Tom Meuzelaar

Hi Thomas: Attached is a working script that appends the input data to the output file. Have a look at the script in a text editor to see how the code is written. Let me know if this helps you. Regards, Tom

Hi Mathew: The default is closed, but it is not the only option. From the v8 Reactive Transport Modeling Guide: "In X2t, you most commonly let the program calculate the groundwater flow field as it evolves over the course of the simulation. You set the left and right boundaries to be either open or closed to flow, or to be crossed by a certain discharge. The top and bottom boundaries are closed to flow. You then set the head or potential drop across the domain and either the production or injection rate, or the head at each well. You can also import the flow field from another program. In this case, you set up a table of the fluid discharge from node to node along x, and another for flow along y. X2t reads the tables and uses the values they contain to set the flow field. In this case, fluid may enter or leave the domain across any of the boundaries, not just the left and right side." Regards, Tom

Hi Herdis: Whichever values you wish to plot as scatter data, whether it be your input file values (are these lab data?) or the alkalinity that SpecE8 calculates. By "export", I assume you mean: saving alkalinity data calculated by SpecE8 via the Gtplot interface, correct? To do this, plot the Carbonate alkalinity variable on the Y-axis - this is available under the System parameters variable type. Next, choose the File - Save Image.. menu option and save as type Text File (tab delimited) (*.txt). This should get it close to the form you'll need for plotting scatter data. I hope that helps, Tom

Hi Herdis: In your scatter data file, simply create a column with header Carbonate alkalinity and specify the correct values (mg/kg as CaCO3). Given that you have specified a bicarbonate concentration and pH, SpecE8 is already calculating alkalinity values for you. I don't think this pertains to your issue. SpecE8 will calculate an alkalinity value based on your pH and HCO3- input. What the user's guide is referring to pertains to setting an alkalinity value as input (suppose you have an alkalinity measurement, rather than bicarbonate). In this case, alkalinity be can set by first loading the HCO3- component into the Basis panel, and then choosing the alkalinity option in the units drop-down menu to the right. Alkalinity can not be set via the H+ component, hence the note that pH must be set explicitly. I hope that helps, Tom Meuzelaar RockWare, Inc.

Hi Thomas: Which database did you find this data in? Regards, Tom

Hi Thomas: You can simply add the "Go" statement to the end of your script (open the script in Notepad, add the statement "Go" as the last line, and re-save the script). It simply tells React to execute the script after loading. Can you email your input file and database to me at gwb@rockware.com? Thanks, Tom

Hi Johan: The scatter plot issue has been addressed in the latest patch release, v8.0.3. Please visit this thread for more information about the 8.0.3 patch. I hope that helps, Tom Meuzelaar RockWare, Inc.

Hi Thomas: You can accomplish this by appending the line: $type Input_script.sp8 >> SpecE8_output.txt after the 'Go' statement in your input script. Hope that helps, Tom Meuzelaar RockWare, Inc.

Hi Ari: The attached is close to what you are asking for- this is an Eh-pH diagram for Chromium, assuming that Cr6+ is not in equilibrium with the other Cr redox species. To plot total Chromium on the x-axis, you'll want to need a range of Cr+++ activity values as input. I hope that helps, Tom Meuzelaar RockWare, Inc.

Hi Ari: You cannot load multiple data files into SpecE8 v7 - you can speciate one fluid composition at a time. In version 8, you can store multiple analyses in the GSS spreadsheet, and call the SpecE8 module directly. I hope that helps, Tom Meuzelaar RockWare, Inc.

Hi Patrice: If you speciate your dataset via the Data -> Calculate menu in GSS, there's no provision for charge balancing (although you can calculate a charge imbalance and manually adjust one of your component concentrations based on this). If you speciate multiple samples using the Analysis -> Launch menu option, then simply set charge balance for an analyte as you normally would in SpecE8 when the first instance of SpecE8 comes up. The charge balance will be automatically set to the same analyte for subsequent instances, although you can change any instance if you'd like. I hope that helps, Tom Meuzelaar RockWare, Inc.

Dear GWB Users: We have released GWB 8.0.3 which addresses the following issues: Fix various issues in Gtplot and Xtplot, especially with respect to selecting units. Correct several problems with overlaying scatter data in Gtplot and Xtplot. New predefined variable "Time elapsed" in GSS to simplify adding scatter data to plot of kinetic simulations. Landscape printing of GSS data sheets. Assure data legend fits onto printouts of scatter plots User's Guides are hyperlinked Better support for landscape and color printing from GSS Improved "connect scatter points" feature in Gtplot and Xtplot Show per-kg units in GSS when calculating charge imbalance Fix a problem in multithreaded polythermal runs using Pitzer model Improve label positioning when copying special plots to clipboard Implement control scripts Provide two header files for user DLLs missing in 8.0 install Correct minor problem with report command Fix all known problems with the GUI Resolve all known issues with 8.0 through 8.0.2 Please contact me with any questions. Regards, Tom Meuzelaar RockWare, Inc.

Hi Patrice: We're unable to reproduce this from Excel- would you mind sending me the dataset that caused this error, and describe the import process? Feel free to send the data to gwb@rockware.com Thanks, Tom Meuzelaar RockWare, Inc.

