swhitman Posted May 18, 2020 Share Posted May 18, 2020 Hello, I am interested in calculating the charge balance of some chemical analyses and representing them graphically (e.g. with a pie graph in units of meq). The question I have is how to represent species that can be present in multiple valences (e.g. Fe). The default for Fe in GSS is as Fe+++, which is likely to be true for some of my samples, but not all. Do I need to do a SpecE8 run first and specify some kind of redox conditions in order to have Fe as both Fe++ and Fe+++? This question would apply to other elements with multiple charge states. When I calculate charge balance within the GSS program, is a speciation calculation run for the solution? Thanks, Spencer Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted June 1, 2020 Share Posted June 1, 2020 Hello Spencer, For your example of Fe++ and Fe+++, you can enter both valences on your spreadsheet if you decouple the redox coupling reactions between Fe+++ and Fe++. Decoupling the reaction will make Fe+++ available to add as a basis species to your spreadsheet. Secondary parameters such as charge imbalance and mineral saturation indices are done using SpecE8 for each fluid entry. Hope this helps, Jia Wang Quote Link to comment Share on other sites More sharing options...
swhitman Posted June 12, 2020 Author Share Posted June 12, 2020 Hello Jia, Thanks for the reply. Good to know I can manually specify the redox distribution by decoupling. What I was thinking I would like to do was to enter total iron, then enter either a redox couple (e.g. O(0)/O(-2) or my pe measurement, or specify redox equillibrium with a mineral phase (e.g. pyrite), and then speciate all redox species based on that. Is that possible to do? If so, can you help me with how to do it? Thanks, Spencer Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted June 15, 2020 Share Posted June 15, 2020 Hello Spencer, You can certainly calculate the redox species speciation given the proper constraints (e.g. the Eh or O2(aq) concentration) and total component concentration. GSS can use SpecE8 to calculate values for your spreadsheet, including species concentration. To do so, go to "+ analyte" and select "Calculate with SpecE8". Then select species concentration for variable type. In your example, you would select Fe+++ and Fe++. The species concentration calculated should be added to your spreadsheet once you hit apply at the bottom of the analyte dialog. Not that that the order of the analytes in the data sheet is important. In its calculations, SpecE8 will use the first constraint it finds for a particular basis component. For example, if both Eh and O2(aq) are present, SpecE8 will use whichever is first in the data sheet. You can easily change the order of the analytes by dragging, or hide analytes you don’t want used in the calculations. For more information, please refer to section 3.2.5 Calculating analytes in the GWB Essentials User Guide. Hope this helps, Jia Wang Quote Link to comment Share on other sites More sharing options...
swhitman Posted June 15, 2020 Author Share Posted June 15, 2020 Thanks Jia, very helpful. I think I am almost there. I can calculate the concentrations of the various species as you describe. However, using the Graphs -> Pie Chart (or Bar Chart) option in GSS, all of the iron is still listed as Fe++, but from doing the calculations, I know that most of the iron is present as Fe(3) (mostly FeSO4+). Does the "Fe++" on the bar chart just mean that that portion of cations is from the BASIS species (Fe++), and not actually Iron in the Fe(2) state? Also, I assume that "total component concentration" would be Fe in the original basis species (Fe++)? Quote Link to comment Share on other sites More sharing options...
swhitman Posted June 15, 2020 Author Share Posted June 15, 2020 Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted June 18, 2020 Share Posted June 18, 2020 Hello Spencer, Glad to hear that you are getting closer. The concentration you enter for the basis species represents the total component composition (e.g. Fe++, Fe+++, FeSO4+, FeCl+). In a bar graph, the concentration displayed assumes the concentration reflects the oxidation state of the analyte you have chosen, in this case Fe++. I think you might want to add in Fe+++ and represent the concentration for that analyte separately and select "free" unit for Fe++ and Fe+++. You can show all ions in the bar plot by unchecking "Common ions" in the parameters for Bar Chart dialog. Please see section 8.1 Plots type for an example. Hope this helps, Jia Quote Link to comment Share on other sites More sharing options...
