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: 2124416
• 负责人: Brian Popp
• 金额: $ 50.75万
• 依托单位: University of Hawaii
• 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=2124416&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.

作为生物泵过程的一部分，有机物质向下沉降，将碳输送出海洋表面。然而，表层水中生物产生的有机物质中只有一小部分能够进入深海。被细菌或更大的生物体破碎或消耗（呼吸）；在太平洋的最新研究结果的指导下，研究人员将使用氨基酸中碳和氮的稳定同位素来确定新鲜的输入。藻类材料、浮游动物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，以便它们可以用来帮助预测全球碳传输模式。一项大型海洋学现场计划（NASA EXPORTS），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，为了广泛分享结果，研究人员将制作并分发几集“海洋之声”。将播出的当地电视节目该项目将在夏威夷和太平洋岛屿上发布并通过社交媒体向迈阿密大学的一名博士生和一名本科生提供支持，该大学为 25% 的西班牙裔人口提供服务。以及夏威夷大学（指定的少数民族服务机构）的一名博士生和一名本科生。拟议的工作将评估粪便材料中包装有机物、颗粒分解、微生物再加工和浮游动物饮食使用的相对重要性垂直图案研究人员根据太平洋低通量环境中现有的工作，使用独立于孵化技术或代谢率测量的经验方法，开发了两个新兴模型：（1）使用混合模型。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的颗粒成分，从而可以了解这些材料的垂直变化机制和尺寸分布检测到；（2）进入深海的碳通量与中层食物网对小型降解颗粒的依赖之间存在反比关系。在这个项目中，研究人员将通过对最近的 NASA EXPORTS 应用相同的方法来测试这两个模型。北大西洋春季水华的实地研究在亚北极太平洋地区进行，为研究人员新开发的同位素指标的应用和完善提供了一些材料。能够开发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饮食资源的关系，包括通常不被视为后生动物饮食资源的小型微生物降解颗粒。这项工作利用了现有的综合性资源。实地计划特别侧重于建立一个将表面海洋特性与有机碳垂直通量相关的预测框架。拟议的工作直接解决出口科学问题 2：什么控制着有机物垂直转移的效率。这项工作的结果还将提供与碳通量组成和远洋食物网资源的全球模型的观测比较。该奖项是 NSF 的法定使命，并且通过使用基金会的智力价值和更广泛的评估，被认为值得支持。影响审查标准。