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

布鲁克/1643722该奖项支持一个项目，该项目旨在测量被困在南极冰芯中的空气中甲烷气体的浓度。这些数据将通过将南极甲烷的变化与其他冰芯的类似数据进行匹配来提供年龄标尺(年龄与深度的函数)，这些冰芯的年龄与深度的关系是众所周知的。所提供的年龄将允许在南极核心上进行的所有其他气体测量(由PI和其他NSF支持的调查人员)被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一氧化碳、二氧化碳、乙烷、丙烷、甲基氯和甲基溴等稀有气体的历史。尽管这些气体对大气化学和气候很重要，但人们对大气中这些气体的控制因素知之甚少。本科生助理将参与该项目，并通过他们的工作被介绍给独立研究。作为该项目的一部分，国际和平协会将继续访问当地中学，向学生介绍极地科学，以及其他外展活动(例如，实验室参观、与当地公民或专业组织的讲座)。来自新南极冰芯主要部分(两个深度区间，不包括在宾夕法尼亚州立大学测量的脆弱冰区)的甲烷浓度将被用于通过将新的南极冰芯记录与WAIS划分冰芯记录进行匹配来创建气体年代学。结合宾夕法尼亚州立大学的测量，这将提供整个5万年记录的气体测年。将使用先前演示过的简单但功能强大的中间点方法进行关联，并将探索其他匹配记录的方法。这项工作的学术价值在于，气体年代学将是这个冰芯项目的基本组成部分，将被PI和其他调查人员用来测定大气成分的年代记录，并独立于冰川学模型确定气体年龄-冰川年龄差，这将限制过去影响降雪致密化的过程。甲烷数据还将提供对全球生物地球化学循环的重要扰动的直接地层标志(例如，与北半球突然变暖和突然冷却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。作为甲烷测量的副产品，还将产生总空气含量的记录，这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本数据集，研究南极冰芯气体记录的所有其他调查人员将使用年龄尺度(或其变体)。该项目将在两年内聘请一名本科生助理(S)，他将指导一项本科生研究项目，该项目将成为学生高级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站点项目提供至少一个研究职位。访问当地中学和其他外展活动(如参观实验室、向当地公民或专业组织发表演讲)也将是该项目的一部分。

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.