A typical sequence of bacteria mediated oxidation - reduction reactions in ocean sediment from the surface to deeper in the sediment may be:
(a) Carbon to CO2, nitrate to N2, Fe3+ to Fe2+ , sulphate to H2S, carbon to CH4.
(b) Sulphate to H2S, Fe3+ to Fe2+, carbon to CO2, carbon to CH4.
(c) Carbon to CO2, nitrate to N2, Fe2+ to Fe3+ , sulphate to H2S, carbon to CH4.
(d) Carbon to CH4, carbon to CO2, nitrate to N2, sulphate to H2S.
A) spell out CoN-FeSH
- Sulp---> H2S
they are all loosing an electron