Re: Oxygen saturation concentration

> From: Stephen.Pushak at saudan_HAC.COM
> Plants photosynthesize at different rates although I expect
> that most are capable of producing enough oxygen under ideal
> circumstances to achieve the ~9 milligrams / liter H2O which
> is the saturation point for oxygen at room temperature and
> pressure. 

	This oxygen concentration corresponds to the equilibrium
between oxygen in solution and the oxygen in the air.  It corresponds
to an oxygen partial pressure of about 0.2 atmospheres.  If you want
oxygen bubbles to form, you need a local concentration corresponding
to 1 atmosphere pressure of oxygen, i.e. thirty-odd mg/litre.
	The word "saturation" has to be used carefully - it must
be clear what the other phase is; in this case a bubble of oxygen gas
at 1 atmosphere.

Paul Sears    Ottawa, Canada