The Measurement of Mass Independent Isotopic Compositions in Atmospheric Species as a New Indice of Global Processes

这项研究的重点是测量几种重要的大气气体，即臭氧(O_3)、二氧化碳(CO)、一氧化碳(CO)和水(H_2O)中的稳定同位素比值。先前由美国国家科学基金会资助的项目通过对平流层臭氧样品中氧-17和氧-18的精确同位素测量表明，平流层臭氧和二氧化碳之间存在化学联系。此外，以前的研究结果表明，平流层臭氧富含O-17和O-18两种氧同位素，这种同位素富集物通过与这种富含同位素的臭氧光解产生的激发氧原子O(1D)反应转移到二氧化碳中。在接下来的三年里，该研究小组将继续扩大他们的同位素测量方案，以便对从地面到30公里、从北纬68度到南极的空气样本进行同位素分析。这些测量将解决以下问题：二氧化碳-臭氧相互作用的全球和海拔变化；导致观测到的分子氧(O2)、臭氧、二氧化碳、一氧化碳、一氧化二氮(N2O)和水蒸气同位素分馏的化学和动力学过程；N2O来源未知的平流层的可能性；以及二氧化碳及其独特的平流层同位素特征对量化中间层-平流层-对流层混合的潜在用途。气体样本将与一些国内和国际科学家合作收集，这些科学家正在使用飞机和气球平台进行垂直大气测量，样本将使用加州大学圣地亚哥分校化学系提供的同位素比质谱仪进行分析。两名研究生将在资深科学家的直接指导下参与这项研究。

This research project is focused on the measurement of stable isotope ratios in several important atmospheric gases, that is, ozone (O3), carbon dioxide (CO2), carbon monoxide (CO), and water (H2O) vapor. The previous NSF-supported project demonstrated from precise isotopic measurements of oxygen-17 and oxygen-18 in stratospheric ozone samples that a chemical link exists between stratospheric ozone and carbon dioxide. In addition, the results from this prior research revealed that stratospheric ozone is enriched in the two oxygen isotopes of O- 17 and O-18, and that this isotopic enrichment is transferred to CO2 by its reaction with excited oxygen atoms O(1D) derived from the photolysis of this isotopically enriched ozone. During the next three years this same research team will continue to expand their isotopic measurement program so as to isotopically analyze air samples collected from ground level to 30 km and from 68oN to the south pole. These measurements will address the questions of the global and altitudinal variations of the CO2-O3 interactions; the chemical and dynamical processes responsible for the observed isotopic fractionations of molecular oxygen (O2), O3, CO2, CO, nitrous oxide (N2O), and water vapor; the possibility of an unknown stratospheric source of N2O; and the potential utility of CO2 with its unique stratospheric isotopic signature for quantification of mesosphere-stratosphere- troposphere mixing. The gas samples will be collected in collaboration with a number of national and international scientists who are performing vertical atmospheric measurements with aircraft and balloon platforms, The samples will be analyzed with the isotope ratio mass spectrometers that are available in the Department of Chemistry at the University of California--San Diego. Two graduate students will participate in this research under the direct supervision of the senior scientist.