrometry and multi-stage fragmentation coupled to liquid chromatography, the scientists will determine the spatial variability in the composition of DOM along the flow path of the water masses, as well as assess the source water, transport, and surface processes that contribute to temporal changes in DOM composition. These results will be augmented with structural elucidation and quantitative assays of unique marker compounds for each water mass. Results will provide important insights into the biogeochemical reactions that govern DOM dynamics in the deep ocean. The broader impacts component of the proposal was well developed. Besides supporting and training one graduate student, as part of their outreach efforts, the proponents plan to develop and teach a new class on ultrahigh resolution mass spectrometry for graduate students and postdocs. This class would provide them with hands-on experience and teach them to run samples on various mass spectrometers. In addition, the proponents plan to create a fund to train students and postdocs on the use of multivariate statistical tools for data processing and interpretation.