Tracing Past Methane Variations with Stable Isotopes in Antarctic Ice Cores

用南极冰芯中的稳定同位素追踪过去的甲烷变化

• 批准号: 1745078
• 负责人: Edward Brook
• 金额: $ 48.94万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2023-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1745078&HistoricalAwards=false
• 关键词: Tracing; Past; Methane; Variations; Stable

This project will develop methods to measure the ratios of carbon-13 to carbon-12, and heavy to light hydrogen in methane in air trapped in ice cores. The ratios of the different forms of carbon and hydrogen are "fingerprints" of different sources of this gas in the past--for example wetlands in the tropics versus methane frozen in the sea floor. Once the analysis method is developed, the measurements will be used to examine why methane changed abruptly in the past, both during the last ice age, and during previous warm periods. The data will be used to understand how methane sources like wildfires, methane hydrates, and wetlands respond to climate change. This information is needed to understand future risks of large changes in methane in the atmosphere as Earth warms. The project involves two tasks. First, the investigators will build and test a gas extraction system for methane isotopic measurements using continuous flow methods, with the goal of equaling or bettering the precision attained by the few other laboratories that make these measurements. The system will be interfaced with existing mass spectrometers at Oregon State University. The system consists of a vacuum chamber and sequence of traps, purification columns, and furnaces that separate methane from other gases and convert it to carbon dioxide or hydrogen for mass spectrometry. Second, the team will measure the isotopic composition of methane across large changes in concentration associated with two past interglacial periods and during abrupt methane changes of the last ice age. These measurements will be used to understand if the main reason for these concentration changes is climate-driven changes in emissions from wetlands, or whether other sources are involved, for example methane hydrates or wildfires.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.

该项目将开发方法来测量碳13与碳12的比率，并在冰芯中被困在空气中的甲烷中重氢。 不同形式的碳和氢的比率是该气体不同来源的“指纹” - 在过去的湿地中，热带地区的湿地与在海底冷冻的甲烷中的湿地。 一旦开发了分析方法，测量结果将用于检查为什么在过去的冰河时代和以前的温暖时期，甲烷过去突然变化。 这些数据将用于了解诸如野火，甲烷水合物和湿地之类的甲烷源如何应对气候变化。需要此信息来了解当地球变暖时，大气中甲烷发生巨大变化的未来风险。该项目涉及两个任务。 首先，研究人员将使用连续流量方法建立和测试甲烷同位素测量的气体提取系统，其目的是相等或改善其他少数进行这些测量的实验室所达到的精度。 该系统将与俄勒冈州立大学的现有质谱仪连接。该系统由一个真空室和陷阱，纯化柱和熔炉组成，这些熔炉和熔炉将甲烷与其他气体分开，并将其转化为二氧化碳或氢的碳质量光谱法。 其次，该团队将测量与过去两个冰川间时期以及最后一个冰河时期甲烷变化期间甲烷的同位素组成。 这些测量值将用于了解这些集中度变化的主要原因是气候驱动的湿地的变化，或者是否涉及其他来源，例如甲烷水合物或野火。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和广泛影响的评估来评估CRETERIA的评估。

项目成果

Methane, ethane, and propane production in Greenland ice core samples and a first isotopic characterization of excess methane

• DOI: 10.5194/cp-19-999-2023
• 发表时间: 2023-05
• 期刊: Climate of the Past
• 影响因子: 4.3
• 作者: Michaela Mühl;J. Schmitt;B. Seth;James E. Lee;J. Edwards;E. Brook;T. Blunier;H. Fischer