GEOTRACES Arctic Section: Actinium-227 as a Naturally-occurring Tracer of Dissolved Material Transport in the Arctic Ocean

GEOTRACES 北极部分：Actinium-227 作为北冰洋溶解物质运输的天然示踪剂

• 批准号: 1436958
• 负责人: Douglas Hammond
• 金额: $ 13.55万
• 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: 2014
• 资助国家: 美国
• 起止时间: 2014-12-01 至 2018-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1436958&HistoricalAwards=false
• 关键词: GEOTRACES; Arctic; Section; Actinium; 227

In this project, a group of investigators participating in the 2015 U.S. GEOTRACES Arctic expedition will measure profiles of actinium-227, a naturally-occurring radioisotope that can be used as a tracer of oceanic water movement, in the Arctic Ocean. In common with other multinational initiatives in the International GEOTRACES Program, the goals of the U.S. Arctic expedition are to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions. Some trace elements are essential to life, others are known biological toxins, and still others are important because they can be used as tracers of a variety of physical, chemical, and biological processes in the sea. The isotope measured as part of this study, actinium-227, has a 22 year half-life, making it well-suited as a tracer of mixing and solute transport in the Arctic Ocean. This study will involve educational opportunities in scientific research for high school and undergraduate students.Quantifying the biogeochemical dynamics of the deep sea is necessary to understand the ocean carbon cycle. Despite having a half-life that is well suited for the study of both vertical and lateral transport in the deep ocean, few actinium-227 measurements have been made in the deep sea. 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. The measurements of actinium-227 from this study will aid in defining the rates of boundary exchange, particularly when combined with estimates based on radium-228 (measured as part of a separate award) and will be useful for deducing the transport and the dynamics of other solutes measured by GEOTRACES in deep waters. 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.

在该项目中，参加 2015 年美国 GEOTRACES 北极探险的一组研究人员将测量北冰洋中锕 227 的分布，锕 227 是一种天然存在的放射性同位素，可用作海洋水运动的示踪剂。与国际地理追踪计划中的其他多国倡议一样，美国北极探险的目标是识别控制海洋中关键微量元素和同位素分布的过程和量化通量，并确定这些分布对变化的敏感性。环境条件。有些微量元素是生命所必需的，有些是已知的生物毒素，还有一些很重要，因为它们可以用作海洋中各种物理、化学和生物过程的示踪剂。作为本研究的一部分，测量的同位素 Actinium-227 的半衰期为 22 年，非常适合作为北冰洋混合和溶质运输的示踪剂。这项研究将为高中生和本科生提供科学研究的教育机会。量化深海的生物地球化学动力学对于了解海洋碳循环是必要的。尽管 Actinium-227 的半衰期非常适合研究深海的垂直和横向传输，但在深海中进行的测量却很少。仪器方面的最新进展促进了这种分析，GEOTRACES 计划提供的协同作用将为获取额外数据提供理想的机会，这些数据将用于两个目的。本研究对锕 227 的测量将有助于确定边界交换率，特别是与基于镭 228 的估计（作为单独奖励的一部分进行测量）相结合，并将有助于推断通过 GEOTRACES 在深水中测量的其他溶质。通过使用具有不同半衰期的多种示踪剂，可以区分这些过程的单独作用，从而可以更全面地了解溶质行为的动态。