GEOTRACES Arctic section: Dissolved micronutrient trace metal distributions and size partitioning

在这个项目中，参加2015年美国GEOTRACES北极考察队的调查人员将从北冰洋西部的各种海水和冰样本中测量铁、锰、锌、铜、镉和镍的浓度。这些通常被称为“微量营养素”，因为它们在海洋中的浓度极低，而且对海洋生物至关重要。与国际地质足迹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，并确定这些分布对不断变化的环境条件的敏感性。有些微量元素是生命所必需的，有些是已知的生物毒素，还有一些很重要，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。本研究中要测量的六种微量元素可以说是海洋中最重要的生物活性微量元素，它们的测量将提供北极生物和物理过程的关键信息。该项目将在博士后研究员的指导下进行，为早期职业科学家提供独特的职业发展机会。此外，这项研究将包括培训一名本科生研究员，并为K-12教师和学生以及阿拉斯加的土著居民提供公共宣传机会。该项目测量的六种微量元素都已被确定为GEOTRACES项目的关键微量元素。这项研究将允许对北极的物理和生物过程进行严格的测试，其中许多过程已经由于气候变化而发生了根本性的变化，这些过程控制着北冰洋中关键微量营养素金属的输入和命运。胶体分布是特别有针对性的，以便获得关于独特的物理化学形式和不同溶解金属池的反应性的额外信息。该项目还将通过测量这六种金属在海冰、雪、融化池和海冰下的海水中的浓度和大小分配，探索海冰融化在推动这些元素近地表浓度方面的作用。考虑到北极是一个被广阔的大陆架包围的相对较小的盆地，沉积源和沉积汇也将在控制这些元素的分布方面发挥重要作用。因此，也将从白令海和楚科奇海的岩心中测定海底沉积物孔隙水样品中的金属浓度，以便调查底栖生物的交换。

In this project, investigators participating in the 2015 U.S. GEOTRACES Arctic expedition will measure the concentrations of iron, manganese, zinc, copper, cadmium, and nickel from a variety of seawater and ice samples in the Western Arctic Ocean. These are commonly referred to as 'micronutrients' because they are present in the ocean in extremely low concentrations and because they are essential for marine organisms. 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. The six trace elements to be measured in this study are arguably the most important bioactive trace elements in the oceans, and their measurement will provide key information on biological and physical processes in the Arctic. This project will be carried out under the direction of a postdoctoral researcher, providing a unique professional development opportunity for an early career scientist. In addition, the research will involve the training of an undergraduate researcher, and provide public outreach opportunities to K-12 teachers and students, and indigenous populations in Alaska.The six micronutrients to be measured under this project have all been identified as key trace elements for the GEOTRACES Program. This research will allow rigorous testing of the Arctic physical and biological processes, many of which are already undergoing fundamental changes as a result of climate change, that control the inputs and fate of key micronutrient metals in the Arctic Ocean. Colloidal distributions are specifically targeted in order to derive additional information on the unique physicochemical form and reactivity of distinct dissolved metal pools. The project will also explore the role of melting sea ice in driving near-surface concentrations of these elements by measuring concentrations and size partitioning of these six metals in sea ice, snow, melt ponds, and in the seawater immediately under sea ice. Given that the Arctic is a relatively small basin surrounded by broad continental shelves, sedimentary sources and sinks will also play a major role in controlling the distributions of these elements. Thus, metal concentrations in porewater samples from bottom sediments will also be determined from cores in the Bering and Chukchi Seas, in order to investigate benthic exchanges.