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

合作研究：深海珊瑚中成对的钕同位素和放射性碳分析校准一种新的海洋通风示踪海洋通气率描述自深水团最后一次与大气接触以来的时间。理解和限制现代和过去海洋的这一时期是非常重要的，因为高纬度深水的形成涉及与大气的碳交换，从而对气候产生关键影响。这里提出的研究将开发一种新的方法来确定过去的海洋通气率：来自深海珊瑚的配对的钕(ND)同位素和放射性碳(14C)测量。U系列深海珊瑚的放射性碳测量已成功地用于约束上次冰川消融期间深海的放射性碳含量，但在不知道不同水团的混合比例的情况下，我们无法将放射性碳数据转换为海洋通气率。海洋中不同的水团具有不同的Nd同位素组成，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。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周围深水的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新的方法来准确确定过去的海洋通气率。这种多重代理方法的结果有可能为研究碳酸盐化学、海洋中的地球化学循环、全球碳循环和古海洋学领域的一系列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。暑期实习的本科生将通过涉及现代和化石深海珊瑚分析测量的离散项目，向学生介绍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.