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冰川冻土 ›› 2002, Vol. 24 ›› Issue (2): 116-120.doi: 10.7522/j.issn.1000-0240.2002.0020

• 冰冻圈与全球变化 • 上一篇    下一篇


徐柏青1, 姚檀栋1, Chappellaz J2   

  1. 1. 中国科学院寒区旱区环境与工程研究所冰芯与寒区环境重点实验室, 甘肃, 兰州, 730000;
    2. Laboratoire de Glaciologie et Géophysique de l’Environnement, CNRS, BP96, 38402, Saint Martind Hères Cedex, France
  • 收稿日期:2001-05-15 修回日期:2002-02-05 出版日期:2002-04-25 发布日期:2012-04-26
  • 基金资助:

Extraction and Analysis of the Methane Trapped in Ice Core by Melting-Refreezing Method

XU Bai-qing1, YAO Tan-dong1, Chappellaz J2   

  1. 1. Key Laboratory of Ice Core and Cold Regions Environment, CAREERI, CAS, Lanzhou Gansu 730000, China;
    2. Laboratoire de Glaciologie et Géophysique de l’Environnement, CNRS, BP96, 38402, Saint Martind Hères Cedex, France
  • Received:2001-05-15 Revised:2002-02-05 Online:2002-04-25 Published:2012-04-26

摘要: 用融化 -再凝结方法对达索普冰芯气泡中的CH4 进行了提取分析.大约 80g的冰芯样品在真空容器中融化,通过特殊方式,使融水自容器底部向上结冰,并经气相色谱仪对释放出气体中的CH4含量进行测试.空白测试结果表明,该方法仅产生 15± 4nmol·mol-1的污染;对每个样品 3次重复测试结果的标准偏差上限为± 25nmol·mol-1.中国和法国的对比实验结果具有相当好的重现性

关键词: 融化-再凝结, 冰芯气泡, 甲烷

Abstract: Air was extracted from the bubbles trapped in the Dasuopu ice core by melting-refreezing method, of which the methane was measured. A core sample of a certain depth was cut to four pillars vertically. One pillar, 15 cm in length, was separated into three specimens for repeated measurement. The outer surface of each specimen was removed to eliminate any external contamination. Ice specimen, about 80 g in weight, was melted in an evacuated stainless-steel container sealed with tinfoil, and then a piece of bronze was fitted to the base of the container and soaked into a -60 ℃ alcohol bath. The melted specimen was thus slowly refrozen from the bottom and completely expels the dissolved air. The expelled gas was then expanded into an evacuated sample loop and injected into a Gas chromatograph equipped with a flame ionization detector through a six-port valve. Thus methane was extracted and its concentration can be measured. Blank tests were performed by adding 776 nmul.mol-1 standard gas to artificial bubble-free ice. The contamination caused by melting appears to be proportional to melting time. However, the contamination is less than 15 nmol×mol-1 when melting time is within 10 min. In the measurement melting time was controlled within approximately 5~7 min. Therefore, the contamination during the testing was estimated to be 15±4 nmol×mol-1. The scattering of methane concentrations for three or four injections was ±25 nmol×mol-1. The agreement between two measurements taken in China (LICCRE) and France (LGGE) was examined at two levels. First, a glass flask filled with LGGE standard gas was measured in LICCRE. Second, an ice sample from the Antarctic D47 ice core, which contains gas since the 1700s and is free of any melt feature, was cut lengthways and analyzed several times in both laboratories. As the preindustrial CH4 trend was already determined from Greenland and Antarctic ice cores in LGGE using the same technique as for the Dasuopu samples. It is confident that the results presented here can be directly compared to the polar records for determining the difference in CH4 mixing ratio between sub-tropical and polar latitudes.

Key words: melting-refreezing, air bubble trapped in ice core, Methane


  • P343.6