permafrost


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permafrost,

permanently frozen soil, subsoil, or other deposit, characteristic of arctic and some subarctic regions; similar conditions are also found at very high altitudes in mountain ranges. In 1962 measurements in a borehole drilled on Melville Island, Northwest Territories, Canada, showed that the ground was frozen to a depth of at least 1,475 ft (450 m); comparable thicknesses have been found in other far north regions. Tundrastundra
, treeless plains of N North America and N Eurasia, lying principally along the Arctic Circle, on the coasts and islands of the Arctic Ocean, and to the north of the coniferous forest belt.
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, though underlaid by permafrost, today support centers of population in Alaska, Canada, and Siberia. Permafrost is a very fragile system that may easily be damaged or destroyed by the presence of human-generated heat. A controversy developed in the late 1960s and early 70s over the construction of an oil pipeline from the Alaska North Slope to the southern part of the state. Critics of the project argued that if the pipeline containing hot oil ever came into contact with the permafrost, it would melt the permafrost; the pipeline would then sink and eventually break. The oil spilled during the breakage would result in a major ecological disaster. It was decided to build the pipeline with insulated pipe raised above the permafrost or on gravel beds in order to prevent melting and thus preserve both the pipeline and the ecosystem.

Permafrost

 

a vague term of many meanings applied to the phenomenon of the cooling of rocks on the upper part of the earth’s crust to temperatures of zero and below; the rocks themselves that have hardened as a result of the freezing of the moisture they contained; and the stratum (layer) or zone (region of horizontal spread) of rocks that do not thaw for a long time.

The term “permafrost” was introduced into scientific usage in 1927 by the founder of the school of Soviet geocryologists, M. I. Sumgin, who defined it as ground frost that exists for two to several thousand years. The phrase “ground frost” was not clearly defined in this formulation, and this led to the use of permafrost in various meanings.

As geocryology developed, investigators found themselves increasingly inconvenienced by the word “permafrost,” and as a result it was sharply criticized by P. F. Shevtsov, L. A. Meister, and others in the 1950’s at the V. A. Obruchev Institute of Geocryology of the Academy of Sciences of the USSR. This led to a prolonged discussion of all geocryological terminology. Of the many scientific terms suggested to replace “permafrost,” “perennial frozen rocks” and “perennial cryolithozone” are in widest use.

REFERENCES

Osnovy geokriologii (merzlotovedeniia), parts 1-2. Moscow, 1959.
Materialy po obshchemu merzlotovedeniiu. Moscow, 1959.
Popov, A. I. Merzlotnye iavleniia v zemnoi kore (kriolitologiia). Moscow, 1967.
Dostovalov, B. N., and V. A. Kudriavtsev. Obshchee merzlotovedenie. Moscow, 1967.

A. E. SNOPKOV

permafrost

[′pər·mə‚frȯst]
(geology)
Perennially frozen ground, occurring wherever the temperature remains below 0°C for several years, whether the ground is actually consolidated by ice or not and regardless of the nature of the rock and soil particles of which the earth is composed.

permafrost

Permanently frozen soil, subsoil, or other deposits in arctic or subarctic regions.

permafrost

ground that is permanently frozen, often to great depths, the surface sometimes thawing in the summer
References in periodicals archive ?
When the lakes form, they flash-thaw these permafrost areas," said Walter Anthony, an associate professor with UAF's Water and Environmental Research Center.
The other permafrost sample came from the Kolyma River in northeastern Siberia, and the age of nearby deposits was around 42,000 years old, scientists said.
The purpose of our work is to evaluate the biogenic elements and labile organic matter in the active, protective, and permafrost layers of the ice complex that is in the stage of destabilization of the established soil system at its present stage of development.
The influences of different protective measures on the temperature field and thawing depth of underlying permafrost of wide embankment were investigated based on numerical analysis.
"There's no doubt that the permafrost will remain in the mountainside where the seeds are," said Marie Haga, head of the Bonn-based Crop Trust that works with Norway to run the vault.
He said: "The warmer the Earth becomes, the more permafrost is likely to be released, ultimately resulting in more greenhouse gases causing the earth to warm further."
The new five projects include INVACOST: Invasive Insects and Their Cost Following Climate Change; CPATEMP: Continental PAst TEMPeratures since the last glacial cycle and recently developed organic biomarkers; APT: Acceleration of Permafrost Thaw by Snow-Vegetation Interactions; SOCLIM: Southern Ocean and Climate; and FATES: FAst Climate Changes, New Tools to Understand and Simulate the Evolution of the Earth System.
But thawing, drilling and mining of ancient permafrost could potentially unleash viruses that infect people, say the discoverers of the oversized microbe.
Since 2005, about 20 GPS stations have been installed in permafrost across Mackenzie Delta.
According to a statement issued by France's National Centre for Scientific Research (CNRS), the work shows that viruses can survive being locked up in the permafrost for extremely long periods.
Earlier studies showed that permafrost harbors a diverse microbial community including bacteria and archaea [10-12].
Foram produzidos tambem estudos especificos sobre o processo de ornitogenese/fosfatizacao de solos, dinamica do carbono, indicadores bioquimicos de metais pesados e contaminantes antropicos, quimica das aguas de degelo, estudos de comunidades vegetais e ecologia microbiana, zonemanto ambiental, geomorfologia periglacial, e monitoramento do regime termico da camada ativa e permafrost, numa complexa rede de sensores e registradores automaticos instalados em todas as areas estudadas.