Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sand layer plays a key role in protecting the underlying permafrost in the Qinghai-Tibet Plateau

05.03.2012
The permafrost is degrading, and at the same time, the desertification is also developing at the surface of Qinghai-Tibet Plateau, under the condition of global warming. Sand layer is accelerated permafrost degradation or protecting permafrost? No significant conclusions have been drawn currently.

Some studies have shown that ground temperature in regions of windblown sand within the permafrost zone of the Qinghai-Tibet Plateau are higher than in regions not affected by sand, which may accelerate the degradation of permafrost.

Other studies have shown the dual nature of the sand layer on the ground temperature: the ground temperature in a zone of thick sand layer coverage is higher than that in a non-sandy zone, thereby accelerating the thawing of permafrost, whereas the ground temperature in a zone of thin sand layer coverage is lower than that in a non-sandy zone, thereby protecting the permafrost. Because of the conditions and technical limitations during that period, the above researches comprise only sporadic observations and simple reasoning. Moreover, lack long-term observations and systematic research; therefore, the conclusions vary, and sometimes even contradict one another.

In order to clarify the scientific problems, Prof. Jianjun Qu and his student Dr. Shengbo Xie of the Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, were funded by the National Natural Science Foundation of China and the Knowledge Innovation Project of Chinese Academy of Sciences, an experimental field was set up by them in the hinterland desert permafrost regions of Qinghai-Tibet Plateau, in 2010. Synchronized contrasting observations were made in an open area, and observations of the ground temperature of permafrost below sand layer covering were conducted more than one year. Sand layer was found to plays a key role in protecting the underlying permafrost in Qinghai-Tibet Plateau. Their research work, entitled "New discoveries on the effects of desertification on the ground temperature of permafrost and its significance to the Qinghai-Tibet Plateau", was published in Chinese Science Bulletin. 2012, Vol 57.

The result shows that, in the desert permafrost regions of Qinghai-Tibet Plateau, the ground temperature below thick sand layer was bounded near the permafrost table, compared to that of the natural ground surface. The ground temperature of the permafrost below this depth decreased during the observation period. Moreover, the ground temperature in the active layer above the depth varied with the seasons. i.e., the ground temperature decreased during the summer half-year (May to September), and increased in negative value, however, the whole permafrost layer below the ground surface was in a frozen state during the winter half-year (November to March), lead to the annual range of ground temperature decreased, with April and October being transitional stages. During the month of April, the soil turned from the frozen state into the thawed state, and the ground temperature of the active layer below the thick sand layer was lower than the temperature of the natural surface. During the month of October, the soil turned from the thawed state into the frozen state, and the ground temperature of the active layer below the thick sand layer was higher than the temperature of the natural surface. The ground temperature near the permafrost table below the thin sand layer was decreased throughout the year, whereas the ground temperature difference in the upper active layer and underlying permafrost layer gradually decreased. Thus, the sand layer in the Qinghai–Tibet Plateau, in general, preserves the underlying permafrost. The method of sand coverage can be considered in the future practice of permafrost protection; this work could provide a new idea to protect the permafrost in the regions of engineering construction.

The result also shows that, the changes in the ground temperature of the permafrost below sand layer can be attributed mainly to the differences of reflectivity and heat conductivity between the sand layer and natural ground surface in Qinghai-Tibet Plateau. The sand layer causes a stronger blocking effect to the heat exchange of land–atmosphere system because of its high reflectivity and poor heat conductivity, compared to that of the natural ground surface. During the summer half-year, the surface air temperature was positive in value and higher than the ground temperature, the sand layer blocked the downward transfer of surface heat; during the winter half-year, the surface air temperature was negative in value and lower than the ground temperature. Similarly, the sand layer prevented the upward transfer of underground heat.

The scientific significance of the research is not only to present an exploration of the interaction between desertification and permafrost, enriched the theoretical system of geocryology and desert science, but also has the reference value to permafrost engineering.

See the article: Xie S B, Qu J J, Zu R P, et al. New discoveries on the effects of desertification on the ground temperature of permafrost and its significance to the Qinghai-Tibet Plateau. Chinese Science Bulletin, 2012, 57:838-842

Qu Jianjun | EurekAlert!
Further information:
http://www.lzb.ac.cn
http://zh.scichina.com/english/

More articles from Earth Sciences:

nachricht Ice cave in Transylvania yields window into region's past
28.04.2017 | National Science Foundation

nachricht Citizen science campaign to aid disaster response
28.04.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>