Hi Thomas: You can certainly constrain the oxidation state of the system by swapping dissolved hydrogen in for oxygen- this would be one way to set up reducing conditions. You might review the sections on redox equilibrium and disequilibrium- by default, all redox reactions in the system are constrained via the master redox species, Oxygen. You can see all of your model constraints by looking at your saved model script in an ASCII editor, like Notepad. Best regards, Tom

Hi Thomas: You can model the partial pressure of any gas by simply swapping the gas in for the component it constrains and specifying its fugacity. You cannot model changes in confining pressure during a simulation. You could modify a thermodynamic database (using SUPCRT) for a different confining pressure, and model at that specific pressure. GWB does not calculate/track gas volumes. I hope that helps, Tom

Hi Thomas: You would need to compare equilibrium constant data between the databases for ChemApp and GWB. The GWB default database is compiled at 1 atm pressure. It is possible to create databases for higher confining pressures, but in most cases, doing so will not result in new log K data that exceed the inherent error of the database at 1 atm. I hope that helps, Tom Meuzelaar RockWare, Inc.

Dear Ari: Have a look at the Appendix entitled 'Multiple Analyses' in the GWB version 7 Reference Manual. I hope that helps, Tom Meuzelaar RockWare, Inc.

Hi Ari: It sounds like GWB is trying to write the calculation results to a directory that you don't have 'write' privileges to. By default, if you don't set an output directory, GWB will write to the /Program Files/Gwb directory. Have you tried changing the output directory using the File - Change Working Directory menu option? Be sure to set this to a directory that you have Admin privileges to. Cr6+ is available in the thermo.dat file as CrO4-- which forms a redox couple with Cr++++. So the easiest way to specify Cr6+ in your Basis is to swap CrO4-- in for Cr++++. But you might review the sections on redox equilibrium so that you know whether to initially specify a system in redox equilibrium or disequilibrium. I hope that helps, Tom Meuzelaar RockWare, Inc.

Hi: In this case, just enter a direct value for the H+ component as pH, and then swap in your pCO2 value, as CO2(g) for the HCO3- component. You are now constraining HCO3- based on partial pressure of CO2. Let me know if that makes sense, Tom Meuzelaar RockWare, Inc.

Hi Thomas: Without seeing your scripts, databases, model assumptions and configuration, it is really impossible to comment on the results. Regards, Tom Meuzelaar RockWare, Inc.

Hi Thomas: Charge balance issues may be one reason for non-convergence. A second may be that reaction path increments that are too large, or too small- this is especially true for kinetic models. For example, if you trace a reaction path over a million years, that includes a kinetic reaction which completes in a few days, GWB will likely run into numerical difficulty. You have the option to increase or decrease the default number of reaction path steps via the Config - Variables - delxi setting. Additionally, for kinetic simulations, React may choose the decrease reaction path intervals (thereby increasing the total number of reaction path steps) in order to come to a solution. Regards, Tom Meuzelaar RockWare, Inc.

Hi Thomas: Yes, I believe that is the default setting for the forum software- I am not exactly sure why- maybe the assumption is that people prefer to come back and check the forum for responses automatically and don't like getting the extra emails. Regarding the additional valence states for Vanadium and other reducing/oxidizing species- this is a critical issue that could be affecting solution stability. When you define your starting system, you want to define a system that is initially not too far out of equilibrium. For instance, if you have a large amount of Fe component in your system, and the system is initially oxidizing, it is better to specify your Basis species in terms of the oxidized species, Fe+++. Or, if you have a system that contains Uranium that's initially reducing, specify the Basis concentration in terms of U++++, and not U++++++. This is probably why you are running into trouble with adding certain components to your configuration. I hope that helps, Tom Meuzelaar RockWare, Inc.

Rob: Can you send me the complete surface dataset? You can email it to me at gwb@rockware.com if that's easier. Thanks, Tom

Hi Rob: I'm not quite sure how you've configured your script and surface databases, nor am I familiar with the acronym 'SCM' - however, in short, yes it is possible to configure a system with two sorbing minerals, either in equilibrium or metastable equilibrium. I hope that helps, Tom Meuzelaar RockWare, Inc.

Hi Thomas: Re-constructing the database is not just a matter of deleting extra species and minerals - the databases have to be constructed using the same basis species, same formation/dissolution reactions, and same log K values. For starters, I recommend that you take a look at the Appendix on Thermo Datasets in the GWB Reference Manual (you can access this as a PDF file from any of the module Help menus, or download this from the RockWare website). A couple of other details will help you get going: Always rename the database before you start modifications, in case it becomes corrupted Increment or decrement the number of Minerals, Aqueous Species in the section header whenever you delete or add a species Molar volumes, molar weights, log K values etc. must be carried out to the same number of decimal units shown for other species, or GWB will report an error Be careful to keep the same formatting, or GWB will report an error Unfortunately, there are no automated tools for doing this- formatting databases takes time and should be done only when you have scientifically valid reasons for doing so. Haphazard deletion or addition of species will result in compromising the integrity, internal consistency and validity of the database. Additionally, if you delete species upon which other reactions are built, you risk compromising the database beyond repair. You can receive instant notification when someone replies to one of your posts, by adjusting your email settings. This is described in this section of the forum Quick Start guide. I hope that helps, Tom Meuzelaar RockWare, Inc.