I am attaching the source databases that I have for llnl.dat and the newest minteq database (Fall of 2000, I believe), which I have not yet translated into PHREEQC format. I believe the equations in the two databases are different. llnl.dat writes the equation with acetic acid, while minteq writes the reaction with acetate. References are included as comments in the llnl.dat database. Minteq lists abbreviated references as well. David (See attached file: llnl.thermo.dat)(See attached file: minteq.thermo.dbs) David Parkhurst (dlpark@xxxxxxxx) U.S. Geological Survey Box 25046, MS 413 Denver Federal Center Denver, CO 80225 Zhi Ling Zeng <z.zeng@xxxxxxxx To: dlpark@xxxxxxxx edu.au> cc: In-Reply-To: <220.127.116.1110417194839.007331a8@xxxxxxxxxxxxxxx> Subject: Please help! 04/17/01 02:48 AM Dear Sir, I have noticed something interesting whilst using PHREEQC for copper speciation modeling. I have noticed that the llnl.dat database has provided different stability constants for the various copper acetate complexes to the Minteq database (please see the table below): Cu Acetate Log_k llnl.dat 1 1 2.525 1 2 5.882 1 3 9.379 1 4 - Minteq.dat 1 1 2.22 1 2 3.63 1 3 3.1 1 4 2.9 The constants shown above, especially the ones displayed in llnl.dat, are significantly higher than the literature values. Since the quality of the speciation model predictions is solely dependant on the stability constants used, the discrepancies between the logK values may result in confusion and inaccurate predictions of the speicies distribution. Could you please comment on the situation and could you please also tell me what the sources of the constants listed in llnl.dat and Minteq.dat are? Thanks in advance for your help! Yours sincerely, Zhi Ling ZENG
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