The chemistry of seawater at conditions of 350?? to 500??C, 220 to 1000 bars (22 to 100 MPa) is controlled by reactions involving magnesium hydroxide sulfate (MHSH) and anhydrite. During progressive heating from 350?? to 500??C at 1000 bars (100 MPa), MHSH with a Mg SO4 ratio of 1.25 is formed via precipitation from solution and via reaction of solution with pre-existing anhydrite. During adiabatic expansion the MHSH extracts additional SO4 from seawater and converts to a stoichiometry in which Mg SO4 = 1.16. These reactions control and greatly change the concentrations of Ca, Mg, SO4 in solution and produce significant ionizable hydrogen, attaining 11.7 mmoles kg-1 at maximum conditions. ?? 1983.
Additional Publication Details
A note on the chemistry of seawater in the range 350??-500??C