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  1. Processing multiple samples

    From: Tiziano Boschetti Subject: Processing multiple samples I'm using a GWB 4.0.3 version. I've a database of 200 water samples and I'd like to calculate the saturation indexes. It's possible to copy at the same time more of one sample data in the spreadsheet form (edit--> Paste From Spreadsheet)? It's possible to include in the dataset, other than basis concentrations, a parameter as density?" From: Tom Meuzelaar Subject: Re: Processing multiple samples The ability to process multiple samples is not available in GWB version 4, but is available in GWB version 6 via TCL scripting. In the GWB 6 reference guide which you can preview on the GWB support page at: http://www.rockware.com/catalog/pages/gwbs...ort.html#guides there is an Appendix entitled "Multiple Analyses", which gives a sample script using SpecE8 that speciates and calculates saturation indices for multiple samples which are initially stored in a spreadsheet. You can use the control scripting features with any of the GWB 6 applications. You can set your initial fluid density in React via the Config- Variables menu. The default density unit is g/cm3.
  2. ACT2 and REACT not in agreement

    From: Andrew L. Scott Subject: ACT2 and REACT not in agreement I have been trying to model the Yucca Mountain J-13 well water in preparation for performing a sensitivity analysis for U speciation. Attached you will find the Statement of the Problem, some REACT output, the thermo dB, scripts for ACT2 and REACT and some calculation macros. I updated the thermo.com.v8.r6+ dB with the NEA 2003 numbers for U species only at 25 deg C. I hope someone is able to understand and help with my problem. I have tried to be as complete as possible with the materials I have provided, but if there is anything that I have not included or you do not understand something I have done, please feel free to ask. [A note from the admin: The files are not available From: Mark Logsdon Subject: Re: ACT2 and REACT not in agreement You certainly have been complete in your information. I regret that I don't have time to go throuygh all your calculations, but I have a quick question on the two bases you use. Your REACT basis gives Na at 2 mmolar and Cl at 0.2 mmolar. But the ACT2 basis has log a Na at - 3.5 and log a Cl at -2.8. Are you sure you are calculating the acivities properly? If you just take log C (as a quick consistency check) I get -2.7 and -3.7, respectively, so the log a values look funny to me - and in fact, their order doesn't look right either. I haven't tried to do this for other components or to check your spreadsheet. From: Tom Meuzelaar Subject: Re: ACT2 and REACT not in agreement I think I see the problem. If you allow NO3- to speciate over your activity diagram (in Act2, Basis tab, click the right-most arrow for the NO3- entry, and choose "Speciate over X-Y"), you'll get a very similar diagram to your Act2 plot (the "correct" plot) without NO3- (if you additionally suppress Coffinite, the diagrams look even more similar). In your original "incorrect" activity diagram, there is an implicit assumption that NO3- is stable over your entire Eh-pH range- React predicts, however, that most of your NO3- component will occur as the N2(aq) species- you can confirm this by looking at your React output file. By choosing the "speciate" option in Act2, you're allowing the program to predict which nitrogen species is stable- the outcome greatly effects the final diagram. From: Andrew L. Scott Subject: RE: ACT2 and REACT not in agreement Thanks for the feedback, particularly Tom Meuzlaar and Mark Logsdon. Based on their comments, I recalculated the basis and allowed speciation over the X-Y axis in ACT2, and now have perfect agreement (and a greater understanding of process) between ACT2 and REACT. ............... view attachments ........... http://gwb.eligeos.org/attachments/al-scott1.jpg http://gwb.eligeos.org/attachments/al-scott2.jpg ................................................... If the silicon species is not allowed to speciate, quartz will not precipitate, and allows the precipitation of Haiweeite, a uranyl silicate mineral, at equilibrium. This calls into question the kinetics of the two processes (quartz and Haiweeite precipitation/dissolution) with regard to the mobility of the U in the Yucca Mountain J-13 water (represented by the top-most green dot). ............... view attachments ........... http://gwb.eligeos.org/attachments/al-scott3.jpg http://gwb.eligeos.org/attachments/al-scott4.jpg ...................................................
