Collaborative research: Does dissolved organic matter influence the concentrations and distributions of trace elements in the Arctic Ocean?

研究人员建议利用已经获得资助的三个研究考察来调查北冰洋中天然溶解有机物质（DOM）循环的分布，特别是它与微量金属（如铁）循环的关系。北冰洋在过去30年里经历了重大变化，包括海冰减少和大陆径流增加。北极被认为是碳和水文循环变化的先兆，对区域和全球气候具有重要影响。北冰洋的物理、化学和生物结构将如何应对这些根本性的变化，人们知之甚少。所提出的研究将为溶解有机物及其在微量元素循环中的作用提供新的见解。最近的研究提供了诱人的数据，表明DOM和微量金属在北冰洋的运输和命运密切相关，并表明大陆径流和海冰形成在DOM和相关微量金属的分布中起着重要作用。在2015年的3次考察中，将分别搭乘USCGC Healy号、德国破冰船北极星号（Polarstern）和日本研究船未来号（Mirai）收集和分析水样，分析溶解的有机碳和氮、氨基酸、木质素酚类物质，并对变色DOM （CDOM）进行详细的光学表征。结合光学和分子分析将用于区分和量化陆源和海洋DOM及其与微量元素的潜在相互作用。用于测量DOM原位荧光的探针将与CTD/玫瑰花结相连接，用于高分辨率绘图和实时检查有趣的特征，以指导采样工作。美国和德国的考察是国际GEOTRACES计划的一部分，其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，并确定这些分布对不断变化的环境条件的敏感性。美国北极GEOTRACES项目已经为这项研究项目建立了一个中心外展计划，包括与阿拉斯加当地社区的会议，招募一名高中教师参加考察，并通过博客与美国和其他地区的学校进行互动。这些调查人员将与现有的GEOTRACES外展工作联系起来，并将感兴趣的德克萨斯州和南卡罗来纳州的学校与探险博客联系起来。本项目将培养3名研究生和约6名本科生到北冰洋进行研究。本项目教学部分的目标是为学生提供展示科学方法的经验，从目标和假设的发展到实验设计和结果的呈现。该项目的研究结果将通过与当地报纸建立的联系向公众传达，学生用自己的语言描述研究项目。

The investigators propose to take advantage of three already-funded research expeditions to investigate the distribution of cycling of natural dissolved organic material (DOM) in the Arctic Ocean and in particular its relationship to the cycling of trace metals such as iron. The Arctic Ocean has experienced significant changes over the last 30 years, including declining sea ice and increasing continental runoff. The Arctic is considered a harbinger of changes in the carbon and hydrological cycles, with important implications for regional and global climate. How the physical, chemical and biological structure of the Arctic Ocean will respond to such fundamental changes is poorly understood. The proposed research will provide novel insights about dissolved organic matter and its role in trace element cycling. Recent studies provide tantalizing data indicating the transport and fate of DOM and trace metals are closely linked in the Arctic Ocean, and suggesting an important role of continental runoff and sea ice formation in the distribution of DOM and associated trace metals.Water samples will be collected and analyzed for dissolved organic carbon and nitrogen, amino acids, lignin phenols and detailed optical characterization of chromophoric DOM (CDOM) during 3 expeditions in 2015 aboard the USCGC Healy, the German ice breaker Polarstern, and the Japanese research vessel Mirai. The combined optical and molecular analyses will be used to distinguish and quantify terrigenous and marine DOM and their potential interactions with trace elements. A probe for measuring in situ fluorescence of DOM will be interfaced with the CTD/rosette for high-resolution mapping and real-time examination of interesting features to guide sampling efforts. The U.S. and German expeditions are part of the international GEOTRACES program, whose goals 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. The U.S. Arctic GEOTRACES project has established a central outreach program for this research program including meetings with local communities in Alaska, recruiting a high school teacher to participate in the expedition and interact with schools in the US and beyond via a blog. These investigators will tie into the existing GEOTRACES outreach efforts and will link interested Texas and South Carolina Schools to the expedition blog. This project will train 3 graduate students in and expose about 6 undergraduate students to research in the Arctic Ocean. The goal of the teaching component of this project is to provide students with an experience that demonstrates the scientific method, from development of goals and hypotheses to experimental design and presentation of results. Findings of this project will be conveyed to the public using established links with local newspapers where students describe research projects in their own words.