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Kirkoff Xn

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Everything posted by Kirkoff Xn

  1. Hi there, Just to ask if there is a definition of the acronym GSS (the GWB spreadsheet program). This may be applied to other GWB programs. I am asking for publication purposes. Thanks
  2. Yeah, It's due to large residuals. Can you please advise how to go with this considering there might be a large difference in electroneutrality(?)Injectant.gss
  3. Hi there, I am running into an issue. It looks like it's a bug as I am receiving an error message "calculation error report" (see below screenshot) When trying to calculate mineral saturation or charge imbalance by clicking to "analyte"---> "calculate with specE8", I get this error.
  4. I understand that the domain area cross-section in this case is 2,000 m^2 and that the volumetric flux is dependent on the length of the domain (considering that cell lengths are all the same). My question here is how to set up an accurate vol. flux value so that one can further be able to calibrate observed and simulated values of solutes (in a 3D).
  5. Hi Jia, Just a follow-up to this question. Let's say an injection well has a capacity of 0.26 m3/s and you want to run a 2D model in GWB with the same domain dimension above (1Kmx 1kmx 2m). How would you input the volumetric flux? Am not sure if considering the domain area cross section as unit (1m2) is accurate so that the flux would be 0.26 m/s(?). Thanks
  6. As you advised, I wanted to check the groundwater composition in equilibrium with the 3 main mineral phases of the aquifer matrix since in my 3D model, the reactants (the 3 minerals) did not have any influence on the ground-water composition throughout the reactive model run. Since these minerals are initially present in my system, It is possible that O2(aq) reported is not accurate. React is though limited in mimicking the operational methodology I am trying to investigate. That's why I am using React to just investigate the initial composition of the native groundwater before injection. As far as the Volume % in the mineral phase goes, I know that the aquifer is made of calcite (98%) and a small amount of pyrite (1.5%), and arsenopyrite (0.5%) with 0.2 porosity.
  7. Thank you, Jia! I will try using React to simplify this conceptual model. There is no Fe(OH)3 based on the results from the aquifer matrix mineralogy. Question: Is there an example out there that could help in computing/correcting mineralogy and fluid chemistry using React? It looks like that's where I should have first started from. Also, I can calculate the zone influenced by the ASR well stresses, but not in GWB. Can you elucidate how to go with it using GWB? Does it mean I can just plot Br- (or Chloride) versus X position? Thanks
  8. Maybe I need to further give a context of my conceptual model adding the below figure. As you can see, the cumulative storage volume as a negative correlation with arsenic concentrations, meaning that the more the buffer zone is maintained and enhanced, the more the arsenic is immobilized and the only way I am thinking of it is the formation of Fe(OH)3ppd for surface complexation around the ASR well. And yes, I neglected the background groundwater flow considering the high flow rate induced by the ASR well during the operation. And you're right that the No Buffer" scenario yields more Fe(OH)3ppd than the buffer scenario, which is quite unexpected!
  9. Hi Jia, Thank you for your insightful comment. As far as the amount of O2 assigned goes, the native groundwater (initial system and Native_GW) has O2 of 0.01 mg/L and the injectant has O2 of 4.5 mg/L. The operational methodology developed can be found in "Wells" pane and there you can see that both scenarios totally differ in their operations. In the case of Buffer Zone, the methodology is such that a buffer zone (see attached picture below) is maintained and there is no over recovery of water that has been injected, hence promoting more oxidizing environment around the ASR well. However, in the 2nd case of "No Buffer zone" there is over-recovery and therefore oxygen concentration is way lower than in the case of "Buffer Zone" scenario. I understand that the pH also controls the sorption capacity; maybe I need to set a fixed pH considering the buffering capacity of carbonates? But even that, it does not help. I was expecting high oxidizing conditions around the ASR well to promote more Fe(OH)3ppd for surface complexation in the buffer zone scenario, but it looks like I need to refine my conceptual model. Thanks
  10. Hi Brian and Jia I come across an issue and would appreciate if you would help out , and maybe suggest how to go with my model. Conceptually, I am trying to test an operational methodology that has shown promised in attenuating the geogenic arsenic contamination during aquifer storage and recovery. Basically, I am running two model scenarios: the first one (ASR_Buffer Zone) aims in creating a buffer zone by promoting an oxidizing environment around the ASR well during all cycle tests (3 cycles in this case). The second (ASR_No Buffer_Zone) corresponds to over-recovery that usually results in releases of arsenic up to levels higher than their maximum contaminant level (10 µg/L) in the groundwater. While the first scenario promotes formation of Fe oxyhydroxide with high sorption capacity of trace elements (hence arsenic attenuation around the ASR well), the second scenario tends to deplete oxygen around the ASR well; with oxygen depletion, arsenic would tend to remobilize following Fe oxyhydroxide reduction dissolution. I am working with the thermos database developed by Lazareva et al. (2013) called (Thermo_GKD.tdat, see attached) and the two-layer surface complexation database (FeOH+.sdat). As you can see on the ppt attached, the oxygen concentration in the first scenario is quite higher than in the second scenario, meaning that ideally the first scenario would promote more arsenic attenuation with formation of Fe oxyhydroxide (most of them, if not all, being weak HFO forms in my case). However, as seen on the 2nd slide, both scenarios seem to form almost the same amount of Hydrous ferric oxides by the end of the simulation time (954 days buffer zone scenario versus 884 days in the case of no buffer zone). I have tried to go with kinetic model scenarios of arsenopyrite, but it didn’t improve the results. Any advice to improve my model?
