CHNOSZ:Thermodynamic Calculations and Diagrams for Geochemistry
An integrated set of tools for thermodynamic calculations in aqueous geochemistry and geobiochemistry. Functions are
provided for writing balanced reactions to form species from
user-selected basis species and for calculating the standard
molal properties of species and reactions, including the
standard Gibbs energy and equilibrium constant. Calculations of
the non-equilibrium chemical affinity and equilibrium chemical
activity of species can be portrayed on diagrams as a function
of temperature, pressure, or activity of basis species; in two
dimensions, this gives a maximum affinity or predominance
diagram. The diagrams have formatted chemical formulas and axis
labels, and water stability limits can be added to Eh-pH,
oxygen fugacity- temperature, and other diagrams with a redox
variable. The package has been developed to handle common
calculations in aqueous geochemistry, such as solubility due to
complexation of metal ions, mineral buffers of redox or pH, and
changing the basis species across a diagram ("mosaic
diagrams"). CHNOSZ also implements a group additivity algorithm
for the standard thermodynamic properties of proteins.
