Dissolved Organic Matter Composition in the Deep Atlantic Ocean

深海中溶解有机物（DOM）的转化对大气中二氧化碳（CO2）的封存对全球碳循环产生了深远的影响。虽然对这种材料的高分子量组分进行了研究，但对低分子量DOM的研究却并非如此，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，在本项目中，他们将首次在西大西洋开展深海DOM的系统调查，以表征北大西洋南向深水（NADW）、南极南向底水（AABW）和南极中间水（AAIW）中DOM的低分子量部分。利用超高分辨率质谱和液相色谱相结合的多级破碎技术，科学家们将确定沿水团流动路径DOM组成的空间变异性，并评估水源、运输和地表过程对DOM组成的时间变化的影响。这些结果将通过结构解析和每个水团的独特标记化合物的定量分析来增强。研究结果将对控制深海DOM动力学的生物地球化学反应提供重要见解。该建议的更广泛影响部分得到了很好的发展。除了支持和培训一名研究生外，作为拓展工作的一部分，支持者还计划为研究生和博士后开设一门关于超高分辨率质谱法的新课程。本课程将提供他们实际操作的经验，并教他们在各种质谱仪上运行样品。此外，支持者还计划设立一个基金，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.