Trapped Gases in the Greenland Ice Sheet: CO2 Isotope Ratios & Concentration in the Past Atmosphere

作为格陵兰冰盖项目的一部分，该项目将 延长大气CO2浓度和同位素组成 最早的记录 这将由以下人员完成： 测量二氧化碳的浓度和C13/C12比， 大气中的气体截留在相对较小的样品（250克）， 来自格陵兰冰芯的冰 技术是把 样品在一个专门设计的真空系统，并升华 将冰置于-80 ℃冷阱的表面上。 该天然气将 通过这一程序释放。 由此获得的CO2样品量 将被精确测量并确定其C13/C12比率。 样品中的空气将在分子筛上回收。 的 每单位冰的空气量将记录下 在封冻时的冰盖 二氧化碳与空气的比例 准确测量（优于0.5%）， 捕获大气样品的CO2浓度， 优于1 ppm。 大气中二氧化碳的C13/C12比率 也将被测量。 这种变化 在冰川/后冰川过渡期的比例将是一个 对大剂量（80 ppm）的拟议机制的重要测试 二氧化碳浓度的变化。 其他 与气候有关的问题包括详细研究的结束 末次冰期和冰期/后冰期过渡， 新仙女木事件和丹斯高-厄施格事件。 这些 浓度和稳定同位素数据，结合放射性碳 CO2的数据，将能够测试碳循环模型， 过去和未来的气候变化。

As part of the Greenland Ice Sheet Project, this project will extend the atmospheric CO2 concentration and isotope composition record back through Holocene times. This would be done by measuring the concentration and C13/C12 ratio of carbon dioxide in atmospheric gases trapped in relatively small (250 g) samples of ice from Greenland ice cores. The technique would be to place the sample in a specially designed vacuum system and to sublime the ice onto the surface of a -80 c cold trap. The gas will be released by this procedure. The amount of CO2 sample so obtained would be accurately measured and its C13/C12 ratio determined. The air in the sample would be recovered on molecular sieve. The amount of air, per unit of ice, would record the altitude of the ice sheet at the time of seal-off. The ratio of CO2 to air would be accurately measured (to better than 0.5%) which would record the CO2 concentration of the sample of trapped atmosphere to better than 1ppm. The C13/C12 ratio of atmospheric carbon dioxide during glacial times will also be measured. The change of this ratio during the glacial/post-glacial transition will be an important test of the proposed mechanisms for the large (80 ppm) CO2 concentration change that occurred at that time. Other climate-related questions include a detailed study of the end of the last glacial and the glacial/post-glacial transition, the Younger Dryas event, and the Dansgaard-Oeschger events. These concentration and stable isotope data, combined with radiocarbon dates for CO2, will enable testing of carbon cycle models relating to past and future climate change.