Collaborative Research: GEOTRACES Arctic Section: Nd isotopes and REEs in the Arctic

在该项目中，参加2015年美国GEOTRACES北极考察的研究人员将测量从北冰洋西部收集的海水、沉积物和颗粒物中的钕同位素和稀土元素。与国际GEOTRACES计划中的其他国家倡议一样，美国北极考察的目标是确定控制海洋中关键微量元素和同位素分布的过程和量化通量，并确定这些分布对环境条件变化的敏感性。一些微量元素是生命所必需的，另一些是已知的生物毒素，还有一些是重要的，因为它们可以用作海洋中各种物理，化学和生物过程的示踪剂。稀土元素是海洋学示踪剂，这项研究的数据将为其他微量元素和同位素研究提供基准，以更好地了解它们的周期以及未来环境变化将如何影响这一重要的海洋盆地。该项目将支持本科生、研究生和博士后研究人员的培训，并将通过公共宣传活动传播成果。钕（Nd）同位素是水体来源、运输和混合的示踪剂，稀土元素（REE）在环境过程中显示出系统分馏。它们共同提供了一个强大的工具，用于分析海洋中的来源和过程，反映了环境对微量元素及其同位素分布的控制。固有的后勤困难使得北冰洋的TEI数据（包括Nd同位素和REE浓度）特别稀缺，这阻碍了对这些示踪剂的理解和应用。在这项研究中，研究人员将检查在北冰洋西部收集的海水，沉积物和颗粒样品中的Nd和REE浓度，目的是（1）根据Nd同位素和REE评估北极环流和水团混合;（2）试图量化TEI的颗粒溶解交换;（3）使用Nd同位素和REE来表征TEI的源，汇和交换。预计通过对Nd同位素和稀土元素示踪剂的更好理解，科学家将能够将这些发现与其他TEIs以及对过去，现在和未来北极海洋变化的更广泛理解联系起来。

In this project, investigators participating in the 2015 U.S. GEOTRACES Arctic expedition will measure neodymium isotopes and rare earth elements in seawater, sediment, and particulates collected from the western Arctic Ocean. In common with other national initiatives in the International GEOTRACES Program, the goals of the U.S. Arctic expedition are to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions. Some trace elements are essential to life, others are known biological toxins, and still others are important because they can be used as tracers of a variety of physical, chemical, and biological processes in the sea. Neodymium and rare earth elements are oceanographic tracers, and data from this research will provide benchmarks for other trace element and isotope studies to better understand their cycles and how future environmental changes will impact this important ocean basin. The project will support the training of undergraduate, graduate, and post-doctoral researchers, and results will be disseminated via public outreach activities.Neodymium (Nd) isotopes are tracers of water mass sources, transport and mixing, and rare earth elements (REEs) show systematic fractionations during environmental processes. Together they provide a powerful tool for analyzing provenances and processes in the oceans that reflect the changing environmental controls on the distribution of trace elements and their isotopes (TEIs). Inherent logistical difficulties make the Arctic Ocean especially scarce in TEI data (including Nd isotopes and REE concentrations), which hinders understanding and application of these tracers. In this study, researchers will examine Nd and REE concentrations in seawater, sediment, and particulate samples collected in the western Arctic Ocean, with the aim of (1) assessing Arctic circulation and water mass mixing in light of Nd isotopes and REEs; (2) attempting to quantify particle-dissolved exchanges of TEIs and; (3) using Nd isotopes and REEs to characterize the sources, sinks and exchanges of TEIs. It is expected that through improved understanding of the Nd isotope and REEs tracers, scientists will be able to relate these findings to other TEIs and to the broader understanding of Arctic oceanographic change in the past, present, and future.