16 - Inverse Modelling

This example corresponds to the “Example 16-Inverse Modeling of Sierra Spring Waters” from the Phreeqc manual. It can be retrieved from the Phreeqc Website.

This example repeats the inverse modeling calculations of the chemical evolution of spring-water compositions in the Sierra Nevada that are described in a classic paper by Garrels and Mackenzie (1967).

Studies

This project contains 1 Studies.

PhreeqcStudy: “study_16 - Inverse Modelling”

Db used: “Phreeqc_dat” database

TITLE Example 16.--Inverse modeling of Sierra springs

SOLUTION_SPREAD

        -units mmol/L

Number	pH	Si	Ca	Mg	Na	K	Alkalinity	S(6)	Cl

1	6.2	0.273	0.078	0.029	0.134	0.028	0.328      	0.01	0.014

2	6.8	0.41	0.26	0.071	0.259	0.04	0.895    	0.025	0.03

INVERSE_MODELING 1

        -solutions 1 2

        -uncertainty 0.025

        -range

        -phases

                Halite

                Gypsum

                Kaolinite               precip

                Ca-montmorillonite      precip

                CO2(g)

                Calcite

                Chalcedony              precip

                Biotite                 dissolve

                Plagioclase             dissolve

        -balances

                Ca      0.05     0.025

PHASES

Biotite

        KMg3AlSi3O10(OH)2 + 6H+ + 4H2O = K+ + 3Mg+2 + Al(OH)4- + 3H4SiO4

        log_k  0.0      # No log_k, Inverse modeling only

Plagioclase

        Na0.62Ca0.38Al1.38Si2.62O8 + 5.52 H+ + 2.48H2O = \

                0.62Na+ + 0.38Ca+2 + 1.38Al+3 + 2.62H4SiO4

        log_k  0.0      # No log_k, inverse modeling only

END

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