| 大气甲烷的冰芯记录 |
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| 引用本文： | 徐柏青,姚檀栋,刘先勤,郭学军.大气甲烷的冰芯记录[J].冰川冻土,2005,27(3):360-367. |
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| 作者姓名： | 徐柏青 姚檀栋 刘先勤 郭学军 |
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| 作者单位： | 1. 中国科学院, 青藏高原研究所, 北京, 100085;
2. 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 |
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| 基金项目： | 中国科学院知识创新工程项目
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国家自然科学基金 |
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| 摘 要： | 冰芯包裹气体的提取分析提供了历史时期大气CH4含量变化最直接的信息.“三极(南极、格陵兰及青藏高原)”冰芯的大气甲烷记录的恢复,刻画了自然变化时期大气CH4含量的详细变化情景及不同纬度间的变化差异,并以此可进一步分析大气CH4含量变化与气候变化的关系以及陆地CH4排放随时间的变化特征.冰芯研究揭示,工业革命以来大气CH4含量的急剧增长及其现阶段的大气含量是过去几十万年来任何气候变化时期从未发生过的.
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| 关 键 词： | 冰芯 甲烷记录 气候变化 |
| 文章编号： | 1000-0240(2005)03-0360-08 |
| 收稿时间： | 2004-10-21 |
| 修稿时间： | 2004年10月21日 |
Atmospheric Methane Recorded in Ice Cores |
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| XU Bai-qing,YAO Tan-dong,LIU Xian-qin,GUO Xue-jun.Atmospheric Methane Recorded in Ice Cores[J].Journal of Glaciology and Geocryology,2005,27(3):360-367. |
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| Authors: | XU Bai-qing YAO Tan-dong LIU Xian-qin GUO Xue-jun |
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| Institution: | 1. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China;
2. Key Laboratory of Ice Core and Cold Regions Environment, CAREERI, CAS, Lanzhou Gansu 730000, China |
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| Abstract: | Ice cores methane reconstructions are believed to reflect atmospheric CH4 concentration fluctuation with time and to reveal the past changes in terrestrial methane emissions. It has been proposed that the past natural CH4 fluctuations were mainly due to changes in the source strength, through variability of the wetland extent in tropical regions. This was partly confirmed by the combined analysis of ice cores from Greenland and Antarctica, allowing quantifying the difference of mixing ratio between the two Polar Regions with time. For the most recent time (last 1000 years), these data suggested that tropical sources became more important, potentially due to the already significant contribution of human-induced sources. Still, this analysis of available CH4 data from Greenland and Antarctica relied on several critical assumptions, among them that the CH4 sources between 30°S and 90°S remain unchanged with time. The lack of constrain on the CH4 mixing ratio in tropical regions appeared as the major caveat in this exercise. This work has thus put an urgent task in reconstructing CH4 concentration from the low and mid-latitude areas, based on ice cores drilled at very high altitude in mountain glacier. The Dasuopu ice core provides a unique opportunity for obtaining sub-tropical latitude CH4 reconstruction, because of its high altitude (7000 m a.s.l, making it the highest-ever drilled site in the World), which provides low ice temperature and limited summer melting, so that the original CH4 concentration has a good chance to be preserved.;The Dasuopu record shows an obvious CH4 concentration increase in the low-mid latitude since industrialization, and reveals similar trend of methane concentration fluctuation with the polar region records. This sub-tropical CH4 record also allows quantifying for the first time the difference of CH4 mixing ratio between polar and sub-tropical latitudes during pre-industrial time. The average CH4 concentration in the record from the Dasuopu ice core is 782 nmol 5mol-1 in the time interval of 0~1850 AD, and the maximum temporal variation exceed 220 nmol 5mol-1, which has never been found in polar ice records. The average difference is 66 nmol 5mol-1 with Greenland and 107 nmol 5mol-1 with Antarctica. The record suggests that the tropical latitudes might represent as much of the global CH4 sources in pre-industrial time.;The last low concentration period in CH4 appeared around 1790 AD. Since 1850, there has been a record increase in CH4. Although some polar ice cores seem recorded a very early start (1750 AD) of anthropogenic input of CH4, it is difficult to see this in the Dasuopu ice core. In the Polar Regions, the study of Rasmussen and Khalil concluded that a rapid and significant CH4 concentration increase started about 150 years ago, which is consistent with the results here. It is also found that the CH4 concentration in the atmosphere 150-year ago was about 45% of present level and was not significantly influenced by human activities. |
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| Keywords: | ice core methane record climate change |
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