Chemval project. Comparison of thermodynamic databases used in geochemical modelling

The following four thermodynamic databases used by European groups for geochemical modelling have been compared: UWIST; AERE, Harwell; CHEMVAL Stage I; EIR. The number of aqueous species and solid species as well as components in each database is listed. There are many cases where numbers in the different databases are not directly comparable and have not been compared here. There are five different reasons why this can occur. In each case these are noted. When numbers are directly comparable, they are not necessarily the same between databases. When differences occur we have highlighted them by marking with those cases where β values differ by between a factor of two and an order of magnitude (or the difference in log β is ≥ 0.3 but ≤ 1.0) and where the difference in β values is more than an order of magnitude (difference in log β > 1.0). This work is a component of the Chemval/Mirage project, performed within the third CEC R and D programme on radioactive waste management and storage