swhitman Posted June 18, 2020 Author Share Posted June 18, 2020 Thanks again, sorry to belabor this, but I just can't seem to make these plots in a way that actually reflect the data, as explained below. I had gone over section 8.1 and de-selected "common ions". Something still seems wrong, but I can't figure out what. One thing I notice is that the bar chart (posted above) would seem to indicate about double the amount of ionic strength as what the results show (see text results below from SpecE8 for this water). I ended up making the plot I wanted using a combination of PHREEQC and Python, included below. The ionic strength is pretty consistent with that reported by the SpecE8 results, and it shows the major species that make up the composition of the solution, not just the basis species. I have tried to replicate this in GWB by doing as you suggest (adding or swapping basis species), but no luck so far. Temperature = 25.0 C Pressure = 1.013 bars pH = 2.510 log fO2 = -26.406 Eh = 0.6900 volts pe = 11.6642 Ionic strength = 0.187967 molal Charge imbalance = 0.014914 eq/kg (7.833% error) Activity of water = 1.000000 Solvent mass = 1.0000 kg Solution mass = 1.0124 kg Mineral mass = 0.00000 kg Solution density = 1.019 g/cm3 Solution viscosity = 0.009 poise Chlorinity = 0.000000 molal Dissolved solids = 12210 mg/kg sol'n Elect. conductivity = 8336.46 uS/cm (or umho/cm) Hardness = 2681.46 mg/kg sol'n as CaCO3 Water type = Mn-SO4 Bulk volume = 994. cm3 Fluid volume = 994. cm3 Mineral volume = 0.000 cm3 Inert volume = 0.000 cm3 Porosity = 100. % Permeability = 98.7 cm2 Nernst redox couples Eh (volts) pe ---------------------------------------------------------------------------- e- + H+ + .25 O2(aq) = .5 H2O 0.6900 11.6642 No minerals in system. Aqueous species molality mg/kg sol'n act. coef. log act. --------------------------------------------------------------------------- SO4-- 0.04130 3919. 0.2786 -1.9390 Mn++ 0.01958 1062. 0.3399 -2.1769 MnSO4 0.01480 2207. 1.0000 -1.8297 Fe++ 0.01175 648.0 0.3399 -2.3987 Mg++ 0.008345 200.3 0.3934 -2.4838 FeSO4 0.007277 1092. 1.0000 -2.1380 Ca++ 0.006824 270.2 0.3399 -2.6346 MgSO4 0.006378 758.3 1.0000 -2.1953 CaSO4 0.005576 749.8 1.0000 -2.2537 HSO4- 0.004752 455.7 0.7363 -2.4560 H+ 0.003794 3.777 0.8146 -2.5100 AlSO4+ 0.001625 197.4 0.7363 -2.9222 Al(SO4)2- 0.001462 316.4 0.7363 -2.9680 Zn++ 0.001348 87.07 0.3399 -3.3388 ZnSO4 0.001236 197.1 1.0000 -2.9079 Al+++ 0.0007423 19.78 0.1370 -3.9928 AlF++ 0.0002196 9.973 0.3103 -4.1666 K+ 0.0001531 5.913 0.7129 -3.9620 SiO2(aq) 0.0001208 7.167 1.0491 -3.8972 KSO4- 1.214e-05 1.621 0.7363 -5.0486 Cd++ 3.421e-06 0.3799 0.1332 -6.3411 AlF2+ 2.469e-06 0.1585 0.7363 -5.7404 CdSO4(aq) 1.513e-06 0.3115 1.0000 -5.8202 Cd(SO4)2-- 1.433e-06 0.4309 0.1332 -6.7192 AlOH++ 1.233e-06 0.05357 0.3103 -6.4173 HF 3.064e-07 0.006055 1.0000 -6.5137 F- 9.258e-08 0.001737 0.7250 -7.1731 MgF+ 1.886e-08 0.0008068 0.7363 -7.8574 MnF+ 1.327e-08 0.0009691 0.7363 -8.0101 FeF+ 1.196e-08 0.0008841 0.7363 -8.0553 H2SO4 1.068e-08 0.001035 1.0000 -7.9712 CaF+ 2.664e-09 0.0001554 0.7363 -8.7075 AlF3 1.532e-09 0.0001271 1.0000 -8.8147 Al(OH)2+ 1.139e-09 6.865e-05 0.7363 -9.0763 ZnF+ 7.515e-10 6.263e-05 0.7363 -9.2571 Al2(OH)2++++ 5.360e-10 4.658e-05 0.0428 -10.6399 FeOH+ 1.162e-10 8.364e-06 0.7363 -10.0677 MnOH+ 7.540e-11 5.359e-06 0.7363 -10.2556 H3SiO4- 8.648e-12 8.124e-07 