A question of water?

[anobium]

This question has been bothering me for some time and I will probably get some stick for asking it but here goes.
Many years ago a teacher told me that this planet has only ever had so much water since the day it was formed.
By that he meant in liquid ,solid and gas form.
Excluding what we have removed when we went to the moon was he right or am I just being a thicko and missing the obvious.

 

[gcol]

As the saying goes..... what goes around, comes around.

 

[JohnD]

That will be approximately right, but not entirely.

Although water evaporates, forms clouds; falls as rain or snow; goes into rivers; evaporates again; form clouds again...

Some of the water is broken down into oxygen and hydrogen by plants in photosynthesis; so there is less water. If the plants are later burned, then the carbon within them binds with oxygen in the air to form carbon dioxide, so there is now less oxygen in the air to re-form water. If they are turn into coal or oil, then the hydrogen is locked away for millions of years as well.

 

[WoodYouLike]

You better hurry, they are about to ban it.

Water, that is

 

[anobium]

.

If the plants are later burned, then the carbon within them binds with oxygen in the air to form carbon dioxide,

Thanks for the reply JohnD but you can't burn water can you, it just gets converted to a gas ?

If they are turn into coal or oil, then the hydrogen is locked away for millions of years as well.

On this point the water or moisture is still on this planet, isn't it?

 

[JohnD]

I meant, a water molecule is composed of hydrogen and oxygen. If the atoms become separated, and then one of them is locked into something else, they can't re-form into water, so that water molecule is gone forever.

 

[joe-90]

The hydrogen/ oxygen bond is extremely strong and takes plenty of energy to part.

 

[ipjodan]

Has'nt a lot of the water on mars been stripped out of the atmosphere into space by the solar wind?

http://www.flamsteed.info/fascoates.htm

Does the same happen here?