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
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