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Re: trouble downloading PHREEQC for Windows

> QUESTION: I appreciate the role of kinetics.  However, assuming that
kinetics are not an issue, how can I best apply PHREEQC to determine, at
equlibirum, what remains in solution and what (eventually) precipitates -
for a given a water quality?

You're asking a pretty basic question. The short answer is that the
saturation indices (SIs) calculated for a solution indicate the
thermodynamic state of the solution relative to minerals. Positive SI
indicates the mineral could precipitate, negative, it could dissolve. The
key factors for what happens are the minerals present in the system and the
rate at which the minerals react. You must decide which minerals will react
to equilibrium, in which case, you include them in EQUILIBRIUM_PHASES and
react these phases with the SOLUTION. The result is equilibrium between the
solution and the selected phases (unless a mineral is undersaturated and
has zero moles initially).

The long answer is the field of low temperature geochemistry.


David Parkhurst (dlpark@xxxxxxxx)
U.S. Geological Survey
Box 25046, MS 413
Denver Federal Center
Denver, CO 80225

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