Development and Application of a Radiotracer Rate Method for Ethane and Propane Consumption

作为光合作用和石油工业的副产品，乙烷和丙烷通过自然渗漏大量释放到海洋中。例如，在深水地平线事件中，乙烷和丙烷共占总泄漏量的5%以上，是泄漏期间墨西哥湾东北部深水氧气下降的主要驱动因素。尽管这些气体很重要，但人们对它们释放到海洋中的情况、海洋细菌消耗它们的能力、以及它们储存的碳和能量的命运和影响知之甚少。在这个项目中，加州大学圣巴巴拉分校的研究人员将通过开发、验证和应用高灵敏度示踪技术来量化海洋中乙烷和丙烷的消耗率，具体解决海洋中乙烷和丙烷的消耗问题。为了更好地了解控制海洋中乙烷和丙烷消耗的因素，将测试两个特定的假设。假设1：乙烷和丙烷的氧化能力在整个海洋上层和大陆边缘是普遍存在的，其组成率取决于区域输入和总细菌丰度；假设2：丙烷和乙烷的消耗在时间尺度上很容易诱导超过基础水平，丙烷的消耗比乙烷的消耗更容易诱导。研究小组将分两步解决这些假设。第一步将需要开发一种方法来量化乙烷和丙烷的消耗率，包括实验室合成放射性标记的乙烷和丙烷，产品的纯化，对示踪剂储存的系统调查，以尽量减少自辐射分解交换的影响，并通过相互比较验证测量结果。第二步是应用该方法来询问乙烷和丙烷在海洋中的消耗速率，包括沿海海洋和沿着加利福尼亚的大陆边缘。研究的实地部分将在圣巴巴拉盆地的一系列短途巡航期间进行，并在联索特派团的一艘船上进行一次增值巡航。本项目将为一名研究生的论文研究提供支持。几名本科生将接受实验室训练并参与沿海研究。实地研究课程将带领几名本科生进行研究考察，并为他们提供丰富的实践教育经验，真正将教学与研究结合起来，使用既定的方法。PI将继续以身作则地领导外联工作，作为记者、联邦机构和国会议员的资源，并通过普及这项研究的适当方面

Ethane and propane are released in abundance to the ocean through natural seepage, as byproducts of photosynthesis, and by the petroleum industry. For example, ethane and propane together constituted greater than 5% of the total mass release during the Deepwater Horizon event and were the primary drivers of oxygen decline in the deep waters of the NE Gulf of Mexico during the spill. Despite the importance of these gases, little is known about their release into the ocean, the capacity of marine bacteria to consume them, or the fate and impacts of the carbon and energy they store. In this project researchers at the University of California at Santa Barbara will specifically address the consumption of ethane and propane in the ocean by developing, validating and applying highly sensitive tracer techniques to quantify consumption rates for these gases in ocean waters. Two specific hypotheses will be tested with the goal to better understand the factors controlling ethane and propane consumption in the ocean. Hypothesis 1: The capacity for ethane and propane oxidation is ubiquitous throughout the upper ocean and along continental margins, with constitutive rates that depend on regional input and total bacterial abundance; Hypothesis 2: Propane and ethane consumption are readily inducible beyond a basal level on the timescale of days, propane consumption more so than ethane consumption. The research team will address these hypotheses in two steps. The first step will entail the development of a method to quantify the consumption rates for ethane and propane, including the laboratory synthesis of radiolabeled ethane and propane, purification of the products, systematic investigations of tracer storage to minimize effects of autoradiolytic exchange, and validation of the measurement through intercomparison. The second step is the application of the method to interrogate the rates of ethane and propane consumption in the ocean, including the coastal ocean and along the continental margin off California. The field component of the research will take place during a series of short cruises in the Santa Barbara Basin, and during one value added cruise aboard a UNOLS vessel. Broader impacts This project will provide support for the dissertation research of one graduate student. Several undergraduate students will receive laboratory training and participate in the coastal research. A field studies course will bring several undergraduates on a research expedition and provide them a rich hands-on educational experience, truly integrating teaching and research, using an established methodology. The PI will continue to lead outreach efforts by example, serving as a resource to journalists, federal agencies, and members of Congress, and through popularization of appropriate aspects of this research