Oxygen Content in Water

I am no expert in this but my thought is about PRESSURE, anything that is designed to extract O2 from the water and supply it to the lungs would have to supply it at a pressure great enough to overcome the water pressure on the diver. It's supply pressure would also have to be precisely controlled I would think. Also, at some depth a breathing supply needs to be a mix of gases not just O2,so provisions need to be made to mix this, say helium, or what ever the mix is now. Where are we going to get these from? Dunno.

remember that what we normally breath is 79% nitrogen and 21% oxygen, not exactly because of the trace elements and pollution :)

breathe pure oxygen at depth and you convulse and drown..............

It's quite cold in the depths, so less oxygen is required.

Another point to take note of: aside from the fact that most deep sea creatures are cold-blooded and required less oxygen due to the low temperatures there, it should also be noted that due to the lower temperatures and higher pressures, gases also become more soluble.

"The communities of organisms van Andel found around hydro-thermal vents east of the Galapagos Islands were remarkable in that they derived energy through chemosynthesis. This was performed by more than a million sulphur-eating bacteria per milli-litre of sea-water. Massive mussels and huge tubworms which play host to these bacteria were prominent amongst the creatures seen by van Andel."

Perhaps those creatureswe are not necessarily using O2.

My guess is that one factor is that cold-blooded creatures require a lot less oxygen. I don't know of any warm blooded animals that get oxygen from the water.

These deep sea creatures also tend to have very slow metabolisms and move very slowly, thus requiring less oxygen.

Although the oxygen interface is at the surface there is significant levels at great depths, especially in the North Atlantic. There is also significant amounts off the Antarctic Ice fields. The Ice sheets melt taking high density cold oxygenated water down to great depths. The North Pacific does not have the exposure to large ice sheets and looses its O2 content around 300 meters.

Check out the website http://www.nodc.noaa.gov/cgi-bin/OC5/WOA05F/woa05f.pl
then drop down to below 1000 m and observe the water is actually O2 rich, especially as you go deeper in the North Atlantic.

The other problem for deep sea creatures is the lack of food. The photosynthesis stops in a relatively short distance from the surface because light does not penetrate. As previously noted very deep organisms thrive on chemo-synthesis.

For a device to extract O2 from the water for human consumption we would need to absorb the O2 across a membrane at significant rates against a positive gradient. Very difficult.

However, it appears James Bond had such a device in the movie Octopussy(?).

try:

http://www.nodc.noaa.gov/OC5/WOA05F/woa05f.html

then select dissolved Oxygen and select your depths.

CO₂ sequestration from exhaust breath into say CaO, replace the CO₂ with the O₂ to 20% O₂ and rebreathe. At depths of greater than 60 m, dump rebreather of air (N₂) and substitute He or Ar. No oxygen need be exhausted with each breath, which is normally 18% O₂ so that a similar sized pressure tank will result in an increase of availability by a factor of nearly 35. 5 X as pure O₂ and another 7X by 100% usable rather than 86% exhausted waste. 95% O₂/5% CO₂ is a fatal mix. The maximum livable mix is less than 5% CO . 21% Oxygen less 3% conversion to Carbon Dioxide (32 grams O → 44 g Carbon Dioxide) is 18% waste Oxygen exhaled., 6 parts waste per 7 parts of compressed air.

At least a small quantity of air would probably be handy as an emergency in the event of failure.

Also, in remote areas, the CaO is rechargeable by heating.

Any better ideas?

RichH