Jia Wang

Hello Katerina, The sit activity model was added to the software in a later GWB release. The free GWB Community Edition includes the sit activity model. If you need more advanced features, you can upgrade your GWB 10 license to a GWB Subscription to get access to all the latest updates. Our special offer currently offers a 50% savings on the first year of subscription when you upgrade from an eligible license. If you are interested, please fill out our contact form to request more information. We also can provide a demo license of the latest release if you are interested in trying out the software. Best regards, Jia Wang Aqueous Solutions LLC

Hello Gregg, Glad to hear that helped. Best, Jia

Hello Zhidi, Thank you for attaching your script. To troubleshoot, I checked "Follow Output" in the Results pane and "explain on" in the Stepping dialog before running your model to get a better idea what is limiting the size of the time step in the simulation. Doing so, I noticed that the rate limiting constraint right before the model runs into the newton-raphson iteration error is due to the change in Q/K for reactant Illite. To test, I simplified your model by setting Illite to a reaction rate of 0 and was able to run your simulation to completion. I also noticed that the reaction rates for various minerals do vary quite a lot be Could you provide a bit of context regarding your fluids and simulation? I noticed that a lot of component concentrations are the same but with a few differences. Are these fluids you have created or measured? I noticed that you have added all minerals as a kinetic reaction except Halite as a simple mineral. In general, kinetic reactions are useful for reactions that are proceeding slowly but measurable over the time period of interest. I noticed that Quartz is dissolving so slowly that it's not really doing anything. If the mineral barely reacts then perhaps you do not need to consider it in your model. This can help to simplify things in terms of the kinetic reactions running through your system. We don't typically see simple minerals, which are incrementally added to the domain over the course of the simulation in a reactivate transport simulation. If a mineral is in equilibrium with the initial fluid in the system, you should consider swapping it in for a component in your Initial pane. In general, it is good to check that the log Ks in the thermo database are suitable for the type of reactions occurring in your system. Hope this helps, Jia Wang Aqueous Solutions LLC

Hello Peter, There is theoretically nothing stopping you from overwriting a memory location. However, 'Order1', for example, is defined reactant by reactant in the Reactant class. Based on your description, it appears that you would want to use a member from the Reactant_status class instead of reactants. A member in the Reactant_status class is reported at every nodal block. Hope this helps, Jia Wang Aqueous Solutions LLC

Hello, You're welcome. I'm glad to hear that you're familiarizing yourself with TEdit. The GWB does not maintain any datasets. If you'd like to include the Zn-hydroxide reactions in thermo.tdat, simply copy and paste them from thermo.V8.R6+.tdat and save the customized dataset under a new name for your own use. Best regards, Jia

Hello Gregg, Millivolt isn't among the default units for Eh in Act2. However, you can easily adjust the units by editing the image in PowerPoint. Simply copy the image (‘Edit’ -> Copy as -> Enhanced Metafile) and paste it onto a PowerPoint slide. Once pasted, right-click the image, select 'Ungroup', then edit the y-axis values and change the label to mV. Hope this helps, Jia Wang Aqueous Solutions LLC

Hello Zhidi, 1 and 2. Section 2.9 Boundary conditions and 2.10 Reaction intervals in the Reactive Transport Modeling guide explains how to set the fluid composition that you would inject at the boundary and the time length for how long you set the injection to last for. In section 3.2 Setting flow rate specifically informs how you can set the flow. You can set discharge directly but X1t also accepts pore_volumes flushed over the time length of your simulation. The pore space is considered as the saturated volume of the domain. In reactive transport models, the bulk volume of the domain is set by what you provide in the Domain tab. Unlike single-node apps, the bulk volume in a reactive transport model is determined by the domain size. 3. Please refer to section 2.12 Porosity evolution to see how this is handled in RTM apps. 4. Please see chapter 2.11 Kinetic reactions and gas buffers about setting reactants. If you are adding a Simple reactant, this is titrating in a set amount of mass over the course of the simulation, which is the same as React. If you are adding a kinetic mineral, then the mass or volume of the mineral set is in your initial domain. You can go about this in two ways, using either a relative unit (e.g. volume %) or absolute unit (e.g. mg) for each nodal block. Please section 2.7 Initial conditions in the same user guide to see how different types of units affect the way your problem is set up. Before jumping into the reactive transport modeling applications with your own problem, I think it is best to familiarize yourself by examining the examples provided with the guide. A good one to start would be the example of rainwater infiltering a quartz aquifer in section 3.6 of the RTM guide. Another good example is Chapter 3.8 Example: weathering in a soil profile. Hope this helps, Jia Wang Aqueous Solutions LLC

