In this article, we use a thermodynamic approach and a range of physico-chemical parameters (i.e. temperature, pressure, salinity, pH, sulfate, sulfide) to predict the Gibbs energy of reaction for S0 disproportionation in seawater. We then calculate the free-energy values of S0 disproportionation from environmental data at four hydrothermal sites located in different geological settings and characterized by contrasted fluid compositions. We show that S0 disproportionation is energetically favourable in most, if not all, niches of the hydrothermal vent ecosystem, whatever the geological and geochemical context and depth.
