Collaborative Research: GEOTRACES Arctic Section: The Geochemistry Size-fractionated Suspended Particles Collected by in-situ Filtration

伍兹霍尔海洋研究所的一名研究员参加了2015年美国GEOTRACES北极考察队，他将收集和分析北冰洋西部的悬浮颗粒物，以更好地了解该地区微量元素的循环。与国际地质足迹计划中的其他多国倡议一样，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。粒子是GEOTRACES程序的一个关键参数，因为它们在微量元素的源、汇和循环中起着重要作用。这项研究的结果将与阿拉斯加的土著群体分享。该项目将包括研究生和本科生的培训。北冰洋的粒子循环与其他海洋盆地截然不同。在常年冰雪覆盖的北极中部，初级产量极低，导致生物泵非常弱。由于来自上方的颗粒通量很少，北极盆地的主要颗粒来源似乎是来自边缘的横向运输，这些横向运输的颗粒比其他海洋盆地的颗粒具有更高的岩性含量。北极颗粒的不同来源和组成可能为从水柱中去除颗粒反应性微量元素及其同位素建立了一种与目前所了解的完全不同的动态。目前还没有对北极悬浮粒子的浓度和组成进行全面调查。在本研究中，将分析大小分级悬浮颗粒的主要相和微量元素组成，以及确定清除颗粒活性元素所需的测量，并提供控制生物泵的机制。

An investigator from Woods Hole Oceanographic Institution participating in the 2015 U.S. GEOTRACES Arctic expedition will collect and analyze suspended particulate matter in the Western Arctic Ocean to better understand cycling of trace elements in the region. In common with other multinational 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. Particles are a key parameter for the GEOTRACES program because of their role as sources, sinks, and in the cycling of trace elements. Results from this study will be shared through outreach to native groups in Alaska. The project will involve training of graduate and undergraduate students.Particle cycling in the Arctic Ocean is profoundly different from other ocean basins. Extremely low primary production in the perennially ice-covered central Arctic leads to a very weak biological pump. With little particle flux coming from above, the dominant source of particles to the Arctic Basin appears to be lateral transport from the margins, and these laterally transported particles have much higher lithogenic content than is typically found in particles in other ocean basins. The different source and composition of particles in the Arctic potentially sets up a completely different dynamic for the removal of particle-reactive trace elements and their isotopes from the water column than is currently understood. There has yet to be a comprehensive survey of the concentration and composition of suspended particles in the Arctic. In this study, the size-fractionated suspended particles will be analyzed for major phases and trace element composition, measurements needed to determine scavenging removal of particle reactive elements and provide insight into the mechanisms controlling the biological pump.