What is Permafrost?

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Overview:

Thawing permafrost in the Arctic could release radon, a radioactive gas that has the potential to cause cancer, scientists have warned.

About Permafrost

  • Permafrost is any ground—from soil to sediment to rock—that has been frozen continuously for a minimum of two years and as many as hundreds of thousands of years. 
  • It can extend down beneath the earth’s surface from a few feet to more than a mile, covering entire regions, such as the Arctic tundra, or a single, isolated spot, such as a mountaintop of alpine permafrost.
  • Although the ground is frozen, permafrost regions are not always covered in snow.
  • Global Distribution: 
    • They can be found on land and below the ocean floor.
    • It is found in areas where temperatures rarely rise above freezing.
    • They are most common in regions with high mountains and in Earth’s higher latitudes—near the North and South Poles.
    • Permafrost is found almost exclusively in the far northern reaches and high elevations of the Northern Hemisphere, in places like Siberia, Alaska, the Canadian Arctic, Greenland, and the Tibetan Plateau.
  • Composition: 
    • Permafrost is made of a combination of soil, rocks, and sand that are held together by ice. The soil and ice in permafrost stay frozen all year. 
    • Near the surface, permafrost soils also contain large quantities of organic carbon—a material leftover from dead plants that couldn’t decompose or rot away due to the cold.
    • Lower permafrost layers contain soils made mostly of minerals. 
    • A layer of soil on top of the permafrost does not stay frozen all year. This layer, called the active layer, thaws during the warm summer months and freezes again in the fall.

Key Facts about Radon

  • It is a radioactive gas that forms naturally when uranium, thorium, or radium, which are radioactive metals, break down in rocks, soil, and groundwater. 
  • It is an inert, colourless, and odourless gas.
  • Radon gas usually exists at very low levels outdoors, but the gas can accumulate in areas without adequate ventilation, such as underground mines.
  • Radon can get into homes and buildings through small cracks or holes and build up in the air.
  • Radon levels may be higher in homes that are well insulated, tightly sealed, and/or built on soil rich in the element’s uranium, thorium, and radium.
  • As we breathe, these particles are deposited on the cells lining the airways, where they can damage DNA and potentially cause lung cancer.
  • It is the second-most important cause of lung cancer after smoking and the leading cause of lung cancer among non-smokers.

Q1) What is the Northern Hemisphere?

Places north of the equator are part of the Northern Hemisphere.The Northern Hemisphere includes North America, Central America, Europe, and mainland Asia. About half of Africa and a small part of South America are also in the Northern Hemisphere

Source: Thawing Arctic permafrost could release radioactive, cancer-causing radon