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

重建北太平洋 231 镤的古预算

• 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

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.

海水中产生的天然同位素通过公海中的沉降颗粒进入深海沉积物，是物理、化学和生物过程随时间变化的有力指标。最近在北太平洋沉积物中发现的231 Pa的埋藏量与其在上覆水体中的产生量接近平衡。与此相反，少数现存的较长的沉积记录表明，在过去的冰河时期，231 Pa被掩埋的数量明显少于产生的数量，这增加了生物生产力、洋流或海洋化学变化的可能性。该项目将从过去的时间间隔产生高质量的数据集，以调查沉积231帕预算的变化，并探索这些海洋学的可能性，使用来自整个北太平洋的深海沉积物岩心阵列。由此产生的数据将用于测试有关231 Pa在海洋中的分布和埋藏的假设，并提供对生物生产力，化学海洋学和海洋环流过去变化的见解。该项目将促进不同教育水平学生的培训和学习。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。沉积物231 Pa/230 Th是一种广泛使用的代理，可以提供有价值的洞察现代和过去的海洋环流，表面生产力和热液活动。虽然现代北太平洋的231 Pa收支似乎是平衡的，但沿着海盆边缘埋藏的231 Pa几乎是今天公海中的两倍。东北太平洋最近产生的几个记录表明，这个主要的下沉沿着边缘可能没有在最后一个冰河时代的效果。事实上，东北太平洋的231 Pa埋藏似乎随着气候条件的变化而变化，过度埋藏只发生在间冰期。该项目将提供一个系统的，定量的评估如何北太平洋231帕预算已经演变了最后一次冰期循环。这项研究将产生太平洋每个主要海洋地理区的231 Pa/230 Th时间序列和生产力记录，包括开阔洋环流和周围大陆边，以评估太平洋海洋地球化学循环如何随时间演变。这些数据将确定在末次冰期期间，明显缺失的边缘231 Pa是否以及在何处被掩埋，评估驱动这种转变的机制，并评估231 Pa掩埋的空间分布如何随时间演变。该奖项反映了NSF的法定使命，并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，被认为值得支持。

项目成果

Productivity and sediment focusing in the Eastern Equatorial Pacific during the last 30,000 years

过去 3 万年生产力和沉积物集中在东赤道太平洋

• DOI: 10.1016/j.dsr.2019.03.007
• 发表时间: 2019
• 期刊: Deep Sea Research Part I: Oceanographic Research Papers
• 作者: Thiagarajan, Nivedita;McManus, Jerry F.
• 通讯作者: McManus, Jerry F.