Irrigation water degradation is of the utmost interest to water and soil scientists throughout the world yet meaningful and accurate equations to describe the equilibria of one of the most important solid phases controlling water quality, calcium carbonate, are lacking.

The objectives of this research were to: 1) develop a model capable of describing carbonate equilibria in aqueous systems open to the air, and 2) to test the model against data for aqueous and soil-water systems.

A chemical model was developed that adequately described calcite equilibria over a range of ionic environments that have practical significance to water and soil scientists. The model includes equations to account for activity coefficient and ion-pair effects, and was verified utilizing data from the literature for aqueous systems open to the air.

Project Number 3109-59, 3109-144, A-048-NMEX