GEOTRACES Pacific Section: 227Ac Distribution in Deep Waters as a Constraint on Mixing and Mass Transport of Solutes

GEOTRACES 太平洋部分：深水中的 227Ac 分布作为溶质混合和传质的约束

• 批准号: 1235124
• 负责人: Douglas Hammond
• 金额: $ 14.74万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1235124&HistoricalAwards=false
• 关键词: GEOTRACES; Pacific; Section; 227Ac; Distribution

Because of its potential as a tracer of ocean mixing and transport, 227Ac (22 year half-life) has been identified as a parameter of interest for the International GEOTRACES Program, a multi-national effort to map and study the geochemical behavior of a suite of trace elements and isotopes in the global ocean. Quantifying the biogeochemical dynamics of the deep sea is necessary for understanding the oceanic cycling of carbon and other materials. Defining these dynamics requires knowledge of mixing and advective transport rates that can be applied to interpret concentration fields of biogeochemically important solutes. Despite having a half-life that is well suited for the study of both vertical and lateral transport in the deep ocean, few 227Ac measurements have been made in the deep sea. In this project, a research team at the University of Southern California will make measurements of 227Ac water column profiles on the 2013 US GEOTRACES Pacific transect, a section from Peru to Tahiti, one of several American contributions to the International GEOTRACES effort. The team will also do analyses of archived sediments to constrain the regional benthic flux of this isotope and provide a boundary condition for interpreting its water column distribution. Recent advances in instrumentation facilitate this analysis, and the synergy provided by the GEOTRACES program will provide an ideal opportunity to obtain additional data that will serve two purposes. First, 227Ac will be of value in defining the spatial variability of mixing rates in the deep South Pacific, particularly when combined with estimates based on 228Ra (6 year half-life), a tracer field that a collaborating GEOTRACES proposal seeks to determine. Second, the mixing and transport rates defined by this tracer pair will be useful for deducing the transport and the dynamics of other solutes measured by GEOTRACES in deep waters. Solute transport is due to both mixing and advection. By using multiple tracers with different half-lives, the separate roles of these processes may be distinguished, allowing a more complete understanding of the dynamics of solute behaviors. Broader Impacts: As part of this effort, at least one undergraduate and one high school student will have the opportunity to participate in the research experience, gaining insight into the possibilities of careers in this area and learning the approaches taken in scientific research.

由于它作为海洋混合和运输的示踪剂的潜力，因此已将227AC（22年半衰期）确定为国际地理领域计划的感兴趣参数，这是一种跨国努力，旨在绘制和研究套件的地球化学行为全球海洋中的微量元素和同位素。 量化深海的生物地球化学动力学对于理解碳和其他材料的海洋循环是必要的。 定义这些动力学需要了解混合和对流运输速率，这些知识可用于解释生物地球化学上重要溶质的浓度场。 尽管有一个半衰期非常适合在深海中研究垂直运输和横向运输，但在深海中几乎没有进行227AC测量。 在该项目中，南加州大学的一个研究团队将在2013年美国太平洋型号上对227AC水柱的概况进行测量，这是从秘鲁到塔希提岛的一节，这是美国对国际地理领域努力的几项贡献之一。 该团队还将对存档沉积物进行分析，以限制该同位素的区域底栖通量，并为解释其水柱分布提供边界条件。 仪器的最新进展促进了这一分析，而Geotraces计划提供的协同作用将为获得有两个目的的其他数据提供理想的机会。 首先，227AC在定义深南太平洋混合率的空间变异性方面将是有价值的，尤其是与基于228RA（6年半衰期）的估计相结合时，这是一个示踪剂领域，这是一个合作的地理特殊性提案，旨在确定。 其次，该示踪剂对定义的混合速率和运输速率将有助于推论深水中的地理位置测量的其他溶质的传输和动力学。 溶质传输既是由于混合和对流造成的。 通过使用具有不同半衰期的多个示踪剂，可以区分这些过程的不同角色，从而更完整地了解溶质行为的动力学。 更广泛的影响：作为这项努力的一部分，至少一名本科生和一名高中生将有机会参与研究经验，深入了解该领域的职业可能性，并学习科学研究中所采取的方法。