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Jia Wang

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Jia Wang last won the day on November 19 2020

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  1. Hello Peter, Thanks for reporting this issue. We are not able to reproduce this issue on our end. Can you provide more context with regards to when this started occurring? Were any settings on your machine changed recently? Can you try restarting your computer to see if that resolves the issue? Best regards, Jia Wang
  2. Hello Andrew, The amount of mineral reported in the output text file is the amount of mineral in the whole system and not per kg of solvent. The g/kg unit in the Gtplot configuration dialog is grams of mineral per kg of solution. If you divide the mineral mass(g) by the solution mass(kg) in the same block from the text file, then it should match the value displayed in Gtplot for that step. For example, I ran the attached input file and looked at the results in the output text file at step #100. The mass of anhydrite is 0.03558 grams and the solution mass is 1.3669 kg, dividing the anhydri
  3. Hello Isaac, If you are prescribing a kinetic mineral reaction, then React is calculating the dissolution and precipitation of the mineral according to the kinetic rate law. The amount of mineral you prescribe for this kinetic mineral is the amount you have included in the Reactants pane is in the system at the start of the simulation. You can also set a kinetic mineral with no initial mass and the mineral can precipitate according to the rate law. You can check by plotting time elapsed vs mineral in Gtplot. For simple minerals, the program adds a small amount of the mineral over the enti
  4. Hello Dave, I have sent a message with regards to resetting the license activation on your machine to the email address that you have listed for the forum. If you didn't receive the message, please check your spam folder. Best regards, Jia Wang
  5. Hello Zixuan, I took a quick look at your input script and surface dataset and here are a couple of suggestions to help you get started. Check to make sure the log Ks in the dataset are in the correct format for reactions written in GWB. You might need to negate the log Ks from the paper if the reaction is written in the reversed direction. For more information on triple-layer model datasets, see section 2.5.2 in the GWB Essentials guide. For surface dataset formatting, see section 4 in the GWB reference guide. I think you would need to provide a SiO2(aq) concentration for you
  6. Hello, If your lab analysis reported the pH at the end-point for the total alkalinity titration, you should use that value for the titration simulation. However, if you don't have that information, you might want to figure out if the difference between titrating to the endpoint of pH = 4.5 vs 4.8 is significant for the amount of total carbonates. If the titration ends when the change in pH is greatest, Gtplot can show the results in pH vs. acid added so you can match up your simulation end point to point It might be good to check the carbonate concentration from your titration simulation
  7. Hello Andrew, Adding a trailer command "temperature = 80" should work. Perhaps the change wasn't saved? Can you double check in the Options dialog by clicking Apply or Ok? After adding the trailer command, did you recalculate calcite saturation? The spreadsheet won't automatically update so you have to trigger the recalculation by right clicking on calcite and select 'Recalculate Analyte'. If this doesn't help, please attach an example GSS file so we can take a further look. Hope this helps, Jia Wang
  8. Hello Brent, I am made a mistake in the above post. The example for the rate law script is in section 5.2 Rate law scripts and not section 5.1. Best regards, Jia
  9. Hello Brent, Unchecking the precipitation option disables any new mineral from precipitating but if some amount of the mineral is in the system initially, it will precipitate or dissolve according to thermodynamics and the kinetic constraints prescribed. The critical saturation index parameter is used in mineral nucleation calculation, that is if your system initially contained none of the kinetic mineral, then the program uses the nucleus density and crit SI values to calculate initial mineral precipitation. With a kinetic mineral reactions, you can use a custom rate law to specify
  10. Hello Johan, The release candidate is a fix to the issue of dataset opening incorrectly if the file contains tab characters. If this is the issue you're experiencing, the release candidate should be a good fix for you. We do not have another release update to GWB 2021 currently. If the release candidate didn't resolve your issue, please attach your thermo dataset or send it to support@gwb.com so we can take a closer look at the issue. Please also include screenshots of any error messages you encountered. Best regards, Jia Jia Wang Aqueous Solutions
  11. Hi Karen, You're welcome. I am glad to hear that you find Rxn useful in your work! With regards to your confusion, I think I have a bit more information to offer. I revisited the Austin_Chalk_As.x1t script and tried to run it again. I ran into an issue where the NO3- concentration in the initial pane wasn't constrained so I used the value of 5.5 mg/l that was commented out. I also changed the balancing ion to HCO3- for the inlet fluid to help with convergence, since there was quite a bit more HCO3- in the fluid than Cl-. I ran this simulation for just several days and saw that Fe(OH)3(pp
  12. Hello Reza, I am glad to hear that helped. I hope you enjoy using the software. Best regards, Jia
  13. Hello Peter, The activity for water is calculated differently than species activity. The water activity in the Bdot method is calculated using the mole number of water, stoichiometric or actual ionic strength, and osmotic coefficient. The equation to calculating the osmotic coefficient is given as power series in equation 8.8 in section 8.1.2 'B-dot model' of the Geochemical and Biogeochemical Reaction Modeling text. The water activity coefficients used in the calculation of the osmotic coefficient is given in the Tables section of the thermodynamic dataset. You can find the equation for
  14. Hello Ben, The water activity in the Bdot method is calculated using the mole number of water, stoichiometric or actual ionic strength, and osmotic coefficient. The equation to calculating the osmotic coefficient is given as power series in equation 8.8 in section 8.1.2 'B-dot model' of the Geochemical and Biogeochemical Reaction Modeling text. The water activity coefficients given in the thermodynamic dataset is used in this equation to calculate water activity. The text does not discuss the derivation of the values given but a good place to start might the papers and other text books re
  15. Hello Karen, Thanks for reattaching the files. They worked this time. I think the primary issue here is that your input file Austin_Chalk_As_KJ.x1t doesn’t contain a mineral that has sorbing sites defined in your surface dataset. The surface dataset FeOH_Arsenic_HFO.sdat has sorbing sites defined for Hematite, Goethite, and Fe(OH)3(ppd). Since the two-layer surface complexation model calculates sorption by the presence of surface area of a mineral with sorbing sites, your simulation will need to include one of these minerals either initially or the mineral may precipitate during the
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