Brian Farrell

Dear GWB users, We are pleased to announce our latest maintenance release, GWB 11.0.6. The 11.0.6 update gracefully handles phase rule violations arising in buffered paths; when installing to an unexpected directory, installs software in a subdirectory "GWB"; overwrites existing files when installing, rather than deleting them; allows unix-style line endings in thermo datasets; increases the breadth of mass balance audits in X1t/X2t; fixes drag-and-drop for virial coefficients in TEdit, and in the Alter and Isotope dialogs in the various apps; no longer display announcements on dashboard; and resolves all known issues. Update from 11.0 - 11.0.5 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 Support tab of the GWB dashboard. Regards, Brian Farrell Aqueous Solutions

Hi Ben, I noticed a few things in your input file. First, you're actually adding a ferric sulfate, Fe(SO4)2-, instead of ferrous sulfate, FeSO4. As a result the Eh was increasing slightly instead of going down. Second, there are several redox sensitive basis entries that are playing an important role in the simulation as you've set it up. Looking at Manganese, for example, Pyrolusite is supersaturated in the initial system so it precipitates (consuming most of the free O2(aq) in the process) before the reaction path begins. The Fe++ in the ferrous sulfate at first goes into reducing the Pyrolusite to Mn++ (which you can see in plots of mineral mass or the concentration of Mn species vs. added FeSO4). You'll need to add a little more FeSO4 to start Cr(VI) reduction. If you expect all Manganese to be present as Mn(II), you can disable all of the redox coupling reactions involving Manganese. If you do this, the O2(aq) initially present will be the main consumer of the added ferrous iron, but once it's used up you'll eventually get into Cr(VI) reduction. If you'd like to specify Eh instead of the dissolved oxygen concentration, just swap the e- into the Basis and set Eh units. Either way, that is the variable controlling the initial oxidation state of all enabled redox couples. Hope this helps, Brian Farrell Aqueous Solutions LLC

Hi, The GWB doesn't draw diagrams exactly like that, but a solubility diagram made with Act2 should be useful. In a solubility diagram you don't set the activity of the main species to a fixed value like you do in an Eh-pH diagram. You instead set its activity to vary by making it one of the axis variables. The other species, which you set in the "in the presence of" section, are set to fixed composition. In this way you're still considering a range of ion products, but you're only adjusting the activity of one of the species composing the product at a time. To make a diagram, I started by decoupling all the oxidation states of vanadium and uranium. Then, I set VO4--- as the main species and as the y axis variable. I set H+ with pH units as the x axis variable. Finally, I added UO2++ and K+ to the "in the presence of" section and set them to " speciate over x". Hope this helps, Brian Farrell Aqueous Solutions LLC

Hi, You have to hit "More Reply Options" to add attachments if you're replying to an existing conversation. Regards, Brian Farrell Aqueous Solutions LLC

Hi Geoff, You're running GWB8, correct? Have you recently upgraded your computer's OS? What OS are you running? Does your dongle light up? Regards, Brian Farrell Aqueous Solutions LLC

Hello, Currently each separate sample that plots on a Durov diagram will be listed in the legend. If you're making a report and you'd like to clean up the legend, you can do so in another program like PowerPoint or Illustrator. Copy the plot from Gtplot by selecting Edit - Copy, then paste into PowerPoint (you may need to do a Paste Special and select the Enhanced Metafile option). Click on the plot and select Arrange - Ungroup. Once this is done you can select individual elements, such as the markers and text boxes in the legend, to move around or delete. For more information, please take a look at the "How do I export plots and save images?" and "How do I overlay my diagrams?" tutorials on our website. Hope this helps, Brian Farrell Aqueous Solutions LLC

Dear GWB users, Do you need more fun, sun, and Reactive Transport Modeling in your life? Pick your beach and join us in Perth or Miami for two days of hands-on training using The Geochemist’s Workbench®. -Perth, Australia on 8-9 February 2017. Early register by January 9! -Miami, USA on 20-21 March 2017. Early register by February 21! Register early to save $100! Students save an extra $100! And if you’ve participated in a previous workshop with us, you may be eligible to save even more. So many beaches, so little time. We hope to see you there! Cheers, Brian Farrell Aqueous Solutions LLC

