Potassium-40 heating up Earth’s core?
Radioactive potassium could be a significant source of heat in the Earth’s core. V Rama Murthy from the University of Minnesota and colleagues have shown that potassium-40 can exist in the core of the Earth and provide heat via its radioactive decay.
The result could have important implications for theories of thermal evolution of planetary cores and the origin of geomagnetic fields (V Rama Murthy et al. 2003 Nature 423 163).
Potassium-40, which has a radioactive half-life of about 1.2 billion years, could be an important source of heat in the Earth’s core but this has never been unambiguously confirmed in an experiment.
Murthy and colleagues used an iron and iron- sulphur mixture to represent the Earth’s core and potassium silicate glass to represent the shell.
They measured the partition coefficient – the concentration of potassium-40 in the sulphur mix divided by its concentration in the silicate – at temperatures and pressures approaching those found deep in the Earth’s mantle.
The researchers found that the logarithm of the partition coefficient is inversely proportional to temperature.
The results suggest that potassium-40 can move from the silicate ‘shell’ to the iron-sulphur ‘core’ and that it would be possible for a high enough concentration of potassium-40 to build up in the core.
The team calculated a core potassium-40 content of between 60 and 130 ppm, which produces between 0.4 and 0.8 TW of heat.
Estimates of the core-mantle boundary heat flux are between 8 and 10 TW, so the heat produced by potassium-40 could significantly contribute to the heat flux at the boundary.
Recent studies have shown that the present level of heat flux would have been insufficient to sustain the Earth’s magnetic field for the past 3.5 billion years.
This ‘extra’ radioactive heat could thus have allowed the field to exist.
“We now plan to expand these measurements to much higher pressures and temperatures,” Murthy told PhysicsWeb. “We shall also extend the experiments to the other major radioactive heat sources in the Earth, uranium and thorium.”
See more here: physicsworld.com
Header image: National Geographic
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Joseph Olson
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Earth has 259 billion cubic miles of molten rock, heated by decay of 700,000 cubic miles of Uranium and 1.2 million cubic miles of Thorium. Since Ur-238 has Half-life of 4.5 billion years, and Thorium is byproduct, it is logical that at origin, Earth had twice the current Uranium. In addition to Thorium, decay “daughter” atoms produce our atmosphere, our ground water and our “fossil” fuel.
“From Muscle Power to Carbon Empowerment” > principia-scientific.org
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Charles Higley
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This is like blaming all of the bird poop on your car on one bird species. With the strong likelihood that Earth is a supernova remnant chunk, the core is likely rank with neutron-rich and clearly unstable isotopes. And, it does appear that they mostly produce carbon and hydrogen as breakdown products.
Targeting Potassium-40 is simply too simplistic and insular thinking. The same logic and lengthy extrapolations of what they think they know allows me to determine that the rising Sun causes morning traffic and setting Sun turns off traffic.
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Lit
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“With the strong likelihood that Earth is a supernova remnant chunk”
I thought I was the only one with this idea. Nice!
A water quenched supernova remnant.
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Herb Rose
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Hi Charles,
If planets are the remnants of super novas then planets can only happen after suns with no planets explode. Considering the distances in the universe there should be wandering planets everywhere whose velocity makes it impossible for a sun to capture them.
I like my theory better. The sun burns from fission and begins as pure matter (neutrons). Energy is attracted to positive matter and repels negative matter. Energy will mine a neutron star displacing chunks of matter forming atoms (the nucleus is held together by a compressing force of energy which radiates from the nucleus as attractive force of gravity and magnetism.) When stable atoms form (no exposed electrons in the nucleus) they build up to a point where they inhibit further mining and the sun disposes of the trash by shedding atoms (including some that are still being mined like uranium or other radioactive isotopes) which then coalesce due to the attractive force forming planets.
Herb
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