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Re: Perchlorate vs. nitrate (was Re: Finding of perchlorates on Mars m

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David Williams

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Aug 7, 2008, 11:01:00 AM8/7/08
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-> No reason Mars had to have a certain amount of nitrogen. There
-> is a tiny bit in its atmosphere...

-> Venus and Mars have a very low *percentage* of nitrogen, compared
-> with Earth. In fact, it looks like we have the lion's share
-> in-system.

-> David A. Smith

Would Mars's gravity have been able to hold on to nitrogen for billions
of years? Maybe it just escaped into space. Similarly, Venus may have
lost much of the nitrogen it started with. I recall reading somewhere
that even Earth has lost about half of its initial nitrogen.

dow

David Williams

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Aug 8, 2008, 10:47:29 AM8/8/08
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-> > There's enough oxygen and water to ensure that NO
-> > is ultimately absorbed by the surface into nitrates or
-> > nitrites.

-> The oxygen is bound to carbon (or in rock). The water
-> concentration is *really* low. The temperature is really low,
-> requiring even more activation energy. I don't see a
-> non-biological way of making nitrate with this atmosphere.

-> David A. Smith

In Earth's atmosphere, a lot of nitrogen gets fixed by lightning. In
the conditions in a lightning strike, nitrogen and oxygen react to
produce NO, which is then further oxidized to N2O4, and then reacts
with water to produce nitric acid.

Of course, there's no lightning in Mars's atmosphere now, but in its
watery past there may well have been. The question is, was there also
oxygen? Or, if not, would lightning cause a reaction between N2 and CO2
that would fix the nitrogen?

dow

John Curtis

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Aug 8, 2008, 9:41:39 PM8/8/08
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On Aug 8, 7:47 am, david.willi...@bayman.org (David Williams) wrote:
> -> > There's enough oxygen and water to ensure that NO
> -> > is ultimately absorbed by the surface into nitrates or
> -> > nitrites.
>
> -> The oxygen is bound to carbon (or in rock).  The water  
> -> concentration is *really* low.  The temperature is really low,  
> -> requiring even more activation energy.  I don't see a  
> -> non-biological way of making nitrate with this atmosphere.
>
> -> David A. Smith  
>
> In Earth's atmosphere, a lot of nitrogen gets fixed by lightning. In
> the conditions in a lightning strike, nitrogen and oxygen react to
> produce NO, which is then further oxidized to N2O4, and then reacts
> with water to produce nitric acid.
>
> Of course, there's no lightning in Mars's atmosphere now, but in its
> watery past there may well have been. The question is, was there also
> oxygen?
>
Without atmospheric oxygen there would be no jarosite on Mars.
http://www.agu.org/pubs/crossref/2005/2005GL024253.shtml
At the volcano, escaping nitrogen (ammonia?) is oxidized to nitrate
by
atmospheric oxygen:
http://adsabs.harvard.edu/abs/2004E&PSL.218...17M
John Curtis

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