  3. From: Biniam Zerai Subject: Info on CO2(aq) I am trying to model the possible reaction of CO2 gas, albite, annite, siderite, calcite and dolomite in 2 molal of brine solution. I made the correction for fugacity of the gas using Duan and Sun equation of state but I am not sure what is the right way as how to correct the salting-out effect using GWB. I have been told to change the the ionic size in the thermodynamic database that contains the aqueous species, CO2(aq) to -0.5 in order to correct the effect of salinity on CO2(g) solubility. Is this the right way to do it? I did it using the above advise and observe a large difference. Any info, input or comment is highly appreciated. I am using GWB 3.2.2. From: Craig Bethke Subject: Re: Info on CO2(aq) The equations used to calculate activity coefficients for electrically neutral species are given in Chapter 7 of the "Geochemical Reaction Modeling" text. The special meaning of the ion size parameter for neutral species is described in the "Thermo Datasets" appendix to the GWB Reference Manual: The ion size parameter (ao) has special meaning for neutrally charged aqueous species in the thermo dataset. For neutral species with ao = 0, the species' activity coefficient is set to one. When ao = 1/2, the activity coefficient is calculated from the "CO2" coefficients in the data table section, according to equation 7.6 in the "Geochemical Reaction Modeling" text. When ao = 1, the logarithm of the activity coefficient is set to the product B(dot)x I, where B(dot) is given by the data tables above, and I is true ionic strength.
  4. From: Tiziano Boschetti Subject: Correct formula for hydrated minerals I've noted that the water of hydrated minerals in the database thermo_phrqpitz is written as: H2O or ^H2O. So, if I add a new mineral, what's the correct form? From: Tom Meuzelaar Subject: Re: Correct formula for hydrated minerals As far as the software is concerned, the notation you use doesn't matter- what is important is that the formation reaction for the mineral is written only in terms of the 16 basis species in the thermo_phrqpitz database. Maybe another user can shed light as to whether or not there's any significance to the differing notation styles.
  5. From: GOLDEN, D. C. Subject: Evaporation of saline solutions containing Al3+ and Fe3+ I am trying to simulate the evaporation of acidic aqueous solutions containing Na, K, Mg, Ca, Mg, sulfate, Al and Fe. I use the flow through model of the React2 in GWB 4.0.3. I tried to use the data base for the Harvie-Moller-Weare activity model provided in the above package. When I include Al and Fe in the Basis, it responds : Al3+ not in the database, and similarly for Fe3+. Is there a data base for high ionic product solutions which takes into account these ions? How do I update the existing database to include these ions? If any one can help or give suggestions, I will appreciate it very much.
  6. From: Hlanganani Tutu Subject: Modelling geochemical speciation of uranium in sediments I need your help and advice on how I can do thermodynamic modelling of uranium speciation in sediments. Is it proper for instance if I measure the temperature, pH and redox potential of the moist sediment and then leach with deionised water (shake test) and measure sulphates and uranium in the leachate. Finally, I use these results to construct the Eh-pH diagrams. I'm studying the geochemical speciation of uranium in mine tailings and am using GWB release 4.0.1 for modelling. From: Armand R. Groffman Subject: Re: Modelling geochemical speciation of uranium in sediments I worked on a uranium mill tailings project in the USA (UMTRA) and here is what we did to determine U-speciation in pore fluids: Collect pore fluids with a suction lysimeter. If that is not possible performed DI batch tests. If sulphate is the overwhelming anion it is most likely the major complexing agent. Also check into alkalinity. If you need more detail then collect and analyze the pore fluids for organic carbon, major cations and anions (+ NO3), and trace elements including Fe, Mn, and sulfide. Look into the milling process to understand what residual organic products would be in solution and analyze for them or their degradation products. pH is easy. For redox use an ORP probe (a bit wonky) or if the tailings are not too acidic you may be able to determine redox by measuring Mn, Fe, or S-. This may be a better way to understand the redox potential of the system. Your model output will provide speciation and ppt products.
  7. From: Andrew L. Scott Subject: Database Conversion Routines Does anyone have any conversion programs for converting some other database format to that of GWB? I am particularly interested in converting the NIST Standard Reference Database 46- Critically Selected Stability Constants of Metal Complexes- Ver 8, Martell, et al.
