Oxygen atmosphere without ozone layer

[Czcibor]

OK, so I would like the following idea:
-planet which already had its Great Oxygenation Event and life forms including human beings would be able to breath there freely
-no oxygen layer or any other plausible mechanism which would practically preclude any daily life forms on the surface (all life aquatic, nocturnal, or insaniously shielded)

OK, so how can we get rid of ozone in natural way? Higher amount of fluorine in crust and it comes from volcanoes? Any hard SF idea?

(Brighter star which would have most of its radiation in UV? But they are shortlived...)

 

[vemvare]

Perhaps a gamma ray burst took the ozone-layer out (by forming NOx in the upper atmosphere) but it wouldn't do so permanently.

Perhaps chloromethane is a plant hormone or something, released by an organism that is in turn favored by the conditions it causes?

 

[Czcibor]

Perhaps a gamma ray burst took the ozone-layer out (by forming NOx in the upper atmosphere) but it wouldn't do so permanently.

Perhaps chloromethane is a plant hormone or something, released by an organism that is in turn favored by the conditions it causes?

How to get it on permanent basis? A neutron star not far away? (if yes, then how close)

 

[Borek]

Logic tells me gamma ray burst wipes not only the ozone layer, but also life on the planet. Unless it is OK to have a dead planet with just oxygen (but then oxygen level goes down with time).

 

[Czcibor]

Logic tells me gamma ray burst wipes not only the ozone layer, but also life on the planet. Unless it is OK to have a dead planet with just oxygen (but then oxygen level goes down with time).

http://en.wikipedia.org/wiki/Radiation_protection#Shielding

Which degree of protection against gamma ray would I require? Leaving only 1/1000,000th? In this case 3.6 m of water, so a shallow lake could achieve that.

Because it seems that photosynthesis under perfect conditions can work below 200 m under surface:

http://books.google.pl/books?id=AZC...r_esc=y#v=onepage&q=algae light depth&f=false

(Or do I overlook something?)

 

[Borek]

Two thoughts later: even if it will work (I mean: GRB strong enough to wipe out ozone layer, but weak enough to spare the life), I don't think it will work for your purposes. Ozone layer rebuilds itself on a relatively quick timescale in the presence of UV.

 

[Czcibor]

Two thoughts later: even if it will work (I mean: GRB strong enough to wipe out ozone layer, but weak enough to spare the life), I don't think it will work for your purposes. Ozone layer rebuilds itself on a relatively quick timescale in the presence of UV.

I don't think about one time GRB, but nearby pulsar. (opinion about it?)

 

[Czcibor]

One more interesting thing - it seems that air is not so awful protection against gamma radiation:
http://en.wikibooks.org/wiki/Basic_.../Attenuation_of_Gamma-Rays#Mathematical_Model