Collaborative Research: US GEOTRACES GP17-OCE and GP17-ANT: Export and remineralization rates of bioactive and particle reactive trace elements using thorium-234

合作研究：美国 GEOTRACES GP17-OCE 和 GP17-ANT：使用钍 234 的生物活性和颗粒反应性微量元素的导出和再矿化率

• 批准号: 2045408
• 负责人: Ken Buesseler
• 金额: $ 85.86万
• 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=2045408&HistoricalAwards=false
• 关键词: Collaborative; Research; US; GEOTRACES; GP17

The overarching goal of the international GEOTRACES Program is 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 environmental conditions.” These trace elements exist at exceeding low concentrations in the ocean, yet play a key role in the growth and distribution of marine organisms, in particular marine phytoplankton. In addition, many trace elements are important to study as pollutants, such as copper and lead, which at high levels can be harmful to marine life. Thus, studies of the trace metal sources and sinks are needed. To meet this goal, the project is designed to measure how quickly these trace elements are cycled through marine food webs, in particular as they are transported by marine snow, i.e. slowly settling marine particles that carry these trace elements and carbon to the deep sea. The work will be conducted aboard two upcoming US GEOTRACES expeditions to the South Pacific, Southern Ocean, and Amundsen Sea. The project will provide training for two postdoctoral investigators, one focused on sample analysis and one on the modeling. To carry out this study, this proposal will use the naturally occurring particle reactive radionuclide Thorium-234 (234Th, half-life = 24.1 d) to quantify variability in trace elements and isotopes scavenging, residence times, and particle export from the surface ocean and their attenuation into the deep sea. This project will sample across extreme biogeographical and trace elemental gradients that range from the clear waters of the low dust, low productivity South Pacific (GP17-OCE) to the “greenest” high productivity Amundsen Sea and its polynyas in the Southern Ocean (GP17-ANT). Assessing these spatial and vertical gradients requires 234Th sampling at every station (n=66 casts x 13 depths) and measuring the TEI/234Th ratio on particles (n=43 x 8 depths x 2 size classes). There results of this project will lead to an increased understanding of how the trace elements are modified by removal and regeneration associated with scavenging on to, and remineralization off of, sinking particles.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.

国际地理计划计划的总体目标是“确定和量化控制海洋中关键痕量要素和同位素分布的过程，并确定这些分布对环境条件的敏感性。”这些痕量元素的存在在海洋中的浓度低，但在海洋生物的生长和分布中起着关键作用，尤其是海洋浮游植物的生长和分布。此外，许多痕量因素对于作为污染物（例如铜和铅）进行研究很重要，在高水平上可能对海洋生物有害。这是需要对痕量金属源和水槽的研究。为了实现这一目标，该项目旨在衡量这些微量元素通过海洋食物网循环的速度，特别是因为它们是由海洋雪运输的，即缓慢沉降的海洋颗粒，这些海洋颗粒将这些痕量元素和碳带到深海。这项工作将在两次即将到来的美国地理领域探险中进行，前往南太平洋，南大洋和阿蒙森海。该项目将为两名博士后研究人员提供培训，其中一个侧重于样本分析，一个针对建模。为了进行这项研究，该提案将使用天然存在的颗粒反应性放射性放射线234（234，半寿命= 24.1 d）来量化痕量元素的可变性，以及同位素清除，居住时间和粒子从表面海洋及其向深海的衰减。该项目将在极端的生物地理和痕量元素梯度中进行采样，范围从低尘，低灰尘，低生产力的南太平洋（GP17-OCE）到“最绿色”的高生产力Amundsen Sea及其在南大洋（GP17-ANT）的Polynyas。评估这些空间和垂直梯度需要在每个站点进行第234个采样（n = 66个铸造X 13深度），并在颗粒上测量TEI/234的比率（n = 43 x 8深度x 2尺寸类别）。该项目的结果将导致人们对痕量元素如何通过删除和再生的重新降低并提醒下沉的颗粒来改变痕量元素的结果。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的审查审查标准来通过评估来通过评估来获得支持的。