Collaborative Research: Testing Linkages Between Plankton Community Structure and Export of C, Po, and Th in the Sub-Arctic NE Pacific: Field and Lab Studies

合作研究：测试亚北极东北太平洋浮游生物群落结构与 C、Po 和 Th 输出之间的联系：现场和实验室研究

• 批准号: 1303270
• 负责人: Michael Lomas
• 金额: $ 2.64万
• 依托单位: Bigelow Laboratory for Ocean Sciences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-15 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1303270&HistoricalAwards=false
• 关键词: Collaborative; Research; Testing; Linkages; Between

In this project, an interdisciplinary research team from CUNY Queens College, University of Rhode Island and the Bermuda Institute of Ocean Sciences will investigate and directly test hypotheses on ecosystem processes that link variability in plankton community structure to particle production, export, and POC-Po210-Th234 interactions in the upper sub-arctic NE Pacific Ocean. They will use field and lab studies, and a combination of geochemical (Po210, Th234 tracers) and biological (primary production, sediment traps, plankton community structure) techniques that will lead to an improved understanding of these important and complex upper ocean processes, which have wide applicability to the interpretation of current and recent results (e.g., VERTIGO, MEDFLUX, HOT, BATS). An important focus will be on the natural radionuclide Po210, which is bioaccumulated in the marine environment, and which recent studies indicate has promise and utility as a tracer of carbon export. This study is designed to refine our understanding of the mechanisms that control variability in export fluxes of Po210, Th234, and POC from the upper water column, rather than using these radionuclide disequilibria to exclusively estimate POC export fluxes. Specifically the team will investigate the relationships between POC, Po210, 210Pb, and Th234 associated with specific types and size-fractions of sinking particles in the field, and then use controlled laboratory studies to test hypotheses and interpret the field data. This will improve our understanding and provide a valuable comparison of Po210 and Th234 as particle tracers. The research is guided by the following two key questions: 1) How variable is the partitioning of POC, Po210, and Th234 between suspended and settling particles and the dissolved pool in response to seasonal variability in the euphotic zone plankton community? 2) How do rates of mobilization and decomposition of POC, Po210, and Th234 vary with the packaging and export of materials produced by the planktonic community in the surface ocean under low and high flux conditions? Field work will be conducted at the Ocean Station Papa (OSP) time series site, during low and high flux seasons when export is dominated by salps (February), copepods (May), and phytodetritus (August). This well-studied high-nutrient/low-chlorophyll site provides a wealth of necessary supporting data and logistical infrastructure. One of the most exciting outcomes from this proposal would be an experimental and field demonstration of strong and consistent relationships between planktonic food webs and the rates of C, Po210, and Th234 packaging, sinking, and remineralization. This study will illuminate the role of euphotic zone ecosystem processes in predicting the eventual fate of export flux in the mesopelagic. The project is expected to yield information that could be used to guide future use of radionuclide tracers, including mechanistic justifications for which tracer to use, when and where to use each tracer, as well as insight into which particulate C fraction Po210 and Th234 are tracing. Broader Impacts: This project is relevant to several national and international research programs. These include; GEOTRACES, whose focus is the global-ocean distribution of trace elements and isotopes in seawater; and IMBER, whose focus in on the functioning of ocean ecosystems. It will also build upon the results of earlier process studies at OSP including SUPER (Subarctic Pacific Ecosystem Research), VERTEX (VERTical EXchange) and the Canadian JGOFS study. The participating institutions will make provision for graduate and/or undergraduate student involvement in all aspects of the research.

在该项目中，来自纽约市立大学皇后学院、罗德岛大学和百慕大海洋科学研究所的跨学科研究小组将调查并直接测试有关生态系统过程的假设，这些假设将浮游生物群落结构的变异性与亚北极东北太平洋上层的颗粒产生、输出和 POC-Po210-Th234 相互作用联系起来。他们将使用现场和实验室研究，以及地球化学（Po210、Th234示踪剂）和生物（初级生产、沉积物捕集器、浮游生物群落结构）技术的结合，这将有助于更好地了解这些重要而复杂的上层海洋过程，这些过程对于解释当前和最近的结果（例如，VERTIGO、MEDFLUX、HOT、BATS）具有广泛的适用性。一个重要的焦点将是天然放射性核素 Po210，它在海洋环境中生物累积，最近的研究表明它具有作为碳输出示踪剂的前景和实用性。本研究旨在加深我们对控制上部水柱 Po210、Th234 和 POC 输出通量变异性的机制的理解，而不是使用这些放射性核素不平衡来专门估计 POC 输出通量。具体来说，该团队将调查 POC、Po210、210Pb 和 Th234 与现场下沉颗粒的特定类型和尺寸分数相关的关系，然后使用受控实验室研究来检验假设并解释现场数据。这将增进我们的理解，并为 Po210 和 Th234 作为粒子示踪剂提供有价值的比较。该研究以以下两个关键问题为指导：1）随着富光带浮游生物群落的季节变化，悬浮颗粒和沉降颗粒以及溶解池之间的 POC、Po210 和 Th234 分配有多大变化？ 2) 在低通量和高通量条件下，POC、Po210 和 Th234 的动员和分解速率如何随海洋表层浮游群落产生的材料的包装和出口而变化？实地工作将在帕帕海洋站（OSP）时间序列站点进行，在低通量季节和高通量季节，出口主要是樽海鞘（二月）、桡足类（五月）和植物碎屑类（八月）。这个经过充分研究的高营养/低叶绿素地点提供了大量必要的支持数据和后勤基础设施。该提案最令人兴奋的成果之一是通过实验和现场演示，证明浮游食物网与 C、Po210 和 Th234 包装、下沉和再矿化速率之间存在强大且一致的关系。这项研究将阐明亮光带生态系统过程在预测中层出口通量的最终命运中的作用。该项目预计将产生可用于指导放射性核素示踪剂未来使用的信息，包括使用哪种示踪剂的机械理由、何时何地使用每种示踪剂，以及深入了解正在追踪的颗粒 C 组分 Po210 和 Th234。更广泛的影响：该项目与多个国家和国际研究计划相关。这些包括； GEOTRACES，其重点是海水中微量元素和同位素的全球海洋分布；和 IMBER，其重点研究海洋生态系统的功能。它还将以 OSP 早期过程研究的结果为基础，包括 SUPER（亚北极太平洋生态系统研究）、VERTEX（垂直交换）和加拿大 JGOFS 研究。参与机构将为研究生和/或本科生参与研究的各个方面做好准备。