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: 0927559
• 负责人: Michael Lomas
• 金额: $ 14.99万
• 依托单位: Bermuda Institute of Ocean Sciences (BIOS), Inc.
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0927559&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.

在这个项目中，来自纽约州立大学皇后学院、罗德岛大学和百慕大海洋科学研究所的一个跨学科研究小组将调查并直接测试生态系统过程假说，这些假说将浮游生物群落结构的变异性与东北太平洋上层亚北极的颗粒生产、输出和POC-PO210-Th234相互作用联系起来。他们将使用实地和实验室研究，以及地球化学(PO210、TH234示踪剂)和生物学(初级生产、沉积物捕捉器、浮游生物群落结构)技术的结合，这将有助于更好地理解这些重要和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(例如眩晕、MEDFLUX、HOT、BATS)具有广泛的适用性。一个重要的重点将是天然放射性核素Po210，它是在海洋环境中生物积累的，最近的研究表明，它作为碳出口的示踪剂是有希望和有用的。这项研究旨在加深我们对上层水柱PO210、Th234和POC出口通量变化的控制机制的理解，而不是使用这些放射性核素不平衡来专门估计POC出口通量。具体地说，该团队将调查与现场下沉颗粒的特定类型和大小比例相关的POC、PO210、210Pb和Th234之间的关系，然后使用受控的实验室研究来检验假设和解释现场数据。这将提高我们的理解，并为Po210和Th234作为粒子示踪剂提供有价值的比较。这项研究以以下两个关键问题为指导：1)POC、PO210和Th234在悬浮物和沉淀物以及溶解池之间的分配随真光带浮游生物群落的季节变化而变化如何？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浮游生物群落产生的物质的包装和输出而变化？将在海洋站Papa(OSP)时间序列站点进行实地工作，在以盐分(2月)、桡足类(5月)和植物碎屑(8月)为主的出口的低通量和高通量季节。这个经过充分研究的高营养/低叶绿素场地提供了大量必要的支持数据和后勤基础设施。这一提议最令人兴奋的结果之一将是浮游食物网与C、Po210和Th234的包装、下沉和再矿化之间强烈而一致的关系的实验和现场演示。这项研究将阐明真光带生态系统过程在预测中上层海洋出口通量最终命运方面的作用。该项目预计将产生可用于指导今后使用放射性核素示踪剂的信息，包括使用哪种示踪剂的机械理由、使用每种示踪剂的时间和地点，以及对正在示踪的颗粒物C组分Po210和Th234的洞察。更广泛的影响：这个项目与几个国家和国际研究项目有关。其中包括：GEOTRACES，其重点是海水中微量元素和同位素在全球海洋中的分布；以及Imber，其重点是海洋生态系统的运作。它还将以OSP早先进程研究的结果为基础，包括SUPER(亚北区太平洋生态系统研究)、VERTEX(垂直交换)和加拿大联合全球海洋生态系统研究。参与机构将为研究生和/或本科生参与研究的所有方面做好准备。