Collaborative Research: U.S. GEOTRACES PMT: Dissolved trace metal distributions and size partitioning

国际GEOTRACES计划的目标是了解微量化学元素及其同位素在海洋中的分布。许多微量金属，根据定义，含量非常低，是生命所必需的，因此被认为是浮游植物生长的营养物质。其他元素可用于追踪其他海洋过程，有些元素（如铅）很重要，因为它们是污染物。该项目的主要目标是测量溶解在海水中的铁、锰、锌、铜、镉、镍、铅和钪的浓度，这些海水沿着一条从阿拉斯加向南延伸到太平洋塔希提岛的全深度海洋站。专门的取样和过滤技术也将使这些研究人员及其同事能够确定这些金属在非常小的颗粒上的分布。一名研究生和几名本科生将参加该项目。美国GEOTRACES太平洋子午线样带计划于2018年秋季进行，旨在系统和彻底地确定一个巡航样带上微量元素和同位素的分布，该样带跨越沉积、大气和热液金属供应的带状带;与几个带状生物生产和氧化机制相交;穿越复杂的赤道上升流系统，并包括已知最古老的深海沃茨。本提案的主要目标是确定溶解（0.2微米过滤）微量营养素金属铁，锰，锌，铜，镉，镍，以及示踪剂铅和钪的浓度，在每个水柱和表面样本收集，使用两个完善的多元素分析方法，将内部相互校准，以最大限度地提高数据质量。其中许多是分析GEOTRACES巡航所需的“关键要素”。还将对所有样品进行超滤，以确定这些元素的“真可溶”（0.003微米）浓度，并通过差值计算胶体（0.003-0.2微米）部分。拟议研究的总体目标是了解控制微量营养素微量金属分布的海洋通量和过程，微量营养素微量金属本身调节太平洋的初级生产和海洋二氧化碳吸收。拟议的研究将允许估计这些金属源通量和过程中的每一个在太平洋的纬向影响，这是不好的限制，由于大多是纬向太平洋巡航断面在过去。胶体分布是专门针对的，以获得额外的信息的反应性（相对于清除和生物利用度）的不同溶解的金属池，以及提供一个基本的限制金属的物理化学形态，这是不明确的许多八种金属。

The goal of the international GEOTRACES program is to understand the distributions of trace chemical elements and their isotopes in the oceans. Many trace metals, which are by definition present in very low amounts, are essential for life and thus considered nutrients for phytoplankton growth. Other elements can be useful for tracing other ocean processes, and some (such as lead) are important because they are pollutants. The primary goal of this project is to measure the concentrations of iron, manganese, zinc, copper, cadmium, nickel, lead, and scandium dissolved in seawater along a line of full-depth ocean stations extending south from Alaska to Tahiti in the Pacific Ocean. Specialized sampling and filtration techniques will also enable these investigators and their colleagues to determine the distribution of these metals on very small particles. A graduate student and several undergraduate students will take part in the project.The U.S. GEOTRACES Pacific Meridional Transect, planned for the fall of 2018, aims to systematically and thoroughly determine the distribution of trace elements and isotopes on a cruise transect that spans zonal bands of sedimentary, atmospheric, and hydrothermal metal supplies; intersects several zonal biological production and oxygenation regimes; traverses the complex equatorial upwelling system; and encompasses the oldest known deep waters in the ocean. The primary goal of this proposal is to determine the concentrations of dissolved (0.2 micron-filtered) micronutrient metals Fe, Mn, Zn, Cu, Cd, and Ni, as well as tracers Pb and Sc, on every water column and surface sample collected, using two well-established multi-element analytical methods that will be intercalibrated internally to maximize data quality. Many of these are "key elements" required for analysis on GEOTRACES cruises. Ultrafiltration will also be completed on all samples to determine the "truly soluble" (0.003 micron) concentrations of these elements and to calculate, by difference, the colloidal (0.003-0.2 micron) fraction. The overarching goal of the proposed research is to understand the ocean fluxes and processes that control the distributions of micronutrient trace metals, which themselves modulate primary production and oceanic carbon dioxide uptake, in the Pacific Ocean. The proposed research will allow for an estimate of the meridional influence of each of these metal source fluxes and processes in the Pacific, which is poorly constrained to date due to the mostly zonal Pacific cruise transects in the past. Colloidal distributions are specifically targeted in order to derive additional information on the reactivity (with respect to both scavenging and bioavailability) of distinct dissolved metal pools, as well as to provide a basic constraint on metal physicochemical speciation, which is poorly defined for many of the eight metals.