Rare earth elements and neodymium isotopes in the South Pacific: impact of hydrothermal activity, particle fluxes, and ocean circulation

南太平洋的稀土元素和钕同位素：热液活动、粒子通量和海洋环流的影响

• 批准号: 417302675
• 负责人: Professorin Dr. Katharina Pahnke-May
• 金额: --
• 依托单位: Lamont-Doherty Earth Observatory
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/417302675?language=en
• 关键词: Rare; earth; elements; neodymium; isotopes

Knowledge of the biogeochemical processes affecting trace elements and their isotopes (TEIs) in the ocean and their impact on TEI distributions and budgets is essential for a comprehensive understanding of the roles of TEIs as micronutrients and tracers. Neodymium (Nd) isotopes and rare earth elements (REEs) are highly useful marine tracers and have been widely applied to improve our understanding of both modern and past processes and changes in the ocean. The particle reactivity of REEs and the source information carried by Nd isotopes make them particularly useful for elucidating dissolved TEI sources and modifications in the ocean, scavenging by particles, and lateral transport by water masses. In the study proposed here, I will test the hypotheses that hydrothermal particles lead to intense REE scavenging and characteristic REE and Nd isotope signatures that allow tracing the fate of hydrothermal plumes in the South Pacific and potentially their upwelling to the surface of the Southern Ocean. Moreover, I will test whether the extremely low particle fluxes in the oligotrophic subtropical South Pacific gyre lead to a dominant control of lateral advection on the distribution of dissolved REEs in this area. The project will further assess the potential modification of the original dissolved Nd isotope signatures of newly formed Southern Ocean water masses through input from New Zealand and/or contact with the New Zealand margin and the Kermadec hydrothermal system. The study will therefore provide insight into the impact of the highly active hydrothermal system of the southern East Pacific Rise, as well as the shallow and with respect to TEIs so far largely unstudied hydrothermal system of the Kermadec Arc on dissolved REEs and Nd isotopes in the Pacific. The expected results will have far-reaching implications for the global REE budget in the ocean, the use of REEs and Nd isotopes as tracers, as well as for the impact of the studied processes on other dissolved TEIs.

了解影响海洋中微量元素及其同位素（TEI）的生物地球化学过程及其对TEI分布和收支的影响，对于全面了解TEI作为微量营养素和示踪剂的作用至关重要。钕（Nd）同位素和稀土元素（ree）是非常有用的海洋示踪剂，已被广泛应用于提高我们对现代和过去海洋过程和变化的理解。稀土元素的粒子反应性和Nd同位素携带的源信息使它们对阐明海洋中溶解的TEI源和变化、粒子清除和水团的横向输送特别有用。在这里提出的研究中，我将测试热液颗粒导致强烈的REE清除和特征REE和Nd同位素特征的假设，这些特征允许追踪南太平洋热液羽流的命运，并可能上涌到南大洋表面。此外，我将测试南太平洋副热带少营养环流中极低的颗粒通量是否导致侧向平流对该地区溶解稀土分布的主导控制。该项目将进一步评估通过新西兰的输入和/或与新西兰边缘和Kermadec热液系统的接触，对新形成的南大洋水团原始溶解Nd同位素特征的潜在改变。因此，该研究将深入了解南东太平洋隆起高度活跃的热液系统，以及迄今为止尚未研究的克马德克弧浅层和TEIs热液系统对太平洋溶解的稀土和钕同位素的影响。预期的结果将对海洋中全球稀土收支、稀土和钕同位素作为示踪剂的使用以及所研究的过程对其他溶解的TEIs的影响产生深远的影响。