Nd and Sr Isotope Tracers of Deep and Shallow Ocean Circulation around South Africa

来自Lamont-Doherty地球天文台的两名研究人员将完善和测试作为水团保守示踪剂的钕(ND)同位素的有效性，以及完善自生Fe-Mn托管的ND作为水团信号档案的应用，并进一步探索陆源碎屑的同位素特征作为当前示踪剂的用途。将使用从南非东南海岸大深度范围内回收的岩芯、水柱样本和水中颗粒物。利用同位素和化学分析，将完成以下任务：(1)示踪重要洋际交换带主要水团的Nd同位素比值；(2)确定颗粒交换对大陆边缘海水ND同位素的影响；(3)比较岩心顶部铁锰渗滤液和浸泡岩心的水团的Nd同位素；(4)确定“未通过”“海水完整性测试”的渗滤液是否包含标志着失败的化学特征；以及(5)在现有数据显示南大西洋沉积物中有阿古拉海流信号的背景下，用海底的陆源碎屑校准阿古拉什水柱颗粒的ND和锶同位素特征。目标是校准一系列有希望的环流示踪剂，这些示踪剂在海洋环流和古环流研究中有许多未来的应用。就更广泛的影响而言，经校准的环流示踪剂的提供将提供一种评估海洋在气候变化中的作用的手段。预期所获得的数据将存入在线数据库，如SedDB(沉积物地球化学综合数据管理)和/或Chronos(沉积地质学和古生物学联合数据和工具的互动网络)，以及世界数据中心，如美国国家海洋和大气局的国家地球物理数据中心。至于外展工作，私家侦察计划继续参与拉蒙特开放日，与公众讨论他们的研究。一名研究生将接受培训和支持。

ABSTRACTOCE-0526884Two researchers from Lamont-Doherty Earth Observatory will refine and test the utility of neodymium (Nd) isotopes as conservative tracers of water masses, as well as refine the application of the authigenic Fe-Mn-hosted Nd as an archive of the water mass signal and further explore the utility of isotopic signatures of terrigenous detritus as current tracers. Cores, water column samples, and water-borne particulates recovered off the southeast coast of South Africa from a large depth range will be used. Using isotopic and chemical analyses, the following tasks will be carried out: (1) trace Nd isotope ratios of major water masses in an important interocean exchange zone; (2) determine the effects of particle exchange on seawater Nd isotopes along a continental margin; (3) compare Nd isotopes of coretop Fe-Mn leachates to the water masses that bathe the cores: (4) determine if leachates that "fail" the "seawater integrity tests" contain a chemical signature that signals failure; and (5) calibrate the Nd and strontium isotopic signature of Agulhas water column particulates with terrigenous detritus on the seafloor in the context of existing data showing an Agulhas Current signal in South Atlantic sediments. The goal is to calibrate a series of promising circulation tracers that have many future applications in ocean circulation and paleocirculation studies. In terms of broader impacts, availability of calibrated circulation tracers will provide a means of assessing the ocean's role in climate change. It is anticipated that data obtained will be deposited into on-line databases such as SedDB (Integrated Data management for Sediment Geochemistry) and/or CHRONOS (an interactive network of federated data and tools for sedimentary geology and paleobiology), as well as a World Data Center such as NOAA's National Geophysical Data Center. As regards outreach efforts, the PIs plan to continue their participation in the Lamont Open House, wherein they discuss their research with the public. One graduate student will be trained and supported.