کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1774997 | 1021181 | 2008 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: The nitrogen cycle on Mars: Impact decomposition of near-surface nitrates as a source for a nitrogen steady state The nitrogen cycle on Mars: Impact decomposition of near-surface nitrates as a source for a nitrogen steady state](/preview/png/1774997.png)
Nitrogen isotopes appear to be escaping from Mars at approximately the primordial ratio 14N/15N ≈ 275 and to have an atmospheric nitrogen depletion time scale of about 800 Myr. For the standard model of a progressive decline of an initial inventory of atmospheric nitrogen, having no source of N, the agreement of the isotopic ratio of escaping N with primitive nitrogen would be coincidental. Here we propose a steady state model in which nitrates, produced early in Mars' history, are later decomposed by the current impact flux. The detection of near-surface nitrates can discriminate between the standard and the steady state models. Based on current estimates of N loss to space, we predict a quantity of nitrates equivalent to 60 ± 30 mbars for a steady state, or a global layer of about 3 m of pure NaNO3.
Journal: Icarus - Volume 197, Issue 1, September 2008, Pages 60–64