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Author Topic: Is the amount of water on Earth fixed?  (Read 2160 times)

Offline annie123

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Is the amount of water on Earth fixed?
« on: 07/06/2014 15:53:31 »
PS. and - re water . . .someone told me that the quantity of water on the earth is the same as it has always been. Is there any way of proving this? Or should I put this in another thread/topic?


 

Offline CliffordK

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Re: Is the amount of water on Earth fixed?
« Reply #1 on: 08/06/2014 12:59:49 »
What do you mean by the "same amount of water"?

Most theories indicate that in the early evolution of our planet, there was essentially no free oxygen, and significantly higher CO2 levels in the atmosphere.

Plants then converted atmospheric CO2 into plant matter (and eventually coal and oil) using the equation (unbalanced)

CO2 + H2O --> Hydrocarbons + oxygen.

Thus, all the coal and oil we have today once began in part as the conversion of water.  So, we may well have many gigatons less water today than we had before the expansion of plants.-
 

Offline chiralSPO

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Re: Is the amount of water on Earth fixed?
« Reply #2 on: 08/06/2014 14:38:38 »
The amount of water we have on Earth definitely does change. Is it a significant change? Not really--at least on our timescale. Water can be chemically converted to other compounds (for instance by photosynthesis)--even water in the upper atmosphere can be cleaved by high energy radiation to form hydrogen atoms and hydroxyl radicals (H2O → H + HO) and the hydrogen atom can even escape Earth's gravity into space. Huge meteorite impacts can also splash water out into space (and comet crashes bring water back)

Long story short: The Earth is almost a closed system, but matter can and does come and go at a small rate.
 

Offline percepts

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Re: Is the amount of water on Earth fixed?
« Reply #3 on: 08/06/2014 19:32:29 »
one of the products of burning petrol is water
 

Offline CliffordK

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Re: Is the amount of water on Earth fixed?
« Reply #4 on: 08/06/2014 20:38:20 »
The Earth also both looses hydrogen, and gains hydrogen with solar winds and cosmic rays.  Most estimates indicate a net loss of hydrogen.

However, the Earth is also bombarded with somewhere around 50 to 100 tons of meteorites and micrometeorites a day.  Some may also contain water.
 

Offline yor_on

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Re: Is the amount of water on Earth fixed?
« Reply #5 on: 22/06/2014 05:41:43 »
Earth has lost a lot of water, but there is still a lot left :)

“Today the atmosphere is rich in oxygen, which reacts with both hydrogen and deuterium to recreate water, which falls back to the Earth's surface. So the vast bulk of the water on Earth is held in a closed system that prevents the planet from gradually drying out."

http://sciencenordic.com/earth-has-lost-quarter-its-water
 

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Re: Is the amount of water on Earth fixed?
« Reply #5 on: 22/06/2014 05:41:43 »

 

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