0.7363 -11.1960 OH- 4.601e-12 7.729e-08 0.7250 -11.4768 Mn2OH+++ 3.331e-12 4.175e-07 0.1199 -12.3988 MgOH+ 2.335e-12 9.531e-08 0.7363 -11.7646 MgH3SiO4+ 9.342e-13 1.102e-07 0.7363 -12.1625 CaH3SiO4+ 3.750e-13 5.008e-08 0.7363 -12.5589 H2F2 2.516e-13 9.943e-09 1.0000 -12.5993 Al(OH)3 2.347e-13 1.808e-08 1.0000 -12.6295 CaOH+ 2.088e-13 1.177e-08 0.7363 -12.8133 HF2- 8.831e-14 3.403e-09 0.7363 -13.1869 AlF4- 3.507e-14 3.567e-09 0.7363 -13.5881 Al3(OH)4(5+) 2.206e-14 3.247e-09 0.0072 -15.7998 CdOH+ 2.004e-14 2.562e-09 0.6123 -13.9111 Mg2OH+++ 1.255e-15 8.132e-11 0.1199 -15.8228 KOH 1.156e-16 6.404e-12 1.0000 -15.9372 Al(OH)4- 1.056e-16 9.906e-12 0.7363 -16.1095 AlF5-- 4.609e-19 5.553e-14 0.2786 -18.8914 MgH2SiO4 4.587e-19 5.365e-14 1.0000 -18.3384 Fe(OH)2 1.582e-19 1.404e-14 1.0000 -18.8009 Mn(OH)2 4.435e-20 3.897e-15 1.0000 -19.3531 CaH2SiO4 2.735e-20 3.625e-15 1.0000 -19.5630 Mg(H3SiO4)2 1.599e-20 3.387e-15 1.0000 -19.7963 Mn2(OH)3+ 2.594e-21 4.122e-16 0.7363 -20.7191 Ca(H3SiO4)2 1.336e-21 3.039e-16 1.0000 -20.8742 H2SiO4-- 5.896e-22 5.480e-17 0.2786 -21.7844 Cd(OH)2(aq) 2.132e-22 3.084e-17 1.0000 -21.6711 H6(H2SiO4)4-- 3.564e-24 1.346e-18 0.2786 -24.0031 AlF6--- 8.397e-26 1.169e-20 0.0552 -26.3342 SiF6-- 5.848e-27 8.207e-22 0.2786 -26.7880 Mn(OH)3- 1.870e-29 1.957e-24 0.7363 -28.8611 Fe(OH)3- 1.096e-29 1.157e-24 0.7363 -29.0932 O2(aq) 4.723e-30 1.493e-25 1.0491 -29.3050 H2(aq) 3.302e-32 6.575e-29 1.0491 -31.4604 Cd(OH)3- 1.265e-32 2.041e-27 0.6123 -32.1111 Mg4(OH)4++++ 6.666e-39 1.088e-33 0.0428 -39.5452 H4(H2SiO4)4---- 9.174e-40 3.448e-34 0.0057 -41.2805 Mn(OH)4-- 1.337e-40 1.624e-35 0.2786 -40.4289 Cd(OH)4-- 1.676e-43 2.987e-38 0.1332 -43.6511 MnO4- 3.648e-52 4.286e-47 0.7363 -51.5709 MnO4-- 5.045e-54 5.927e-49 0.2786 -53.8522 Al13O4(OH)24(7+) 8.224e-67 6.685e-61 0.0001 -70.2934 H2S(aq) 1.805e-80 6.077e-76 1.0000 -79.7434 HS- 9.042e-85 2.953e-80 0.7250 -84.1834 S-- 8.543e-96 2.705e-91 0.3103 -95.5766 S2-- 5.318e-151 3.368e-146 0.2786 -150.8292 S3-- 8.189e-207 7.780e-202 0.2786 -206.6417 S4-- 4.507e-260 5.709e-255 0.2786 -259.9011 S5-- 3.375e-316 5.345e-311 0.2786 -300.0000 S6-- 0.0000 0.0000 0.2786 -300.0000 Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted June 23, 2020 Share Posted June 23, 2020 Hello Spencer, Like I said above, the concentration you enter for Fe++ in the GSS spreadsheet is considered as Fe++ when you are plotting from GSS. So that's why I suggested you adding Fe++ and Fe+++ separately. I don't think the graph is showing twice the ionic strength. If you add the individual species of that component, then you should arrive at the same concentration as shown in the plot. For example, if you summed all the sulfate species concentration and covert to meq/kg, then you should get the same value as seen plotted from the GSS spreadsheet. There should be a section below in your SpecE8 output file that shows you the total component concentration for that species (e.g. SO4--). The bar graph type plot does not plot individual species concentration, only component concentration. You can however retrieve each aqueous species concentration in units of eq/kg and make the plot separately in excel or python. To retrieve those values, you can plot your SpecE8 calculation results in Gtplot (in your SpecE8 window go to Results and click on plot results). An XY plot should pop up, if not, you can go to Plot on