19
votes
Accepted
When did wildfires start to occur on earth?
A definitive statement comes from the abstract of Scott and Glasspool1, 2006:
Charcoal, a proxy for fire, occurs in the fossil record from the Late Silurian (≈420 Myr) to the present.
One of the ...
- 3,208
12
votes
Is oxygen the most abundant element on Earth?
Both of them.
The composition of the atmosphere, crust, mantle, core and bulk earth are all notably different.
The atmosphere is composed of ~78% nitrogen and ~21% oxygen, with small amounts of ...
- 2,211
8
votes
Accepted
Could earth run out of O2?
No, that will not happen. There is just too much oxygen in the atmosphere.
Over 20% of our atmosphere is oxygen.
Only about 0.04 % of our atmosphere is CO2, so too much CO2 would kill us much sooner ...
- 462
8
votes
Accepted
How is the equilibrium of 21% oxygen in Earth's atmosphere established?
I'm not sure I can give a good technical answer. I don't think the amount of oxygen in the Earth's atmosphere is due to equilibrium but more of a consequence of the formation of the solar system, ...
- 5,777
8
votes
Accepted
Why is it said that Amazon creates 20% of the oxygen production of the world, when it accounts with less than 14-12.8% of the forest area?
I cannot find any language in peer-reviewed literature (as far as publicly accessible) that makes the 20% claim reported in the question. I therefore consider this claim to be of obscure and dubious ...
- 473
7
votes
Why did the carboniferous period have so much atmospheric oxygen?
The Carboniferous was when the growth of woody plants took off. Non-plant life had not yet evolved the ability to consume lignins, the key chemical components that makes woody plants "woody". Lignins ...
- 22.7k
7
votes
Difference between the oxygen/$CO_2$ ratio during the period of the dinosaurs and the present
Is it true that during the time of the dinosaurs, both the oxygen
requirements (by all living creatures on the planet) and the CO2
released by volcanoes were higher than the same type of oxygen
...
- 5,777
7
votes
Accepted
Why is Great Oxidation Event associated with Iron oxidation but not Aluminum or Silicon?
Because Al and Si were already oxidised to begin with.
When the Earth formed, it had some amount of metals (Fe, Si, Mg, Al, Ca, etc) and a fixed amount of oxygen to bond with those metals. Certain ...
- 22.9k
6
votes
Why cannot people burn all the atmospheric oxygen?
Photosynthesis has not stopped. It happens all the time, splitting water and carbon dioxide, and producing oxygen and carbohydrates. Likewise, organic matter rots and decomposes all the time, ...
- 2,008
5
votes
Accepted
Why did the carboniferous period have so much atmospheric oxygen?
To complement @DavidHammen answer and address the point "where did so much oxygen come from?" I will elaborate on David's final remark
The end result was a gradual increase in oxygen levels
The ...
- 17.3k
5
votes
Why is it said that Amazon creates 20% of the oxygen production of the world, when it accounts with less than 14-12.8% of the forest area?
Do we need to worry about oxygen?
No. Although some reports have claimed the Amazon produces 20% of the world’s oxygen, it is not clear where this figure originated. The true figure is likely to be ...
- 2,349
5
votes
Accepted
Why limestone formation was not a concern in atmosphere oxidation event?
First, let me clarify this again:
Al2O3 is not clay.
Now, back to topic. You are mixing apples and oranges here. The geological section you are referring it was deposited 2 billion years after the GOE....
- 22.9k
4
votes
How is the equilibrium of 21% oxygen in Earth's atmosphere established?
Atmospheric oxygen is not in an equilibrium of 21%, it just changes very slowly. For instance, oxygen has decreased by 0.7% over the past 800 thousand years, likely due to increased erosion (which ...
- 12.9k
4
votes
Why cannot people burn all the atmospheric oxygen?
If I understand it right, you are assuming that in the beginning we had CO2, which was then split to organic carbon and O2 via photosynthesis. And now you are asking if it's possible to reverse all of ...
