Simulación de la alteración de Microclina. L. Comparación de códigos de modelización geoquímica e incidencia de los datos termodinámicos

Abstract

Simulations of microcline weathering reactions (in closed system and reacting with a HCl solution of pH =4, at 25° C and 50° C) are formulated with the more recent versions of the computer codes EQ3/6, CHILLER, PHREEQE YHARPHRQ. The calculated reaction paths are strongly dependent of the thermodynamic constants for mineral equilibria but almost insensitive to variations in the speciation reactions enclosed in those codes for the selected conditions of simulation. Changes in the thermodynamic values for the mineral equilibria lead to important numerical differences in the predicted mass transfers, solution compositional parameters and also affect the number of secondary minerals involved in the simulation. So, differences in the thermodynamic data can induce variations in reaction path calculations as important as those produced by changes in the initial conditions of simulation. In spite of efforts on database updating, model sensitivity to mineral equilibrium constants is important and it must be taken into account in reaction path modeling of microcline weathering process.