the menu bar up to and select XY plot. Double click on the center of the plot to bring up the plot configuration. You can configure one of the axis to show the variable type "species concentrations" and change the units to meq/kg (or eq/kg). Click ok or apply. Then go to the Edit --> copy as --> spreadsheet and paste your result into excel to view. You can manipulate this numerical result externally to plot as you wish. Hope this helps, Jia Quote Link to comment Share on other sites More sharing options...
swhitman Posted June 23, 2020 Author Share Posted June 23, 2020 Thanks. If I do as you said for the example of sulfate, I get the following for by-component equivalents with the bar graph (169.7 meq/kg for SO4--): Step Xi H2O Al+++ Ca++ Cd++ F- Fe++ H+ K+ Mg++ Mn++ O2(aq) SO4-- SiO2(aq) Zn++ meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg 0 0 0 12.01042 24.50093 0.012581 0.22226 23.2105 16.23034 0.163255 29.09023 67.92366 0 169.7019 0 5.106747 and the following for Total Sulfate Species (91.05 meq/kg) using the xy plot export procedures and selecting only SO4-- species (Total 91.05 meq/kg). Sulfate Species: Rxn progress Al(SO4)2- AlSO4+ CaSO4 Cd(SO4)2-- CdSO4(aq) Fe(SO4)2- FeHSO4++ FeSO4 FeSO4+ H2S(aq) H2SO4 HS- HSO4- KSO4- MgSO4 MnSO4 S-- S2-- S3-- S4-- S5-- S6-- SO4-- ZnSO4 meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg meq/kg 0 1.42095 1.629153 0 0.002644 0 1.338236 0.035607 0 6.387276 0 0 8.57E-82 4.508028 0.01168 0 0 1.58E-92 9.45E-148 1.41E-203 7.52E-257 0 0 75.71746 0 So, it appears there is a mismatch, unless I'm still missing something about how these plots are representing the data? Quote Link to comment Share on other sites More sharing options...
Jia Wang Posted June 25, 2020 Share Posted June 25, 2020 Hi Spencer, The bar chart expresses the bulk composition of the fluid in electrical equivalents and does not account for speciation. You can use SpecE8 to calculate the distribution of mass for each component and plot these results in an XY plot as electrical equivalents. The calculated results can be exported and be plotted externally. Please also note that the axis on the bar chart does not represent ionic strength of the fluid. If you want to check if mass balance is honored, you should use molality as the unit. If you add up the concentration of individual species, you will arrive at the bulk composition of that component. Best regards, Jia Wang Quote Link to comment Share on other sites More sharing options...
swhitman Posted June 25, 2020 Author Share Posted June 25, 2020 Quote The bar chart expresses the bulk composition of the fluid in electrical equivalents and does not account for speciation. Ah, OK. This is what I was looking for. I understand what it is doing now. It is not really a visualization of charge balance showing the major species, just which basis cations and anions make up the solution. Quote Please also note that the axis on the bar chart does not represent ionic strength of the fluid. If you want to check if mass balance is honored, you should use molality as the unit. If you add up the concentration of individual species, you will arrive at the bulk composition of that component. That makes sense. I'm not sure what I was thinking with the ionic strength for these charts. Thanks Again for your help. Spencer Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.