Collaborative Research: Measurement of tritium, helium isotopes, and noble gases on GO-SHIP line P18

合作研究：在 GO-SHIP P18 线上测量氚、氦同位素和稀有气体

• 批准号: 1947640
• 负责人: William Jenkins
• 金额: $ 63.72万
• 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: 2020-05-15 至 2024-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1947640&HistoricalAwards=false
• 关键词: Collaborative; Research; Measurement; tritium; helium

The GO-SHIP program seeks to characterize the time-evolving global scale ocean distributions of heat, freshwater, carbon, oxygen, nutrients and other chemical tracers with a view to illuminating and quantifying important physical and biogeochemical processes and to document global change. As part of this international effort, the meridional section P18 was occupied in 2016 along approximately 110°W in the eastern Pacific and Southern Ocean (from Baja California to the ice edge off Antarctica). The grant will fund efforts to measure ocean tracers – tritium, 3He/4He isotope ratio, and the full suite of noble gases (He, Ne, Ar, Kr, and Xe) – on approximately 500 archived water samples collected on the 2016 P18 section. The tracer samples will be processed on specialized extraction systems and mass spectrometers at the WHOI Isotope Geochemistry Facility. Evolving ocean-climate systems present us with challenges that are never more important than now. Increased glacial and sea-ice melting, increasing sea level, ocean acidification, and deoxygenation are a few of the societally important effects that must be anticipated and if possible quantitatively predicted using global ocean circulation and biogeochemical models. Such models require a better understanding of the inherent processes, and because they are necessarily complex, yet incomplete abstractions of reality, they need observations for calibration, testing, and (if ever possible) verification. Evaluation and documentation of the distributions of these tracers and their evolution, within the context of many other observational data sets and theories, will provide valuable constraints on global ocean-climate physical and biogeochemical models that are key to understanding and dealing with global change. The new P18 tritium–3He and noble gas data will be made publicly available to any interested parties through the CLIVAR and Carbon Hydrographic Office (CCHDO) site. The project science objectives are to: (1) Document the evolving tritium and 3He distributions in 2016 on the P18 section relative to the earlier 1994 and 2008 occupations to illuminate decadal-scale patterns and possible climatic changes in ventilation and circulation in the eastern Pacific; (2) Make the first high quality noble gas measurements in the eastern Pacific and Southern Ocean to characterize air-sea exchange effects and diapycnal mixing on dissolved gases in the Pacific, and glacial melt contributions to the Circumpolar Deep Water. In the U.S. Global Ocean Carbon and Repeat Hydrography Program, tritium–3He is a Level 2 (“highly desirable”) data set that is funded separate from, but heavily leverages and adds to the measurements and ship time conducted by the core GO-SHIP program. The new tritium–3He and noble gas data will be interpreted in the context of the 2016 GO-SHIP P18 hydrographic and tracer observations (e.g., CFCs, SF6, O2), tritium–3He data from previous P18 occupations in 1994 and 2008, and Pacific basin-scale tritium–3He data from other GO-SHIP and GEOTRACES sections. The new tracer data offer unique and valuable information on physical and biogeochemical processes in the eastern Pacific and Southern Ocean: Tritium as a transient tracer has a unique hemispheric asymmetry that can be used as a diagnostic tracer of north vs south water mass provenance in the tropics. Tritium-helium dating provides a unique and sensitive measure of shallow ventilation and circulation on annual to decadal time-scales that is distinct from other tracers such as CFCs and SF6, giving estimates of water mass origins, ages, and modification in shallow waters. Helium Isotopes in the deep water provide important information regarding hydrothermal plume provenance, dispersion and dilution, and constraining deep-water circulation models. Noble gases are sensitive and unambiguous tracers of air-sea exchange, water mass provenance, ice-ocean interaction, upwelling, and in situ diapycnal mixing.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.

GO-SHIP 项目旨在描述热量、淡水、碳、氧气、营养物和其他化学示踪剂随时间变化的全球范围海洋分布，以阐明和量化重要的物理和生物地球化学过程，并记录全球变化。在这项国际努力中，2016 年，沿东太平洋和南大洋（从下加利福尼亚州到南极洲冰缘）沿约 110°W 的经向部分 P18 被占领。这笔赠款将为这些努力提供资金。测量海洋示踪剂 – 氚、3He/4He 同位素比以及全套稀有气体（He、Ne、Ar、Kr 和 Xe） – 对 2016 年 P18 部分收集的约 500 个存档水样进行测量。由 WHOI 同位素地球化学设施的专门提取系统和质谱仪进行处理 不断变化的海洋气候系统给我们带来了前所未有的挑战。冰川和海冰融化的增加、海平面的上升、海洋酸化和脱氧是必须预测的一些对社会具有重要影响的影响，如果可能的话，可以使用全球海洋环流和生物地球化学模型进行定量预测。更好地理解固有过程，并且因为它们必然是复杂的，但对现实的不完整抽象，它们需要进行校准、测试和（如果可能的话）验证这些示踪剂的分布及其演变的观察和记录。上下文许多其他观测数据集和理论的基础，将为全球海洋气候物理和生物地球化学模型提供有价值的约束，这些模型对于理解和应对全球变化至关重要。新的 P18 氚-3He 和稀有气体数据将向任何人公开。通过 CLIVAR 和碳水道测量办公室 (CCHDO) 网站向感兴趣的各方提供该项目的科学目标是： (1) 记录 2016 年 P18 部分中不断变化的氚和 3He 分布。 1994年和2008年早期的职业，以阐明东太平洋通风和环流的十年尺度模式和可能的气候变化；（2）在东太平洋和南大洋进行首次高质量稀有气体测量，以表征海气交换效应和太平洋溶解气体的二重混合，以及冰川融化对极地深水的贡献 在美国全球海洋碳和重复水文学计划中，氚-3He 是一个水平。 2（“非常理想”）数据集独立于核心 GO-SHIP 计划进行资助，但增加了测量和运输时间 新的氚-3He 和稀有气体数据将在上下文中进行解释。 2016 年 GO-SHIP P18 水文和示踪观测（例如 CFC、SF6、O2）、1994 年以前 P18 职业的氚-3He 数据和2008年，以及来自其他GO-SHIP和GEOTRACES部分的太平洋盆地规模的氚-3He数据，新的示踪剂数据提供了有关东太平洋和南大洋物理和生物地球化学过程的独特且有价值的信息：氚作为瞬态示踪剂具有独特的特性。半球不对称性可用作热带地区南北水团来源的诊断示踪剂，氚氦测年提供了每年浅层通风和循环的独特而灵敏的测量。与其他示踪剂（例如 CFC 和 SF6）不同的年代际时间尺度，对浅水区的水团起源、年龄和变化进行估计，提供有关热液羽流来源、分散和稀释的重要信息，稀有气体是空气-海洋交换、水团来源、冰-海洋相互作用、上升流和原位的敏感且明确的示踪剂。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。