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Table 1 Summary of model approaches used in the present work

From: Validation of hydrogeochemical databases for problems in deep geothermal energy

Code PHREEQC ChemApp
Parameter file phreeqc.dat llnl.dat pitzer.dat slop16.dat
Source of thermodynamic data Unknown Mainly: slop Unknown slop16
Activity model Extended Debye–Hückel equation Pitzer equations Davies equation
Approx. ionic strength limits of the activity model \(\left( {\mathrm {mol}}/{\hbox {kg}}\right)\) 0.1–3a 0.1–3a 6a 0.1–0.5a
Pressure dependence HKFmoRR None HKFmoRR HKF
Temperature dependence Fitted polynomial equation or two-term extrapolation [cf. Eqs. (1) and (2)] HKF
  1. aDepending on system composition