Investigation into the Variability of the Stable Isotopic Composition of Tropospheric Nitrous Oxide

对流层一氧化二氮稳定同位素组成的变异性研究

• 批准号: 9975427
• 负责人: Martin Wahlen
• 金额: $ 25万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-10-01 至 2002-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9975427&HistoricalAwards=false
• 关键词: Investigation; into; Variability; Stable; Isotopic

The goal of the proposed research is to investigate the temporal evolution of the stable isotopic composition of atmospheric nitrous oxide in order to elucidate the global budget of this important greenhouse gas. Time series measurements will be made at four sites: La Jolla, CA; Clifton, NC; Trinidad Head, CA; and Cape Grim, Tasmania. Despite the long atmospheric lifetime of nitrous oxide (about 125 years), local concentration measurements show up to 3 percent excursions above baseline concentrations at La Jolla, CA and at Clifton, NC. Simultaneous measurements of other trace gases during periods of nitrogen oxide excursion point to an urban contribution at La Jolla and agricultural activity at Clifton. Measurements at these sites will be compared to those conducted at the two clear air sites in order to improve the global nitrous oxide budget. Separation and purification techniques have been developed for the isolation of pure N2O from air samples suitable for precise isotopic analysis by isotope ration mass spectrometry. Calibration and correction procedures have been developed to account for isobaric interferences caused by minute amounts of carbon dioxide, which are difficult to completely remove.

拟议研究的目的是调查大气中一氧化二氮稳定同位素组成的时间演变，以阐明这一重要温室气体的全球收支。时间序列测量将在四个地点进行：加利福尼亚州拉霍亚、北卡罗来纳州克利夫顿、加利福尼亚州特立尼达Head和塔斯马尼亚州格里姆角。尽管一氧化二氮在大气中的寿命很长(约125年)，但当地的浓度测量显示，加利福尼亚州拉霍亚和北卡罗来纳州克利夫顿的浓度比基线浓度高出3%。在氮氧化物漂移期间对其他痕量气体的同时测量表明，拉霍亚的城市贡献和克利夫顿的农业活动。将把在这些地点进行的测量与在两个清洁空气地点进行的测量进行比较，以改善全球一氧化二氮预算。为了从空气样品中分离纯净的N2O，用同位素比值质谱仪进行精确的同位素分析，发展了分离和纯化技术。已经开发了校准和校正程序，以解决微量二氧化碳引起的等压干扰，这些干扰很难完全消除。