The Oxygen
Cycle
Oxygen is essential for life...... (e.g. respiration,
stratospheric ozone)
...... but what supplies
the oxygen consumed by living beings?
oxygen is created by photosynthesis and net emission
due to burial of atmospheric carbon (CO2)
oxygen is consumed by both living beings and the
net uptake of oxygen due to weathering of fossilized carbon
...... where does most of the oxygen in the Earth system reside?
most of the Earth's oxygen resides in mineral oxides
of the crust
a small fraction resides in the atmosphere and an
even smaller fraction resides in the biosphere
still the biosphere is crucial to understanding the
atmospheric oxygen budget as it controls short term exchanges between sediments
and the atmosphere
...... how long will
atmospheric oxygen last?
-
because oxygen creation and destruction
are in near equilibrium, it is unlikely that oxygen will run out soon,
either in response to increased combustion or deforestation
-
nonetheless, some estimates can be
given for the lifetime of atmospheric oxygen under simple scenarios
-
if photosynthesis were to cease, atmospheric
oxygen would be depleted in 5000 years due to respiration, weathering,
and combustion
page 1 : page
2 : page 3 : page
4 : page 5 : page 6 : back
to the PJW Class page
a link to the worksheet
if you're curious about our upcoming study of the carbon cycle, check
out these figures that estimate your production
of carbon