A good Idea

snipped-for-privacy@aol.com wrote in news: snipped-for-privacy@z14g2000cwz.googlegroups.com:

Most of the earth's atmospheric free oxygen comes from water evaporation, which covers about 80% of the earth's surface. The rain forest is a net- zero contributor to atmospheric oxygen.

Cite your source. BTW, water does not evaporate to its constituent molecules. It evaporates to gaseous H2O. Our atmosphere would burn constantly, like the Hindenburg, if your theory were true.

The O2 comes from algae and cyanobacteria photosynthesis. Algae and bacteria are more effective because of the chemistry of photosynthesis: the carbon is used from the air to create carbohydrates, which are either reused (releasing CO2 again) or are used for building the plant structure. Woody perennials, like trees, need less for the plant structure while short-lived algae and bacteria need the most (high school biology).

I don't have any links for the relative amounts - I haven't looked that up in years - but I'm quite sure it's accurate. Well, not the "evaporation" part, but I have trouble with words at times, too! Currently I'm looking for world livestock census for the last century or so, looking for the source of atmospheric CO2 rise. I've pretty much ruled out deforestation as a major cause. That's partly for the reason TeGGeR cites, partly because deforestation of the Middle East (which was on a far larger scale than South American deforestation has been) didn't produce the rise we are seeing, and partly for lag times and other numbers issues. If anybody has any good sources on that, I'll appreciate them.

Mike

"Enrico Fermi" wrote in news:X7xXe.5641$GK2.5167@lakeread07:

Free oxygen and oxygen bound with hydrogen atoms are not the same thing.

Water (bound oxygen/hydrogen combination) also contains free oxygen that is not bound. It is this which is released on evaporation.

If you were to try to crack the water molecule into its constituent atoms, this would requires vast amounts of energy. More, in fact, than the hydrogen itself would provide.

In spite of certain school texts stating that the rain forest provides up to 40% of the earth's oxygen, plant-generated oxygen is not a significant source of atmospheric oxygen. Source: Facts not Fear, by Michael Sanera & Jane Shaw. Regnery Books, 1996.