Generating an Isotopic Record of Atmospheric Methane and Nitrous Oxide Over the Last Century from South Pole Firn Air

[125981]该奖项支持一个项目，该项目旨在从南极的空气中构建过去一个世纪大气甲烷和氧化亚氮的同位素记录。在过去的150年里，由于各种人为活动的排放增加，大气中的甲烷和一氧化二氮浓度有所上升。由于这一趋势在可预见的未来可能会持续下去，因此了解导致这两种温室气体排放的生物地球化学过程非常重要。在此背景下，在冰芯和靠近冰盖表面的雪间隙（稀薄空气）中发现的微量气体大气负荷变化记录为重建历史排放记录提供了基本的边界条件。提高我们对生物活性微量气体循环及其排放记录的理解的一种方法是使用稳定同位素示踪剂，这些示踪剂已经记录在冰芯和冷空气中。该项目将记录甲烷的碳-13和氘同位素比率，以及2001年1月在南极收集的空气样本中捕获的氮-15、氧-18和氧化亚氮的同位素组成。这些测量将使这些大气气体的同位素记录在整个20世纪得以重建。这种记录将有助于确定个别来源的相对贡献，其可信度将高于目前的水平。

0125981SowersThis award supports a project to construct an isotopic record of atmospheric methane and nitrous oxide over the last century from South Pole firn air. Over the last 150 years, atmospheric methane and nitrous oxide concentrations have risen in response to increased emissions from various anthropogenic activities. As this trend is liable to continue in the foreseeable future, it is important to understand the biogeochemical processes that contribute to the emissions of these two greenhouse gases. In this context, records of the variations in the atmospheric loading of trace gases found in ice cores and interstitial spaces in the snow near the surface of the ice sheet (firn air) provide fundamental boundary conditions for reconstructing historical emission records. One way to improve our understanding of the cycling of bioactive trace gases and their emission records is to use stable isotope tracers, which have been recorded in the ice cores and firn air. This project will develop records of carbon-13 and deuterium isotope ratios of methane, as well as the nitrogen-15, oxygen-18 and the isotopomer composition of nitrous oxide trapped in firn air samples collected in January 2001 at the South Pole. These measurements will allow isotopic records of these atmospheric gases to be reconstructed throughout the 20th century. Such records will help to establish the relative contribution of individual sources with a higher degree of confidence than is currently available.