The Speed, Signature, and Significance of Barium Transformations in Seawater

海水中钡转变的速度、特征和意义

• 批准号: 2023456
• 负责人: Tristan Horner
• 金额: $ 68.91万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023456&HistoricalAwards=false
• 关键词: Speed; Signature; Significance; Barium; Transformations

The biological cycling of carbon in the oceans entrains many other elements, some directly (like nutrients that are essential for life) and some indirectly, as they become chemically involved in the processes that are affecting carbon. One such element is barium (Ba). Particles of the mineral barite (barium sulfate) have been found to form in association with microbial consumption of organic material in the ocean’s “twilight zone.” These particles settle to the ocean floor, and their presence in sediments has been used to infer changes in the conditions in the ocean back in time. Both the amount of barite in sediments and the isotope composition of Ba in barite are potentially sensitive to processes occurring in the twilight zone. However, several long-standing questions remain about Ba cycling in the oceans, which complicates the interpretation of barium-based proxy records. Examples of remaining questions include how much barium enters the oceans at mid-ocean ridge hydrothermal sites, and what controls the precipitation and dissolution of barite in the water column. This project seeks to tackle these questions using new approaches, on three scheduled research expeditions in the Pacific and Southern Oceans. In doing so, this project will support the education, training, and career development of a graduate student, postdoctoral researcher, and junior investigator. Undergraduate students from underrepresented groups will be recruited to conduct complementary shore-based experiments. This proposal seeks to answer four questions central to the utility of barium-based proxies in oceanography: What are the major inputs of new Ba to the ocean? What are their isotopic compositions? What controls the amount of pelagic barite precipitated during the remineralization of organic matter? What influences its isotopic composition? These questions will be addressed using a field-centric approach combining: in situ and shipboard tracer-incubation experiments, AUV-led adaptive sampling of Ba cycling ‘hotpots’, and section-based surveying of the surrounding oceanographic features. This multi-pronged approach will be used to investigate: the flux and isotopic composition of Ba released from the largest hydrothermal fields in the ocean, the Southern East Pacific Rise, with a focus on low-temperature venting; rates and signatures of pelagic barite precipitation associated with different phytoplankton assemblages in the Southern Ocean; and, the importance of environmental conditions, such as low ambient oxygen concentrations, in setting the efficiency of barite precipitation in the Eastern Tropical Pacific. The significance of each transformation will be assessed, which may lead to ruling out the importance of certain processes, or identifying new dependencies that could form the basis of new proxies.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.

海洋中碳的生物循环许多其他元素，有些是直接的，因为化学与矿物质碳酸盐（硫酸钡）HABE的碳颗粒相关。在海洋的伊利特地区。基于钡的项目。和少年的研究人员将招募基于海岸的实验控制有机物的回忆期间沉淀的质体的量？ X和同位素从海洋中最大的水热场释放出来，南部太平洋上升，重点是低温播种；条件，例如低环境氧浓度，在设定东部热带地区的芳酸盐效率时，每种转化的重要性都将被关注，这可能会导致某些过程的重要性，这些过程可能构成新代理的基础。奖项反映了NSF'Stututory任务，并通过评估Usindation的智力优点和更广泛的影响审查标准而被认为值得支持。

项目成果

Barium in seawater: dissolved distribution, relationship to silicon, and barite saturation state determined using machine learning

• DOI: 10.5194/essd-15-4023-2023
• 发表时间: 2023-09
• 期刊: Earth System Science Data
• 影响因子: 11.4
• 作者: Öykü Z. Mete;A. Subhas;Heather H. Kim;A. Dunlea;L. Whitmore;A. Shiller;Melissa Gilbert;William D. Leavitt;Tristan J. Horner

A spatially and vertically resolved global grid of dissolved barium concentrations in seawater determined using Gaussian Process Regression machine learning

使用高斯过程回归机器学习确定海水中溶解钡浓度的空间和垂直解析全局网格

• DOI: 10.26008/1912/bco-dmo.885506.2
• 发表时间: 2023
• 期刊: Biological and Chemical Oceanography Data Management Office (BCO-DMO
• 作者: Horner, Tristan J.;Mete, Oyku Z.
• 通讯作者: Mete, Oyku Z.

Barium isotope fractionation in barite–fluid systems at chemical equilibrium

• DOI: 10.1016/j.chemgeo.2023.121453
• 发表时间: 2023-03
• 期刊: Chemical Geology
• 影响因子: 3.9
• 作者: J. Middleton;Wei Hong;A. Paytan;M. Auro;E. Griffith;T. Horner

Microbial functional diversity across biogeochemical provinces in the central Pacific Ocean.

• DOI: 10.1073/pnas.2200014119
• 发表时间: 2022-09-13
• 期刊: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• 影响因子: 11.1
• 作者: Saunders, Jaclyn K.;McIlvin, Matthew R.;Dupont, Chris L.;Kaul, Drishti;Moran, Dawn M.;Horner, Tristan;Laperriere, Sarah M.;Webb, Eric A.;Bosak, Tanja;Santoro, Alyson E.;Saito, Mak A.
• 通讯作者: Saito, Mak A.

Bioactive Trace Metals and Their Isotopes as Paleoproductivity Proxies: An Assessment Using GEOTRACES‐Era Data

生物活性微量金属及其同位素作为古生产力指标：使用 GEOTRACES Era 数据进行评估

• DOI: 10.1029/2020gb006814
• 发表时间: 2021
• 期刊: Global Biogeochemical Cycles
• 影响因子: 5.2
• 作者: Horner, T. J.;Little, S. H.;Conway, T. M.;Farmer, J. R.;Hertzberg, J. E.;Janssen, D. J.;Lough, A. J. M.;McKay, J. L.;Tessin, A.;Galer, S. J. G.
• 通讯作者: Galer, S. J. G.