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

本研究的目的是研究大气中氧化亚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：加州拉霍亚；克利夫顿,数控;特立尼达黑德，加利福尼亚州；塔斯马尼亚的格里姆角。尽管一氧化二氮在大气中的寿命很长（约125年），但局部浓度测量显示，在加利福尼亚州拉霍亚和北卡罗来纳州克利夫顿，其浓度比基线浓度高出3%。在氮氧化物漂移期间同时测量的其他微量气体表明拉霍亚的城市贡献和克利夫顿的农业活动。这些站点的测量结果将与两个洁净空气站点的测量结果进行比较，以改善全球氧化亚氮收支。分离和净化技术已经开发出来，用于从空气样品中分离纯N2O，适用于同位素定量质谱法的精确同位素分析。已经制定了校准和校正程序，以解释由微量二氧化碳引起的等压干扰，这些干扰很难完全消除。

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.