GGSD Program Details for PHREEQE

PHREEQE

Category	Geochemistry
Platform	DOS
Status	Public domain
Description	PHREEQE is a geochemical reaction model which is based on an ion pairing aqueous model. It can determine pH, redox potential, and mass transfer as a function of reaction progress, and also solution composition in equilibrium with multiple phases. The aqueous model, including elements, aqueous species, and mineral phases, is exterior to the computer code, is completely user definable, and has been regularly updated by the authors since its first release. It can simulate several types of reactions including addition of reactants to a solution, mixing of two waters, and titrating one solution with another. In each of these case, it can simultaneously maintain the reacting solution at equilibrium with multiple phase boundaries. It solves the set of non-linear governing equations using a combination of two techniques: 1) a continued fraction approach for mass balance equations, and 2) a modified Newton-Raphson technique for all other equations; the resulting linear equations are solved using Gaussian elimination. Activity coefficients are calculated from either the Debye-Huckel or Davies formulation. The data base includes the following elements: allumium, barium, borium, bromide, cadmium, calcium, carbon, chloride, copper, fluoride, hydrogen, iron, lead, lithium, magnesium, manganese, nitrogen, oxygen, phosphorus, potassium, silica, sodium, strontium, sulfur and zinc. It also has a database for arsenic, cesium, iodine, nickel, rubium, selenium, silver, and uranium.
Cost	US Dollars
Data formats supported	None stated
Supplier in United States of America	International Ground Water Modeling Center
Supplier in United States of America	Scientific Software Group