  8. Since GWB does not natively run on Linux you have emulate Windows to get GWB running. So far I have tested two options: VMWare and Crossover Office. There is a slight difference between the two. In VMWare you install Windows as your virtual machine and then install GWB as you would in Windows. There are no major problems I know about, however, I recommend a fast machine for VMWare to operate fast enough. The cost is ~190USD (http://www.vmware.com). Crossover Office (based on Wine), on the other hand, will trick GWB (and a lot of other Windows programs) into believing it is being installed and run on Windows. While being a more efficient of the two, this option has more problems. As of now, it works but with numerous issues. It is possible that in the future (perhaps as soon as end of this year) GWB will run smoothly on COO/Linux. I am an official "advocate" for GWB at Codeweavers Compatibility Center. Please see http://www.asmirnov.org/os/gwb for details, screenshots and most up-to-date information. The cost is ~40 USD (http://www.codeweavers.com). Please let me know (alex[at]asmirnov.org) if you have any questions/suggestions/experience with anything mentioned above.
  9. Edward Grew Subject: Cerium redox equilibria Is anybody aware of experimental work on CeO2 - Ce2O3 equilibria? I am looking for a T - f(O2) diagram for Ce oxides. From: J. Michael Palin Subject: Re: Cerium redox equilibria I seem to remember various multiple valence oxide pairs, including CeO4-Ce2O3 and Eu2O3-EuO, shown on a T-fO2 diagram in: Carmichael, I.S.E. & Ghiorso, M.S. (1990): The effect of oxygen fugacity on the redox state of natural liquids and their crystallizing phases. in ¨Modern methods of igneous petrology: Understanding magmatic processes¨, J. Nicholls & J.K. Russell, eds., Mineralogical Society of America, Reviews in Mineralogy, 24, 191-212. There may also be something particular to Ce in: H.D. Schreiber, H.V. Luer, T. Thanyasiri (1980) The redox state of cerium in basaltic magmas: an experimental study of iron-cerium interactions in silicate melts, Geochim. Cosmochim. Acta 44: 1599-1612. From: Kees Linthout Subject: Re: cerium redox equilibria For a logfO2 vs. T diagram of the CeO2/Ce2O3 equilibrium and its calculation from the delta G data, see Appendix 1 in Hanchar et al. (2001, Am. Min. 86, 667-680). From: Eric Essene Subject: Re: Cerium redox equilibria You don't need experiments, just the delta G data for Ce2O3 and CeO2. That is only a crude guide however for the oxidation state of Ce in silicate crystals or liquids, unfortunately.
  10. From: Henry B. Kerfoot Subject: Request for kinetic data (calcite) I am looking for kinetic data on the reaction of calcite with low-pH water. In particular, I wish to be able to estimate an appropriate residence time for pH 3.5 water in commercially available limestone gravel.
  11. Pitzer and React

    From: Kirk J Cantrell Subject: Pitzer and React I am using React to calculate the solubility of a mineral at high ionic strength using the Phrqpitz thermo database. I modified the database to include a solubility constant for a mineral I am interested in, as well as some associated Pitzer parameters. Without giving you all the details, I have determined that the model is not using the new theta parameters for the interaction of two anionic species that I added to the Phrqpitz thermo database. The reason I know this is that at zero ionic strength, React is calculating the solubility correctly. When I go to 2 m NaCl, where the theta interaction parameters has a significant influence, the solubility calculated by React is less than half of what it should be (based on the model used to determine the solubility and Pitzer parameters for the mineral I am working with). If I go back and set the theta parameter in the thermo database to zero, I get the same solubility at 2 m NaCl. This suggests to me that for some reason, React is not including my newly added theta interaction parameter in the equilibrium calculation and that this is the reason the calculated solubility is too low. Do you have any clues as to why this could happen? To make locating my additions to the thermo database easier to find, I have indicated them here: In elements: Uranium (U ) mole wt.= 238.0290 In basis species: UO2(CO3)3---- charge= -4.0 ion size= 9.0 A mole wt.= 450.0554 3 elements in species 1.000 U 11.000 O 3.000 C In aqueous species: (UO2)3(CO3)6------ charge= -6.0 ion size= 20.0 A mole wt.= 1170.1386 g 3 species in reaction 3.000 H+ 3.000 UO2(CO3)3---- -3.000 HCO3- -19.5000 -19.5000 -19.5000 -19.5000 -19.5000 -19.5000 -19.5000 -19.5000 In minerals: Cejkaite type= formula= Na4UO2(CO3)3 mole vol.= 150.000 cc mole wt.= 542.0146 g 2 species in reaction 4.000 Na+ 1.000 UO2(CO3)3---- -4.0800 -4.0800 -4.0800 -4.0800 -4.0800 -4.0800 -4.0800 -4.0800 In beta virial coefficients: Na+ UO2(CO3)3---- beta0 = 0.61 beta1 = 18.2 beta2 = 0.0 cphi = 0.0 alpha1 = 2.0 alpha2 = 0.0 Na+ (UO2)3(CO3)6------ beta0 = 2.4 beta1 = 46.6 beta2 = 0.0 cphi = 0.0 alpha1 = 2.0 alpha2 = 0.0 In theta virial coefficients: Cl- UO2(C03)3---- theta = -0.13 SO4-- UO2(C03)3---- theta = -0.37 Note that (UO2)3(CO3)6------ is not required for the current calculations. This species is required for very high carbonate conditions and I intended to put estimates for its theta virial coefficients in the database later. Attachments to this post: http://gwb.eligeos.org/attachments/React-1...aiteSolPitz.rea http://gwb.eligeos.org/attachments/React-1...hrqpitz_kjc.dat From: Craig Bethke Subject: Re: Pitzer and React I think you will find that the cause of your trouble is that in entering theta values in the thermo dataset, you refer to species "UO2(CO3)3----" as "UO2(C03)3----". In other words, for these entries you've typed in C-zero-3, not C-Oh-3.
