Figure 5.

f(O2) vs. pH iron stability diagram at 25°C and 1 bar showing the natural domains of the main groups of iron oxidizing bacteria recalculated from an Eh–pH diagram in Lundgren and Dean.[21] Activities of dissolved iron, carbonate, and sulfur species are 10-6, 10° and 10-6, respectively, from Garrels and Christ.[75] The boundary between Fe3+ and Fe2+ which is missing in the Lundgren and Dean diagram, has been added here. Other thermodynamic databases suggest the presence of FeHCO+3 supplanting siderite between 6.4 and 7.0 pH and acetates supplant other phases and species below -75 logf(O2).

Boyd and Scott Geochemical Transactions 2001 2:45   doi:10.1186/1467-4866-2-45