William Atkins
Friday, 11 December 2009 20:53
Science -
Space
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According to a new theory from British and American scientists, much of the elements in Earth’s atmosphere originated from gas, dust, and ice inside comets and meteorites that impacted the early Earth. Volcanoes helped a little bit, but their eruptions were not the major way the atmosphere of Earth first formed.
Chris J. Ballentine and Greg Holland, both from the University of Manchester (U.K), and Martin Cassidy, from the University of Houston (U.S.A.), were the team of scientists that came up with this new theory.
They published their conclusions in the journal Science under the title “
Meteorite Kr in Earth’s Mantle Suggests a Late Accretionary Source for the Atmosphere" (December 11, 2009, volume 326, number 5959, pages 1522-1525; doi: 10.1126/science.1179518).
They stated within the paper’s abstract,
“Noble gas isotopes are key tracers of both the origin of volatiles found within planets and the processes that control their eventual distribution between planetary interiors and atmospheres.”
They based their conclusions on the elements krypton and xenon, which they extracted over the past several years from deep wells in New Mexico, United States. The ancient gases were trapped deep underground.
Krypton (Kr) and xenon (Xe) were studied by the scientists because they are both noble gases; that is, they do not mix readily with other elements. Consequently, they are much easier to decipher with respect to what they looked like millions of years ago.
The noble gases are a group of chemical elements that have very similar properties. Under the same physical conditions, they are all colorless, odorless, monatomic gases, with very low chemical reactivities.
The six noble gases that occur naturally are argon (Ar), helium (He), krypton (Kr), neon (Ne), xenon (Xe), and the radioactive radon (Rn).
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