David, The radium01.txt runs (converge in that sense), just give gabage results. I did remove the knobs data block. -Chen --- David L Parkhurst <dlpark@xxxxxxxx> wrote: > > > > I have run into a couple of non-convergence with > phreeqc lately. I have attached 3 input files. The > file radium01.txt attempts to simulate solid > solution > formation (Ra,Ba)SO4 in a reactive transport regime. > I > have tested the same solid solution model without > transport, and it ran fine. When there is transport, > it does not converge, and also, it simply gives > equal > mole fraction of the two end-members. Additionally, > I > suspect that the equilibrium sulfate and barium > concentrations are shifted a little, that is, the > product or IAP is right but the relative activities > of > sulfate and barium are shifted. > > If you remove the KNOBS data block, the file runs. > If there is still a > problem with the mole fractions, let me know. > > > The file kinetics qrtz2.txt attempts to simulate > reactive transport when quartz kinetics is involved. > It does not converge. The kinetics01alb.txt for > albite > dissolution converged. So does a similar file for > K-feldspar. However, when I have both albite and > k-feldspar kinetics, it did not converge. > > I'm not sure what you are trying to do here. With > the number of minerals in > EQUILIBRIUM_PHASES, the activity of H4SiO4 is > probably nearly invariant. I > ran a little test adding a millimole of SiO2 and > the solution composition > barely changed. Adding kinetics of quartz to this > system may not make much > sense. I'm not sure if albite/k-spar is related or a > different problem. > > > > Separately, I am going to attend GSA in Denver. If > you > are still interested in conducting a short course > next > year, I can come in early or stay late for > discussions. I have taught a geochemical modeling > course for a semester and you probably have some > teaching materials too. I don't think it will take > that much time to prepare the short-course. > > I think I really do not want to teach a short course > at GSA. There are too > many other things I'd rather do and time is always > at a premium. > > David > > > David Parkhurst (dlpark@xxxxxxxx) > U.S. Geological Survey > Box 25046, MS 413 > Denver Federal Center > Denver, CO 80225 > > Project web page: > https://wwwbrr.cr.usgs.gov/projects/GWC_coupled > > > __________________________________________________ Do You Yahoo!? Yahoo! Finance - Get real-time stock quotes http://finance.yahoo.com
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