Dear GWB users, Please join us February 8-9, 2017 in Perth, Australia for two days of hands-on training in Reactive Transport Modeling using The Geochemist’s Workbench. Register by January 9 and save $100! Students save an extra $100! And if you’ve participated in a previous workshop with us, you may be eligible to save even more. We hope you can join us! Sincerely, Brian Farrell Aqueous Solutions LLC

Hello, 1) Yes, you can certainly apply the GWB in corrosion research. 2) You can calculate the saturation state of minerals in a fluid using SpecE8, which is included in the GWB Student Edition, but to precipitate the minerals you’ll need React, which is included in the GWB Standard package. You might also want to use X1t and X2t from the Professional package, if you’re interested in reactive transport. Finally, Act2 and Tact, included in the GWB Student Edition, can be useful for understanding the geochemical conditions under which various minerals are stable. 3) You can use a thermo dataset compiled at the pressure of interest, but hydrothermal chemists not uncommonly assume the effects of confining pressure are small compared to the uncertainty in determining log Ks and activity coefficients. Note, however, that gas partial pressures are almost invariably significant. You account for the partial pressure of a coexisting gas by setting its fugacity. 4) The HCO3- basis entry in SpecE8 most commonly (and in its default state) is set up as a bulk constraint, meaning it refers to the sum of carbon species (CO2, HCO3-, CO3--, CaHCO3+, etc.). If you select the “free” option from the units pulldown, however, you’re specifying that the concentration you entered refers only to the individual ion. You should compare your constraints with the concentrations of individual species and the thermodynamic components in SpecE8’s output to verify your calculations. For more information, please see 2.1 Configuring a calculation, 2.2 Setting and constraining the basis, 7.1 Example calculation, and 7.2 Equilibrium models in the GWB Essentials Guide. If you’re referring to fluid produced from a wet-steam well (vapor and liquid phases), then you’ll need to use React to recombine the vapor and liquid phases to find the composition of the original fluid. For more information, see 23.3 Geothermal fields in Iceland in Craig Bethke’s Geochemical and Biogeochemical Reaction Modeling text. Regards, Brian Farrell Aqueous Solutions LLC

Also, are there any more ions (particularly anions) in the fluid that might also be sorbing to your sediments?

Hi Clark, Can you double-check whether the Kd for Pb in your surface dataset is correct? I ask because it's orders of magnitude higher than any of the other sorbing species. This is certainly possible, but you end up with a huge amount of sorbed Pb. The surface reactions aren't actually accounted for in the default setup with 100% solution, since no mineral mass is implied, but by setting porosity to .99, for example, you imply a small sediment mass which allows the surfaces reactions to be accounted for. The system needs a lot of Cl- to balance out the positive charge of the >Pb++ species. I think the problem is related to this. Like you, I'm not able to run the calculation with a porosity of .25, which is presumably the only correct porosity for your Kd. Another question, do the concentrations that you specify on the Basis pane refer to the concentrations measured in the fluid, or for the whole system (i.e. in the fluid and on the mineral surfaces)? If I assume the latter (using the "sorbate include" option), the calculations works just fine, but I'm not sure whether or not that's appropriate for your system. I'll continue to think on this, but if you could check into my questions that would help a lot. Regards, Brian Farrell Aqueous Solutions LLC

Hi, Act2 and Tact draw traditional stability diagrams accounting for aqueous species, minerals, and gases, but not surface species. I recommend using React to trace adsorption of your nutrients as a function of pH. You can repeat the procedure assuming a few different Eh values to see its effect. If you'd like, you can do a little post-processing work to assemble the results of each calculation into a single diagram. For some tips, take a look at the "How do I overlay my diagrams?" and "How do I retrieve numerical data from my plots" slideshows in the Using GWB section of our Tutorials webpage. Hope this helps, Brian Farrell Aqueous Solutions LLC

