Basic isotope calculation issue

[Tom Meuzelaar]

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Dec 10 2007, 10:52 PM

G'day,

 

I am very rusty on my GWB, but was hoping to use it to calculate some equilibrium sulfur isotopic compositions. reading the manuals, I am unsure whether I should be using RXN or REACT. My basic task is calculating the isotopic composition of different aqueous sulfur species across an FO2-pH diagram at T=300, by specifiying the bulk sulfur value. Is this feasible? I would love an example recipe, if there is one out there.

Thanks.

 

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Dec 11 2007, 12:48 PM

Hi:

 

Equilibrium table isotope fractionation calculations can be done using the React module. As a starter, I highly recommend looking at the "Fraction of stable isotopes" section starting on p. 26 in the GWB Reaction Modeling Guide (PDF). p. 27-28 gives an example that has some similarity to the system you are modeling.

 

To address your problem specifically, I'd recommend creating an initial system in equilibrium with a sulfur phase, and then adding a sliding oxygen fugacity or pH reaction path model, so that you can study the changes in sulfur isotopic composition over those composition gradients.

 

Regards,

 

Tom Meuzelaar

RockWare, Inc.