How much oxygen does green-blue algae produce, and how
big are they?
Blue-green algae (cyanobacteria) are generally under one micron (1e-6
meter) in diameter, mostly in the 0.5-1.0 range.
How much oxygen they make depends on how many there are already and how
fast they're growing. Let's say you start out with about 1 mg in 1 liter of
water, and they're doubling once per day (that is, 24 hours later you now
have 2 mg in 1 liter). Although cells aren't entirely carbohydrate, it's a
good enough first approximation for photosynthesis:
6 CO2 + 6 H20 > C6H1206 + 6 O2
1e-3g / 180g per mole glucose = .0056e-3 moles glucose
Since they make 6 moles O2 for every mole of glucose, they make
6 x .0056e-3 = .03e-3 moles O2, and since O2 is 32g per mole,
that's 1.07e-3g O2, or a little more than 1 mg O2 per day, for 1 mg of new
cells per day (dried weight).
Donald Yee Ph.D.
They're microscopic (cyanophyta or cyanobacteria).
Anthony R. Brach, Ph.D.
Click here to return to the Biology Archives
Update: June 2012