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Sci Rep:奇特永冻土的启示

摘要 : 近日,国际学术权威刊物自然出版集团旗下子刊《Scientific Reports》杂志在线发表了中国科学院寒区旱区环境与工程研究所牛富俊研究员的一篇论文,研究论文描述了中国华北地区一块永冻土的形成过程,这块自然形成的永冻土出现在了永冻土的通常范围之外,或将对寒冷地区的工程和建设产生影响。

 近日,国际学术权威刊物自然出版集团旗下子刊《Scientific Reports》杂志在线发表了中国科学院寒区旱区环境与工程研究所牛富俊研究员的一篇论文,研究论文描述了中国华北地区一块永冻土的形成过程,这块自然形成的永冻土出现在了永冻土的通常范围之外,或将对寒冷地区的工程和建设产生影响。 2011年,人们在河北省平泉县山区的一块碎石斜坡上发现了永冻土,这一地点在欧亚大陆永冻土界限最南端以南600多公里,而且海拔只有900米。 牛富俊及同事使用地热数据和数值模拟,研究了永冻土在这个年平均气温6到8摄氏度的地区是如何保持稳定的。作者发现,在冬季,多孔岩石中的空气对流将暖空气替换成了冷空气;夏季则是因为没有对流。 作者还发现,覆盖着冻土的30厘米深的泥炭土层(大约有1000到1600年历史)充当了有效的隔热层。他们提出,温暖气候条件下存在永冻土证明了使用碎石层保护其下永冻土的有效性。这一技术最近被使用在了青藏铁路的建设中。


A naturally-occurring ‘cold earth’ spot in Northern China


Permafrost is determined to a large extent by the Earth’s surface temperature, therefore it distributes mainly in high altitude and latitude regions. However, stable, warm (about −1 °C) permafrost occurs within a scree slope in northern China that is more than 600 km south of the southernmost limit of latitudinal permafrost on the Eurasian Continent. It is at an elevation of only 900 m above sea level (ASL). The area has a mean annual air temperature (MAAT) of 6 to 8 °C. Thermal processes of the scree slope, investigated through field monitoring and numerical simulation, showed that the permafrost is caused by winter air convection within the porous rock deposits and is stable as air convection does not occur in summer time. The deposit is covered by a 30-cm-thick peaty soil layer dated (carbon C-14) to between 1,000 to 1,600 years ago. The layer also contributes to the permafrost’s existence due to the peat’s thermal conductivity offset when frozen and thawed. The existence of permafrost under such warm climatic conditions confirms the effectiveness of using crushed rock layer as basement or slope cover to protect the warm permafrost subgrade of the recently-constructed Qinghai-Tibet Railway (QTR), even under the predicted climate warming conditions.

来源: Scientific Reports 浏览次数:0


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