Hello, Changing the thermo file in your Preferences dialog will only affect new instances of the GWB applications. You can change dataset of any current or existing input file by going to "File" menu -> "Open" -> "Thermo Data...". Please see my response to your other post for how to view the currently loaded thermo dataset. Please consider posting to the same thread when you are following up on issues. It would be easier to keep track of related topics when you post to the same thread. Hope this helps, Jia

Hello, Thank you for attaching your input file. The best way to see the reactions in a thermodynamic dataset loaded into your current calculation is to go to the "File" menu -> "View" -> click on the file with the extension .tdat or .dat to open in the TEdit application. You can filter on the element Zn and see all species containing Zn in its reaction. You can also use TEdit to edit datasets to add reactions from literature. For more information on using TEdit, please refer to chapter 9 in the GWB Essentials Guide. The default thermo dataset, thermo.tdat, doesn't contain any Zn-hydroxide species. An expanded version of the LLNL database, thermo.com.V8.R6+.tdat, is included in the software installation. Please see section 2.3 Thermodynamic datasets in the same guide for more information on datasets installed with the software. Hope this helps, Jia

Hello Nick, You're welcome. I hope the rest of your project goes smoothly. Best regards, Jia

Hello, It is very difficult to say what the issue might be without seeing your input file. A common error is that the species of interest may not be included in the thermo dataset. In that case, you will need to switch to another dataset that contains the species reaction you want to draw the activity diagram for. Another common error is that more stable species may appear and you need to suppress these for species unstable species may appear. Please see section 2.3 for more information on Thermodynamic datasets of the GWB Essentials Guide. You can find examples using Act2 in chapter 5 in the same guide. If this doesn't help and you would like someone to take a closer look, please attach your input file and thermodynamic dataset, and provide more context on what you are trying to create. Hope this helps, Jia Wang Aqueous Solutions LLC

Hello, Thank you for providing additional details. I do not have access to the models presented in Lazavera et al., 2015 and Horne et al. 2022. If you are trying to replicate their results or are working with their script but not seeing the expected results, I would suggest that you contact the corresponding authors on the publications. Swapping a mineral for a component in the basis tells the program to calculate that component's dissolved concentration in equilibrium with that mineral. You would only want to do this if you can assume that the mineral is in equilibrium with your initial fluid. Based on what you said above, it doesn't sound like this would be the appropriate path. You can find more about configuring your system in chapter 2 of the GWB Essentials Guide. Best regards, Jia

Hello, Thank you for your thoughts and feedback on the program. This change is one of many updates to the software year about a decade ago. At this point, many other features in the program have been built upon this, and it would be very difficult to revert back to older behavior. Best regards, Jia Wang Aqueous Solutions LLC

Hello Nick, Are you talking about entering data into GSS or another GWB application? The software by default sets the total concentration (the mass of the thermodynamic component). What you enter for HPO4-- is a bulk constraint equal to the sum of H2PO4-, HPO4--, PO4---, etc. species. The software does allow you to specify the HPO4-- free ion concentration and calculate additional mass for other phosphorus species. To specify a free species concentration in GSS, you can right-click on the unit (e.g. mmol/kg) and select "Free". In another application like SpecE8 or React, you would left-click on the unit and select "Free". For more information regarding free vs. bulk concentrations, please see section 7.2 Equilibrium Model in the GWB Essentials Guide. Best regards, Jia Wang Aqueous Solutions LLC

