I observed in the taffel plot from the CV scans a reduction that starts at -0.160V vs Ag/AgCl (3M). Theoretically sulphate reduction reaction take place at -0.029V vs Ag/AgCl (3M). This peak can also be oxigen reduction.

In literature the reduction that is take in consideration is from SO42- to S2-. This reaction is only catalyze by bacteria or at high temperatures, because it needs many steps. Why they all defend that limiting step is sulphate reduction?