A High Resolution Atmospheric Methane Record from the South Pole Ice Core

该奖项支持一个项目，该项目测量从南极收集的冰芯中捕获的空气中甲烷气体的浓度。通过将南极甲烷变化与其他冰芯的类似数据相匹配，这些数据将提供一个年龄尺度（年龄作为深度的函数），而其他冰芯的年龄与深度关系是众所周知的。提供的年龄将允许（由PI和其他NSF支持的研究人员）对南极核心进行的所有其他气体测量，准确地解释为时间的函数。这一点至关重要，因为南极取心项目的一个主要目标是了解大气中稀有气体的历史，如一氧化碳、二氧化碳、乙烷、丙烷、氯甲烷和甲基溴。尽管这些气体对大气化学和气候很重要，但人们对它们的控制机制知之甚少。本科生助理将参与该项目，并通过他们的工作进行独立研究。项目将继续访问当地中学，向学生介绍极地科学，并开展其他拓展活动（例如参观实验室，与当地民间或专业组织交谈）。新的南极冰芯的主要部分（2个深度间隔，不包括宾夕法尼亚州立大学正在测量的脆性冰带）的甲烷浓度将通过将新的南极冰芯记录与精确测定的WAIS Divide冰芯记录相匹配，用于创建气体年代学。结合宾夕法尼亚州立大学的测量结果，这将为整个5万年的记录提供气体年代。将使用一种简单但功能强大的中点方法进行关联，该方法已被证明，并将探索其他匹配记录的方法。这项工作的智力价值在于，气体年代学将是这个冰芯项目的一个基本组成部分，PI和其他研究人员将使用它来确定大气成分的年代记录，并独立于冰川学模型确定气体-冰河时代的差异，这将限制过去影响冰层致密化的过程。甲烷数据还将为全球生物地球化学循环的重要扰动提供直接的地层标记（例如，与北半球突然变暖和变冷同步的甲烷快速变化），这将把其他冰芯气体记录直接与这些扰动联系起来。总空气含量的记录也将作为甲烷测量的副产品产生，并将有助于理解这一参数。更广泛的影响包括，这项工作将为南极冰芯项目提供基础数据集，而年龄尺度（或其变体）将被所有其他研究冰芯气体记录的研究人员使用。该项目将在两年内雇用一名本科生助理，他将进行一项本科生研究项目，该项目将成为学生毕业论文或其他研究论文的一部分。该项目还将为俄勒冈州立大学夏季REU项目提供至少一个研究职位。参观当地中学和其他拓展活动（如实验室参观，与当地民间或专业组织交谈）也将是项目的一部分。

Brook/1643722This award supports a project to measure the concentration of the gas methane in air trapped in an ice core collected from the South Pole. The data will provide an age scale (age as a function of depth) by matching the South Pole methane changes with similar data from other ice cores for which the age vs. depth relationship is well known. The ages provided will allow all other gas measurements made on the South Pole core (by the PI and other NSF supported investigators) to be interpreted accurately as a function of time. This is critical because a major goal of the South Pole coring project is to understand the history of rare gases in the atmosphere like carbon monoxide, carbon dioxide, ethane, propane, methyl chloride, and methyl bromide. Relatively little is known about what controls these gases in the atmosphere despite their importance to atmospheric chemistry and climate. Undergraduate assistants will work on the project and be introduced to independent research through their work. The PI will continue visits to local middle schools to introduce students to polar science, and other outreach activities (e.g. laboratory tours, talks to local civic or professional organizations) as part of the project. Methane concentrations from a major portion (2 depth intervals, excluding the brittle ice-zone which is being measured at Penn State University) of the new South Pole ice core will be used to create a gas chronology by matching the new South Pole ice core record with that from the well-dated WAIS Divide ice core record. In combination with measurements made at Penn State, this will provide gas dating for the entire 50,000-year record. Correlation will be made using a simple but powerful mid-point method that has been previously demonstrated, and other methods of matching records will be explored. The intellectual merit of this work is that the gas chronology will be a fundamental component of this ice core project, and will be used by the PI and other investigators for dating records of atmospheric composition, and determining the gas age-ice age difference independently of glaciological models, which will constrain processes that affected firn densification in the past. The methane data will also provide direct stratigraphic markers of important perturbations to global biogeochemical cycles (e.g., rapid methane variations synchronous with abrupt warming and cooling in the Northern Hemisphere) that will tie other ice core gas records directly to those perturbations. A record of the total air content will also be produced as a by-product of the methane measurements and will contribute to understanding of this parameter. The broader impacts include that the work will provide a fundamental data set for the South Pole ice core project and the age scale (or variants of it) will be used by all other investigators working on gas records from the core. The project will employ an undergraduate assistant(s) in both years who will conduct an undergraduate research project which will be part of the student's senior thesis or other research paper. The project will also offer at least one research position for the Oregon State University Summer REU site program. Visits to local middle schools, and other outreach activities (e.g. laboratory tours, talks to local civic or professional organizations) will also be part of the project.