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

海水中钡转变的速度、特征和意义

基本信息

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

项目摘要

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夹带了许多其他元素，有些是直接的（例如生命必需的营养物质），有些是间接的，因为它们以化学方式参与影响碳的过程，其中一种元素是钡（Ba）。人们发现矿物重晶石（硫酸钡）颗粒的形成与海洋“暮色带”中有机物质的微生物消耗有关。这些颗粒沉降到海底，它们在沉积物中的存在已被用来推断沉积物中重晶石的含量和重晶石中 Ba 的同位素组成可能对暮色区的过程敏感。然而，关于 Ba 循环的几个长期存在的问题仍然存在。这使得基于钡的代理记录的解释变得复杂化，剩下的问题包括有多少钡进入洋中脊热液地点的海洋，以及是什么控制着重晶石在海洋中的沉淀和溶解。该项目旨在通过计划在太平洋和南大洋进行的三个研究考察，利用新方法解决这些问题，从而支持研究生、博士后研究员的教育、培训和职业发展。该提案旨在回答与钡基代理在海洋学中的应用有关的四个核心问题：新 Ba 对海洋的主要输入是什么。？他们是什么同位素组成？什么控制着有机物再矿化过程中沉淀的远洋重晶石的量？什么影响其同位素组成？这些问题将通过结合现场和船上示踪剂孵化实验、AUV 主导的自适应方法来解决。对Ba循环“热点”进行采样，并对周围海洋特征进行剖面测量。这种多管齐下的方法将用于研究：Ba的通量和同位素组成。从海洋中最大的热液田——东南太平洋海隆释放出来，重点关注与南大洋不同浮游植物组合相关的中上层重晶石降水的速率和特征，以及环境条件的重要性；例如低环境氧浓度，在设定东热带太平洋重晶石沉淀效率时，将评估每个转变的重要性，这可能导致排除某些过程的重要性，或识别新的依赖性。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。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Speciation and cycling of iodine in the subtropical North Pacific Ocean

副热带北太平洋碘的形态和循环

DOI：
10.3389/fmars.2023.1272968
发表时间：
2024-01
期刊：
Frontiers in Marine Science
影响因子：
3.7
作者：
Ştreangă, Iulia;Repeta, Daniel J.;Blusztajn, Jerzy S.;Horner, Tristan J.
通讯作者：
Horner, Tristan J.

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

海水中的钡：溶解分布、与硅的关系以及使用机器学习确定的重晶石饱和状态

DOI：
10.5194/essd-15-4023-2023
发表时间：
2023-01
期刊：
Earth System Science Data
影响因子：
11.4
作者：
Mete, Öykü Z.;Subhas, Adam V.;Kim, Heather H.;Dunlea, Ann G.;Whitmore, Laura M.;Shiller, Alan M.;Gilbert, Melissa;Leavitt, William D.;Horner, Tristan J.
通讯作者：
Horner, Tristan J.

Barium isotope fractionation in barite–fluid systems at chemical equilibrium

化学平衡状态下重晶石流体系统中的钡同位素分馏