  12. From: Burnol Andre Subject: Convert Phreeqc format to GWB format or EQ3 format I am wondering wether a code converting Phreeqc to EQ3 format for the thermodynamic database is available ? I know that, recently, thermo_phreeqc.dat - The thermodynamic database from PhreeqC release 2.8 - is ready for use with GWB. But I don't know how the conversion was made ?! if a code was developed for this purpose, it will be not very difficult for me to adapt this convertor if the sources are available. I am currently using a modified llnl.dat in Phreeqc format and I would like to convert it in EQ3 format. It will be for me a big help not to have to rewrite all my modifications in EQ3 format or to develop myself the convertor.
  13. 'Best' database

    From: Andrew L. Scott Subject: 'Best' database I am performing uranium speciation of natural ground waters under various conditions, including speciation with organic and inorganic ligands. What are your opinions on the 'best' database to use for this application (please also consider databases that are not necessarily in GWB format, as I can convert if necessary). I am currently using thermo.com.v8.r6+, but want to ensure I am using the 'best' available data. I have available, for example, NIST standard reference database 46, critically selected stability constants of metal complexes v7.0, and could easily obtain v8.0 if necessary. From: J.L. Fernandez Turiel Subject: RE: 'Best' database You can try with the JNC database. The updates are recent. http://migrationdb.jnc.go.jp/english.html
  14. [OLD] Fe/As redox and sorption

    From: Brian Gibney Subject: Fe/As redox and sorption I am modeling the sorption of arsenic to Fe(OH)3 under the following circumstances: 1) Arsenic consistently oxidized, Fe redox slides from reduced to oxidized 2) Fe consistently oxidized, As redox slides from reduced to oxidized The basis for my reaction has been set up as below: hematite/Fe+++ = 1 free gram e-/O2 = 0 Eh Na = 100 mmolal Cl- = 100 mmolal (charge balance) SO4- = 10 mmolal Ca++ = 10 mmolal As(OH)4- = 0.1 mmolal H+ = 7 (pH) Reactants: react 1 g Fe(OH)3 ppd slide Eh to 1 Plots of reactions don't show a decrease in As sorption at low Eh (as iron is reduced), as one would expect. Any suggestions?
  15. Speciate different components over x-y

    From: "Brugger, Joel (SAM)" Subject: Speciate different components over x-y I'm trying to calculate a log f O2(g) vs pH diagram to show relationships between Fe-Ni sulfides. I therefore speciate SO4-- and Fe++ over x-y and make the diagram for Ni++. I get a nice diagram, but something disturbs me. The dashed boundaries correspond to the overlap of the boundaries for the pure Fe-O-H and S-O-H systems. It seems more appropiate that the boundaries for Fe should take into account Fe sulfides (e.g. pyrite), i.e. the Fe should be speciated in the Fe-S-O-H system. So my question is: is there any way to tell GWB to speciate S in the S-O-H system, and then Fe in the Fe-S-O-H system, and then to calculate the nickel speciate over these two diagrams? From: Craig Bethke Subject: Re: Speciate different components over x-y I think you'll find that the scheme you propose is not internally consistent and will not result in a unique solution. To convince yourself, try drawing such a diagram by hand. I think you will find that you end up with more than one way to balance the reactions among the Ni species.