Hi Kelly, Gtplot currently requires that all samples have unique names. You should go back into GSS and add a suffix to any of your samples that are not uniquely named (i.e. B1W3_1, B1W3_2). Then, just go to Graphs -> Update Graphs in GSS or File -> Update Plot Data in Gtplot to refresh your plot. Hope this helps, Brian Farrell Aqueous Solutions LLC

Hi Morgan, Density is calculated from a correlation developed by Phillips et al. 1981 for NaCl solutions. The correlation uses the temperature, pressure (which corresponds to the principal temperatures in the thermo dataset), and salinity of the fluid. The program normally figures density as that of an NaCl solution with the same TDS (which it calculates by adding the masses of solutes) as the fluid in question, at the temperature of interest. With the command “density = chlorinity” you can tell the program to instead use the density of an NaCl solution of equivalent chlorinity. Please see 5.15, density, in the GWB Reference Manual for more information. Phillips, S. L., A. Igbene, J. A. Fair and H. Ozbek, 1981, A technical databook for geothermal energy utilization. Lawrence Berkeley Laboratory Report LBL-12810, 46 p. Hope this helps, Brian Farrell Aqueous Solutions LLC

Glad to hear that took care of the problem. Cheers, Brian

Hello Muhsin, 1) You can view the contents of any thermodynamic dataset loaded into a GWB app by going to File – View and selecting the .tdat file. This launches the TEdit app with the selected thermo dataset. The dataset lists all the chemical reactions (and their log K’s) considered by the programs. The datasets also include some bibliographic information for the sources of their thermodynamic data. 2) I don’t know what’s included in the FACT database. As mentioned above, you can look at the contents of any thermodynamic dataset used by the GWB programs with the TEdit app. And after you draw a diagram in Act2, you can look at the equations calculated for each reaction line by clicking “View Results” on the Plot pane. By the way, assuming you set an activity of 0.01 for HCO3, the program will assume equal activities for species like CO2, CO3--, CH4, etc., but for ethanol (C2H5OH), which has two C’s, it will assume an activity of 0.005. The text output file helpfully states these assumptions. If you want the calculations done in the GWB to match those done by hand or with another software package, you need to make sure they’re using consistent sets of thermodynamic data. The GWB datasets are fully editable, so this is something you can do without much trouble. 3) An Eh-pH diagram shows the predominant form of a chemical component at each of the pH and Eh values considered. It’s possible that CO2, HCO3-, CO3--, methane, and ethanol all exist at equilibrium with each other, but one species will predominate at any given condition, so only one species can plot at any condition. Try using Rxn to calculate equilibrium lines like those that appear on an Eh-pH diagram. You can set the activities of species in the reaction and the temperature to determine whether any reaction would favor the reactants or products at the conditions considered. Basically, there are areas where ethanol would be favored over methane, but in those same areas the inorganic carbon is favored over the ethanol. The ethanol, then, will never be a predominant species unless you suppress the more predominant forms of carbon. You could also try using the SpecE8 app to create an equilibrium model of a fluid with dissolved carbon at different pH and Eh values and look at the list of aqueous species. Ethanol will be in equilibrium with all of the above-mentioned species, but it will never be the most abundant species. Hope this helps, Brian Farrell Aqueous Solutions LLC

Hi Clark, The Ra++ in your reaction doesn't look like it's being recognized as an actual species, so I'm guessing it's +2 charge isn't being considered in the reaction. Did you originally use TEdit or a text editor to add this surface reaction? The thermo_minteq.tdat dataset doesn't include any Radium species, but you can certainly add them then make sure that modified dataset is being used to provide all the dissolved and mineral species necessary for your custom surface dataset. You can check the thermo dataset that's being read with your surface dataset by going to the Header pane of TEdit and looking at the "Thermo data" entry. If necessary, you can load a different dataset, such as your modified minteq dataset with Ra, by clicking the Browse button. Hope this helps, Brian Farrell Aqueous Solutions LLC

