GEOTRACES Atlantic Section: Measurement of Helium Isotopes and Tritium

这项快速反应研究赠款（RAPID）将为伍兹霍尔海洋研究所的一个研究小组提供资金，以继续在中断的GEOTRACES北大西洋带状部分收集氚和氦同位素样品，最初是通过NSF ARRA奖资助的。由于研究船KNORR的推进系统发生机械故障，原定的巡航缩短了约三分之一的路程，大部分科学考察队不得不在佛得角群岛下船。需要作出额外努力，重新整修取样船，并重新安排2011年10月第二次巡航的取样工作。该研究小组将进行氦同位素和氚测量，为在第一次美国GEOTRACES全球调查部分继续进行的更重要的TEI测量提供有用的地球化学速率信息。氚和3 He测量对该计划的主要贡献包括：（1）定量过渡时间尺度和MOC中的TEI稀释：3 H和3 He是确定深部西部边界电流示踪剂输运率和内部混合稀释尺度的有用示踪剂，这是许多TEI的重要问题。(2)作为一个浅水精密计时器：使用氚-3He钟，我们可以确定流体包在6个月到几十年的时间尺度上被俯冲所经过的时间。我们也可以结合联合收割机3 H-3 He年龄和演变的3 H和3 He分布与地转，T，S，O2，营养，和TEI分布，以估计转化率。(3)TEI温跃层回流计：3 He e是唯一的？营养素类？瞬变示踪剂，可用作所谓的通量计，以确定温跃层化TEI返回上层海洋的速率。这对地球化学模型很重要。(4)测量TEI热液稀释尺度：在热液活动期间注入的火山3 He是这些羽流中稀释的强大保守示踪剂，允许诊断某些TEI中的非保守行为，并允许与盆地和全球尺度上的热液活动相关的通量估计。私家侦探将负责氚和3 He的获取、测量、解释和建模，以实现上述目标。更广泛的影响：拟议的工作是为了支持GEOTRACES计划，因此有助于该计划所支持的更广泛的社会目标和知识目标。与此相关的主要问题涉及了解碳循环和预测/减缓气候变化，以及海洋食物网和人类活动对海洋的影响。

This Grant for Rapid Response Research (RAPID) will provide funding to a research team at the Woods Hole Oceanographic Institution to continue their collection of tritium and helium isotope samples on the interrupted GEOTRACES North Atlantic Zonal Section originally funded through an NSF ARRA award. Due to the mechanical failure of the research vessel KNORR's propulsion system, the original cruise was cut short about one third of the way through, and most of the scientific party was obliged to disembark in Cape Verde Islands. Extra effort is required to refurbish sampling vessels and re-stage the sampling effort for the second cruise set for October, 2011. The research team will make helium isotope and tritium measurements to provide useful biogeochemical rate information for the more centrally important TEI measurements made on the continuation of the first U.S. GEOTRACES global survey section. The primary contributions that tritium and 3He measurements can make to the program include: (1) Quantifying transit timescales and TEI dilution in the MOC: 3H and 3He are useful tracers for determining deep western boundary current tracer transport rates and interior mixing dilution scales, an important issue for many TEIs.(2) As a shallow water chronometer: using the tritium-3He clock, we can determine the time elapsed since fluid parcels have been subducted on timescales ranging from 6 months to several decades. We can also combine 3H - 3He ages and evolving 3H and 3He distributions with geostrophy, T,S, O2, nutrient, and TEI distributions to estimate transformation rates. (3) A TEI thermocline reflux gauge: 3He e is a unique ?nutrient-like? transient tracer that can be used as a so-called flux gauge to determine the rates at which thermocline-remineralized TEIs are returned to the upper ocean. This is important for biogeochemical models. (4) Gauging TEI hydrothermal dilution scales: Volcanic 3He injected during hydrothermal activity is a powerful conservative tracer of dilution in these plumes, allowing diagnosis of non-conservative behavior in some TEIs, and permitting flux estimates associated with hydrothermal activity on basin and global scale. The P.I. will be responsible for the acquisition, measurement, interpretation and modeling of the tritium and 3He to achieve the above objectives. Broader Impacts: The proposed work is in support of the GEOTRACES program, as such contributes to the broader societal goals and intellectual objectives espoused by that program. The primary issues related to this are pertinent to understanding the carbon cycle and predicting/mitigating climate change, as well as the marine food web and anthropogenic impacts on the oceans.