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，一组参加2015年美国地理位置北极探险队的研究人员将测量Actinium-227的概况，Actinium-227是一种自然存在的放射性同位素，可以用作北极海洋中的海洋水运动示踪剂。美国北极探险队的目标是与国际地理计划计划中的其他跨国公司计划相同，是确定过程并量化流量，以控制海洋中关键的微量元素和同位素的分布，并确定这些分布对不断变化环境条件的敏感性。一些痕量元素对生命至关重要，另一些是已知的生物毒素，而另一些则很重要，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。作为这项研究的一部分测量的同位素Actinium-227具有22年的半衰期，使其非常适合在北极海洋中混合和溶质运输的示踪剂。这项研究将涉及高中和本科生科学研究的教育机会。Quantive深海的生物地球化学动态对于了解海洋碳循环是必要的。尽管半衰期非常适合在深海中研究垂直运输和横向运输，但在深海中很少进行Actinium-227测量。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。这项研究的阳极-227测量将有助于定义边界交换速率，尤其是与基于辐射228的估计值（作为单独奖励的一部分测量）结合使用，对于推论深水中Geotraces测得的其他溶质的传输和动力学将很有用。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。