Fe3

1
The Iron Cycle
Air
O2
Water
H2O
e-
Fe3
Sediment
Fe3
Start
Fe2
2H
e-
Continue
Organic Matter
CO2
Biogeochemical cycling of iron in aquatic
sediments is driven by oxidation of organic
matter below the surface where there is no oxygen
present. This produces excess electrons. The
electrons are used to reduce Fe3 to Fe2. When
the reduced iron comes into contact with air, the
electrons are transferred to oxygen and the Fe2
is oxidized back to Fe3. All of these reactions
can be carried out by different groups of
bacteria