Dear forum members, This license management question was responded to privately. Regards, Brian Farrell Aqueous Solutions LLC

Hello, You'll want to use Act2 to make an Eh-pH diagram. If you're interested in ethanol or methanol, you should load a thermo dataset containing those species into the program. The thermo.com.V8.R6+.tdat dataset installed with the GWB contains info for both of these species. If you draw an Eh-pH diagram for HCO3- using that dataset, you'll find that methane is the predominant species under reducing conditions. Your best bet is to disable all of the redox coupling reactions involving carbon except for that between ethanol and HCO3-. To do so, just go to Config - Redox Couples... and in the pulldown that says "select with" choose Carbon, then hit decouple>>. Next, find the couple for Ethanol/HCO3- and re-enable that by hitting << couple. There are a few different minerals or aqueous species in equilibrium with ethanol, such as "C" or 1-Pentanol(aq) that take precedence over the ethanol, but you can remove them from the diagram by suppressing them from the Config - Suppress dialog. For more information on Act2, please see section 5, Using Act2, in the GWB Essentials Guide. For info on the thermo datasets included with the software and redox coupling reactions, please see sections 2.3, Thermodynamic datasets, and 2.4, Redox couples, respectively, in the GWB Essentials Guide. Hope this helps, Brian Farrell Aqueous Solutions LLC

Dear GWB users, Just a gentle reminder, there is only one month remaining until our Applied Geochemical Reaction Modeling workshop in Sapporo. The workshop will be held on October 20-21 in the Jozankei Hot Springs District, just outside Sapporo, at the very height of the autumn colors season. Your registration cost includes two nights of traditional accommodation at a genuine Japanese onsen, your meals, and transit between Sapporo and the famous Jozankei hot springs. We hope you can join us! Please register as soon as possible to reserve your place at this special event. Participants returning from previous workshops are eligible to save $100. Please pass this message along to your colleagues. Sincerely, Brian Farrell Aqueous Solutions LLC

Dear Hiro, We're very excited about GWB Release 12, but it likely won't be released for quite some time. For your information, Release 11 came out in January of this year, and we typically space new releases two years apart. As for your question, you cannot configure basis entries in X1t with custom units like SMOW-^2H or SMOW-^{18}O. Without accounting for fractionation, though, I'm not sure what you'd gain by transporting the stable isotopes instead of the thermodynamic components containing those isotopes (H2O, H+, O2(aq), etc.). Regards, Brian

Hi Hiro, The GWB's stable isotope fractionation model is currently limited to the React program. The feature is being generalized and developed for use in the reactive transport programs X1t and X2t for GWB Release 12. Regards, Brian Farrell Aqueous Solutions LLC

Dear GWB users, Just a gentle reminder: September 5 is the last day to early register for the Applied Geochemical Reaction Modeling short course to be held September 24-25 in Denver just before the 2016 GSA Annual Meeting. Register early and save $100! Best regards, Brian Farrell Aqueous Solutions LLC

Hi Neda, The GWB 11.0.5 maintenance release, now available, fixes the problem you encountered with gas transfer kinetics. You can update from the release candidate that we sent you earlier from the Help menu of any GWB app. Regards, Brian Farrell Aqueous Solutions

Dear GWB users, We are pleased to announce our latest maintenance release, GWB 11.0.5. The 11.0.5 update adds command line arguments and environmental variables for setting thermo, surface, conductivity, and isotope datasets, and for the default dataset directory; kills a false positive in an inconsistency test for the gas transfer kinetics feature; improves convergence when dramatically re-scaling system extents; corrects a problem when the Reactants pane displays exported function names in 64-bit rate law DLLs; and fixes a problem in Xtplot saving the coordinates of contour lines as text. Update from 11.0 - 11.0.4 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 Support tab of the GWB dashboard. Regards, Brian Farrell Aqueous Solutions