OCE-PRF Isotopic and microbial investigations of the iron geochemistry and bioavailability of glaciogenic particles

OCE-PRF 冰川形成颗粒的铁地球化学和生物利用度的同位素和微生物研究

• 批准号: 2126562
• 负责人: Kiefer Forsch
• 金额: $ 29.8万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2126562&HistoricalAwards=false
• 关键词: OCE; PRF; Isotopic; microbial; investigations

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Trace element micronutrients such as iron, play important roles in biological processes in the ocean. In surface waters where phytoplankton grow and support the base of the marine food web, iron is often present at vanishingly small concentrations and near the poles, can limit phytoplankton productivity. Motivated by widespread oceanic iron deficiency, microbes have developed specialized strategies for accessing even relatively unavailable mineral forms of iron, such as particulate matter. One source of iron-rich particles is the delivery of glacial meltwater to the ocean, which is expected to increase as the climate continues to warm. The research proposed here seeks to study the relationships between iron supplied from the melting of glaciers and the ability of microbes to take advantage of this new source of iron nutrition. To do this, the growth of microbes will be tested on glacial ice particles from two coastal locations heavily influenced by glaciers: Antarctica and Alaska. This project will support the training of a postdoctoral scholar, and the participation of the PI in education and outreach activities carried out through the Alaskan Native Science & Engineering Program (ANSEP) and Scripps Undergraduate Research Fellowship (SURF) programs, including mentorship of an undergraduate in a research project. Glacial meltwater is expected to fertilize the high-latitude oceans due to its high content of bioavailable iron (Fe). Bioavailability of glacially-derived Fe is typically inferred from size and chemical lability, and previous investigations in biological systems use a limited number of Fe substrates to probe the bioavailability with select phytoplankton species. A mechanistic understanding of glaciogenic Fe acquisition and biological uptake in marine environments is still needed. Mechanistic studies which fully characterize the geochemical and microbial acquisition of glaciogenic iron have the potential to greatly inform our understanding of the coupled interaction between the supply of glacial meltwater and ecosystems productivity. This proposal seeks to assess the bioavailability of glacially-derived Fe-bearing particles by combining examinations of the Fe isotopic composition of chemically treated glaciogenic particles from discrete glacial ice pieces with growth experiments using a genetically-modified marine heterotrophic bacteria. Two hypotheses regarding chemical lability and bioavailability of glaciogenic particles will be examined in the proposed work: 1) The Fe-stable isotopic signatures of glaciogenic particles are linked to chemical lability, and can be used to gauge the fertilization potential of sediment transported to marine environments and its subsequent fate; and 2) Chemical lability can be directly linked to bioavailability via microbial iron acquisition, which in turn affects Fe-stable isotopic signatures. This project stands to contribute to our understanding of which members of the marine microbial community will benefit from glacially-derived Fe, the role of Fe acquisition strategies in Fe isotopic signatures and bioavailability in marine systems, and the fertilization potential of increased cryospheric weathering inputs to the ocean.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.

该奖项是根据2021年《美国救援计划法》（公共法第117-2）的全部或部分资助的。轨道元素微量营养素（例如铁）在海洋的生物过程中起重要作用。在浮游植物生长并支持海洋食品网的基础的地表水中，铁通常存在于消失的小浓度和杆子附近，可能会限制浮游植物的生产力。在广泛的海洋铁缺乏症中，微生物开发了专门的策略，即使是相对不可用的矿物形式的铁，例如颗粒物。富含铁的颗粒的一种来源是将冰川融合物传递到海洋，随着气候的持续变暖，预计将增加。这里提出的研究旨在研究冰川融化所提供的铁与微生物利用这种新的铁营养来源的能力之间的关系。为此，将对来自两个受冰川影响的冰川冰粒的生长进行测试：南极洲和阿拉斯加。该项目将支持对博士后学者的培训，以及PI通过阿拉斯加土著科学与工程计划（ANSEP）和Scripps本科研究奖学金（SURF）计划进行的教育和外展活动，包括在研究项目中的本科生指导。 由于其高含量的生物利用铁（FE），冰川融化物有望受精高纬度海洋。冰川衍生的Fe的生物利用度通常是根据大小和化学劳动来推断的，并且先前对生物系统的研究使用有限数量的FE底物来探测精选的浮游植物物种的生物利用度。仍然需要对冰原Fe获取和在海洋环境中生物学吸收的机械理解。充分表征冰川铁的地球化学和微生物获取的机械研究可能会大大了解我们对冰川融化和生态系统生产率供应之间耦合相互作用的理解。该提案旨在通过结合离散冰川冰块的​​化学处理的冰川颗粒的Fe同位素组成的检查，并使用遗传改性的海洋学原子质异亲子细菌来评估冰川衍生的含含氧颗粒的生物利用度。 在拟议的工作中将检查有关冰川颗粒的化学不稳定和生物利用度的两个假设：1）冰川原颗粒的Fe稳定的同位素特征与化学稳定性有关，可用于评估运输到海洋环境及其后续效率的沉积物潜能的施肥； 2）化学稳定性可以通过微生物采集直接与生物利用度联系起来，这又影响了Fe稳定的同位素特征。该项目将有助于我们对海洋微生物社区的哪些成员的理解，将从冰川衍生的FE中受益，收购策略在Fe同位素特征中的作用和海洋系统中的生物利用度的作用，以及通过cryospheric效力增强的投入，通过评估NSF的NSF宣传，其法定宣传的价值均可表现出cryospheric的潜在。更广泛的影响审查标准。