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.

铁金属和锌等痕量对于在阳光表面海洋中主导光合作用的微观植物（浮游植物）的生长至关重要。铜或汞等其他微量金属对这些相同的生物具有剧毒。即使在数万亿克海水中的浓度低至一克的浓度下，痕量元素也可以改变二氧化碳的社区消费和海洋生态系统的氧气产生。所得的有益和/或有毒反应取决于每种痕量金属的化学形式。这些金属溶解在海水中，可以作为个体，自由离子或附着在其他溶解的化学化合物中，通常称为配体。络合是痕量金属化学连接到配体的过程。该项目将研究六种具有生物学重要的微量金属与称为硫化氢的配体的络合。从阿拉斯加到大溪地的太平洋探险中完成的工作的数据将提供有关硫化氢在控制各种海洋水域基本和有毒金属生物利用度中重要性的新科学见解，从而对海洋碳和生态系统模型产生科学影响。研究生将在该项目中发挥主导作用。 通过与其他世界一流的科学家一起作为大型协作计划的参与者，将大大增强教育机会。 额外的研究生学习和外展活动将包括与公众与博客进行交流和研究结果，并通过与本科生作为助教的互动。在氧化的海洋中，硫化氢是在阳光地表水中生物学产生的，并从海脊上的热液通风口发射。然后，它可以复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，基本痕量要素的丰度和循环都将受到影响，目前尚不清楚这些反应的重要性。这些硫化物 - 痕量金属研究将作为2018 US Geotraces Pacific Meridional crantect（PMT）的一部分进行，该巡航轨道允许对生产性沿海水，低营养的地表水以及底部附近的金属和硫化物富含水热水的羽毛进行采样。硫化氢的溶解离子将在收集后不久在海上测量。包含在颗粒中和颗粒上的金属硫化物也将被过滤和分析。该项目将解决一些具体的科学问题。硫化物的络合与遇到的各种生物学和化学状态的关系有什么不同？是否通过在上水柱中用硫化氢来除去必需的金属？金属与硫化物在水热水中的反应是否稳定了这些溶解的复合物并允许远程转运？相关研究将从与其他地理位置的科学家进行密切合作，研究痕量金属及其与其他硫化物的配体的络合，从而提供了整体上下文和新的能力，以充分了解海洋中的痕量元素周期。

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