Collaborative Research: Isotopic Indicators for Mechanisms of Organic Matter Degradation under High Productivity and High Carbon Flux Conditions (EXPORTS)

合作研究：高生产率和高碳通量条件下有机物降解机制的同位素指标（出口）

• 批准号: 2124415
• 负责人: Hilary Close
• 金额: $ 48.15万
• 依托单位: University of Miami
• 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: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2124415&HistoricalAwards=false
• 关键词: Collaborative; Research; Isotopic; Indicators; Mechanisms

The downward settling of organic material transports carbon out of the ocean surface, as part of a process called the biological pump. However, only a small fraction of organic material produced by organisms in surface waters makes it to the deep ocean. The rest can be fragmented or consumed (respired) by bacteria or larger organisms; the role of each process remains in question. Guided by recent results from the Pacific Ocean, the investigators will use the stable isotopes of carbon and nitrogen in amino acids to identify the input of fresh algal material, zooplankton feces, and bacteria to the biological pump in the North Atlantic spring bloom. With data from contrasting locations, the investigators will test and develop their isotopic models so they can be used to help predict global patterns in carbon transport. The work will be part of a large oceanographic field program (NASA EXPORTS). The tremendous amount of data collected in this program will aid the development and interpretation of the isotopic models. To share results broadly, the investigators will produce and distribute several episodes of Voice of the Sea, a local television program that will air in Hawaii and the Pacific islands. Episodes will be posted online and publicized through social media to the south Florida community. The project will support a Ph.D. student and an undergraduate student at University of Miami, which serves a 25% Hispanic population, and a Ph.D. student and an undergraduate student at University of Hawaii, a designated minority-serving institution.The proposed work will assess the relative importance of packaging organic matter in fecal material, particle disaggregation, microbial reworking, and zooplankton dietary usage on vertical patterns of particle flux across contrasting oceanic provinces, using empirical methods independent of incubation techniques or metabolic rate measurements. From their existing work in relatively low-flux environments of the Pacific Ocean, the investigators have developed two nascent models: (1) a mixing model that uses the compound-specific isotope analysis of amino acids (AA-CSIA) to estimate the phytodetritus, fecal pellet, and microbially degraded composition of particles, such that the vertical alteration mechanisms and size distribution of these materials can be detected; and (2) an inverse relationship between carbon flux into the deep ocean and the reliance of mesopelagic food webs on small, degraded particles. In this project, the investigators will test these two models by applying the same methods to the recent NASA EXPORTS field study in a high productivity, high flux regime, the North Atlantic spring bloom. The first EXPORTS field study in the subarctic Pacific provided some of the materials from which the models were developed. Application and refinement of the investigators’ newly developed isotopic indicators will enable development of a globally generalized isotopic framework for assessing the degradative history of particulate organic matter and its relationship to mesopelagic dietary resources, including small, microbially degraded particles that are often not accounted for as a metazoan dietary resource. This work capitalizes on existing, comprehensive field programs specifically focused on building a predictive framework relating surface ocean properties to the vertical flux of organic carbon. The proposed work directly addresses EXPORTS Science Question 2: What controls the efficiency of vertical transfer of organic matter below the well-lit surface ocean? The results of this work additionally will provide observational comparisons to global models of carbon flux composition and pelagic food web resources.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.

有机物质的向下沉降将碳从海洋表面运输出来，这是生物泵过程的一部分。然而，只有一小部分由表面沃茨中的生物产生的有机物质进入深海。其余的可以被细菌或更大的有机体分解或消耗（呼吸）;每个过程的作用仍然存在疑问。在太平洋最近结果的指导下，研究人员将使用氨基酸中碳和氮的稳定同位素来确定北大西洋春季水华中新鲜藻类材料，浮游动物粪便和细菌对生物泵的输入。利用来自不同地点的数据，研究人员将测试和开发他们的同位素模型，以便用于帮助预测全球碳运输模式。这项工作将是一个大型海洋学领域计划（NASA出口）的一部分。该计划收集的大量数据将有助于同位素模型的开发和解释。为了广泛分享调查结果，调查人员将制作并分发几集“海洋之声”，这是一个当地电视节目，将在夏威夷和太平洋岛屿播出。埃普雷蒂安将在网上发布，并通过社交媒体向南佛罗里达社区宣传。该项目将支持一个博士学位。一位是迈阿密大学的学生和一位本科生，该大学为25%的西班牙裔人口提供服务。学生和本科生在夏威夷大学，一个指定的少数民族服务机构。拟议的工作将评估包装有机物质的粪便材料，颗粒解聚，微生物改造，浮游动物的饮食使用的颗粒通量的垂直模式的相对重要性，在对比海洋省份，使用独立的孵化技术或代谢率测量的经验方法。根据他们在太平洋相对低通量环境中的现有工作，研究人员开发了两个新生模型：（1）混合模型，使用氨基酸的化合物特异性同位素分析（AA-CSIA）来估计植物碎屑、粪便颗粒和微生物降解颗粒的组成，以便可以检测这些物质的垂直变化机制和粒度分布;以及（2）流入深海的碳流量与中层食物网对小的、降解的颗粒的依赖之间的反比关系。在这个项目中，研究人员将通过将相同的方法应用于最近NASA EXPORTS在高生产力，高通量制度，北大西洋春季水华的实地研究来测试这两个模型。EXPORTS在亚北极太平洋的第一次实地研究提供了一些用于开发模型的材料。研究人员新开发的同位素指标的应用和改进将有助于开发一个全球通用的同位素框架，用于评估颗粒有机物的降解历史及其与中层食物资源的关系，包括通常不被视为后生动物食物资源的微生物降解的小颗粒。这项工作利用了现有的综合实地项目，专门致力于建立一个将表层海洋特性与有机碳垂直通量联系起来的预测框架。拟议的工作直接解决了出口科学问题2：是什么控制了有机物质在光照良好的海洋表面以下垂直转移的效率？这项工作的结果还将提供碳通量组成和远洋食物网资源的全球模型的观测比较。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

项目成果

Deconvolving mechanisms of particle flux attenuation using nitrogen isotope analyses of amino acids

使用氨基酸氮同位素分析的粒子通量衰减去卷积机制

• DOI: 10.1002/lno.12398
• 发表时间: 2023
• 期刊: Limnology and Oceanography
• 影响因子: 4.5
• 作者: Wojtal, Paul K.;Doherty, Shannon C.;Shea, Connor H.;Popp, Brian N.;Benitez‐Nelson, Claudia R.;Buesseler, Ken O.;Estapa, Margaret L.;Roca‐Martí, Montserrat;Close, Hilary G.
• 通讯作者: Close, Hilary G.