Origins of Earth’s Water May Not Be as Complicated as We Thought

Planetary scientists have long believed that Earth’s water came from external sources, such as hydrogen-rich rocks and comets, which arrived after the planet formed, given the apparent lack of moisture in the early building blocks of Earth.

New Research Challenges the Conventional Theory

However, a recent study by researchers from the University of Oxford and the UK’s national synchrotron science facility challenges this notion. The study suggests that water may have always been a part of Earth’s composition from the start.

The research examines rare meteorites known as enstatite chondrites (ECs), which are believed to resemble the original rocks that formed our planet. Using X-Ray Absorption Near Edge Structure (XANES) spectroscopy—a technique that “fingerprints” materials with X-rays—the team discovered enough hydrogen to imply that Earth’s oceans could have formed without any external contributions.

This hydrogen could have combined with oxygen already present in the planet’s early rocks. In essence, Earth had the necessary ingredients for water and, eventually, life, as early as 4.55 billion years ago.

We now realize that the material used to form our planet—something we can study through these rare meteorites—was much richer in hydrogen than we originally thought, said James Bryson, an Earth scientist at the University of Oxford.

This finding supports the idea that water formation on Earth was a natural process, not a random occurrence from hydrated asteroids bombarding the planet after it formed.

Hydrogen Location and Evidence of Native Origin

The location of the hydrogen in the meteorites played a key role in the discovery. The researchers found hydrogen concentrated in pristine sections of the meteorites, well away from areas that external sources might have contaminated.

The team proposes that hydrogen gas could have reacted with the iron sulfide mineral pyrrhotite in the rocks, trapping the hydrogen and preventing it from escaping until conditions were suitable for water formation.

Earth scientist Thomas Barrett from Oxford said, ‘Our analysis thrilled us when it showed the sample contained hydrogen sulfide—just not where we expected.

Because contamination is extremely unlikely to produce this hydrogen sulfide, this research strongly supports the idea that Earth’s water is native—that it naturally resulted from the materials that made up the planet.

While this concept isn’t entirely new, the researchers refer to a 2020 study that also found hydrogen within ECs. Still, there was some doubt as to whether the hydrogen was original to these meteorites.

The more detailed analysis in this study strengthens the theory that these ECs—and likely the original rocks that made up Earth—contained intrinsic hydrogen, enough to enable the planet to eventually develop into the blue world we know today.

Read the original article on: Science Alert

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