Hello, Thank you for attaching your input file. From your input file, it looks like you are titrating a set amount of mass into the entire domain over the course of the simulation. When you add minerals as simple reactants, they are added to the domain incrementally throughout the simulation to alter the composition of your system. Was this what you intended? Perhaps you need to consider swapping in minerals if they can be treated as in equilibrium with the initial system or set them as kinetic reactions instead. If you plot the Mineral Saturation index for Arsenopyrite2 you will see that the mineral is undersaturated with respect to the fluid, so any simple Arsenopyrite2 added will not remain in the solid phase. You can check the mass of Arsenopyrite2 added in by plotting the Variable type "Reactants properties". If you would like further help with troubleshooting, please provide a bit more context as to what you are trying to do. Hope this helps, Jia Wang Aqueous Solutions LLC

You're welcome Scott. Glad to hear that helped. Best regards, Jia

Hello, I apologize for the delay. I was revisiting the previous post and the new file posted. I can see that the files have slightly different chemistry and a sliding Eh path. To start troubleshooting, I would suggest that you simplify your run by removing your sliding Eh path and perform a speciation calculation with just your basis composition. You can check the resulting H2(aq) concentration and see that it's very large, on the order of hundreds of thousands of molal. You may also need to consider whether redox disequilibrium is necessary for any reactions. The software assumes by default that redox species are in equilibrium, as such the program will distribute the bulk concentration set across different redox species. You can disable redox equilibrium for the appropriate species pair and specify the bulk concentration for each oxidation as needed. Please see section 2.4 Redox couples and 7.3 Redox disequilibrium of the GWB Essentials Guide for more information. Could you clarify what you are trying to do by swapping in FeCl3 into the basis? Reading your description, it sounds like you might want to titrate in FeCl3 or an FeCl3 solution to create a fluid which then needs to be evaluated at a range of Eh or pH. Is this what you are trying to do? If so, you would want to enter the constraints for your original fluid in the basis and then set up a titrate path in the Reactants pane for FeCl3 or FeCl3 solution. You can examine the concentration at the end of this titration simulation. Then, decide whether to slide Eh or pH from the end point, or perhaps to change assumed value for initial Eh or pH and rerun to compare. The ionic strength of your solution is high. You might eventually want to consider using a virial activity model. Thermo.tdat is the default dataset and uses the bdot activity model. The bdot model typically loses accuracy as the fluid ionic increases pass ~ 0.3 molal. I would suggest you take a look at the virial models available (SIT or hmw) and consider them. You can view a summary of thermo datasets on the thermo page or find out more in section 2.3 Thermodynamic dataset in the GWB Essentials Guide. Please consider posting to the same thread when you are following up on issues. It would be easier to keep track of progress when you post to the same thread. Hope this helps, Jia

Hello Scott, The Kd.sdat file draws its elements and species from thermo.tdat, which does not contain molybdenum. You can view and change the thermo file loaded for this surface dataset on the Header pane. Hit the "Browse" button to change thermo file to one that contains the elements and species that you need to draw from to create your surface reaction dataset. Hope this helps, Jia

Hello, Thank you for providing the update on your script. The program accepts most of its configuration command prior to the time marching loop. Only some variables can be updated after initialization by sending the Config() command with a new value. These variables are "adjust_rate", "inert", and "adjust_mass" (Appendix: Configuration Commands chapter in the ChemPlugin User Guide). Some variables, like kinetic rate constants, are transient field variables, which can be set to be evaluated and updated during the simulation. The Log K for reactions cannot be updated with Config() after initialization and it is not a field transient variable. Best regards, Jia

Hello Scott, Could you provide a bit more detail about your attempt? Are you unable to find the element in your dataset? Or, is adding the desired reaction the issue? Best regards, Jia Wang Aqueous Solutions LLC

