React - Low temperature simulations

[Vincent]

Hello,

 

I'm relatively new in the use of GWB (version 6.0.3). I'm especially interested in React to trace the evolutions of evaporating solutions and as function of temperature.

 

I know that for example it is possible to determine the precipitating parageneses with increasing temperature. However, my models aim at simulating surface processes on Mars. Therfore, I'd like to simulate the processes occuring under 0 C. I know that saline solutions at low temperatire have a lower eutectic temperature. In some cases some eutectic solutions can remain liquid down to -70 C (Ferric sulfate for example). I previously modelled such behaviors on simple salts using the Pitzer model. I know there is a Pitzer database working very well for evaporation but I would like to be able to use it in models at low temperature. Is there a way I could model/program this in the command section?

 

Also two quick questions:

- How can I calculate the water-to-rock ratio during evaporation other than manually by adding all the precipitated phases and dividing by the amount of water

- How can I extract the water activity (for example as a text file) calculated using the Pitzer model after running a model?

 

Thank you very much.

 

Vincent

[Tom Meuzelaar]

Hello,

 

I'm relatively new in the use of GWB (version 6.0.3). I'm especially interested in React to trace the evolutions of evaporating solutions and as function of temperature.

 

I know that for example it is possible to determine the precipitating parageneses with increasing temperature. However, my models aim at simulating surface processes on Mars. Therfore, I'd like to simulate the processes occuring under 0 C. I know that saline solutions at low temperatire have a lower eutectic temperature. In some cases some eutectic solutions can remain liquid down to -70 C (Ferric sulfate for example). I previously modelled such behaviors on simple salts using the Pitzer model. I know there is a Pitzer database working very well for evaporation but I would like to be able to use it in models at low temperature. Is there a way I could model/program this in the command section?

 

Also two quick questions:

- How can I calculate the water-to-rock ratio during evaporation other than manually by adding all the precipitated phases and dividing by the amount of water

- How can I extract the water activity (for example as a text file) calculated using the Pitzer model after running a model?

 

Thank you very much.

 

Vincent

 

Hi Vincent:

 

One of the two Pitzer databases compatible with GWB allows for temperature extrapolation at temperatures above 25C, but not below - this is the PHRQPITZ database (thermo_phrqpitz.dat). The other database, the Harvey-Moller-Weare database (thermo_hmw.dat) contains data at only 25C. So, there's currently no provision for working with Pitzer data below 25C.

 

As to your two questions - both the activity of water and total rock mass are reported in the header section of the text output file that is generated after you finish a React simulation. You can also use the Report command from the Command pane to explore simulation results interactively - have a look at the appendix section on the Report command in the v6 GWB Reference manual.

 

I hope that helps,

 

Tom Meuzelaar

RockWare, Inc.