Enhancement of Capabilities for Molecular-Level Radiocarbon Studies of Water Column and Sedimentary Organic Matter

自从从海洋沉积物中分离出的单个有机化合物的14C含量的测量结果在近十年前首次发表以来，化合物特定放射性碳分析（CSRA）引起了海洋科学界越来越大的兴趣。虽然这种方法的后续应用为海洋中溶解有机物和颗粒有机物的循环提供了重要的新见解，但我们的解释仍然是初级的，主要是因为现有数据集的稀疏性。分子水平14C信息的缺乏表现在两个方面：迄今为止研究的样品数量有限，以及同位素表征的分子种类范围狭窄。通过这笔资金，伍兹霍尔海洋研究所的有机地球化学家团队将购买仪器，升级和增强他们现有的CSRA能力，目标是(1)扩大可用于14C测量的化合物的范围，(2)增加样品吞吐量。该仪器包括一个制备型毛细管气相色谱（PCGC）系统，以取代已有12年历史的型号，以及一个半制备型液相色谱/质谱（LC/MS）系统。总之，这些工具将提供广泛的能力，这些能力将在pi之间共享，并满足pi的需求。未来的应用包括溶解和颗粒有机物质的难熔大分子组分的分子同位素表征，以及挥发性和溶解的卤化有机化合物。在不久的将来，利用连续流加速器质谱法（CF-AMS）测量自然丰度14C无疑将成为现实。PCGC和LC都是CF-AMS样品导入的可行模式，pi将投入大量的时间和精力来开发与这一令人兴奋的新技术兼容的色谱方法。科学价值和更广泛的影响。分子水平天然丰度14C的测量已成为海洋溶解性和颗粒性有机物生物地球化学研究的重要组成部分。这种诞生于海洋科学的方法论，现在正在环境化学和考古学等其他领域得到应用。通过使用拟议的仪器，pi希望进一步扩大化合物特定放射性碳分析的适用性和实用性。这些pi都积极为研究生和本科生提供建议，通过拟议的仪器提供的新研究能力将为学生参与跨学科研究提供独特而具有挑战性的机会。作为该提案的一部分，一名研究生将在探索新仪器的功能方面发挥不可或缺的作用，以期开发通过CF-AMS进行分子水平14C测量的协议

Since measurements of 14C contents of individual organic compounds isolated from marine sediments were first published almost a decade ago, compound specific radiocarbon analysis (CSRA) has met with increasing interest by the ocean science community. While subsequent applications of this approach have provided important new insights into the cycling of dissolved and particulate organic matter in the ocean, our interpretations remain rudimentary, largely because of the sparse nature of existing data sets. This paucity of molecular-level 14C information manifests itself in two ways -- the limited number of samples investigated thus far, and the narrow range of molecular species that have been isotopically characterized. With funding through this grant, a team of organic geochemists at the Woods Hole Oceanographic Institution will purchase instrumentation that upgrades and enhances their existing capabilities for CSRA, with the goal of (i) expanding the range of compounds amenable to 14C measurement, and (ii) increasing sample throughput. The instrumentation includes a preparative capillary gas chromatography (PCGC) system to replace the preexisting 12-year-old model, and a semi-preparative liquid chromatography/mass spectrometry (LC/MS) system. Together, these instruments will provide broad capabilities that will be shared among, and meet the needs of, the PIs. Future applications include molecular isotopic characterization of refractory macromolecular components of dissolved and particulate organic matter, and of volatile and dissolved halogenated organic compounds. In the near future, natural abundance 14C measurements by continuous-flow accelerator mass spectrometry (CF-AMS) will undoubtedly become reality. Both PCGC and LC represent viable modes of sample introduction for CF-AMS, and the PIs will devote considerable time and effort to developing chromatographic methods compatible with this exciting new technology.Scientific Merit and Broader Impacts. Molecular-level natural abundance 14C measurements have become an important component of biogeochemical studies of marine dissolved and particulate organic matter. This methodological approach, which was born in the ocean sciences, is now finding applications in other fields such as environmental chemistry and archaeology. Through access to the proposed instrumentation, the PIs hope to further expand the applicability and utility of compound specific radiocarbon analysis. The PIs are each active in advising graduate and undergraduate summer students, and the new research capabilities made available through the proposed instrumentation will provide unique and challenging opportunities for students to become involved in, and spearhead, interdisciplinary research. As part of this proposal, a graduate student will play an integral role in exploring the capabilities of the new instrumentation with a view towards developing protocols for molecular-level 14C measurements via CF-AMS