PHREEQC and pH

["Richard Johnston" <johnstonrh@xxxxxxxxxxxxxx>]

Hi Dr. Parkhurst -

I'm just starting to learn PHREEQC and am making diagrams to show parameters
(e.g. speciation) changing with pH. Right now I'm defining a new solution
for each pH value, but this takes up a lot of lines. Is there a way to tell
PHREEQC to sweep through a range of pH values? I know you can compactly vary
temperature using REACTION_TEMPERATURE, and can tell it what size step to
take. I also know you can fix pH by defining a phase like FIX_H+ and then
invoking EQUILIBRIUM_PHASES for a given solution, but if I want say 20
different pH values I have to define 20 different SOLUTION blocks. Can I use
REACTION or some other trick to 'titrate' with Fix_H+? Perhaps somehow using
a BASIC loop?

I can imagine wanting to do the same thing with other constituents (e.g.
adding incremental amounts of Cu+2 to a system), and it seems like it should
be possible to do it compactly, I just haven't been able to figure out how
to do it yet.

Thanks in advance, and have a good weekend.


Rick Johnston


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Richard Johnston
Doctoral Candidate
Department of Environmental Sciences and Engineering
University of North Carolina - Chapel Hill
CB #7400
Chapel Hill, NC 27599-7400
Tel: 919-967-5468
Email: johnstonrh@xxxxxxxxxxxxxx
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