Transcript Slide 1

The Iron Cycle
Air
O2
Water
H2O
e-
Fe3+
Sediment
Fe3+
2H+ eOrganic Matter
Start
Fe2+
CO2
Continue
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