Using GetConcentrations() for redox reaction case

[SaiP]

Hi David,

I have a question regarding the use of 'GetConcentrations()' function in phreeqcRM. I am running a redox reaction with transport (transport solved by a CFD solver). When I have Fe+2, Fe+3 in the system, normal phreeqc classifies these as 2 different components. But in phreeqcRM, using GetConcentrations() returns me a single set of data which is a mix of Fe+2 and Fe+3 data (like the boundary concentration data of Fe+2 and internal concentration data of Fe+3).

My question:
1. Considering the scenario I want to model (redox reactions in a clogging system), do I need to consider transport of both Fe+2 and Fe+3 seperately (which I think shall be the case) or is the concentration data of Fe only is sufficent [in such a scenario I am not sure how can phreeqc distinguish between Fe+2 and Fe+3]?

2. If I need both the concetrations of Fe+2 and Fe+3, how can I get them. It looks like GetConcentrations() cant return the concentrations of both Fe+2 and Fe+3?

Thanks. 

[dlparkhurst]

You do not need to separate Fe into Fe(II) and Fe(III). A solution composition is defined uniquely by moles of H, total O, charge, and total moles of other elements (including total Fe).

There is an option to transport H2O, excess H (H not in water), excess O in place of total H and total O. The idea was that it might be numerically easier to transport because most H and O are in water.