- 22.9k
4
votes
Causes of fluctuations in atmospheric oxygen in past 300 Mya
Here's a somewhat different looking graph, from Oxygen and Evolution,
Robert A. Berner et al., Science 316, 557 (2007):
The graph shows three marked drops in O2 levels, each corresponding to an ...
- 22.7k
3
votes
Accepted
What rate of deforestation would be needed until we run out of oxygen?
As Jan points out, there are many other factors in the oxygen balance, not just trees. But for a bit of fun, let us suppose that we burn all the trees on the planet. The global biomass of carbon is ...
- 14.1k
3
votes
Is oxygen spread equally on Earth's surface?
Based upon links from a similar question on atmospheric distribution in Chemistry SE, I looked into the latitudinal difference by making a couple images using the MSIS model chemistry plotting website ...
- 8,612
3
votes
Accepted
How much nitrogen would you need to replace all oxygen in a room of 1,000 cubic feet?
Your assumption about constant pressure can't actually exist while everything is closed. I am not using this assumption here because it is more correct and a bit easier:
$$\pu{10 feet} = \pu{3.048 m}$$...
- 628
2
votes
Is oxygen the most abundant element on Earth?
"How can this be reconciled?" In two words: silicon dioxide :-)
Yes, that's simplistic, but reflects the fact that virtually all the oxygen occurs in chemical combinations with other elements, not ...
- 1,698
2
votes
Accepted
How is there enough $\ce{O2}$ in the atmosphere to breathe if you are in a desert with no plants?
The short answer is, $\ce{O2}$ is all around us!
You aren't breathing the $\ce{O2}$ that the trees next to you are respirating (at least not much). No matter which way the wind is blowing, you ...
- 12.9k
2
votes
How is there enough $\ce{O2}$ in the atmosphere to breathe if you are in a desert with no plants?
Look at it this way: According to the American National Center of Atmospheric research, the Earths atmosphere weighs 5.148 x 10^^18 kg., and that atmosphere is composed of about 20.8 to 20.9% oxygen (...
- 14.1k
2
votes
Percentage of Oxgen left after burning all the available biomass
Estimates of earth's total biomass vary widely, from 0.5 to 4 trillion tons C, so instead of citing a source, I'll just go with an assumption of $1\times10^{15} \text{kg C}$. Measuring biomass in ...
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2
votes
Are we consuming more oxygen than the world is producing due to fossil fuels?
Yes, atmospheric oxygen is being depleted by fossil fuel burning.
From https://cdiac.ess-dive.lbl.gov/trends/oxygen/modern_records.html -
Oxygen concentrations are currently declining at roughly 19 ...
- 1,768
2
votes
How many mole of oxygen gas is there in the atmosphere?
It is easier to calculate:
The pressure of air on the ocean level is $\approx 100 \rm {kPa}$.
Thus, its weight is $\approx$ 100000N over $1 \rm m^2$.
Considering that the overwhelming majority of the ...
- 660
2
votes
Accepted
How could oxygen levels have ever been higher if there is so little carbon dioxide present?
Where did all the CO2 go?
Shell organisms stored it in the sediments and rocks in the form of CaCO3. This is known as the main sink of CO2.
There are other C sinks on the Earth, but lithosphere is ...
1
vote
Accepted
What was the oxygen concentration in the air during the late miocene period?
R. Tappert et al (2013) used carbon isotopes in ambers as proxies for atmospheric oxygen concentrations. Their work indicates an initial Miocene O2 concentration of 16% and rising to about 20% at the ...
- 2,783
1
vote
Are we consuming more oxygen than the world is producing due to fossil fuels?
Since pre-industrial times $CO_2$ has increased from 280 to 415 ppm. Considering only carbon (ignoring the hydrogen in hydrocarbons), atmospheric $O_2$ decreased by the same amount, 135 ppm. The ...
- 2,349
1
vote
Filtered pressured oxygen 80 miilion years ago
What filter? Modern vertebrate blood is always red (with just one exception AFAIK: https://en.wikipedia.org/wiki/Channichthyidae ) because it is based on hemoglobin. Given that birds, which descend ...
- 1,698
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