Mr. Parkhurst, I was trying to use your program to duplicate some results that I found in: Marine Chemistry, 1988, volume 23 p. 295-309 authors: Luther and Church Specifically, on p. 305, they claim to use PHREEQE to calculate pE's for known pH, Fe(II), and SO4. They assume equilibrium with pyrite. To perform this in PHREEQC I wrote the following: 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 pH 6.22 temp 25 S(6) 43700 Fe(2) 67 PHASES pH_Fix H+=H+ log_k 0.0 EQUILIBRIUM PHASES Pyrite 0.0 pH_Fix -6.22 HCl 10 END 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. Dan
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