Capacities and Fluxes
The following tables offer estimates of oxygen cycle reservoir capacities and fluxes. These numbers are based primarily on estimates from (Walker, J.C.G.):
Table 1: Major reservoirs involved in the oxygen cycle
| Reservoir | Capacity (kg O2) |
Flux In/Out (kg O2 per year) |
Residence Time (years) |
|---|---|---|---|
| Atmosphere | 1.4 * 1018 | 30,000 * 1010 | 4,500 |
| Biosphere | 1.6 * 1016 | 30,000 * 1010 | 50 |
| Lithosphere | 2.9 * 1020 | 60 * 1010 | 500,000,000 |
Table 2: Annual gain and loss of atmospheric oxygen (Units of 1010 kg O2 per year)
| Photosynthesis (land) Photosynthesis (ocean) Photolysis of N2O Photolysis of H2O |
16,500 13,500 1.3 0.03 |
| Total Gains | ~ 30,000 |
| Losses - Respiration and Decay | |
| Aerobic Respiration Microbial Oxidation Combustion of Fossil Fuel (anthropogenic) Photochemical Oxidation Fixation of N2 by Lightning Fixation of N2 by Industry (anthropogenic) Oxidation of Volcanic Gases |
23,000 5,100 1,200 600 12 10 5 |
| Losses - Weathering | |
| Chemical Weathering Surface Reaction of O3 |
50 12 |
| Total Losses | ~ 30,000 |
Read more about this topic: Oxygen Cycle
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