GEOTRACES Arctic Section: Shipboard determination of key trace elements

在这个项目中，参加2015年美国地理轨迹北极探险队的调查人员将在船上测量巡航期间收集的海水、冰、雪和融化池塘样本中溶解的铝、铁和锰。与国际地质勘测计划中的其他国家倡议一样，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。一些微量元素对生命是必不可少的，另一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。该项目对整个北极考察的成功具有特别重要的意义，因为对海水中痕量金属的测量需要高度专业化的清洁采样技术，以防止污染。因此，这个科学小组所做的船上测量将允许及早发现和纠正仍在海上的任何样品污染问题。就更广泛的影响而言，教育和培训下一代海洋微量元素科学家，包括本科生和研究生，以及公众宣传将是该项目的关键方面。本研究中船上溶解铝、铁和锰的测定将提供对这些参数分布的近乎实时的洞察，这些参数可用于潜在地修改采样策略，也可用于在GEOTRACES北极考察期间识别任何系统性采样污染问题。溶解的铁和锰的最终数据将由岸上的电感耦合等离子体质谱(ICPMS)产生，这是一种能够检测极低浓度金属的质谱仪。然而，由于岸基电感耦合等离子体质谱仪无法确定溶解铝的数据，作为该项目的一部分收集的船上数据集将为这一关键的GEOTRACES参数提供最终的数据集。此外，研究人员将在水柱上部10米进行高分辨率水样采样，以确定这一高度分层区域的痕量金属分布特征，这是常规玫瑰花环无法采样的。这次采样将在浮冰或小船的边缘进行，远离考察船的干扰影响。

In this project, investigators participating in the 2015 U.S. GEOTRACES Arctic expedition will make shipboard measurements of dissolved aluminum, iron, and manganese in seawater, ice, snow, and melt pond samples collected during the cruise. 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. This project will be of particular importance to the success of the overall Arctic expedition because measurements of trace metals in seawater require highly-specialized clean sampling techniques to prevent contamination. Accordingly, the shipboard measurements made by this scientific team will allow for the early detection and rectification of any sample contamination problems while still at sea. In terms of broader impacts, education and training of the next generation of marine trace element scientists, including undergraduate and graduate students, as well as public outreach will be key aspects of this project.The shipboard determinations of dissolved aluminum, iron, and manganese in this study will provide near real-time insights into the distribution of these parameters, which can be used to potentially modify sampling strategies and can also be used to identify any systemic sampling contamination issues during the GEOTRACES Arctic expedition. Definitive data for dissolved iron and manganese will be produced by shore-based ICP MS, a type of mass spectrometry capable of detecting metals at very low concentrations. However, since dissolved aluminum data cannot be determined by shore-based ICP MS, the shipboard data set collected as part of this project will provide the definitive data set for this key GEOTRACES parameter. In addition, the researchers will undertake high resolution water sampling in the upper 10 m of the water column to characterize the trace metal distribution in this highly stratified region, which cannot be sampled by a conventional rosette. This sampling will be conducted from the edge of ice-floes or a small boat, away from the disturbing effects of the research vessel.