Mass of water in Earth's oceans over 4 billion years old declined by a quarter due to the loss of hydrogen, easily "flies" in the space to the saturation of the atmosphere with oxygen, the Internet portal ScienceNordis with reference to the study by researchers at the Danish Natural History Museum.
Scientists came to this conclusion by comparing the isotopic composition of modern ocean water and "petrified water" — serpentine, formed in what is now Greenland about 3.8 million years ago. Geological mineral serpentine formed at high temperatures, when the ocean water enters the cracks and fissures of the crust. It turned out that in the modern water contains much less light isotopes of hydrogen than in serpentine.
"In the water that covered the planet in the dawn of time, the predominance of light over heavy hydrogen isotopes was greater than it is now," — explained the study's author, an employee of the Danish Natural History Museum Emily Pope (Emily Pope), the words of which are given in the message.
Scientists explain that hydrogen "flew" into space in the synthesis of methane ancient archaea — single-celled organisms. In this light isotopes, despite the fact that initially they form large, easily and left the planet, and over billions of years, the proportion of deuterium (heavy hydrogen isotope with an atomic mass of 2) increased.
The current proportion of deuterium in the ocean water relative to normal, "light" hydrogen is 0.015% of the number of atoms, or 0.017% by weight.
"The hydrogen and deuterium still go into space, but now the process is very slow," — said the Pope.
She explained that at some point in the evolutionary history of the planet (about 2,4-2,2 billion years ago) the proportion of oxygen in the atmosphere has increased so much that it will launch a chemical process replenish water. Atmospheric oxygen is a barrier, reacting with atoms, "The Fugitive", forming a molecule of water, which then fall back into the ocean.
In addition, the scientists were able to determine that 4 billion years ago, methane in the atmosphere was 50-500 times more than now.