Hi all, I am having issues with convergence while trying to simply calculate saturation indices. My water samples are from column experiments treating AMD so I initially made these calculations using WATEQ4f database. These solutions had really high percent errors. I switched over to the minteq.v4 database as it has volatile organic acids which are very high in some of my samples. I am having issues with convergence which I suspect is due to differences in calculated alkalinity and measured total alkalinity. Total alkalinity was measured at the time of sampling through titration and reported in mg/l as CaCO3. any advice on how to make this sample converge would be appreciated. [DATABASE C:\Program Files (x86)\USGS\Phreeqc Interactive 3.6.2-15100\database\minteq.v4.datSOLUTION_SPREAD -units mg/l Temperature pH Acetate Fe S(6) S(-2) Ca Mn Br Cl Formate K Na Mg P Si Propionate pe Alkalinity ug/l as Ca0.5(CO3)0.5 21 5.59 657.3452458 163.9 2652.729722 4.06 858.2 12.32 52.58985847 4.504965294 8.05079465 48.8 17.07 329.1 28680 13.12 362.4737729 -1.380772192 638.46]
C(4) 1 CO2(g) -3.4 10
--------------------------Distribution of alkalinity--------------------------- Total alkalinity (eq/kgw) = 1.467e-02 Species Alkalinity Molality Alk/Mol Acetate- 8.684e-03 8.684e-03 1.00 Propionate- 4.039e-03 4.039e-03 1.00 Ca(Acetate)+ 7.446e-04 7.446e-04 1.00 Mg(Acetate)+ 6.248e-04 6.248e-04 1.00 Ca(Propionate)+ 1.950e-04 1.950e-04 1.00 Mg(Propionate)+ 1.419e-04 1.419e-04 1.00 Fe(Acetate)+ 1.185e-04 1.185e-04 1.00 HPO4-2 2.786e-05 2.786e-05 1.00 CaHPO4 2.410e-05 2.410e-05 1.00 MgHPO4 2.220e-05 2.220e-05 1.00 FeHPO4 1.938e-05 1.938e-05 1.00 Fe(HS)2 1.148e-05 5.741e-06 2.00 Mn(Acetate)+ 1.026e-05 1.026e-05 1.00 HS- 5.172e-06 5.172e-06 1.00 K(Acetate) 4.032e-06 4.032e-06 1.00 H+ -3.261e-06 3.261e-06 -1.00 Na(Acetate) 2.404e-06 2.404e-06 1.00 HSO4- -1.762e-06 1.762e-06 -1.00 H(Formate) -1.596e-06 1.596e-06 -1.00 H3PO4 -1.553e-07 1.553e-07 -1.00 KHPO4- 9.039e-08 9.039e-08 1.00 NaHPO4- 8.406e-08 8.406e-08 1.00 FeOH+ 7.042e-08 7.042e-08 1.00 CaPO4- 5.747e-08 2.873e-08 2.00 H3SiO4- 1.452e-08 1.452e-08 1.00 Fe(HS)3- 9.700e-09 3.233e-09 3.00 MgOH+ 4.590e-09 4.590e-09 1.00 S5-2 4.045e-09 2.023e-09 2.00 OH- 3.739e-09 3.739e-09 1.00 S6-2 1.516e-09 7.579e-10 2.00 S4-2 1.017e-09 5.084e-10 2.00 MgPO4- 5.994e-10 2.997e-10 2.00 MnOH+ 3.847e-10 3.847e-10 1.00 CaOH+ 3.542e-10 3.542e-10 1.00 S3-2 1.565e-10 7.823e-11 2.00 PO4-3 2.801e-11 1.401e-11 2.00 S2-2 1.473e-11 7.366e-12 2.00 Fe(OH)2 2.439e-13 1.219e-13 2.00 FeHPO4+ -1.828e-13 1.828e-13 -1.00 Fe(OH)3 1.358e-14 1.358e-14 1.00 FeOH+2 -7.632e-15 7.632e-15 -1.00 Fe(Acetate)3 1.838e-15 1.838e-15 1.00 H2SiO4-2 1.106e-15 5.530e-16 2.00 Fe(OH)3- 5.515e-16 1.838e-16 3.00 Fe(Acetate)+2 -4.362e-16 4.362e-16 -1.00 FeSO4+ -2.280e-16 1.140e-16 -2.00 Fe(Propionate)+2 -1.976e-16 1.976e-16 -1.00 FeH2PO4+2 -5.727e-17 2.863e-17 -2.00 Fe(SO4)2- -3.507e-17 1.753e-17 -2.00 S-2 2.772e-17 1.386e-17 2.00 Fe+3 -2.529e-17 1.265e-17 -2.00 Fe(OH)4- 2.198e-17 1.099e-17 2.00 FeCl+2 -2.037e-20 1.018e-20 -2.00 Mn(OH)3- 1.483e-22 4.943e-23 3.00 FeCl2+ -5.136e-24 2.568e-24 -2.00 Fe2(OH)2+4 -1.857e-25 9.287e-26 -2.00 FeCl3 -4.088e-29 2.044e-29 -2.00 Mn(OH)4-2 5.054e-30 1.263e-30 4.00 Fe3(OH)4+5 -3.452e-34 1.726e-34 -2.00