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Variability in oxygen concentrations in Atlantic intermediate waters during the last deglaciation

末次冰消期大西洋中间水域氧气浓度的变化

基本信息

批准号：
1946185
负责人：
Kassandra Costa
金额：
$ 37.03万
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：
2020-03-01 至 2023-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1946185&HistoricalAwards=false
关键词：
Variability oxygen concentrations Atlantic intermediate

项目摘要

Oxygen is a primary component of the biological and chemical cycles of the ocean. Its involvement in photosynthesis and respiration links the changes of oxygen concentration to that of carbon in the ocean, and ultimately in the atmosphere. As the oceans take up more and more carbon, oxygen concentrations in the ocean are declining, with the potential to reach levels low enough to reduce biodiversity. The last ice age provides a natural experiment to investigate how oxygen concentrations may have varied under different climate conditions in order to help forecast what might happen in the future. Most previous studies have only been able to distinguish the relative change in oxygen concentrations (higher or lower), but in this project a new application will be developed that can quantitatively constrain oxygen concentrations in the past. In regions like the tropical Atlantic, where oxygen minimum zones (OMZs) approach but do not reach a total absence of oxygen today, it is critical to pinpoint the environmental conditions that can cross that threshold into an absence of oxygen. This project will promote training and learning for several participants, including one early-career scientist without previous NSF support and one undergraduate summer student.This project will produce high quality U-Th isotope and trace element data in a suite of intermediate depth sediment cores from the western tropical Atlantic and one site under the eastern tropical OMZ. These data will be used to test hypotheses regarding the evolution of bottom water oxygen concentrations (BW [O2]) during the last deglaciation in response to changes in the intensity of the eastern tropical OMZ. Specifically this project seeks to understand how the spatial extent and absolute magnitude of the OMZ has varied , and how these changes may relate to intermediate water ventilation and carbon storage. The first component of this proposal involves method development of a quantitative proxy system for BW [O2]. It parameterizes sedimentary [O2] with authigenic uranium and organic carbon fluxes with Baxs fluxes to generate a comprehensive approach to reconstructing BW [O2]. This component focuses on the Demerara Rise, where preliminary data indicate a high probability for successful application, and then it combines the new data from the Demerara Rise with additional work in the Arabian Sea and previously published data from the Pacific to prospect the global utility of the approach. The second component of this proposal investigates how and why oxygen concentrations in tropical intermediate waters may have varied in the past in response to changes in zonal circulation, meridional circulation, and organic matter fluxes.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.

氧气是海洋生物和化学循环的主要组成部分。它参与光合作用和呼吸作用，将海洋中氧浓度的变化与碳浓度的变化联系起来，并最终在大气中。随着海洋吸收越来越多的碳，海洋中的氧气浓度正在下降，有可能达到足以减少生物多样性的低水平。最后一个冰河时代提供了一个自然实验，以研究氧气浓度在不同气候条件下如何变化，以帮助预测未来可能发生的事情。大多数以前的研究只能区分氧浓度的相对变化（更高或更低），但在本项目中，将开发一种新的应用程序，可以定量限制过去的氧浓度。在像热带大西洋这样的地区，氧气最小区（OMZ）接近但今天还没有达到完全缺氧的程度，确定可以跨越这一阈值进入缺氧状态的环境条件至关重要。该项目将促进对若干参与者的培训和学习，其中包括一名以前没有国家科学基金支持的早期职业科学家和一名暑期本科生，该项目将在热带大西洋西部和热带大洋区东部的一个地点的一套中深度沉积物岩心中产生高质量的铀-钍同位素和微量元素数据。这些数据将被用来测试假设的底层水的氧浓度（BW [O2]）的演变在最后一次冰消期间，在东部热带OMZ的强度变化。具体而言，该项目旨在了解OMZ的空间范围和绝对大小如何变化，以及这些变化如何与中层水通风和碳储存有关。本提案的第一部分涉及生物量[O2]定量代用指标系统的方法开发。它参数化沉积[O2]与自生铀和有机碳通量与碳通量生成一个全面的方法来重建BW [O2]。这一部分的重点是德梅拉拉海隆，那里的初步数据表明成功应用的可能性很高，然后将德梅拉拉海隆的新数据与阿拉伯海的其他工作和以前公布的太平洋数据结合起来，前景展望这一方法的全球效用。该提案的第二部分调查热带中间沃茨中的氧浓度如何以及为什么在过去可能会随着纬向环流、纬向环流和有机物通量的变化而变化。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

项目成果

期刊论文数量（4）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Marine sedimentary uranium to barium ratios as a potential quantitative proxy for Pleistocene bottom water oxygen concentrations

海洋沉积物铀与钡的比率作为更新世底层水氧浓度的潜在定量指标

DOI：
10.1016/j.gca.2022.12.022
发表时间：
2023
期刊：
Geochimica et Cosmochimica Acta
影响因子：
5
作者：
Costa, Kassandra M.;Nielsen, Sune G.;Wang, Yi;Lu, Wanyi;Hines, Sophia K.V.;Jacobel, Allison W.;Oppo, Delia W.
通讯作者：
Oppo, Delia W.

Reconstructing the Oxygen Depth Profile in the Arabian Sea During the Last Glacial Period