US GEOTRACES GP17-OCE and GP17-ANT: Sources and Rates of Trace Element and Isotope Cycling Derived from the Radium Quartet

美国 GEOTRACES GP17-OCE 和 GP17-ANT：来自镭四重奏的微量元素和同位素循环的来源和速率

• 批准号: 2048067
• 负责人: Matthew Charette
• 金额: $ 88.73万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-10-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2048067&HistoricalAwards=false
• 关键词: US; GEOTRACES; GP17; OCE; ANT

The goal of the GEOTRACES program is to “identify processes and quantify fluxes that control the distribution of trace elements and isotopes (TEIs) in the ocean and to establish the sensitivity of these distributions to changing environmental conditions”. This ambitious objective requires coordinated seagoing field work for collection of samples to measure many elements simultaneously across the earth’s major ocean basins. However, these comprehensive global concentration maps for trace elements cannot be properly interpreted without concurrent measurement of radioactive tracers like radium isotopes that can provide time scales of their ocean input. In this project, the investigators will measure the abundance and distribution of radium isotopes in the Southern Ocean between the southern tip of South America and Antarctica, including a detailed characterization of the Antarctic coastal marine environment. The project will support a postdoctoral research associate and involve two undergraduate student researchers in post-cruise analyses.The main motivation of the proposed research is to utilize the quartet of radium (Ra) isotopes (224Ra, 223Ra, 228Ra, 226Ra) to enable source identification and flux quantification of TEIs during the forthcoming US GEOTRACES GP17-OCE and GP17-ANT expeditions. Measurement of Ra isotopes will allow the team to address several key questions related to ocean margin and benthic boundary processes and their role in supplying and transporting TEIs to marine ecosystems including: (1) What are the rates of lateral transport of TEIs from the Antarctic and Patagonian continental margins out to and including the high nutrient low chlorophyll (HNLC) Southern Ocean? (2) What are the TEI fluxes associated with Antarctic glacial meltwater? and (3) What are the time scales of TEI transport associated with Pacific-Antarctic Ridge neutrally buoyant hydrothermal plumes? Boundary inputs are considered to be the dominant source of many key TEIs to the ocean including iron, however, TEI concentrations must be coupled with input and transport rates to determine their effect on marine biogeochemical cycles. The wide range of Ra isotope half-lives (3.66 days to 1600 years) allow for the quantification of TEI transport processes on time scales relevant to ocean mixing processes. The proposed coupled Ra-TEI measurements will allow the full value of the distribution of numerous TEIs as measured by GEOTRACES PIs to be realized.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.

GEOTRACES 计划的目标是“识别控制海洋中微量元素和同位素 (TEI) 分布的过程并量化流量，并确定这些分布对不断变化的环境条件的敏感性”。这一雄心勃勃的目标需要协调一致的航海领域。然而，如果不同时测量镭同位素等放射性示踪剂（可以提供时间），就无法正确解释这些全面的全球微量元素浓度图。在该项目中，研究人员将测量南美洲南端和南极洲之间的南大洋镭同位素的丰度和分布，包括对南极沿海海洋环境的详细描述。一名博士后研究员，并涉及两名本科生研究人员参与巡航后的研究。拟议分析研究的主要动机是利用镭（Ra）同位素四重奏（224Ra， 223Ra、228Ra、226Ra）在即将到来的美国 GEOTRACES GP17-OCE 和 GP17-ANT 探险期间实现 TEI 的源识别和通量量化，Ra 同位素测量将使团队能够解决与海洋边缘和底栖边界过程相关的几个关键问题。及其在向海洋生态系统供应和运输 TEI 方面的作用，包括： (1) TEI 从海洋生态系统的横向运输率是多少？南极和巴塔哥尼亚大陆边缘延伸至并包括高营养低叶绿素 (HNLC) 南大洋？ (2) 与南极冰川融水相关的 TEI 通量是多少？以及 (3) 与太平洋相关的 TEI 传输的时间尺度是多少？南极海脊中性浮力热液羽流被认为是包括铁在内的许多关键 TEI 的主要来源，然而，TEI浓度必须与输入和传输速率相结合，以确定它们对海洋生物地球化学循环的影响 Ra 同位素半衰期的广泛范围（3.66 天到 1600 年）允许在与海洋混合过程相关的时间尺度上量化 TEI 传输过程。拟议的耦合 Ra-TEI 测量将实现由 GEOTRACES PI 测量的众多 TEI 分布的全部价值。该奖项反映了 NSF 的法定使命，并被认为是值得的。通过使用基金会的智力优势和更广泛的影响审查标准进行评估来获得支持。

项目成果

The distribution of 227Ac along the GA01 section in the North Atlantic

北大西洋 GA01 断面 227Ac 分布

• DOI: 10.1016/j.marchem.2023.104207
• 发表时间: 2023
• 期刊: Marine Chemistry
• 影响因子: 3
• 作者: Le Roy, Emilie;van Beek, Pieter;Lacan, François;Souhaut, Marc;Sanial, Virginie;Charette, Matthew A.;Henderson, Paul B.;Deng, Feifei
• 通讯作者: Deng, Feifei