Specifications

Although initially developed for coupling with transport models, CHESS has evolved to an easy to use, stand-alone and complete geochemical speciation tool, including (among others) the following processes and cool features:

• thermodynamic equilibrium of mineral, colloidal, organic, gaseous or aqueous species
• oxidation and reduction processes
• precipitation and dissolution of mineral phases
• formation and dissolution of colloidal phases (organic, inorganic)
• surface interface reactions:
  • surface complexation
  • an amended surface complexation approach
  • cation exchange
  • Kd
• multi-site and multi-surface reactions
• reaction paths
  • titration
  • flushing
  • mixing
• temperature dependence (0 to 300 C)
• extended kinetic control of dissolution and precipitation reactions
• heterogeneous size distributions of colloids
• diagrams
  • Pourbaix diagrams
  • General activity/activity diagrams, straight or mosaic
  • Piper diagrams
• Extended possibilities for database management:
  • run-time selection of other databases
  • many options to fine-tune the database for specific purposes
  • "analyzer", a powerfull tool to question the database on specific species and/or items

The multi-site, multi-surface aspect of CHESS is essential when it comes to modelling aqueous and surface chemistry of heterogeneous natural geological systems. CHESS deals with multiple sites per surface, whatever type of surface, colloidal or mineral: the number of sites is unlimited. And CHESS allows you to include several (again, unlimited) solids in the system.