Electrode studies of hydrogen sulfide in marine sediments

Abstract

An electrode has been prepared and applied to the measurement and detection of hydrogen sulfide in natural sediments and in laboratory experiments. When properly calibrated, the silver-silver sulfide electrode used in conjunction with platinum and glass electrodes can be used to determine equilibrium activities of dissolved sulfide and polysulfide species, as well as the partial pressure of H 2S. The potential of the electrode is a direct function of the logarithm of the activity of sulfide ion. To demonstrate the usefulness of the silver-silver sulfide electrode, an experimental study of bacterial sulfate reduction has been conducted. The process of H 2S formation by sulfate-reducing bacteria can be followed with the electrode. Through use of the platinum and silver-silver sulfide electrodes, it has been discovered that the Eh of many sediments containing H 2S is controlled by the reversible half-cell: HS aq. − i ̌ > ag S rhmb. 0 + H aq. + + 2e which is equivalent to the half-cell: S aq. 2− i ̌ > ag S rhmb. 0+ 2e Many additional sediments should be found where this Eh controlling mechanism operates.