(Non-TEP) Abiotic Particle Formation From Dissolved Organic Matter in Marine Environments: Possible Shunt to the Microbial Loop

（非 TEP）海洋环境中溶解有机物形成的非生物颗粒：可能分流至微生物循环

• 批准号: 0404420
• 负责人: James Cowen
• 金额: --
• 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: 2004
• 资助国家: 美国
• 起止时间: 2004-06-15 至 2007-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0404420&HistoricalAwards=false
• 关键词: Non; TEP; Abiotic; Particle; Formation

In the ocean autotrophs are the principle particle vector converting dissolved inorganic carbon (DIC) to particulate organic matter (POM). Exudates, principally derived from phytoplankton as dissolved organic matter (DOM), exist in the ocean as labile, semi-labile and refractory DOM. As an alternate particulate pathway the microbial loop represents a process where bacteria are able to metabolize a portion of this DOM and therefore convert DOM to POM. This conversion of DOM to POM has been found to be substantial, providing significant energy for higher trophic levels. Recently, a process has been described where 0.2 um filtered and poisoned river water produced particles abiotically in dark incubations. The analysis of particles and source waters showed that the particles are distinctly different from TEP (transparent exopolymers particles) and were derived from DOM and contained organic components found in living organisms (i.e., DNA, carbohydrates, lipids, proteins). Over the incubation period the rate and magnitude of formation, as well as size, of these abiotic microparticles were similar to bacteria, and carbon-nitrogen ratios suggest they could be nutritionally important. If a similar process occurs in the marine environment it would by-pass the traditional biotic microbial loop in terms of transforming DOM to POM and may constitute an important alternate pathway, especially if labile DOM comprise major components of the abiotic particle formation pathway. However, if the source material of the microparticles are composed primarily of the refractory fraction of the DOM pool then they may provide a poor nutritional source, but may still make a significant contribution to the deep sea carbon flux. The proposed study will examine the abiotic formation of organic particles in two major contrasting ocean environments: the oligotrophic North Pacific near Station ALOHA and the highly productive upwelling zone off the Pacific coast of N. America (cruise of opportunity). Carefully controlled time-series experimental incubations will be conducted with filtered and poisoned surface (1% light level) and deep (~1000 m) seawater to elucidate the formation rate, size, quantity, composition and nutritional quality of abiotically formed particles as well as a determination of source material. Intellectual Merit: The results of this research will provide a first-order global estimate of the magnitude of this process in the sea and its significance relative to the traditional microbial loop pathway. If the abiotic formation of organic particles is a significant process in the sea, then this process could be a significant shunt to the microbial loop and would expand our understanding of particle dynamics in the sea. Broader Impacts: There is a strong educational benefit to these studies. Undergraduate students will be intimately involved in the planning and implementation of this project, and will benefit from exposure to interdisciplinary faculty from UH and other institutions involved with HOTs and other cruises (informal education in the form of dissemination of ideas, techniques and field experience). Project PI Cowen is a faculty member of the Global Environmental Sciences, a rigorous undergraduate science major administered through the Department of Oceanography; it is anticipated that undergraduate participation in this project will lead to at least one student Senior Thesis. Cowen is also involved in Science-Teacher outreach projects and will continue the very successful .Teacher at Sea. outreach program initiated by Cowen as part of another NSF project; this program integrates local teachers and their classrooms into all phases of the research project; in this project we will involve teachers in the local sample collections, incubation experiments and analyses. Teachers. students will be invited to UH ships and to analytical facilities for examination of project samples.

在海洋中，自养生物是将溶解的无机碳（DIC）转化为颗粒有机物（POM）的主要颗粒载体。 渗出物主要来源于浮游植物的溶解有机物（DOM），存在于海洋中的不稳定，半不稳定和难降解DOM。 作为替代颗粒途径，微生物环路代表了细菌能够代谢一部分DOM并因此将DOM转化为POM的过程。 已发现DOM向POM的这种转化是显著的，为更高的营养级提供了显著的能量。 最近，已经描述了一种方法，其中0.2 μ m过滤和中毒的河水在黑暗培养中产生非生物颗粒。 颗粒和源沃茨的分析表明，颗粒明显不同于TEP（透明外聚合物颗粒），并且来源于DOM并且含有在活生物体中发现的有机组分（即，DNA、碳水化合物、脂质、蛋白质）。 在培养期间，这些非生物微粒的形成速率和大小与细菌相似，碳氮比表明它们可能具有重要的营养价值。 如果类似的过程发生在海洋环境中，它将绕过传统的生物微生物循环的DOM转化为POM，并可能构成一个重要的替代途径，特别是如果不稳定的DOM包括非生物颗粒形成途径的主要组成部分。 然而，如果微粒的源材料主要由DOM池的难熔部分组成，则它们可能提供较差的营养源，但仍可能对深海碳通量做出显著贡献。 拟议的研究将研究两个主要对比海洋环境中有机颗粒的非生物形成：ALOHA站附近的贫营养北太平洋和北太平洋沿岸的高产上升流区。美国（机会号邮轮）。 将使用过滤和中毒的表层（1%光照水平）和深层（~1000 m）海水进行严格控制的时间序列实验孵育，以阐明非生物形成颗粒的形成速率、大小、数量、组成和营养质量，并确定源材料。 智力优势：这项研究的结果将提供一个一阶全球估计的幅度，这一过程在海洋中，其意义相对于传统的微生物环路途径。 如果有机颗粒的非生物形成是海洋中的一个重要过程，那么这个过程可能是微生物循环的一个重要分流，并将扩大我们对海洋中颗粒动力学的理解。 更广泛的影响：这些研究有很强的教育效益。本科生将密切参与该项目的规划和实施，并将受益于接触来自UH和其他参与HOTs和其他邮轮的机构的跨学科教师（以传播思想，技术和实地经验的形式进行的非正式教育）。 项目PI考恩是全球环境科学的教员，通过海洋学系管理的严格的本科科学专业;预计本科生参与该项目将导致至少一名学生的高级论文。 考恩还参与了科学教师外展项目，并将继续非常成功的。海上教师。作为另一个NSF项目的一部分，Cowen发起了一个外展计划;该计划将当地教师和他们的教室整合到研究项目的各个阶段;在这个项目中，我们将让教师参与当地的样本收集，孵化实验和分析。 教师学生将被邀请到UH船舶和分析设施的项目样品的检查。