Hello Zhidi, Thanks for attaching your input file and your thermodynamic dataset. If I render the results in Gtplot and plot Mineral saturation vs. Time from your simulation, I find that Calcite is initially undersaturated with respect to your fluid but very quickly becomes oversaturated, with a Q/K value hovering right above 1. If I plot the amount of calcite (in Gtplot Variable type -> Mineral) available, it shows that there's an initial dip which indicates that calcite dissolved initially and then slowly increases, which means the mineral is precipitating. In this case, Ca is only added to the fluid from calcite in the first instances of the simulation and later removes Ca due to precipitation. Also, note that Dolomite and Anhydrite are both Ca containing minerals. These two minerals remain undersaturated with respect to the fluid and as they dissolve, they release Ca into the solution. In a multi-component system like this, the overall component concentration reflects the total effect of all reactions. The default built-in rate law for kinetic mineral reactions is r = A_s * k * (1-Q/K), where A_s is the surface area, k is the rate constant, Q is the ion activity product, and K is the equilibrium constant. In the GWB, a positive r means dissolution and negative r represents precipitation. When you are adjust the specific surface area or intrinsic rate constant in your rate law, the rate is linearly affected. The term Q/K determines whether the reaction is saturated, undersaturated, or in equilibrium. If your mineral is undersaturated, (Q/K is less than 1), then r is positive and the mineral dissolves. For more information on kinetic reactions, please see section 4 in the GWB Reaction Modeling User Guide. I think it would help you understand how the software handles kinetic reaction. If you make an example with just 1 kinetic mineral and look at how the results change with your simulation, without the effects from other minerals. The question of how to get your concentrations of your simulation to match that of your simulation is rather difficult to say without knowing anything about your system. You want to check that the kinetic constraints you are putting in are reflecting on what is actually occurring in your simulation. Maybe some requires a different rate law for constraining its kinetic reaction. Or maybe some minerals that are dissolved very fast can just be added as simple minerals. I am not really sure what is the most appropriate for your system. Best regards, Jia

Hello Karen, Thanks for attaching all your files. With every version of the software, you will need to recompile the function. In general, we recommend working in your own file space and not within Program Files, which has been known to cause issues. I noticed that in your screenshot of the command prompt, there was not a command executed for compiling the function. I think it would be best for you to try again, working in a local directory, and follow the most up-to-date steps for Compiled Rate laws in Chapter 5.3 of the GWB Reaction Modeling User Guide. Examples are provided for compiling and linking a function for a React run but you can make simple modifications for a corresponding X1t file. I would also recommend checking that you are working with the correct version of the compiler for your GWB installation. For example, if you have a 64-bit version of the software installed, you should use a 64-bit compiler. If this doesn't help to resolve the issue, please let us know what you have tried and which step had gone awry. Best regards, Jia Wang Aqueous Solutions LLC

Hello Zhidi, Thank you for attaching your input file. Could you also attach your thermodynamic dataset so we can run your input file? Best regards, Jia Wang Aqueous Solutions LLC

Hello Frank, The issue of plotting isotope user analyte is now corrected in the maintenance release 17.0.3. If automatic update is enabled, you should be prompted to update in the next few days when you open the GWB dashboard. You can also manually update by going to check for updates under the "Help" menu of any app or on the Support pane of the GWB dashboard. Best regards, Jia

Dear GWB users, We are pleased to announce our latest maintenance release for GWB subscribers, GWB 17.0.3. GWB 17.0.3 corrects a volume scaling issue under certain configurations, fixes a crash bug when plotting isotopic user analytes from GSS, streamlines floating license checkout, and addresses all known issues. Update from earlier releases of GWB17 at no charge to ensure you have all the newest features and bug fixes. Existing installations should automatically update to this release, unless auto-update is disabled. In that case, users should update their installations from the GWB dashboard or from the Help menu of any GWB app. Regards, Jia Wang Aqueous Solutions LLC