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.

海水中产生的天然同位素通过在公海中沉降的颗粒传递到深海沉积物中，可以作为物理、化学和生物过程随时间变化的有力指标。据观察，最近北太平洋沉积物中 231Protactinium (Pa) 的埋藏量与其上覆水体中的产量接近平衡。相比之下，现有的少数较长沉积记录表明，埋藏的 231Pa 明显少于过去冰河时期产生的，这增加了生物生产力、洋流或海洋化学发生变化的可能性。该项目将使用来自北太平洋的一系列深海沉积岩芯，生成过去时间间隔的高质量数据集，以调查沉积 231Pa 预算的变化并探索这些海洋学的可能性。由此产生的数据将用于检验有关 231Pa 在海洋中的分布和埋藏的假设，并提供对过去生物生产力、化学海洋学和海洋环流变化的见解。该项目将促进多个不同教育水平的学生的培训和学习。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 231Pa/230Th 是一种广泛使用的代理，可以为现代和过去海洋的环流、表面生产力和热液活动提供有价值的见解。尽管北太平洋的现代 231Pa 预算似乎是平衡的，但盆地边缘埋藏的 231Pa 几乎是当今公海中的 231Pa 的两倍。最近从东北太平洋生成的少数记录表明，边缘的这个主要下沉可能在上一个冰河时期并未发挥作用。事实上，东北太平洋 231Pa 的埋藏似乎随着气候条件的变化而变化，过度埋藏仅发生在间冰期。该项目将对北太平洋 231Pa 预算在上一个冰川周期中的演变情况进行系统、定量的评估。该研究将生成太平洋每个主要生物地理省份（包括公海环流和周围大陆边缘）的 231Pa/230Th 时间序列和生产力记录，以评估太平洋生物地球化学循环如何随时间演变。这些数据将确定明显缺失的边缘 231Pa 在末次冰期是否被埋藏以及在何处被埋藏，评估驱动这一转变的机制，并评估 231Pa 埋藏的空间分布如何随时间演变。这将允许对有关北太平洋生物生产力和深海环流潜在变化的假设进行测试。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。