Collaborative Research: GEOTRACES Arctic Section: Marine Cycling of Bioactive Trace Metals in the Arctic Ocean

在这个项目中，一组参加2015年美国地质调查局北极考察的调查人员将研究北冰洋中七种痕量金属的化学和地区分布：铁、锰、锌、镉、铜、镍和钴。这些所谓的生物活性金属具有特殊的科学价值，因为它们在多种生物地球化学过程中发挥作用，包括海洋的生物生产以及碳和氮的行星循环。与国际地质勘测计划中的其他多国倡议一样，美国北极探险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通量，并确定这些分布对不断变化的环境条件的敏感性。这项研究将特别有助于我们了解这七种生物活性金属的来源和汇，并检查它们与生物过程的相互作用。该项目将侧重于两个主要的研究问题：(1)北极地区微量营养素和大量营养素的来源和汇是什么？以及(2)生物活性微量元素营养如何影响北极的生产力和物种组成，反过来，生物过程又如何影响这些金属的循环？就更广泛的影响而言，该项目的私人投资机构将积极参与教育推广工作，研究小组本身将包括两名博士后研究人员和一名研究生。研究小组组长还计划出版一本以探险为基础的儿童海洋教育书籍，目的是让下一代人对现代海洋科学感到兴奋。在技术细节方面，研究小组将测量生物活性金属Fe、Mn、Zn、Cd、Cu、Ni和Co的溶解海水相，溶解的稳定金属同位素56Fe、66Zn和114Cd，以及Co的化学形态。多元素和多同位素分析方法的最新发展，与GEOTRACES计划的高分辨率采样相结合，使高效地产生这个金属和金属同位素的密集数据集成为可能。这将是一种以团队为基础的方法，以实现全面复制，以分析溶解金属浓度的关键参数。每名研究人员将进一步对金属同位素和溶解的钴(具有独特的分析挑战)和钴的形态进行专门的额外测量。对这些丰富的数据集的解释将与其他美国地质勘探局的参与者合作，以确定源和汇以及它们的生态化学计量，测量协同参数。总之，这一北冰洋生物活性痕量金属数据集有望为理解微量营养素在北极生物地球化学过程中的作用作出重要贡献。这些结果也应该与对古代海洋的研究高度相关，在古代海洋的研究中，微量金属分析通常被用来追踪各种过程，包括古海洋环流和生物生产力。最后，了解现代海洋中元素的来源和汇是预测生物活性元素的浓度在未来气候变化中可能如何变化的关键。

In this project, a group of investigators participating in the 2015 U.S.GEOTRACES Arctic expedition will study the chemistry and regional distribution of seven trace metals in the Arctic Ocean: iron, manganese, zinc, cadmium, copper, nickel, and cobalt. These so-called bioactive metals are of special scientific interest because of their role in multiple biogeochemical processes including biological production of the sea and the planetary cycling of carbon and nitrogen. Like other multinational 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. This study in particular would contribute to our understanding of the sources and sinks of these seven bioactive metals as well as examine their interaction with biological processes. The project will focus on two major overarching research questions: (1) What are the sources and sinks for micronutrients and macronutrients in the Arctic? And (2) How does bioactive trace element nutrition influence productivity and species composition in the Arctic, and conversely, how do biological processes influence the cycling of these metals? In terms of broader impacts, the PIs on this project will be actively involved in educational outreach efforts, and the research team itself will include two postdoctoral researchers and a graduate student. The team leaders also plan to publish a children's ocean education book based on the expedition with the aim of generating next-generation excitement about modern ocean scienceWIth regard to technical specifics, the research team will measure the dissolved seawater phases of the bioactive metals Fe, Mn, Zn, Cd, Cu, Ni, and Co, the dissolved stable metal isotopes 56Fe, 66Zn, and 114Cd, and the chemical speciation of Co. The recent development of methods for multi-element and multi-isotope analysis methods, in conjunction with the high-resolution sampling of the GEOTRACES program, make it possible to efficiently produce this dense dataset of metals and metal isotopes. This will be a team-based approach to achieve comprehensive duplication for analysis of the key parameters of dissolved metal concentrations. Each investigator will further conduct specialized additional measurements of metal isotopes and dissolved Co (which has unique analytical challenges) and Co speciation. Interpretation of these rich datasets would will be directed toward determination of sources and sinks as well as their ecological stoichiometry, in collaboration with other U.S.GEOTRACES participants measuring synergistic parameters. Together, this Arctic Ocean bioactive trace metal dataset is expected to provide an important contribution to the understanding of micronutrient roles in Arctic biogeochemical processes. These results should also be highly relevant to research studies of the ancient ocean, in which trace-metal analyses are commonly used to trace a wide variety of processes including paleo-ocean circulation and biological productivity. Finally, understanding the sources and sinks for elements in the modern ocean is key to predicting how the concentrations of bioactive elements might vary in a changing future climate.