Sauerstoffkreislauf

The oxygen cycle is the biogeochemical cycle that describes the movement of oxygen within and between its three main reservoirs: the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for the modern Earth's atmosphere and life as we know it. If all photosynthesis were to cease, the Earth's atmosphere would be devoid all but trace amounts of oxygen within 5000 years. The oxygen cycle would no longer exist.

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Phosphorus

An interesting theory is that phosphorus (P) in the ocean helps regulate the amount of atmospheric oxygen. Phosphorus dissolved in the oceans is an essential nutrient to photosynthetic life and one of the key limiting factors. High oxygen levels in the oceans promote P removal by increasing the productivity of certain types of bacteria which uptake dissolved P to make their tissues. The decreasing phosphorus availability subsequently suppresses the population growth of the photosynthesizers and O₂ production diminishes. Low oxygen levels lead to increased mortality of oceanic organisms which, during decomposition, release P back into the ocean. This increasing phosphorus availability subsequently elevates the population growth of photosynthesizers and O₂ production increases.

References

Cloud, P. and Gibor, A. 1970, The oxygen cycle, Scientific American, September, S. 110-123
Fasullo, J., Substitute Lectures for ATOC 3600: Principles of Climate, Lectures on the global oxygen cycle, http://paos.colorado.edu/~fasullo/pjw_class/oxygencycle.html
Morris, R.M., OXYSPHERE - A Beginners' Guide to the Biogeochemical Cycling of Atmospheric Oxygen, http://seis.natsci.csulb.edu/rmorris/oxy/Oxy.htm
Walker, J. C. G., 1980, The oxygen cycle in The natural environment and the biogeochemical cycles, Springer-Verlag, Berlin, Federal Republic of Germany (DEU)