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Arsenic Thermodynamic Data and Environmental Geochemistry



D K. Nordstrom, Donald G. Archer


Thermodynamic data are critical as input to models that attempt to interpret the geochemistry of environmentally important elements such as arsenic. Unfortunately, the thermodynamic data for mineral phases of arsenic and their solubilities have been highly discrepant and inadequately evaluated. This paper presents the results of a simultaneous non-linear weighted least-squares multiple regression on more than 75 thermochemical measurements of elemental arsenic, arsenic oxides, arsenic sulfides, their aqueous hydrolysis, and a few related reactions. The best fitted thermodynamic database is related to minearl stability relationships for native arsenic, claudetite, arsenolite, orpiment, regular with peplison}-pH diagrams and with known occurences and minearl transformations in the environment to test the compatibility of thermodynamic measurements and calculations with observations in nature. The results provide a much more consistent framework for geochemical modelling and the interpretation of geochemical processes involving arsenic in the environment.
Arsenic in Ground Water: Geochemistry and Occurrence
Publisher Info
Springer, New York, NY


arsenic, geochemistry, minearl stability, modelling, speciation, thermodynamics


Nordstrom, D. and Archer, D. (2003), Arsenic Thermodynamic Data and Environmental Geochemistry, Springer, New York, NY (Accessed July 18, 2024)


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Created December 31, 2002, Updated October 12, 2021