na'vi and human air

[keyeung]

I have run several searches on this subject, and was wondering if there is any evidence as to whether the Na'vi are able to breath the human atmosphere,

regards

Keyeung

[Crickett]

I would assume they can. The reason we can't breathe Na'vi air has to do with the increased level of carbon dioxide, hydrogen sulfide and xenon in their air. But they still have a primarily nitrogen-oxygen atmosphere. This is why Jake didn't immediately suffocate and die. He may have passed out, but he wasn't breathing that stuff in for four minutes. Not even close.


Or, to put it another way. If we went to a planet with an atmosphere just like ours, except with 10% less nitrogen, and no argon or neon, would any of us notice much of a difference?

[Disco Scratch]

I would imagine the Na'vi would be able to breathe in Earth's atmosphere more easily than their own. It would be like stepping inside on a hot summer day.

[Raiden]

Copied from a reply I made to another post recently:

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The only thing that sticks out to me is the difference in CO2 concentration. When CO2 dissolves in water, it forms carbonic acid, which donates hydrogen ions to the water, making it more acidic. Organisms can only survive if they can keep the interior of their cells, tissues, and organs stable, and this includes regulating the pH of the fluid in this interior.

Animals and other organisms here use an array of buffering agents to keep their blood/conductive fluid pH within a very narrow range. This, combined with what I said about carbonic acid, is why holding one's breath for very long periods of time can be dangerous; your cells are still generating CO2, but you are not exhaling it, and so it is building up in your bloodstream. The buffering agents (mostly bicarbonates) can keep the pH stable for a while, but past a certain point they become saturated with hydrogen ions (buffering agents literally act as sponges for hydrogen ions) and the blood pH falls, which becomes lethal very quickly. This is part of the reason why Pandora's atmosphere is toxic to Earth animals (the H2S is the other reason).

So, taking this into account, if the atmosphere on Pandora has a higher CO2 concentration, the Na'vi might have a lower blood pH range than we do. If this is true, they could have the opposite problem, and they would need to be careful not do anything that could raise their blood pH (such as hyperventilating), because they may not have buffers to reduce the pH if the atmosphere keeps their blood pH lower for them.

Anyway...

Everything is the same with the exception of the H2S and CO2. There would be a pressure difference, and this could cause problems if they spent a long time breathing our atmosphere, but aside from the blood pH thing, they should be fine.

[Ja'k Dawsiin]

why is there 80% nitrogen in earth's atmosphere? jw

[Raiden]

Originally Posted by Ja'k Dawsiin

why is there 80% nitrogen in earth's atmosphere? jw

No reason.

It was just a random event that happened billions of years ago when the Earth formed; of the gaseous elements that coalesced into Earth after our star (Sol, or "The Sun") shed some of its outer layers (this is a normal part of the "life cycle" of stars), Nitrogen was the most abundant. It is likely that Earth has always had a high concentration of Nitrogen, but there are other features that affect its abundance.

Nitrogen gas (N2, since Nitrogen gas only exists as a pair of bonded Nitrogen atoms) is relatively unreactive. Oxygen gas reacts with many different metals, including Iron and Magnesium, and so some of it is trapped as a part of other compounds, such as iron oxide (also known as rust, or Fe2O3), or covalently bonded to two hydrogen atoms, forming water. Carbon dioxide, CO2, is a very important part of plant and animal metabolism, and it is transformed directly into plant biomass via photosynthesis; the amount of CO2 in our atmosphere has changed dramatically between different geological eras, and until recently was tied to the amount of functioning plant biomass on the planet versus decaying plant biomass and animal metabolism.

Basically, of the three major gases in our atmosphere (oxygen, carbon dioxide, and diatomic nitrogen), nitrogen is the least reactive. Some plants harbor symbiotic bacteria that can transform nitrogen gas into nitrate (NO3-) which is an important plant nutrient, and the surging energy of lightning bolts is enough to force a reaction between N2 and O2 to form NO3- in the soil at the site of a lightning strike. But these two things happen in limited amounts; gaseous nitrogen doesn't react much, and when it does, it is only in small quantities, and there are a myriad of aquatic bacteria in marine and freshwater biomes that produce more N2 gas from NO3-. These processes keep the balance between gaseous nitrogen and nitrogen in living organisms, but the vast majority of Earth's nitrogen will always be in the atmosphere.