Earth's Water Formed Within, Did not Come from Comets

Scientists say the water on earth may not have come from comets as earlier believed but might  be a result of its own geological processes.

Researchers at the Ohio State University say that the conventional theory that the water came to the earth as a result of a collision with comets might not be entirely true. It has been found the composition of  the water present on comet 67P contains more than three times more deuterium, a heavy form of hydrogen, than the water found here on Earth.

"When we look into the origins of water on Earth, what we're really asking is, why are we so different than all the other planets?" researcher Wendy Panero said in a statement. "In this solar system, Earth is unique because we have liquid water on the surface. We're also the only planet with active plate tectonics. Maybe this water in the mantle is key to plate tectonics, and that's part of what makes Earth habitable."  

Their study says that the earth forms water in the interiors in a process involving billions of years and releases it to the surface through plate tectonics  and feed the oceans.

The scientists believe that rocks, which look dry and arid to the human eye, may be hiding hydrogen atoms in the crevices and oxygen is present in minerals, which acts with the hydrogen to form water. And as mantle forms almost 80 percent of the earth's surface, these rocks add up to a lot of percentage of water.

The scientists used a high pressure and temperature method through a diamond anvil cell, which squeezes a mineral between two diamonds and heats it with a laser imitating earth's interior. With this they observed how a mineral's crystal composition changes and how it is able to store hydrogen.

Through computer calculations and expansion of the model, they uncovered the geochemical process that pushes the water to the suface. Panero called the complex relationship between plate tectonics and surface water "one of the great mysteries in the geosciences.  

"If all of the Earth's water is on the surface, that gives us one interpretation of the water cycle, where we can think of water cycling from oceans into the atmosphere and into the groundwater over millions of years," she said. "But if mantle circulation is also part of the water cycle, the total cycle time for our planet's water has to be billions of years."