[paul cotter]

Any chance you could make that a bit bigger, BC, the ould eyes aint what they used to be! PS joking.

[Bored chemist]

Any chance you could make that a bit bigger, BC, the ould eyes aint what they used to be! PS joking.

Yours are not the eyes I'm targeting...

[alancalverd]

The statement in enormously large print is obvious. According to a tax inspector* somewhere

And we know the world's estimated coal reserves are 1,139,471,430,000 tons

so on the basis that C + O₂ → CO₂ you would need about 3.2 x 10¹⁵ kg of oxygen to burn it all. Add about 250,000,000,000 tons of oil,** and you are still a factor of several hundred short of what you'd need to  use up all the oxygen.

But the original question was "where did all the oxygen come from?" and so far nobody has challenged the geological consensus answer - photosynthesis.

Which raises the next question - where did all the rest of the primordial atmospheric carbon go? And so far, nobody has suggested a plausible (or indeed any) alternative to extant biomass, soil, sedimentary rock, and seabed sludge.



*nobody else would estimate a hidden and unknowable asset to 10 significant figures
** looks more like a petrologist's estimate

[Bored chemist]

But the original question was "where did all the oxygen come from?" and so far nobody has challenged the geological consensus answer - photosynthesis.

The fact that it apparently doesn't explain all the oxygen is, in fact, a challenge.
It seems that it's quite a difficult one.

[Bored chemist]

And so far, nobody has suggested a plausible (or indeed any) alternative to extant biomass

And again, Alan fails reading comprehension/ memory test...

If that happened on a large scale and the H2 got into the atmosphere and escaped (because it's too light for gravity to trap it) then that would explain the surplus of O2 that we now see.
A huge stock of undiscovered oil-shale or some such might also explain it.

[Bored chemist]

nobody else would estimate a hidden and unknowable asset to 10 significant figures

Nobody did.
They added a number of estimates together.
The estimates themselves are published numbers.
The estimate of the mass is known to that precision, but the mass isn't.

It's a little beside the point which is that it's 2 orders of magnitude or so too high for the glib "photosynthesis did it" response, since photosynthesis shouldn't have produced that much oxygen (or equivalently, should have produced more fuel)..


Have you finally realised why chalk etc is irrelevant?

[Bored chemist]

Which raises the next question - where did all the rest of the primordial atmospheric carbon go?

And, after just 42 posts, you finally understand the OP.

[alancalverd]

And the answer.

Sadly, I'm getting too old to waste any more time explaining basic biology and geology here.

[Bored chemist]

Sadly, I'm getting too old to waste any more time explaining basic biology and geology here.

The whole point of the thread is that the " basic biology and geology " do not explain the observations, do they?
There's too much oxygen.

[paul cotter]

I would reckon a lot of the carbon in reduced form is spread thinly throughout the lithosphere. The deposits of fossil fuels often quoted are those that are economical to extract, at the present time. As deposits are exhausted more difficult to mine sources will become economic, eg the Canadian tar sands. Other deposits such as methane clathrates and humous in the soil could be difficult to estimate, I would think.

[alancalverd]

Photosynthesis probably began about 3 x 10⁹ years ago. The Carboniferous (coal and oil formation) period only lasted for about 6 x 10⁷ years - about 2% of the total.

[Bored chemist]

Photosynthesis probably began about 3 x 10⁹ years ago. The Carboniferous (coal and oil formation) period only lasted for about 6 x 10⁷ years - about 2% of the total.

So?
It's not a scheduling problem.
Where's the carbon?
Where did the O2 come from?

[alancalverd]

I refer the hon gent to the answers I gave some days ago - or to any decent geology textbook. Or maybe the oxygen was found under a gooseberry bush, like babies, and the fairies took the carbon away. 

[Bored chemist]

I refer the hon gent to the answers I gave some days ago

The ones where you were wittering on about elephants or the ones where you were wittering about chalk?

[Petrochemicals]

Many things react with oxygen. There is  plenty of oxygen on/in earth which is 30% by mass, much more than the atmosphere. Do you mean why is there oxygen in the atmosphere?

[Zer0]

https://en.m.wikipedia.org/wiki/Diatom

ps - i Wonder how Wikipedia is still Free & not a Paid Access Service.
GR8!