Mitch Battros / Earth Changes Media
Earth’s core contains up to 45 times more hydrogen than the oceans, making it the largest reservoir of hydrogen on the planet.
In a study this Tuesday in Nature Communicationsresearchers from the School of Earth and Space Sciences at Peking University in China, discovered that a huge amount of hydrogen entered the core during its formation, about 4.5 billion years ago.
The team also discovered that this hydrogen did not arrive via comets that bombarded Earth after the nucleus was established, possibly ending the debate over when and how the hydrogen was delivered to our planet.
This debate has persisted because hydrogen in Earth’s deep interior is extremely difficult to quantify.
As explained by , hydrogen is the smallest and lightest element in the universe, so most techniques do not have the resolution to detect it adequately in high-pressure and high-temperature environments, such as the Earth’s core. However, estimating the amount of hydrogen trapped inside the nucleus is critical to understanding how the hydrogen got there in the first place.
The new study used a method known as atom probe tomography.
This technique can “provide nanoscale three-dimensional compositional mapping of all elements in the periodic table and is ideal for high-pressure samples, leader explained, Dongyang Huangassistant professor at the School of Earth and Space Sciences at Peking University in China, told Live Science.
The researchers simulated the conditions that likely existed when the Earth’s core was forming. First, they coated a small sample of iron metal with hydrated silicate glass to model the magma-covered core.
They then placed this object inside a diamond anvil cell — a device in which two diamond crystals compress to generate extreme pressure similar to that found in the Earth’s core. To create high-temperature conditions, scientists used lasers that heated the object to about 4,830 degrees Celsius.
The researchers discovered that hydrogen, oxygen and silicon dissolve simultaneously in iron’s crystal structures under extreme conditions, thus altering the crystals in previously unknown ways.
Crucially, equal amounts of hydrogen and silicon entered the “core” from the “magma” in the experiment, which helped researchers estimate that the Hydrogen makes up between 0.07% and 0.36% of the Earth’s core by weight.
The results suggest that the Earth’s core contains between nine and 45 times more hydrogen than the planet’s oceans.
If comets had delivered hydrogen to Earth after the nucleus had finished forming, the hydrogen would occur mainly in Earth’s most superficial layers. But the discovery that the core is Earth’s largest reservoir of hydrogen indicates that the hydrogen was delivered before the core was fully formed.
