Eva Stueeken

Hello, I'm having difficulty with a simple mineral dissolution model and was hoping to get some advice. Attached is the REACT file. As you can see, I've set up a solution of essentially pure water (all concentrations of ions are very low) in which I'm trying to dissolve a few minerals, as entered under Reactants. The model runs fine when 'reactant times' is set to 0.015 or 0.008, but it crashes at 0.01. It says, Newton-Raphson didn't converge after 999 iterations, max residual = 0.706, Xi = 0.0000 -- Didn't wake up, abandoning path. I'm trying to understand what the problem is and why the model works with sligthly larger and smaller mineral amounts but not with the amount that I need. Do you see any obvious problems? As a second step, I would like to add gases to this model. Specifically CO2 with fugacity 0.1 and O2 with 0.9 (this is for a model of a hypothetical exoplanet ocean). However, it keeps generating this error: Residuals too large, 731-th interation, Largest residual(s): Resid Resid/Totmol Cbasis --------------------------------------------------------- Cl- 0.02433 1.279e+200 1.903e-202 --------------------------------------------------------- See second attached file. This fails even for the model where 'reactant times' is set to 0.008, which previously worked in the absence of gas. Again, what is the problem here? Is it related to the previous issue? Thanks for any advice! Eva Orthopyroxene.rea Orthopyroxene_gas.rea

Hello, I'm working on thermodynamic models of phosphorus and have added data for reduced P-species from HSC Chemistry to the thermo database in GWB. While doing so, I noticed that HSC Chemistry has different entries for the conversion of phosphate to pyrophosphate compared to thermo in GWB. I tried to find out where the original phosphorus data in thermo come from, but no specific references are mentioned. I can only see the general reference list in the header of the database, but many of those sources are unaccessible to me, and so I can't check which one contributed the P-data. Would anyone be able to help out? Or does somebody happen to know how the thermo database compares in accuracy to the HSC Chemistry database? Thanks a lot! Eva

Hi Jia, Thanks a lot for your help, and sorry for my slow reply! We have finally found an error in our calculations of the equilibrium constants and were able to get something to work. However, we still seem to have a problem with the equilibrium between NOx gas phases and aqueous phases. I'm attaching our modified database, along with a REACT script. In the script, I created a model where 10mmol of NO(g) are reacted with a liter of water. I am able to plot up aqueous NOx species that form as a result of this reaction, but for some reason the gas phases (NO, N2O, NO2, etc.) are all zero. REACT is unable to calculate the equilibrium gas fugacities for all N-gases. I tested the same model with H2S gas, and here the calculation of the H2S(g) fugacity works fine. Something must still be wrong with our NOx gas species in the database. Do you have any idea what could be going on? Any advice you can provide would be extremely helpful. Best regards, Eva thermo_StA-CES.tdat NOx and H2S anoxic.rea

We have made several modifications to the thermo database, specifically to carbon and nitrogen, and are now having trouble with getting it to work. We changed the basis species to CO(aq) and NO(aq) and then redefined various redox couples, aqueous species and gases. However, when we now try to run a model in REACT, for example, and we add anything to do with redox reactions, an error message appears saying that the model did not converge. Our modified database is attached. If anyone can spot a mistake, please let us know. Thanks! thermo_StA-CES 8 (1).tdat