Dissolution from unknown mineral phases

[Loreto Martínez]

I am trying to find out the appropriate methodology for representing the following situation:

The experiment I am trying to model is a cell that contains 1kg sample of soil. This sample is aerated during 1 week, and at the end of the week the sample is flushed with 1 kg of pure water. The results of this experiment are the elemental species that were extracted through this flush, and that are dissolved in the 1 kg of water after the extraction. This soil is aerated and flushed continuously during 11 weeks (and the flush is done with fresh water in every iteration); therefore I have 11 set of results.
 I would like to know which one would be a good methodology to predict the phases that could have conformed the soil for obtaining the dissolved species present in the water.

Thank you so much for your help!

[dlparkhurst]

Check out INVERSE_MODELING in the PHREEQC manual. I would use PHREEQC, but there is additional discussion in the manual for the program NETPATH (https://pubs.er.usgs.gov/publication/wri944169).

Inverse modeling is not as easy as it might sound. You must choose plausible gases and mineral phases for reactants, but at least your initial and final water compositions are well defined.