Collaborative Research: The importance of particle disaggregation on biogeochemical flux predictions

合作研究：颗粒分解对生物地球化学通量预测的重要性

基本信息

批准号：
2326735
负责人：
Matthew Rau
金额：
$ 41.06万
依托单位：
George Washington University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2023
资助国家：
美国
起止时间：
2023-03-15 至 2024-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2326735&HistoricalAwards=false
关键词：
Collaborative Research importance particle disaggregation

项目摘要

Collaborative Research: The importance of particle disaggregation on biogeochemical flux predictionsParticle settling is one of the major ways that material in surface waters reaches the deep ocean. Particulate matter in the open ocean consists primarily of organic material from plankton and other biological detritus, which can readily aggregate to form large flocs. A combination of physical, chemical, and biological processes transforms these flocs as they settle, redistributing material throughout the water column and potentially sequestering elements such as carbon in the deep ocean. The impact of these transformations is affected by the sinking speed of these flocs, with larger and denser particles settling faster than smaller, less-dense ones. One of the key questions facing oceanographers today is what controls particle settling speed (for example, particle size, shape, and density). There is considerable evidence that particles readily break apart as they settle, decreasing their average size and settling speed, but it is not yet understood what conditions cause these disaggregation events. This work will measure the breakup characteristics of organic settling particles both in the laboratory and at sea to quantify the importance of these breakup processes relative to particle transport. The work will be done at the Pennsylvania State University in collaboration with the University of Georgia to target the development of future marine particle disaggregation models for use by the oceanographic community.This research will play an important role in determining the importance of disaggregation on the vertical transport of particulate matter in the ocean. The project will quantify the breakup of organic marine aggregates due to fluid forces caused by turbulence or swimming organisms. Phytoplankton will be cultured and formed into aggregates in the lab prior to disaggregation using calibrated turbulence. The size, shape, and structure of these aggregates before and after breakup will be quantified using high-speed visualization and holographic imaging. In addition to the laboratory measurements, a deployable instrument that can disrupt particles in-situ and measure their size and shape will be built and deployed in the North Atlantic during the spring bloom of phytoplankton. Detailed measurements of particle concentrations, breakup characteristics, organic content, and ambient turbulence as a function of depth in the water column will be collected. This work will represent the first study of marine aggregate breakup in-situ. Specifically, the project will clarify: (1) under what conditions disaggregation is important, (2) how strong different types of natural marine aggregates are and how their strength varies with size, composition, and morphology, and (3) how aggregate size, composition, and structure influences the distribution of its breakup mass. This project will advance the career of a doctoral student and engage numerous undergraduate researchers with the field of ocean science.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.

合作研究：颗粒分解对生物地球化学通量预测的重要性颗粒沉降是地表水中的物质到达深海的主要方式之一。公海中的颗粒物主要由来自浮游生物和其他生物碎屑的有机物质组成，它们很容易聚集形成大的絮凝物。物理、化学和生物过程的结合会在这些絮凝物沉降时发生转变，在整个水体中重新分配物质，并可能隔离深海中的碳等元素。这些转变的影响受到这些絮凝体下沉速度的影响，较大且较密的颗粒比较小、密度较低的颗粒沉降得更快。当今海洋学家面临的关键问题之一是控制颗粒沉降速度的因素（例如颗粒尺寸、形状和密度）。有大量证据表明，颗粒在沉降时很容易分解，从而降低了它们的平均尺寸和沉降速度，但目前尚不清楚是什么条件导致了这些分解事件。这项工作将测量实验室和海上有机沉降颗粒的破碎特性，以量化这些破碎过程相对于颗粒传输的重要性。这项工作将在宾夕法尼亚州立大学与佐治亚大学合作完成，目标是开发未来海洋颗粒分解模型，供海洋学界使用。这项研究将在确定垂直分解的重要性方面发挥重要作用。海洋中颗粒物的输送。该项目将量化由于湍流或游动生物体引起的流体力而导致的有机海洋聚集体的分解。浮游植物将在实验室中培养并形成聚集体，然后使用校准的湍流进行分解。这些聚集体破碎前后的尺寸、形状和结构将使用高速可视化和全息成像进行量化。除了实验室测量之外，还将在浮游植物春季繁盛期间在北大西洋建造和部署一种可部署的仪器，可以现场破坏颗粒并测量其尺寸和形状。将收集颗粒浓度、破碎特性、有机物含量和环境湍流的详细测量结果，作为水柱深度的函数。这项工作将代表首次对海洋骨料原位破碎的研究。具体来说，该项目将阐明：(1) 在什么条件下分解很重要，(2) 不同类型的天然海洋骨料的强度如何，以及它们的强度如何随尺寸、成分和形态变化，以及 (3) 骨料尺寸、成分和结构影响其破碎质量的分布。该项目将推进博士生的职业生涯，并吸引众多海洋科学领域的本科生研究人员。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。