US GEOTRACES PMT: hydrogen sulfide as a strong ligand affecting trace metal cycling

US GEOTRACES PMT：硫化氢作为影响痕量金属循环的强配体

• 批准号: 1737342
• 负责人: Gregory Cutter
• 金额: $ 39.35万
• 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: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2023-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1737342&HistoricalAwards=false
• 关键词: US; GEOTRACES; PMT; hydrogen; sulfide

Trace metals like iron and zinc are essential for the growth of the microscopic plants (phytoplankton) that dominate photosynthesis in the sunlit surface ocean. Other trace metals like copper or mercury are highly toxic to these same organisms. Even at concentrations of as low as one gram in a trillion grams of seawater, trace elements can alter the community consumption of carbon dioxide and the production of oxygen by ocean ecosystems. The resulting beneficial and/or toxic response depends on the chemical form of each trace metal. Dissolved in seawater, these metals can exist either as individual, free ions or attached to other dissolved chemical compounds, generically called ligands. Complexation is the process by which trace metals become chemically attached to ligands. This project will study the complexation of six biologically important trace metals with a ligand known as hydrogen sulfide. Data from work done during an expedition in the Pacific Ocean from Alaska to Tahiti will provide new scientific insight on hydrogen sulfide's importance in controlling essential and toxic metal bioavailability in various marine waters and thus have scientific impact on ocean carbon and ecosystem models. A graduate student will play a leading role in the project. Educational opportunities will be greatly enhanced by working alongside other world-class scientists as a participant in a large collaborative program. Additional graduate learning and outreach will include communicating experiences and research findings with the public with a blog and by interactions with undergraduate students as a teaching assistant. In the oxygenated ocean, hydrogen sulfide is biologically produced in sunlit surface waters and emitted from hydrothermal vents on ocean ridges. It can then complex dissolved trace metals or react with them to form insoluble metal sulfides. In both cases, the abundance and cycling of essential trace elements would be affected and the importance of these reactions are currently not known. These sulfide - trace metal studies will be conducted as part of the 2018 US GEOTRACES Pacific Meridional Transect (PMT), a cruise track that allows sampling of productive coastal waters, low nutrient surface waters, and plumes of metal- and sulfide-rich hydrothermal waters near the bottom. The dissolved ions of hydrogen sulfide will be measured at sea soon after collection. Metal sulfides contained in and on particles will also be filtered and analyzed. This project will address several specific scientific questions. To what degrees does sulfide complexation vary as a function of the various biological and chemical regimes encountered? Are essential metals removed by precipitating with hydrogen sulfide in the upper water column? Does the reaction of metals with hydrogen sulfide in hydrothermal waters stabilize these dissolved complexes and allow long range transport? Related study will develop from close collaborations with other GEOTRACES scientists studying trace metals and their complexation with ligands other that sulfide, providing overall context and novel capacity to fully understand trace element cycles in the ocean.

微量金属，如铁和锌，对微生物（浮游植物）的生长至关重要，这些微生物在阳光照射的海洋表面控制着光合作用。其他微量金属，如铜或汞，对这些相同的生物体具有高度毒性。即使浓度低至1万亿克海水中的1克，微量元素也可以改变海洋生态系统对二氧化碳的社区消耗和氧气的生产。产生的有益和/或毒性反应取决于每种微量金属的化学形式。溶解在海水中，这些金属可以单独存在，自由离子或连接到其他溶解的化合物，一般称为配体。络合作用是痕量金属与配体化学结合的过程。该项目将研究六种生物学上重要的微量金属与硫化氢配体的络合作用。在从阿拉斯加到塔希提岛的太平洋考察期间所做的工作数据将提供新的科学见解，了解硫化氢在控制各种海洋沃茨中必需和有毒金属生物利用度方面的重要性，从而对海洋碳和生态系统模型产生科学影响。一名研究生将在该项目中起主导作用。 通过与其他世界级科学家一起工作，作为一个大型合作计划的参与者，教育机会将大大增加。 额外的研究生学习和推广活动将包括与公众交流经验和研究成果，并通过与本科生的互动作为教学助理。在含氧海洋中，硫化氢是在阳光照射的表面沃茨中生物产生的，并从洋脊上的热液喷口排放。然后，它可以络合溶解的痕量金属或与它们反应形成不溶性金属硫化物。在这两种情况下，必需微量元素的丰度和循环将受到影响，这些反应的重要性目前尚不清楚。这些硫化物痕量金属研究将作为2018年美国GEOTRACES太平洋子午断面（PMT）的一部分进行，PMT是一条巡航轨道，允许对生产性沿海沃茨、低营养表层沃茨以及底部附近富含金属和硫化物的热液沃茨的羽流进行采样。溶解的硫化氢离子将在收集后不久在海上进行测量。颗粒内部和颗粒表面所含的金属硫化物也将被过滤和分析。该项目将解决几个具体的科学问题。在何种程度上，硫化物络合作用作为所遇到的各种生物和化学体系的函数而变化？在上层水柱中，是否通过与硫化氢沉淀来去除必需金属？金属与硫化氢在热液沃茨中的反应是否使这些溶解的络合物稳定并允许远距离迁移？相关研究将与其他GEOTRACES科学家密切合作，研究痕量金属及其与硫化物以外的配体的络合作用，提供全面的背景和新的能力，以充分了解海洋中的痕量元素循环。

项目成果

An intermediate-depth source of hydrothermal 3He and dissolved iron in the North Pacific

• DOI: 10.1016/j.epsl.2020.116223
• 发表时间: 2020-06
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: W. J. Jenkins;M. Hatta;J. Fitzsimmons;R. Schlitzer;N. Lanning;Alan Shiller;N. R. Buckley;C. R. German;D. Lott;G. Weiß;L. Whitmore;K. Casciotti;Phoebe J. Lam;G. Cutter;K. Cahill