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Re: trouble downloading PHREEQC for Windows

Thank you, I  appreciate your taking time to answer my questions.

A final one (hopefully) --

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?

Thank you,

Mickley & Associates
752 Gapter Road
Boulder, Colorado 80303
fax 303-499-5305

----- Original Message -----
From: "David L Parkhurst" <dlpark@xxxxxxxx>
To: "Mike Mickley" <michael@xxxxxxxxxxxxxxxx>
Sent: Monday, August 18, 2003 8:18 AM
Subject: Re: trouble downloading PHREEQC for Windows

> > QUESTION 1:  would you recommend software to use at higher salinities?
> EQ3/6 or something else?
> You need a program that includes the Pitzer formulation for activities to
> run at higher ionic strengths. EQ3/6, Geochemists Workbench, and TEQUIL
> (though I have never successfully downloaded this code) include or are
> based on the Pitzer formulation. Note that as far as I know, the Pitzer
> formulation does not include any redox reactions, aluminum, or silica.
> > Example 1 of PHREEQC determines the speciation of seawater.   The data
> input
> corresponds to standard water quality for seawater.    I have always
> assumed
> that this 'standard' WQ for seawater refers to the common elements in
> dissolved state.  In this instance calcium at 412.3 ppm would be assumed
> be nearly all in ionic form.     Yet the results of the simulation suggest
> that about 10% of the calcium is present as CaSO4.   While nucleation of
> CaSO4 can be such that initially it is dissolved I would assume that here
> CaSO4 implies solids that are precipitated.
> > QUESTION 2:  Is this correct?   OR am I missing something?
> You are missing something. The CaSO4 in the distribution of species is a
> dissolved ion pair or complex. All species listed in the distribution of
> species are dissolved and concentrations defined in SOLUTION refer to
> dissolved concentrations (free ion + complexes). Saturation indices show
> the saturation state of the solution relative to minerals. Mineral
> equilibria are defined with EQUILIBRIUM_PHASES; KINETICS can be used to
> define kinetic reaction of minerals.
> David
> David Parkhurst (dlpark@xxxxxxxx)
> U.S. Geological Survey
> Box 25046, MS 413
> Denver Federal Center
> Denver, CO 80225
> Project web page: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled

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