Constructing Paleoatmospheric Records of the Isotopic Composition of Methane and Nitrous Oxide

该奖项是为了支持一个重建过去20万年古大气甲烷和氧化亚氮同位素组成记录的项目。对浅层冰芯甲烷碳-13同位素组成的高分辨率测量将有助于确定生物源（湿地、稻田和反刍动物）和非生物源（生物质燃烧和天然气）甲烷排放的相对贡献，这些排放导致甲烷浓度在人类活动期间以指数速率增加。冰川/间冰期时间尺度上甲烷和一氧化二氮的同位素数据将有助于确定已知发生的大浓度变化的根本原因。该项目将使用新一代质谱仪，该质谱仪能够产生精确的纳米摩尔甲烷和氧化亚氮的同位素信息，这意味着样品可以比标准同位素比仪器所需的样品小1000倍。这项工作的主要目的是进一步了解这两种温室气体在整个人类活动时期以及冰期间冰期时间尺度上的生物地球化学循环。

This award is for support for a program to reconstruct records of the isotopic composition of paleoatmospheric methane and nitrous oxide covering the last 200,000 years. High resolution measurements of the carbon-13 isotopic composition of methane from shallow ice cores will help to determine the relative contributions of biogenic (wetlands, rice fields and ruminants) and abiogenic (biomass burning and natural gas) methane emissions which have caused the concentrations of this gas to increase at an exponential rate during the anthropogenic period. Isotopic data on methane and nitrous oxide over glacial/interglacial timescales will help determine the underlying cause of the large concentration variations that are known to occur. This project will make use of a new generation mass spectrometer which is capable of generating precise isotopic information on nanomolar quantities of methane and nitrous oxide, which means that samples can be 1000 times smaller than those needed for a standard isotope ratio instrument. The primary objective of the work is to further our understanding of the biogeochemical cycles of these two greenhouse gases throughout the anthropogenic period as well as over glacial interglacial timescales.