B_Kimball
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Posts posted by B_Kimball
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I am trying to estimate dissolved fluoride concentrations assuming a water sample is in equilibrium with both fluorite and calcite. This calculation gives me notably different total fluoride concentrations in GWB (~17 mg/kg F) and PHREEQC (~11 mg/kg F) when I use the wateq4f database for both programs. I have double checked to make sure the log K for fluorite solubility at 25 C is the same in both the GWB and PHREEQC versions of the database. Does anyone know why this discrepancy exists? Relevant files are attached.
Thanks.
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Thanks Brian. Your description of the "activity Kd model" does help.
I have tried using both the Kd approach and a surface complexation model (SCM) to account for uranium attenuation along the flow path. In reference to a SCM, you said the magic words: "if you can parameterize it." I have the age-old problem of desiring more site-specific data to inform my SCM. When I try to incorporate a SCM with the FeOH+.sdat database and our estimates of HFO concentrations in the aquifer, the predicted attenuation of uranium is much lower than we observe in the field. A Kd model gets me closer to what we observe, but as you imply, these models are not ideal, especially when the pH of the system is changing. I will continue to think about this.
Thank you.
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I am trying to model uranium attenuation in X1t using a simple Kd approach. I am using the Pb example and the associated Pb-Kd.sdat file as my template for this. The header of the Pb-Kd.sdat file states that the Kd value is given in units of mol/g solid. In other words, the sorbed concentration (mol/g) is provided instead of the actual Kd value (e.g., L/kg). Why is this the case?
On a related note, is it possible to utilize the Kd approach in X1t using Kd values that change with the pH of the system?
Thank you.
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Thanks Brian! It must have been the memory effect. I was able to get the plot I was aiming for.
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I updated to the latest version this morning. Now I'm finding that if I plot my results from a React run, I only have the option of a Piper diagram. When I open React-generated plots of constituents versus pH, made yesterday with the older version, they too open up as Piper diagrams. Any thoughts? Thank you.
12.0.7 maintenance release
in The Geochemist's Workbench
Posted
Hi Brian,
I just installed this maintenance release and now I get the error in the attached screen shot. I tried reinstalling and got the same error. Now GWB is not working at all. Any advice?
Thanks,
B. Kimball