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

合作研究：美国 GEOTRACES PMT：溶解的痕量金属分布和尺寸划分

• 批准号: 1736875
• 负责人: Claire Till
• 金额: $ 11.65万
• 依托单位: Humboldt State University Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-11-01 至 2021-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1736875&HistoricalAwards=false
• 关键词: Collaborative; Research; U.S.; GEOTRACES; PMT

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.

国际地学研究计划的目标是了解海洋中痕量化学元素及其同位素的分布。根据定义，许多微量金属的含量很低，是生命所必需的，因此被认为是浮游植物生长的营养物质。其他元素可以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沿着从阿拉斯加向南延伸到太平洋塔希提岛的一系列全深度海洋站测量海水中溶解的铁、锰、锌、铜、镉、镍、铅和钪的浓度。专门的采样和过滤技术还将使这些研究人员和他们的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与这一项目。计划于2018年秋季进行的美国地理跟踪太平洋子午线，旨在系统和彻底地确定一条邮轮横断面上的微量元素和同位素分布，该横断面横跨沉积、大气和热液金属供应的地带性带状；横跨几个地带性的生物生产和氧化制度；横跨复杂的赤道上升流系统；并涵盖已知的海洋最古老的深水。这项建议的主要目标是使用两种成熟的多元素分析方法，确定所收集的每个水柱和地表样本中溶解的(0.2微米过滤的)微量营养素金属Fe、Mn、Zn、Cu、Cd和Ni的浓度以及示踪剂铅和Sc的浓度，这两种方法将在内部进行相互校准，以最大限度地提高数据质量。其中许多是对地球轨道系统巡航进行分析所需的“关键要素”。还将对所有样品进行超滤，以确定这些元素的“真正可溶”(0.003微米)浓度，并根据差异计算胶体(0.003-0.2微米)分数。拟议研究的首要目标是了解控制微量金属在太平洋的分布的海洋通量和过程，而微量金属本身调节初级生产和海洋二氧化碳吸收。拟议的研究将能够估计太平洋中这些金属源通量和过程中的每一个的经向影响，由于过去主要是纬向太平洋邮轮横断面，到目前为止这一影响受到的限制很小。胶体分布是专门针对胶体分布的，以便获得关于不同溶解金属库的反应性(关于清除和生物有效性)的额外信息，并提供对金属物理化学形态的基本限制，这对八种金属中的许多都定义得很差。