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Kirkoff Xn

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  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
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