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To: AndrewC
Nope, but then I'm just shooting for ballpark figures. Do you have any figures on how much oxygen per year combines with other chemicals and drops out of the atmosphere, and how much oxygen is liberated from those chemicals through various processes and put back into the atmosphere?
738 posted on 02/25/2002 7:03:00 AM PST by Junior
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To: Junior
Do you have any figures on how much oxygen per year combines with other chemicals

No, but there was a study done on the subject, that I ran across. It showed that photolysis of water to produce oxygen would be offset by the conversion of the created oxygen by reactions which would also apply to the photosynthesis problem. I'll see if I can find it again. I'm off for a while.

741 posted on 02/25/2002 7:14:29 AM PST by AndrewC
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To: Junior
Do you have any figures on how much oxygen per year combines with other chemicals and drops out of the atmosphere, and how much oxygen is liberated from those chemicals through various processes and put back into the atmosphere?

Well, I found the reference (Evolution of Oxygen and Ozone in Earth's Atmosphere), but.....

Two important loss processes for oxygen do operate: oxidation of reduced volcanic gases, primarily H2 and CO; and oxidation of crustal materials at Earth's surface, which may be written schematically as

 

2FeO + O2/2 -> Fe2 O3

 

The crustal loss rate is difficult to evaluate. It turns out not to be necessary to do so, however, since the H2 and CO outgassing from volcanoes appears [152] to be more than sufficient to overwhelm the production of O2 from H2O photolysis followed by hydrogen escape.

If the problem is intractable for these fellows, I am in no position to reasonably solve it.

As to the release of oxygen from other sources, this seems to be precluded by the nature of the discussion, "oxygen atmosphere is indicative of life", which is where I started. If the discussion proceeds as to non-biologic sources of oxygen then along with the photolysis of water we should add the production of oxygen by lightning. From the same source...

The lower limit on oxygen is a result of the production of O2 in lightning discharges, which can be estimated by assuming thermodynamic equilibrium at high temperatures.

Note that the mechanism and reactants are not mentioned.

761 posted on 02/25/2002 10:05:28 AM PST by AndrewC
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