Reconstructing the paleo-budget of 231Protactinium in the North Pacific

重建北太平洋 231 镤的古预算

基本信息

批准号：
1835997
负责人：
Jerry McManus
金额：
$ 52.22万
依托单位：
Columbia University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2023-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1835997&HistoricalAwards=false
关键词：
Reconstructing paleo budget 231Protactinium North

项目摘要

Naturally occurring isotopes produced in seawater and delivered to deep-sea sediments by settling particles in the open ocean serve as powerful indicators of changes in physical, chemical and biological processes through time. The recent burial of 231Protactinium (Pa) in sediments of the North Pacific Ocean is observed to be in near balance with its production in the overlying water column. In contrast, the few existing longer sedimentary records suggest that significantly less 231Pa was buried than produced during past ice ages, raising the possibility of changes in biological productivity, ocean currents, or ocean chemistry. This project will produce high quality datasets from past time intervals to investigate changes in the sedimentary 231Pa budget and explore these oceanographic possibilities, using an array of deep-sea sediment cores from across the North Pacific. The resulting data will be used to test hypotheses regarding the distribution and burial of 231Pa in the ocean and to provide insights into past changes in biological productivity, chemical oceanography, and ocean circulation. The project will promote training and learning for students at multiple different educational levels. A graduate student will play a central role in the research, gaining technical training and professional development.Sedimentary 231Pa/230Th is a widely utilized proxy that can provide valuable insight into circulation, surface productivity and hydrothermal activity in the modern and past ocean. Although the modern 231Pa budget in the North Pacific appears to be in balance, almost twice as much 231Pa is buried along the basin margins than in the open ocean today. The few recently generated records from the Northeast Pacific suggest that this major sink along the margins may not have been in effect during the last ice age. In fact, 231Pa burial in the Northeast Pacific appears to vary in tandem with changing climate conditions, with excess burial only occurring during interglacial periods. This project will provide a systematic, quantitative assessment of how the North Pacific 231Pa budget has evolved over the last glacial cycle. The study will generate 231Pa/230Th time series and productivity records from each of the major biogeographic provinces in the Pacific, including the open ocean gyre and surrounding continental margins, to assess how the biogeochemical cycles of the Pacific Ocean have evolved over time. These data will determine whether and where the apparently missing marginal 231Pa was buried during the last glacial period, evaluate the mechanisms that drove this shift, and assess how the spatial distribution of 231Pa burial may have evolved over time. This will allow the testing of hypotheses regarding potential changes in biological productivity and deep ocean circulation in the North Pacific Ocean.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.

天然存在于海水中产生的同位素，并通过在开阔的海洋中沉降颗粒来传递到深海沉积物中，这是随着时间的推移物理，化学和生物过程变化的有力指标。最近观察到，最近在北太平洋沉积物中埋葬了231种植物（PA），其在上覆的水柱中与其生产几乎平衡。相比之下，少数现有的较长的沉积记录表明，掩埋的231pa比过去的冰时代所产生的少得多，从而增加了生物生产力，洋流或海洋化学的变化的可能性。该项目将从过去的时间间隔开始生产高质量的数据集，以调查沉积231PA预算的变化，并使用来自北太平洋各地的一系列深海沉积物核心来探索这些海洋学可能性。所得数据将用于检验有关海洋中231Pa分布和埋葬的假设，并提供有关生物生产力，化学海洋学和海洋循环的过去变化的见解。该项目将在多个不同的教育水平上为学生促进培训和学习。研究生将在研究中发挥核心作用，获得技术培训和专业发展。231PA/230th是一个广泛使用的代理，可以为现代和过去海洋中的循环，表面生产力和水热活动提供宝贵的见解。尽管北太平洋的现代231PA预算似乎处于平衡状态，但沿着盆地边缘埋葬的几乎是231pa的两倍。最近从东北太平洋地区产生的记录表明，在最后一个冰河时代，这种沿线的主要水槽可能没有生效。实际上，东北太平洋的231PA埋葬似乎与气候条件变化的同时，仅发生过多的埋葬时期。该项目将对北太平洋231PA预算如何在上一个冰川周期中发展进行系统的定量评估。这项研究将产生第231 pa/230次时间序列和太平洋主要生物地理省的生产力记录，包括开阔的海洋循环和周围大陆边缘，以评估太平洋生物地球化学周期如何随着时间的流逝而发展。这些数据将确定在最后一个冰川时期掩埋边缘231Pa的显然以及何处，评估驱动这一转移的机制，并评估231PA埋葬的空间分布如何随着时间的流逝而演变。这将允许对北太平洋生物生产力和深海循环的潜在变化的假设进行检验。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响评估标准，认为值得通过评估来获得支持。