Supply, eastward transport, and temporal variability of trace elements in the zonal current system of the tropical West Pacific - an integrated innovative study using Nd isotopes, rare earth elements, and ocean dynamics

该研究旨在测试热带太平洋纬向流系统在提供微量元素（TE）（包括微量元素）方面的潜在关键作用。从西太平洋源区到含铁有限的东太平洋，特别关注最近发现的中深度急流（水深> 1 000米）。其主要目的是解决其起源，空间范围和地球化学成分，以评估其在东太平洋燃料生产力的潜在作用。该研究将与以前和正在进行的南、西和赤道太平洋的地球化学和物理海洋学研究（自己的项目和我的合作伙伴的项目）相结合，还将解决TE供应和东向运输的时间变化问题。热带西太平洋被认为是微量营养素和其他TE向东流动的纬向流的一个重要来源地区，这些纬向流将它们输送到铁有限的东太平洋，从而维持初级生产力，从而维持该地区的生态系统和渔业。因此，必须了解西太平洋的TE供应，输送它们的海流的起源和结构，以及它们可能的年际变化。特别是，目前还不知道，TE供应是否只发生在表面和地下电流或也到中深射流，以及是否在西部的所有岛屿边缘同样重要的TE源。此外，目前还不清楚，是否中深度射流起源于西方的离散射流运输TE到东方，或者他们是否从其他电流的再循环，在这种情况下，他们将在一个不太重要的作用，包括微量营养素的TE向东运输。钕（Nd）同位素和稀土元素（REE）是理想的适合于确定源和跟踪的TE在热带太平洋的运输，由于其非生物活性的性质和其独特的西太平洋和东太平洋的签名。在与我的德国和法国伙伴、经验丰富的地球化学家和物理海洋学家密切合作下，我提议将来自热带西太平洋的新的、高分辨率的和现有的钕同位素和稀土元素数据与来自同一航次的大量物理海洋学数据以及已发表或即将发表的其他痕量金属数据（铁、锌、铜、镉、锰、铝）相结合。这种多学科的方法将提供深入了解元素（包括。微量营养素）的来源，供应，运输和动力学在热带太平洋。拟议的研究以及与德国和法国专家在数据解释方面的协调努力，是迄今了解热带西太平洋物理和化学海洋学的最全面办法，预计将独特地解决上述未决问题。

The study is aimed at testing the potentially crucial role of the tropical Pacific zonal current system in providing trace elements (TE) (incl. micronutrients) from the West Pacific source area to the iron-limited East Pacific, with a particular focus on recently discovered mid-depth jets (>1000 m water depth). The main aim is to resolve their origin, spatial extent, and geochemical composition to evaluate their potential role in fuelling productivity in the East Pacific. Integrated into previous and ongoing geochemical and physical oceanographic studies of the South, West, and equatorial Pacific (own projects and those of my partners), the study will also address the temporal variability of TE supply and eastward transport. The tropical West Pacific is thought to be an important source area of micronutrients and other TEs to eastward flowing zonal currents that transport them to the iron-limited East Pacific, and thus sustain primary productivity and hence ecosystems and fisheries in this area. It is therefore imperative to understand the TE supply to the West Pacific, the origin and structure of the currents transporting them, and their possible inter-annual variability. Particularly, it is currently not known, whether TE supply occurs only to the surface and subsurface currents or also to the mid-depth jets, and whether all island margins in the West are equally important TE sources. Moreover, it is not yet clear, whether the mid-depth jets originate in the West as discrete jets transporting TEs to the East, or whether they are fed by recirculation from other currents, in which case they would take in a less important role in the eastward transport of TEs including micronutrients. Neodymium (Nd) isotopes and rare earth elements (REE) are ideally suited to identify the source and trace the transport of TEs in the tropical Pacific due to their non-bioactive nature and their distinct West and East Pacific signatures. In close collaboration with my German and French partners, experienced geochemists and physical oceanographers, I propose to combine new, high-resolution and existing Nd isotope and REE data from the tropical West Pacific with extensive physical oceanographic data from the same cruises and with additional trace metal data (Fe, Zn, Cu, Cd, Mn, Al) that are published or will soon become available. This multidisciplinary approach will provide insight into element (incl. micronutrient) sources, supply, transport, and dynamics in the tropical Pacific. The proposed study and concerted effort in data interpretation with German and French experts represents the most comprehensive approach to understand the physical and chemical oceanography of the tropical West Pacific to date and is expected to uniquely address the above-mentioned open questions.