from the a-mineral-named-after-a-beer? dept.
About 78 percent of the air you inhaled is the most abundant pure element found on Earth. Besides its role in the atmosphere, it’s used in all sorts of products: fertilizers, propellants, you name it. It's also an essential component of DNA and proteins. It’s called nitrogen.
But it's something of a mystery. The nitrogen found on Earth doesn’t match the nitrogen found in the Sun or in the tails of comets. Those sources have nitrogen isotope fractions that differ from those on Earth. So how did nitrogen get to Earth in the first place, and where did it come from? One clue is that some very ancient meteorites do match the Earth’s isotopic abundances very closely, implying that the nitrogen may have come from an ancient source that wasn't so much interplanetary, but existed before the planets formed.
In a new study, researchers examined an ancient meteorite using techniques called transmission electron microscopy and secondary ion mass spectrometry. These provide a glimpse of the material it contains and revealed that the meteorite contains a mineral called carlsbergite.
http://arstechnica.com/science/2015/01/where-did-earths-nitrogen-come-from/
[Abstract]: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2339.html
(Score: 4, Interesting) by ikanreed on Thursday January 29 2015, @04:47PM
What an odd way to gloss over silicon, oxygen, and hydrogen.
Pure nitrogen is unreactive enough to be of only occasional use to life and not form solid compounds, and heavy enough to stay in the lower atmosphere, but light enough to easily form by fusion, which is why it accumulates in the troposphere.
Talking about comets where solar wind blows away any such gases and being surprised it's not there is kinda disingenuous. I'm pretty sure there's piles of it in all the gas giants.
(Score: 3, Insightful) by DeathMonkey on Thursday January 29 2015, @06:25PM
Pure nitrogen is unreactive enough to be of only occasional use to life
If by occasional you mean absolutely required by all forms of plant life on the planet, then, yeah...
(Score: 2) by ikanreed on Thursday January 29 2015, @07:46PM
I understand proteins and amino acids. It makes up a small part of our biomass.
(Score: 1) by Bill, Shooter Of Bul on Thursday January 29 2015, @11:59PM
"occasional" means something much different than "always required" to most people in most situations.
(Score: 2) by ikanreed on Friday January 30 2015, @03:24PM
Then I apologize for my phrasing, by not my intended meaning.
(Score: 5, Informative) by Immerman on Thursday January 29 2015, @06:39PM
The point is not that there's no nitrogen in comets, etc - there is. Especially in the form of ammonia and other common compounds. The point is that the nitrogen we've found thus far, in both comets and the solar wind, has had the wrong isotope ratio and is thus unlikely to be the source of the bulk of nitrogen seen on Earth. So far the only place that we've found a similar isotope ratio to Earth is in asteroids believed to predate the formation of the planets.
The pure element bit seems to be mostly empty commentary having nothing to do with the subject being discussed. But still, none of your examples come anywhere close to comparable pure levels. Silicon is mostly found in the form of various silicate minerals, and less frequently as oxides such as sand and quartz. Hydrogen won't even remain gravitationally bound to Earth unless it's bound into some heavier compound, and while oxygen is mostly found as various oxides, it is found in pure form in the atmosphere, but there's 4x as much nitrogen.
Also, maybe that was just poorly phrased, but what the hell does fusion have to do with nitrogen levels in the lower atmosphere?
As for the usefulness to life - plants and animals may be generally unable to capture pure nitrogen, but they release it just fine as part of their normal metabolic processes, and soil bacteria must then bind it back into a form we *can* use. If they didn't then all the bound nitrogen would rapidly be released and all "higher" life would go extinct.
(Score: 2) by gman003 on Thursday January 29 2015, @07:39PM
Depends on what you mean by "pure". The definition that seem to be using is "mainly found in elemental form", which rules out the elements you listed.
Silicon generally is found in the form of silicon dioxide, not as crystalline silicon.
Oxygen is only found in pure form in our atmosphere, and only as a result of life. If it weren't for photosynthesis, it would be bound up in rocks (silicon dioxide), water (hydrogen oxide), carbon dioxide, or any other oxide variant you want to name. That's *why* it's useful for life - it reacts with things.
Hydrogen is found in pure form only in stars (and even then, a hydrogen-helium plasma isn't really H2 anyways, just a jumble of protons, neutrons and electrons). It's too reactive - forming compounds with damn near everything.
(Score: 0) by Anonymous Coward on Thursday January 29 2015, @08:34PM
Uhhh no. Jupiter (atmosphere is ~90% H₂ by volume) says hi.
(Score: 2) by ikanreed on Thursday January 29 2015, @08:38PM
I know, I was objecting to that being... well... relevant.
(Score: 2) by WizardFusion on Thursday January 29 2015, @04:49PM
Really. Advertising much.?
(Score: 2) by janrinok on Thursday January 29 2015, @06:26PM
...hence my 'dept' title.
(Score: 3, Informative) by c0lo on Thursday January 29 2015, @09:27PM
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Thursday January 29 2015, @07:03PM
McDonalds and Taco Bell eating cavemen whose post consumed food created nitrogen emissions from the hind quarters area.
(Score: 2) by frojack on Friday January 30 2015, @02:28AM
The Ars article briefly mentions something I hadn't been aware of:
The researchers propose in their paper that the ices might have been delivered to the inner part of the Solar System by Jupiter, during its “Grand Tack.” The Grand Tack is a model which proposes that Jupiter went through a period of migration early in its history, toward and then away from the inner Solar System. If so, it could have dragged the nitrogen-bearing ices with it, depositing them where they could later accrete onto the forming Earth.
How does something like that happen? The amount you would have to slow, and then speed up a planet size object to change orbits seems to be glibly handwaved away, even in the wiki article.
No, you are mistaken. I've always had this sig.