Estimate the amount and type of Precipitation

[aliahmadi]

Hi
I,m
main concentration of anions and cations in the beginning and end of the experiment (sand column) have been determined.
Mineralogy of the solid phase (within the sand column) is also specified.
How do I calculate the probability of precipitation reactions, and do they rate?

[dlparkhurst]

I suggest two approaches. The simplest is to take the solution compositions before and after and run a speciation calculation. All you need is a SOLUTION or SOLUTION_SPREAD definition for each water composition, but you need at least pH and major ions (Ca, Mg, Na, [K], Cl, SO4). The output will have saturation indices for minerals, positive SI may precipitate, zero SI may be dissolving or precipitating to maintain equilibrium, negative SI may dissolve.

The second approach is to do inverse modeling, where you try to find sets of reactions that account for the change in water composition that occurred while passing through the column (INVERSE_MODELING). You must select a set of minerals and gases that you think may be reacting and the program will try to find reactions that account for the changes in water chemistry. It is perhaps not as easy as it sounds, but it is the most direct way to try to account for the reactions in your system.