1. Enter your fluid composition on the Basis pane. SpecE8 figures concentrations of aqueous and sorbed species, mineral saturation, and gas fugacity. Go to the Results pane, click Run, then view printed or plotted results

2. Concentrations and activity coefficients for all aqueous species are printed.

3. Add species to the Basis pane. Decouple any redox species for which analyses in multiple oxidation states are available. Decouple Fe 3+ from Fe 2+ and As(OH) 4 − from AsO 4 3− Config → Redox couples...

4. First value listed is system Eh Redox state for As(OH) 4 − /AsO 4 3− and Fe 3+ /Fe 2+ pairs are computed using Nernst equation. Widely varying Eh values indicate system has not reached redox equilibrium.

5. Calculated mineral saturation states and gas fugacities are listed in the output file. Calculated mineral saturation states Calculated gas fugacities

6. Plot → Piper Diagram A Piper Diagram shows the fluid's major ion composition.

7. File → Open → Thermo Data... Select thermo_hmw.dat to calculate activity using the Pitzer equations.

8. File → Open → Sorbing Surfaces... Open dataset of sorption reactions. Options include distribution coefficient (Kd), Freundlich and Langmuir isotherms, ion exchange, and Double Layer surface complexation models. Enter your fluid composition on the Basis pane, including the mass of sorbing mineral Fe(OH)3(ppd).

9. View calculated surface charge and potential of sorbing minerals. Compare concentrations of sorbed and aqueous species. View calculated distribution between surface and solution. Concentrations of all surface complexes are listed along with Boltzman factors which show the magnitude of electrostatic corrections.