Scientists debate the origin of water on Earth

Water could be found as deep as 400-600 kilometres under surface of Earth

Scientists have been debating about the Earth’s basic water source for years, reaching two compelling theories, the Conversation reported.

The first theory proposes water could have been “captured from asteroids and comets that collided with the planet” while the other suggests that “water was always present in the rocks of the Earth’s mantle and was gradually released to the surface through volcanoes”.



According to the news site, a recent research found ruthenium’s – a rare transition metal – atomic signature to be different to that of common asteroids from outer space, which implies that asteroids could not have been the source of water. Another study discovered “various evidence that the oldest terrestrial minerals (zircon) crystallised from magma sources interacting with liquid water. These minerals are between 4.1 billion and 4.3 billion years old, but the final late veneer is most commonly thought to have been delivered around 3.9 billion years ago” – provides backing to the former research.

Scientists are now considering the theory that Earth may have lost more during collisions or erosions than gaining any resources. The theory is supported by the levels of chlorine found in the world’s oceans that were formed early on. “Geochemists have long argued that the Earth’s oceans don’t come from captured icy comets because they contain different amounts of “heavy” hydrogen”, the news site adds.

Fresh data from experiments suggests that water could be found as deep as 400-600 kilometres under the surface of the Earth.



It is essential to emphasise here that water could also have been recycled back to the mantle – creating a balance between the ocean’s water and the amount stored up in the mantle. The article further adds that “the average level of the sea surface relative to the continental land has remained relatively constant across nearly four billion years. This suggests a constant cycle of water emerging from and being absorbed back into the mantle has significantly helped life to continue throughout its history on this planet.”