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.

铁是全球海洋中的一种必需营养素，浮游植物需要它来执行几种基本的细胞功能。在南大洋，铁特别稀缺，对初级生产和表层海洋对二氧化碳的吸收起着主要控制作用。南大洋中大多数溶解的铁都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的生物利用度，反应性和运输。胞外多糖（EPS）是一组特别重要的配体，其由局部微生物群落以高浓度产生，用于多种功能，包括作为冷冻保护剂。尽管已知EPS的重要性，大多数铁结合配体的研究集中在总配体浓度或铁载体鉴定。铁载体是微生物利用铁元素获得铁的一种策略，由于其具有极高的铁结合亲和力，被认为在铁循环中起着重要作用。该项目为2023年美国GEOTRACES GP 17-ANT考察阿蒙森海的样本子集增加了基本的EPS浓度测量。该项目首次整合了EPS、铁载体和散装配体测量，从而为有机配体的组成如何控制南大洋铁的供应和命运提供了前所未有的见解。研究计划涉及实地和实验方法的结合。将在从冰缘到开阔水域的GP 17-ANT横断面上收集用于电化学EPS分析的现场样品。之前资助的大量配体浓度和铁载体鉴定的配对样品也将沿同一横断面沿着采集。三项分析的结果将结合起来，以评估EPS和铁载体对总配体库的相对贡献，并解释它们对该地区铁生物地球化学循环的影响。实验室实验将进行评估是否EPS改变铁载体和铁在海水中的大小分馏，穿梭到颗粒相的两个物种。实验结果将被用来解释综合现场数据，并提高对阿蒙森海铁运输和生物利用度的配体的影响的理解。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。