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I've found 2 sources stating that there is new water being formed on Earth. The first site states that it is coming from hydrothermal vents in the sea floor. The second site is basically saying that new water is being generated through biological processes. However, to me, this just seems water that is already here coming up to the surface in the case of hydrothermal vents, or the rearranging of atoms into water molecules through biological processes that are already here on Earth. Maybe this explanation is just semantics, but I'm also wondering if new water is coming here from meteors/meteorites. To me that would be new water on Earth. Is there any definitive proof of new water being formed on or brought to Earth?

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Your explanation(s) sounds correct.

Your first article says as much.

There is a water cycle on earth that takes wet sediments deep into the mantle to be re heated and circulated back up as new sea floor. This is where the water in hydrothermal vents originates - it is NOT new water. However, there remains a possibility that some of the water emerging from the mantle has been there since the formation of the earth so some of it MAY be 'new'.

And your 2nd article

This is at least partly semantics calling it "new" water. When we burn gasoline for example, the hydrocarbon structure becomes Water and CO2 - is that new water, or just re-arranging molecules by chemical reaction and fire?

I'm also wondering if new water is coming here from meteors/meteorites.

Water absolutely reaches the Earth by comets and meteors. We're hit by comets and meteors all the time and comets especially are water-rich. That is new water, though I wouldn't want to put an estimate on how much. Too big a margin of error.

Earth also loses water by UV rays from the sun. Most of the atmosphere the Earth loses is Hydrogen and most of that Hydrogen comes from Water. Losing 90 tonnes of Hydrogen per day works out to nearly 800 tons of water per day, which sounds like a lot, but compared to the vastness of our oceans, it's a proverbial drop in the bucket, even over hundreds of millions of years.

So Earth adds water by comets and Earth loses water by photo-disintigration and atmospheric escape. I've read that it's a net loss, not a net gain, but it's pretty insignificant either way. Some articles suggest Earth has lost a pretty good share of it's water over billions of years. I think there's a pretty big margin of error in those estimates, personally.

In 200 or 300 million years, as the sun grows a little larger and brighter, we might need to begin to worry about Earth losing too much water (maybe). That's if we're still around, of-course.

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    $\begingroup$ Yes, and there is also the balance between water added to the mantle through subduction vs. returned to the surface via volcanoes. As the Earth very slowly cools, we might expect more water to be retained in the mantle. $\endgroup$ – Andrew Jon Dodds Dec 8 '17 at 11:31
  • $\begingroup$ @AndrewJonDodds That's a good addition. I didn't know that. $\endgroup$ – userLTK Dec 8 '17 at 17:54
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New water introduction scenarios, other than through the biological processes mentioned in the question:

  1. When ice(H2O) meteorites/asteroids enter Earth's atmosphere they melt into water
  2. When Meteorite containing Oxygen compounds reacts with hydrogen in the upper atmosphere, and creates water
  3. If Meteorite containing Hydrogen compounds reacts with oxygen in the lower atmosphere, and creates water [unlikely]
  4. If Earth passes through a comet's trail or nebula containing Hydrogen or Oxygen, which reacts with Earth's Hydrogen/Oxygen to create water [unlikely]
  5. If Earth passes through a comet's trail or nebula containing ice(H2O) [unlikely]
  6. If the Hydrogen from the upper atmosphere somehow meets Oxygen in the lower atmosphere [very unlikely]
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Yes, ever tried a vinegar and baking soda reaction, well that reaction produces a little water along with Products. One of the products is sodium acetate (NaC2H3O2). The other products are water(H2O) and carbon dioxide (CO2).

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