US GEOTRACES GP17-OCE: Hydrogen sulfide as a strong ligand affecting the speciation and solubility of key trace metals

US GEOTRACES GP17-OCE：硫化氢作为强配体影响关键痕量金属的形态和溶解度

• 批准号: 2049564
• 负责人: Gregory Cutter
• 金额: $ 46.54万
• 依托单位: Old Dominion University Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-10-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2049564&HistoricalAwards=false
• 关键词: US; GEOTRACES; GP17; OCE; Hydrogen

Trace metals are present at very low parts per trillion concentrations in the ocean but in spite of their scarcity many, like iron and zinc, are essential to the growth of the microscopic plants called phytoplankton. Others, like mercury and arsenic, are toxic. In addition to very low concentrations, the essential or toxic nature of a trace metal also depends on the chemical form of the element – as a free dissolved ion all by itself or as charged ion interacting with other inorganic or organic ions. One of the inorganic ions in seawater that strongly interacts with trace metals is bisulfide, the ionic form of the foul-smelling gas hydrogen sulfide. Its reactivity with metals can be so strong that it forms metal-sulfide particles that sink out and are removed from the water. This research project will study how hydrogen sulfide interacts with trace metals like cadmium, copper, mercury, nickel, and zinc to form dissolved complexes that make these metals less reactive to other ions and phytoplankton, or insoluble particles that remove the metals. The researchers will conduct these studies on an oceanographic expedition from Tahiti to the ice edge around Antarctica to Chile as part of the U.S. GEOTRACES program with many other researchers measuring trace metals from the surface to the ocean bottom. All of this and more will be the subject of a graduate student’s doctoral research. In addition to learning how to work on a major oceanographic expedition and with other researchers, she will communicate her experiences and findings on a blog available to all who follow it. She will also help to create a presentation about her science that will be part of the “Sailing with GEOTRACES” virtual reality experience for schools, libraries/museums, festivals, and public presentations.The US GEOTRACES GP17-OCE cruise from Tahiti to the Antarctic ice edge to Chile will sample waters with large gradients in phytoplankton biomass and species, macronutrients, and trace metals. With anticipated changes in the concentrations and phases of hydrogen sulfide in the oxic water column, the transect offers an ideal opportunity to quantify the linked cycles of hydrogen sulfide and bioactive metals like cadmium, copper, and zinc, and the toxic element mercury. With an overall goal of quantifying the coupled cycles of trace metals and sulfide in the upper, oxic ocean, our specific research objectives for this research will be: (1) Quantify the sources and sinks of dissolved and particulate sulfide as it pertains to the cycling of key trace metals in order to accurately link their cycles; (2) Establish the conditions under which free sulfide reacts with and precipitates trace metals such as cadmium, copper, and zinc, and quantify this removal term; and (3) Evaluate whether nanoparticulate/colloidal pyrite exists in hydrothermal plumes and its contribution to iron transport relative to colloidal iron oxyhydroxides. A fully integrated set of shipboard measurements, laboratory studies, and data synthesis and speciation modeling are designed to meet these objectives. The approach includes close collaborations with investigations of dissolved and particulate trace metals and their speciation, as well as with those studying mixing processes using a variety of tracers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

海洋中的痕量金属浓度非常低，但尽管铁和锌等元素很少，但它们对于浮游植物的生长至关重要，而汞和砷等元素则有毒。除了非常低的浓度外，微量金属的必需或有毒性质还取决于元素的化学形式 - 作为游离溶解的离子本身或作为与其他无机或有机离子相互作用的带电离子。海水中与微量金属发生强烈相互作用的无机离子是二硫化物，它是恶臭气体硫化氢的离子形式，它与金属的反应性非常强，以至于形成金属硫化物颗粒，这些颗粒会下沉并从水中去除。该研究项目将研究硫化氢如何与镉、铜、汞、镍和锌等痕量金属相互作用，形成溶解的络合物，从而降低这些金属与镉、铜、汞、镍和锌的反应性。作为美国 GEOTRACES 计划的一部分，研究人员将在从塔希提岛到南极洲周围冰缘到智利的海洋考察中与许多其他研究人员一起测量地表的痕量金属。所有这些以及更多内容都将成为研究生博士研究的主题，除了学习如何进行大型海洋探险以及与其他研究人员合作之外，她还将交流她的经验。她还将帮助创建一个关于她的科学的演示，该演示将成为学校、图书馆/博物馆、节日和公共演示的“与 GEOTRACES 一起航行”虚拟现实体验的一部分。美国GEOTRACES GP17-OCE航行从塔希提岛到南极冰缘再到智利，将对浮游植物生物量和物种、宏量营养素和微量金属梯度较大的水域进行采样，并发生预期的变化。在含氧水柱中硫化氢的浓度和相中，样线提供了一个理想的机会来量化硫化氢和生物活性金属（如镉、铜和锌）以及有毒元素汞的相关循环。量化上层含氧海洋中痕量金属和硫化物的耦合循环，我们这项研究的具体研究目标是：（1）量化溶解和颗粒物的源和汇(2) 建立游离硫化物与镉、铜和锌等微量金属反应并沉淀的条件，并量化该去除项； (3) 评估热液羽流中存在的纳米颗粒/胶体黄铁矿及其相对于胶体羟基氧化铁对铁传输的贡献。一系列船上测量、实验室研究以及数据合成和形态建模旨在实现这些目标，该方法包括与溶解和颗粒痕量金属及其形态的研究以及使用各种方法研究混合过程的密切合作。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。