GEOTRACES Arctic Section: Shipboard determination of key trace elements

在这个项目中，参加2015年美国GEOTRACES北极考察的调查人员将在船上测量在巡航期间收集的海水、冰、雪和融化池样本中溶解的铝、铁和锰。与国际GEOTRACES计划中的其他国家举措一样，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量化通量，并确定这些分布的敏感性变化的环境条件。一些微量元素是生命所必需的，另一些是已知的生物毒素，还有一些是重要的，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，因为海水中微量金属的测量需要高度专业化的清洁取样技术，以防止污染。因此，该科学小组在船上进行的测量将有助于在海上及早发现和纠正任何样本污染问题。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。本研究中溶解铝、铁和锰的船上测定将提供对这些参数分布的近实时见解，这可用于潜在地修改采样策略，也可用于确定GEOTRACES北极考察期间的任何系统性采样污染问题。溶解的铁和锰的连续数据将由岸基ICP MS产生，ICP MS是一种能够检测极低浓度金属的质谱法。然而，由于溶解铝数据不能由岸基ICP MS确定，作为本项目的一部分收集的船上数据集将为这一关键GEOTRACES参数提供确定的数据集。此外，研究人员还将在水柱上部10米处进行高分辨率水样采集，以表征这一高度分层区域的微量金属分布，这是传统玫瑰花结无法采样的。取样将从浮冰边缘或小船上进行，远离研究船的干扰影响。

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.