  11. Along the same lines, I would like to know how you calculated the Maximum sorbed and metal concentrations in solution [mg/kg] based on below attached table (retrieved from https://academy.gwb.com/acid_drainage.php)
  12. Hi there, I am trying to rework example 10.4 in the Geochemical and Biogeochemical Reaction Modeling book. On Table 10.1, I have hard time to understand how you found % of sites. E.g. the first weak site species, >(w)FeOH2+, Its concentration is 1.232 mmolal. I know that its site density is 0.2 mol/mol mineral. Can you elaborate how you found 65.9% here? Thanks
  13. Hi there, I would need your help in building a 2Dreactive transport model since it's my first time using GWB for this purpose. The model aims to simulate arsenic (As) behavior during aquifer storage and recovery (ASR). I have data from 3 ASR cycles (1 cycle includes Injection -storage-recovery) with injection and recovery rates. There are 1 ASR well and 2 monitoring wells. When the ASR well turns to recovery (negative discharge rate), is it possible to retrieve groundwater data composition at the ASR well grid cell? This will serve to compare this modeled data with the observed one for further calibration. Same with both observation wells (It looks like I would need to set very low recovery rate—instead of an ideal zero recovery rate for an obs. well—to retrieve the simulated data). Thank you,
  14. Hi Jia and Brian, I am running a reaction path model (flush) to ensure whether the aquifer minerals (calcite and dolomite) would dissolve. Dissolution is more likely considering that the injectant is less saturated in both mineral phases. While the reaction path shows calcite dissolution (see figure below), I am a bit perplexed considering that the saturation indices of both minerals show they are saturated throughout the reaction path (see 2nd figure attached). Is it possible for a mineral to dissolve while being stable throughout the reaction path within the system? How can this be explained? Can you advise how I can go with this? I am attaching the react input file. Thank you, Trace Rx Path.rea
  15. Hi Brian I am sorry; It appears that there is some misunderstanding. The volume of 1064.535 cm^3 does not seem to have been retrieved from React since it was used from the beginning (before running React) to calculate the volume of the solid matrix ,hence the volume of each mineral phase (Quartz, Calcite, Dolomite, Muscovite and Kaolinite). I was asking how that value was estimated because I try to find the density of the fluid from GSS (physical parameters....> density), It just gives blank cells with no values.
  16. Thanks Brian. Do you know of any paper (or resource) that can be helpful in estimating the fluid volume from TDS values? Or should I consider 1Kg of water though the groundwater has high TDS value.
  17. Thank you so much, Jia! Just a quick question about the value of fluid volume of 1064.535 cm^3 while the text says "1 Kg of water...". Is that value (1064.535 cm^3) from standard conditions? Thanks
  18. And as a follow-up to the above questions, when calculating carbonate (mineral) volume change, did you take into account both calcite and dolomite minerals or calcite only. With a +42 value, it looks like it's calcite. If it's only calcite, why didn't you consider dolomite? and if you summed up both calcite and dolomite volume change, does it mean that you minimized their difference in kinetics? Thanks for the clarification.
  19. Hi there I am trying to redo the alkali flooding simulation on page range 443-447 in Geochemical and Biogeochemical Reaction modeling book. Is the volume change on Y axis (Fig. 30.4) expressed as "delta"? If yes, I have a couple of questions on values found in Table 30.2 Consider NaOH flood, how did you calculate the change in pore volume (delta % and Alkali consumed (%)? Thanks
  20. Hi Jia I don't know if I misunderstood what's offered in GWB online academy https://academy.gwb.com/mixing_and_scaling.php Here's what's said about proportions "The horizontal axis shows the extent of mixing from purely the first fluid (seawater, on the left) to purely the second (brine, on the right); a mixing value of 0.4, for example, represents a mixture of 60% of the first fluid and 40% of the second." The first fluid is the reactant and the 2nd is in the basis pane...It looks like what you wrote is the reverse of what's written from the GWB online academy. Can you further explain this? And the Cl- concentration in fluid component looks not "geochemically sound"...I don't know if the flash scenario is the appropriate one...but that's what I think! Thank you
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