Basic Geochemistry Doubt

[snjaykdubey]

I have few doubts:

A) What is Inert Mineral Fraction? and How it can be calculated?
B) In transport modeling, can we view the change of porosity with respect to time.? (I would like to understand how the precipitation of mineral is effecting the diffusion process. Where porosity play important role)

[Pak]

I am not sure if that is useful or even true but maybe can help you to start.
Apparently, in the visual basic statements of Phreeqc there is:

GET_POR(10) --> Porosity in a cell (here, cell 10), used in conjunction with Basic function CHANGE_POR in
multicomponent diffusion.

Though I am not sure if it is the porosity as it is defined normally and how it affects Phreeqc. Actually I have not used or found info in the manual.

[snjaykdubey]

I am using below formula to calculate the porosity change with time.
I hope this will be fine.Any other suggestion

The dissolution/precipitation of mineral phases leads to changes
in porosity. These are evaluated through the following expression:

ϕ= 1- ϕinert -ω* ∑Vm*Cm(∑ summation)

where ϕinert is the volume fraction of chemically inert solid, m is the
total number of the mineral species, molar volume (m3 mol-1) cm, are the molar and the molality (mol kgw-1) of the mineral species, respectively.ω is the water mass fraction in the liquid (kgw kg-1).

Does phreeqc can help to understand change of porosity?

[dlparkhurst]

PHREEQC can calculate changes in the number of moles of minerals due to equilibrium or kinetic mineral reactions. This information can be changed into volumes as you have indicated. Changes in permeability or hydraulic conductivity are more difficult to evaluate.

It is possible to adjust the porosity only for multicomponent diffusion using the TRANSPORT data block.