At https://www.eurekalert.org/pub_releases/2018-11/asu-agd110618.php … geoscientists have found that Earth contains within itself six or seven global oceans worth of hydrogen – in addition to all the water in the oceans. Where did that water come from? New research, which may or may not be controversial, from Arizona State University, claims they have found the answer. They say our planet contains much more hydrogen, a proxy for water, than scientists previously imagined. Now it is being asked – where did all that hydrogen come from? Water is hydrogen plus oxygen and oxygen was abundant during the early stage of the universe.
In the Beginning, we are told, hydrogen gas was a major ingredient of the solar nebula and the gases and dust out of which the Sun and the planets were formed. In other words, this hydrogen gas was able to combine with the other material that created our rocky world – and this could be the actual origin of Earth's global oceans. In contrast, another research paper suggests this was not enough and there must have been another mechanism in order to impregnate the earth with so much hydrogen. They claim that there is a different D/H signature with comets, so they are out of the question, but the extra hydrogen, instead, came from asteroids – pointing a finger at the hypothetical asteroidal bombardment between 4.5 and 4 billion years ago, a new theory that seems to have developed a life of its own. In other words, they are using the discovery of all this hydrogen inside the Earth as elaborated in the first paper to bolster the other theory, a bombarment of the planets of the solar system by a blitz of asteroids. One peculiarity of all this of course is that uniformitarian scientists are not very keen on asteroid strikes to account for mass extinction events – although the K/T boundary event was forced upon them. It is still of course being resisted by geologists schooled in gradualist sedimentary deposition – but that is another story. One can only assume they think that anything that occurred over 4 billion years ago is so long ago Joe Public won't notice the double think. What is clear, from the first research paper, is that the interior of the Earth contains a lot of hydrogen and this could have been outgassed at some stage or other (to mix with oxygen and create lots of water). The idea a lot of this hydrogen came from an asteroid bombardment in the early solar system is guesswork and may not be true.