Collaborative Research: Paired Neodymium Isotope and Radiocarbon Analyses in Deep-Sea Corals - Calibration of a Novel Ocean Ventilation Tracer

合作研究：深海珊瑚配对钕同位素和放射性碳分析一种新型海洋通风示踪剂的校准海洋通风率描述了深海团块最后一次与大气接触的时间。了解和限制现代和过去海洋的这段时间是非常重要的，因为高纬度地区深水的形成涉及到与大气的碳交换，从而对气候产生关键影响。这里提出的研究将开发一种确定过去海洋通风率的新方法：从深海珊瑚中成对测量钕（Nd）同位素和放射性碳（14C）。u系列定年深海珊瑚的放射性碳测量已成功地用于限制最后一次冰川消退期间深海的放射性碳含量，但在不知道不同水团混合比例的情况下，我们无法将放射性碳数据转换为海洋通风率。不同的海洋水团具有不同的Nd同位素组成特征，其值最终受区域大陆风化、侵蚀和颗粒-海水相互作用的控制。因此，该代理将用作准保守的水-质混合示踪剂。在这个项目中，pi将评估不同种类的现代深海珊瑚是否记录了环境深水的Nd同位素组成，以及化石珊瑚是否保留了这种Nd同位素特征。这些数据有可能产生一种准确确定过去海洋通气率的新方法。这种多代理方法的结果有可能为研究碳酸盐化学、海洋地球化学循环、全球碳循环和古海洋学等领域的广泛问题的研究人员提供海洋通风、碳循环和气候变化之间的联系。夏季实习的本科生将通过对现代和化石深海珊瑚进行分析测量的离散项目，进入古海洋学和地球化学领域。

Collaborative Research: Paired Neodymium Isotope and Radiocarbon Analyses in Deep-Sea Corals Calibration of a Novel Ocean Ventilation TracerOcean ventilation rates describe the time since a deep water mass last was in contact with the atmosphere. Understanding and constraining this time in the modern and past ocean is of major importance, as the formation of deep waters at high latitudes involves carbon exchange with the atmosphere thereby exerting a key influence on climate. The research proposed here will develop a novel method for determining past ocean ventilation rates: paired neodymium (Nd) isotope and radiocarbon (14C) measurements from deep-sea corals. Radiocarbon measurements in U-series dated deep-sea corals have been successfully used to constrain the radiocarbon content of the deep ocean during the last deglaciation, but without knowing the mixing ratio of different water masses we cannot convert radiocarbon data to ocean ventilation rates. Different water masses in the ocean are characterized by distinct Nd isotopic compositions, whose values are ultimately controlled by regional continental weathering, erosion, and particle-seawater interaction. Therefore this proxy will be used as a quasi-conservative water-mass-mixing tracer.In this project, the PIs will evaluate whether different species of modern deep-sea corals record the Nd isotopic composition of ambient deep water, and whether fossil corals preserve this Nd isotope signature. These data have the potential to produce a new method for accurately determining past ocean ventilation rates. The results of this multiproxy approach have the potential to provide links between ocean ventilation, the carbon cycle, and climate change for researchers studying a broad array of questions in the fields of carbonate chemistry, geochemical cycling in the ocean, the global carbon cycle and paleoceanography. Undergraduate students on summer internships will be introduced to the fields of paleoceanography and geochemistry through discrete projects involving analytical measurements in modern and fossil deep-sea corals.