To understand hydrochemistry and to analyze natural as well as man-made impacts on aquatic systems, hydrogeochemical models have been used since the 1960’s and more frequently in recent times. Numerical groundwater flow, transport, and geochemical models are important tools besides classical deterministic and analytical approaches. Solving complex linear or non-linear systems of equations, commonly with hundreds of unknown parameters, is a routine task for a PC. Modeling hydrogeochemical processes requires a detailed and accurate water analysis, as well as thermodynamic and kinetic data as input. Thermodynamic data, such as complex formation constants and solubility-products, are often provided as databases within the respective programs. However, the description of surface-controlled reactions (sorption, cation exchange, surface complexation) and kinetically controlled reactions requires additional input data. Unlike groundwater flow and transport models, thermodynamic models, in principal, do not need any calibration. However, considering surface-controlled or kinetically controlled reaction models might be subject to calibration. Typical problems for the application of geochemical models are: • speciation • determination of saturation indices • adjustment of equilibria/disequilibria for minerals or gases • mixing of different waters • modeling the effects of temperature • stoichiometric reactions (e.g. titration) • reactions with solids, fluids, and gaseous phases (in open and closed systems) • sorption (cation exchange, surface complexation) • inverse modeling • kinetically controlled reactions • reactive transport Hydrogeochemical models depend on the quality of the chemical analysis, the boundary conditions presumed by the program, theoretical concepts (e.g.

To understand hydrochemistry and to analyze natural as well as man-made impacts on aquatic systems, hydrogeochemical models have been used since the 1960's and more frequently in recent times. Numerical groundwater flow, transport, and geochemical models are important tools besides classical deterministic and analytical approaches. Solving complex linear or non-linear systems of equations, commonly with hundreds of unknown parameters, is a routine task for a PC. Modeling hydrogeochemical processes requires a detailed and accurate water analysis, as well as thermodynamic and kinetic data as input. Thermodynamic data, such as complex formation constants and solubility-products, are often provided as databases within the respective programs. However, the description of surface-controlled reactions (sorption, cation exchange, surface complexation) and kinetically controlled reactions requires additional input data. Unlike groundwater flow and transport models, thermodynamic models, in principal, do not need any calibration. However, considering surface-controlled or kinetically controlled reaction models might be subject to calibration. Typical problems for the application of geochemical models are: * speciation * determination of saturation indices * adjustment of equilibria/disequilibria for minerals or gases * mixing of different waters * modeling the effects of temperature * stoichiometric reactions (e.g. titration) * reactions with solids, fluids, and gaseous phases (in open and closed systems) * sorption (cation exchange, surface complexation) * inverse modeling * kinetically controlled reactions * reactive transport Hydrogeochemical models depend on the quality of the chemical analysis, the boundary conditions presumed by the program, theoretical concepts (e.g.

Auch die zweite Auflage von "Grundwasserchemie" bietet als praxisorientierter Leitfaden einen schnellen Einstieg in die thermodynamische Modellierung. Neben einem minimalen theoretischen Hintergrund liegt der Fokus auf praktischen Beispielen mit dem Computerprogramm PHREEQC. In der Neuauflage sind nun zusatzlich die Moglichkeiten des CD-MUSIC Konzepts zur Oberflachenmodellierung erklart. Beispiele zum reaktiven Stofftransport umfassen nicht nur den 1d Transport in PHREEQC, sondern auch ein 3d Beispiel mittels PHAST und der graphischen Benutzeroberflache WPHAST. Unsicherheiten thermodynamischer Daten konnen mit Hilfe des Programms LJGUNSKILE modelliert werden. Wie in der ersten Auflage helfen detaillierte Beschreibungen der Losungen dem Nutzer, Schritt fur Schritt von einfachen hin zu immer komplexeren hydrogeochemischen Modellierungen zu gelangen. Alle Programme sowie die Losungen zu den Aufgaben befinden sich auf der CD zum Buch.