GEOTRACES Arctic Section: Shipboard determination of key trace elements

在这个项目中，参加2015年美国GEOTRACES北极考察队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。这个项目对整个北极考察的成功至关重要，因为测量海水中的微量金属需要高度专业化的清洁采样技术来防止污染。因此，这个科学小组在船上进行的测量将允许在海上早期发现和纠正任何样品污染问题。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，以及公众宣传将是这个项目的关键方面。在这项研究中，船上对溶解铝、铁和锰的测定将提供对这些参数分布的近实时洞察，这些参数可用于潜在地修改采样策略，也可用于识别GEOTRACES北极考察期间的任何系统采样污染问题。溶解铁和锰的确定数据将由岸上ICP质谱法产生，这是一种能够检测极低浓度金属的质谱法。然而，由于岸上ICP MS无法确定溶解铝的数据，因此作为该项目一部分收集的船上数据集将为关键的GEOTRACES参数提供最终数据集。此外，研究人员将在水柱上方10米处进行高分辨率水样采集，以表征这个高度分层区域的痕量金属分布，这是传统玫瑰花结无法采样的。这次取样将在浮冰边缘或小船上进行，远离科考船的干扰影响。

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.