Utilisation of Cathodic Hydrogen by Sulphate-Reducing Bacteria

The respiration of [35S] sulphate to [35S] sulphide by hydrogen-grown sulphate-reducing bacteria was used as a sensitive indicator to monitor cathodic hydrogen utilisation. The transient depolarisation of both mild steel and X65 pipeline steel electrodes, a rise in pH and a burst of hydrogen [35S] sulphide production, provided strong evidence that the bacteria were utilising cathodic hydrogen.The relatively low levels of sulphate respiration observed indicated that removal of cathodic hydrogen per se is unlikely to be the dominant mechanism whereby sulphate-reducing bacteria stimulate corrosion. The concomitant generation of sulphide, however, isprobably of greater significance in terms of corrosion.