Postdoctoral Fellowship: OPP-PRF: Understanding the Role of Specific Iron-binding Organic Ligands in Governing Iron Biogeochemistry in the Southern Ocean

博士后奖学金：OPP-PRF：了解特定铁结合有机配体在控制南大洋铁生物地球化学中的作用

• 批准号: 2317664
• 负责人: Laura Moore
• 金额: $ 30.24万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-03-01 至 2026-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2317664&HistoricalAwards=false
• 关键词: Postdoctoral; Fellowship; OPP; PRF; Understanding

Iron is an essential nutrient in the global ocean, required by phytoplankton to perform several essential cellular functions. In the Southern Ocean, iron is especially scarce and exerts a primary control on primary production and resulting CO2 uptake by the surface ocean. Most dissolved iron in the Southern Ocean is bound to a complex mixture of organic iron-binding compounds, called ligands. The concentrations and identities of these ligands control iron bioavailability, reactivity, and transport. Exopolysaccharides (EPS) are a particularly important group of ligands that are produced in high concentrations by local microbial communities for a variety of functions, including as cryoprotectants. Despite the known importance of EPS, most iron-binding ligand studies focus on total ligand concentrations or siderophore identification. Siderophores, small iron-binding molecules produced as a microbial iron acquisition strategy, are thought to play a disproportionate role in iron cycling due to their unusually high iron-binding affinities. This project adds essential EPS concentration measurements to a subset of samples from the 2023 U.S. GEOTRACES GP17-ANT expedition to the Amundsen Sea. This project integrates EPS, siderophores and bulk ligand measurements for the first time, thereby offering unprecedented insights into how the composition of organic ligands governs the supply and fate of iron to the Southern Ocean.The research plan involves a combination of field and experimental approaches. Field samples for electrochemical EPS analysis will be collected on a GP17-ANT transect spanning from the ice edge to open water. Previously funded paired samples of bulk ligand concentrations and siderophore identification will also be taken along the same transect. Results from the three analyses will be combined to assess the relative contributions of EPS and siderophores to the total ligand pool and interpret their impact on iron biogeochemical cycling in the region. Lab experiments will be performed to evaluate whether EPS alters the size fractionation of siderophores and iron in seawater, shuttling both species into the particulate phase. Experimental results will then be used to interpret the integrated field data and improve understanding of the impact of ligands on iron transport and bioavailability in the Amundsen Sea.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.

铁是全球海洋中必不可少的营养素，浮游植物要求执行几种必不可少的细胞功能。在南大洋中，铁特别稀缺，并对初级生产产生了主要控制，并在地面海洋中摄入了二氧化碳的吸收。南大洋中大多数溶解的铁与有机铁结合化合物的复杂混合物结合，称为配体。这些配体的浓度和身份控制铁生物利用度，反应性和转运。外多糖（EPS）是一组特别重要的配体，这些配体由当地微生物群落高浓度生产，用于各种功能，包括作为冷冻保护剂。尽管EPS的重要性已知，但大多数铁结合配体研究都集中在总配体浓度或铁载体鉴定上。铁载体是作为微生物铁习得策略产生的小铁结合分子，由于其异常高的铁结合亲和力，因此被认为在铁循环中起着不成比例的作用。该项目将来自2023年美国2023年GP17-ANT Expedition到Amundsen Sea的2023年样本的子集增加了必不可少的EPS浓度测量。该项目首次整合了EPS，铁载体和体积配体测量值，从而提供了前所未有的见解，以了解有机配体的组成如何控制铁对南方海洋的供应和命运。该研究计划涉及现场和实验方法的组合。用于电化学EPS分析的现场样品将在从冰边到开放水的GP17-ANT横断面上收集。先前资助的散装配体浓度和铁载体鉴定的配对样品也将沿着同一样带。将合并这三个分析的结果，以评估EPS和铁载体对总配体池的相对贡献，并解释其对该地区铁生物地球化学循环的影响。将进行实验实验，以评估EPS是否改变了海水中铁载体和铁的大小分馏，将这两种物种都塞入颗粒相。然后，实验结果将用于解释综合现场数据，并提高对配体对Amundsen Sea铁运输和生物利用度的影响的理解。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优点和更广泛的审查标准通过评估来进行评估的。