Re: PHREEQC question

["David L Parkhurst" <dlpark@xxxxxxxx>]

Dan,

> I did get similar numbers (not the same numbers though), but is the
technique correct? You mention several times in you FAQs list that it is
not
a good idea to control pE or pH in this manner... but I couldn't figure out
how else to do it. I don't want to develop poor technique and have
something
critical fail on me in the future.

I don't see any problem with the way you did it. I've given an alternative
way below. The original paper used PHREEQE, not PHREEQC, and neither of
these ways is possible with the earlier program. They must have done
something a little different. I suspect they just let pyrite dissolve in
the original solution; the mole transfer is so small, it won't affect the
pH or totals.

David


TITLE        Example to calculate pE from Luther and Church (1987)

SOLUTION 1 High Salinity site, June 1986(after flood), 2.5 to 5.0cm
units        umol/kgw
pe          0     pyrite      0
pH           6.22
temp         25
# S(6)             43700
S           43700
Fe(2)        67

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