The Oxygen Cycle

Kevin Kwong and John Solder

9.6 x10^9 kg

1.4 x10^18 kg

2.9 x10^20 kg

1.6 x10^16 kg

Modified from http://ilc.royalsaskmuseum.ca/ilc6/pages/62b/63e/pf63ep2p1.htm

Fluxes and Residence

Reservoir Capacity (kg O2) (1020)

Flux In/Out (kg O2/year)

(1010)

Residence Time (years)

Atmosphere0.014 30,000 4,500

Biosphere 0.00016 30,000 50

Lithosphere2.9 60 5*10 8

Hydrosphere.00000000096 450 21 *10 6

Hydrosphere Calculation

Sea-Surface Dissolved Oxygen (0~600 m) 5.4 x 10^16 mol

Anoxic Zone (600~1100 m) Very Low DO

Deep Ocean (1100~4000 m) 2.08 x 10^20 mol

X 32 g/mol => 6.65 x10^18 kg O2

Photosynthesis and Respiration

6CO2 + 6H2O + Energy → C6H12O6 + 6O2

C6H12O6 + 6O2 →6 CO2 + 6H2O + Energy

686 Kcal is the amount of energy imputed and released from these systems

Photodissociation

Breakdown of Ozone by Photons.

O3 + hν → O2 + O

@ λ ~240-310 nm

O3 + O → 2 O2

2 O → O2

The overall amount of ozone in the stratosphere is determined by a balance between production by solar radiation, and removal. The removal rate is slow, since the concentration of O atoms is very low.

Weatheringand Deposition

Oxidation of Earth Materials.

4FeO + O2 → 2Fe2O3

2 Ni + O2 = 2 NiO

2 Fe + SiO2 + O2 = Fe2SiO4

Biological Weathering releases O2 from minerals as other nutrients are consumed.

(Chelate compounds)

Corals and shells of marine organisms are O rich (CaCO3), becomes limestone.