Behavior of Nd isotopes at the Ocean-Sediment Boundary: Addressing the "Nd Paradox"

海洋-沉积物边界 Nd 同位素的行为：解决“Nd 悖论”

• 批准号: 1147407
• 负责人: Brian Haley
• 金额: $ 43.99万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-15 至 2017-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1147407&HistoricalAwards=false
• 关键词: Behavior; Nd; isotopes; Ocean; Sediment

Neodymium isotope ratios (143Nd/144Nd) are increasingly used as tracers of past ocean circulation patterns. However, our understanding of marine Nd dynamics, and thus the reliability of Nd as an oceanic tracer, is currently complicated by an apparent disconnect between the isotopic compositions of Nd (which are distinctive between ocean basins) and the distribution of elemental Nd (which appears to be driven by water column cycling). It is important to resolve this "Nd paradox" in order to refine tracer studies of past ocean behavior. Prior research suggests that the decoupling of isotopic and elemental Nd may occur near the interface between marine sediments and bottom waters. This study, conducted by researchers at Oregon State University, investigates exchange reactions between dissolved and particulate Nd occurring at and around this interface, with a focus on the influence of diagenetic sedimentary processes on Nd isotope ratios. Porewater, sediment, and water column samples will be collected along the Oregon continental margin and analyzed for Nd isotopes and other relevant tracers (including rare earth elements, carbon, and nitrogen). The resulting dataset will not only help to resolve the Nd paradox, but will also be applied to future conceptual and chemical modeling efforts, which in turn will inform the development of paleoceanographic and paleoclimatic models.This project will be incorporated into the COSEE (Center for Ocean Science Education Excellence) Pacific Partnerships ocean literacy effort. A PRIME (Promoting Research Investigations in the Marine Environment) intern, as well as two OSU students (PhD and undergraduate), will be involved in this research. The project includes international collaboration with a geochemist from the University of Bristol, which will strengthen Oregon State University's analytical capabilities. Funding will also help support an early-career researcher at Oregon State University.

钕同位素比 (143Nd/144Nd) 越来越多地用作过去海洋环流模式的示踪剂。然而，目前我们对海洋 Nd 动力学以及 Nd 作为海洋示踪剂的可靠性的理解，由于 Nd 同位素组成（在海洋盆地之间是独特的）和元素 Nd 分布（似乎是由水柱循环驱动的）之间明显脱节而变得复杂。为了完善对过去海洋行为的示踪研究，解决这个“Nd悖论”非常重要。先前的研究表明，同位素和元素 Nd 的解耦可能发生在海洋沉积物和底层水之间的界面附近。这项研究由俄勒冈州立大学的研究人员进行，研究了该界面及其周围发生的溶解态 Nd 和颗粒态 Nd 之间的交换反应，重点关注成岩沉积过程对 Nd 同位素比的影响。将沿着俄勒冈州大陆边缘收集孔隙水、沉积物和水柱样本，并分析 Nd 同位素和其他相关示踪剂（包括稀土元素、碳和氮）。由此产生的数据集不仅有助于解决 Nd 悖论，还将应用于未来的概念和化学建模工作，从而为古海洋学和古气候模型的开发提供信息。该项目将纳入 COSEE（海洋科学教育卓越中心）太平洋伙伴关系海洋扫盲工作。一名 PRIME（促进海洋环境研究）实习生以及两名俄勒冈州立大学学生（博士和本科生）将参与这项研究。该项目包括与布里斯托大学地球化学家的国际合作，这将增强俄勒冈州立大学的分析能力。资金还将帮助支持俄勒冈州立大学的一名早期职业研究员。