PDA

View Full Version : Discussion: Delays for the Earth's Oxygen ...



Fraser
2005-Aug-09, 05:05 PM
SUMMARY: Our planet gained its nice, oxygen-rich atmosphere about 2.4 billion years ago thanks to early bacteria. One question that has puzzled researchers, however, is why it took at least 300 million years for oxygen to build up to large levels, even though the bacteria had been working madly to produce it. Researchers from the University of Washington have developed a model that shows how volcanic gasses could have sucked up this available oxygen. Not only that, but a large layer of iron from meteorite strikes would have used it for rusting. Not until those sinks were filled could oxygen build up.

View full article (http://www.universetoday.com/am/publish/new_model_of_how_oxygen_dominate_earth_atmosphere. html)

What do you think about this story? Post your comments below.

suitti
2005-Aug-09, 06:30 PM
it took at least 300 million years for oxygen to build up to large levels
One hears that oxygen was initially a poison for life. But 300 million years should be long enough for some enterprising microbe to start depending on it - providing yet another oxygen sync. If it happened much faster, life might have been in real trouble. It can take quite a while to develop new chemistry.

It would be easy enough to say that plants need us oxygen consuming animals. However, plants can cope with high oxygen these days. One could imagine that the animals all disappear, the oxygen levels rise, and wild fires become the rage. :o

Guest_Galacsi
2005-Aug-09, 08:03 PM
Originally posted by fraser@Aug 9 2005, 05:05 PM
SUMMARY: Our planet gained its nice, oxygen-rich atmosphere about 2.4 billion years ago thanks to early bacteria. One question that has puzzled researchers, however, is why it took at least 300 million years for oxygen to build up to large levels, even though the bacteria had been working madly to produce it. Researchers from the University of Washington have developed a model that shows how volcanic gasses could have sucked up this available oxygen. Not only that, but a large layer of iron from meteorite strikes would have used it for rusting. Not until those sinks were filled could oxygen build up.

View full article (http://www.universetoday.com/am/publish/new_model_of_how_oxygen_dominate_earth_atmosphere. html)

What do you think about this story? Post your comments below.
Hi

IF i remember my geology lessons , many giant iron deposits , mostly Fe2O3 (hematite) are from this time. The theory was that some bacteries used the new oxygen liberated by the first algae to oxidise ferrous ion in solution in the sea . It produced some kind of stromatolithe made of hematite. Now there is very little iron disolved in the sea . It is a limiting factor for modern life. So came the idea of fertilising the sea by spreading some iron solution.
[B][COLOR=blue]Digression :
And more , the alga growth will suck all the carbon dioxyde from the air and the earth warming is solved ! (What a moronic plan ! , what do happen of all this organic matter when it will be digested or rotten , Dioxide again and methane in addition)
[B][COLOR=blue]Back to oxygen :
Also all the soil at this age was a reducing agent as can be seen where it has been preserved . So it is no surprise than it take million years to oxidise.

And 3rd point May be the oxygen libération indirectely caused some glaciation .

Wow ! it is too much english for me today smilie

cran
2005-Aug-09, 10:29 PM
Hi, Guest_Galacsi, welcome to UT...


IF i remember my geology lessons , many giant iron deposits , mostly Fe2O3 (hematite) are from this time. The theory was that some bacteries used the new oxygen liberated by the first algae to oxidise ferrous ion in solution in the sea . It produced some kind of stromatolithe made of hematite. Now there is very little iron disolved in the sea . Yes, layered sediments called &#39;Banded Iron Formations&#39; or BIF; the oldest known deposits are thought to indicate the beginnings of &#39;oxygen liberation&#39; on a large scale (>thinks< cyanobacterial flatulence... :ph34r:)

And more , the alga growth will suck all the carbon dioxyde from the air and the earth warming is solved &#33; (What a moronic plan &#33; , what do happen of all this organic matter when it will be digested or rotten , Dioxide again and methane in addition) Not so moronic...that is indeed part of the process that goes to locking up CO2 and methanes - when the little plants die (if not eaten first) they sink to the sea floor and form a very fine ooze or mud - over time, it is compressed into rock.

And 3rd point May be the oxygen libération indirectely caused some glaciation . Indeed, that is thought to be a cause for the earlier Ice Ages - called &#39;Snowball Earths&#39; by others... :)
One could imagine that the animals all disappear, the oxygen levels rise, and wild fires become the rage. :o
Oxygen levels, while increasing overall since ~2.5 billion years ago, have fluctuated quite remarkably - the scene you describe, suitti, seems to have happened in the Early Carboniferous (~340MA BP)- very high free atmospheric oxygen (about 35%, compared with today&#39;s 21%), wildfires...and extensive charcoal deposits&#33; :ph34r:

As to the delay...yes to all of that, but perhaps the earliest generations of microbes were not O2-flatulent...maybe that had to wait for the emergence of cyanobacteria...and then they had to do their thing for a while...get past the reduced irons, and other pre-oxides...then the levels start to climb... :blink:

StarLab
2005-Aug-10, 03:55 AM
You silly people...we&#39;re talking small colonies of cyanobacter. SMALL cyanobacter. No surprise that it takes three hundred million years for the whole collection of single-celled cyanobacter to put as much percentage oxygen in the atmosphere as they did&#33; Really - c&#39;mon, people&#33; Use your brains&#33; :rolleyes:

cran
2005-Aug-10, 05:58 AM
Originally posted by StarLab@Aug 10 2005, 11:55 AM
You silly people...we&#39;re talking small colonies of cyanobacter. SMALL cyanobacter. No surprise that it takes three hundred million years for the whole collection of single-celled cyanobacter to put as much percentage oxygen in the atmosphere as they did&#33; Really - c&#39;mon, people&#33; Use your brains&#33; :rolleyes:
...did someone mention &#39;small colonies&#39;?
...small? colonies?
...in a global sea? :unsure:
...with nothing to eat them? :unsure:
...and breeding like...microbes? :unsure: