Collaborative Research: A porewater perspective on benthic sources of neodymium to the North Atlantic

合作研究：从孔隙水角度了解北大西洋的底栖钕来源

• 批准号: 2210596
• 负责人: Anthony Rathburn
• 金额: $ 34.99万
• 依托单位: CSUB Auxiliary for Sponsored Programs Administration
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-01 至 2027-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2210596&HistoricalAwards=false
• 关键词: Collaborative; Research; porewater; perspective; benthic

Documenting deep ocean circulation changes is important to understanding past climate variability. Neodymium (Nd) isotopes, recorded in deep ocean sediments, have been used to reconstruct past ocean circulation. However, several recent studies suggest that some Nd is released into seawater from the underlying sediment, which would complicate the ability to use Nd isotopes to accurately track deep water in the ocean. This project will investigate Nd in seafloor sediments and near bottom water in the Northwest Atlantic. The study region is a location where North Atlantic Deep Water is formed. Broader impacts include mentoring support to allow two early-career scientists to serve as co-chief scientists for the field program. There is also support for high school students from an institution with a high percentage of students that are underrepresented in STEM, and undergraduates from a minority-serving institution.The interpretive framework of Nd isotopes as a paleo circulation proxy relies on deep ocean signals being driven by mixing between water masses with little influence from benthic sources of Nd to the ocean. It also requires that Nd isotopes are recorded accurately in sediments and endmember composition is independently known through time. Recent studies have challenged this framework, suggesting that benthic fluxes from ocean sediments may exert a primary control on deep water isotopic composition. However, the limited global coverage of direct benthic flux measurements (from only 10 published locations primarily in the North Pacific) prevents a complete understanding of the marine Nd cycle. This project will (i) quantify the fluxes of Nd to bottom water from sediments, (ii) examine how those fluxes affect the isotopic composition of North Atlantic Deep Water, (iii) investigate the role of diagenetic reactions in setting pore water rare earth element geochemistry, and (iv) determine what isotopic signals are recorded in marine archives. The field component of this project will occupy sites along two depth transects in the Labrador Sea, and it will involve collecting sediment and pore water from short cores, corresponding filtered bottom water, and deep-sea particles, in order to fully describe the system. The study location will allow for investigation of the role that regional geology and water depth play in setting the benthic flux of Nd to seawater. Altogether, this project will be one of the most thorough investigations to date of the controls on benthic Nd flux, the impact of benthic fluxes on the Nd isotopic composition of North Atlantic Deep Water, the sedimentary environmental conditions that facilitate Nd release, and the impact of these processes on authigenic Nd isotope records.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.

记录深海循环变化对于理解过去的气候变异性很重要。记录在深海沉积物中的肾脱离（ND）同位素已被用于重建过去的海洋循环。但是，最近的几项研究表明，有些ND从潜在的沉积物中释放到海水中，这将使使用ND同位素准确跟踪海洋中的深水的能力变得复杂。该项目将调查海底沉积物和西北大西洋附近的底水。研究区域是形成北大西洋深水的地方。更广泛的影响包括指导支持，以允许两名早期职业科学家担任现场计划的合伙科学家。 There is also support for high school students from an institution with a high percentage of students that are underrepresented in STEM, and undergraduates from a minority-serving institution.The interpretive framework of Nd isotopes as a paleo circulation proxy relies on deep ocean signals being driven by mixing between water masses with little influence from benthic sources of Nd to the ocean.它还要求ND同位素在沉积物中准确记录，并且随着时间的流逝，末日的组成是独立的。最近的研究对该框架提出了挑战，表明海洋沉积物的底栖通量可能对深水同位素组成产生主要控制。但是，直接底栖通量测量值的全球覆盖范围有限（仅来自北太平洋的10个位置）阻止了对海洋和海洋周期的完全了解。该项目将（i）量化沉积物的ND到底水的通量，（ii）检查这些通量如何影响北大西洋深水的同位素组成，（iii）研究成分成岩成岩反应在设置孔隙水稀土元件地球化学中的作用，以及（iv）确定什么同位素信号在海上记录的同位素信号记录在海洋档案中。该项目的田间成分将沿着拉布拉多海的两个深度样带占据位点，它将涉及从短核心收集沉积物和孔隙水，相应的过滤底部水和深海颗粒，以充分描述系统。研究地点将允许调查区域地质和水深在将ND底栖通量设置为海水中的作用。总而言之，该项目将是迄今为止控制底栖和通量控制的最彻底的调查之一，底栖通量对北大西洋深水的ND同位素组成的影响，促进ND释放的沉积环境条件，这些过程的影响以及这些过程的影响以及对身份nd iSOPOPE的影响。基金会的智力优点和更广泛的影响审查标准。