Course content
After a short introduction to the program PhreeqC and existing data bases simple thermodynamic equilibrium reactions between aqueous, gaseous, and solid phases will be the focus. This will demonstrate how changes in environmental conditions affect the composition of natural waters, the distribution of redoxsensitive species and the saturation with regard to certain gas or mineral phases by dissolution and/or precipitation. Drinking water treatment using open and closed aeration, addition of limestone or mixing of different types of waters will be modeled as well as processes of groundwater rehabilitation, e.g. nitrate reduction by addition of methanol, the determination of the half life of reactive iron barriers, or carbonate buffering of acidic groundwaters. Finally, we will turn to more complex examples, considering kinetic processes and reactive transport, e.g. tritium degradation in the unsaturated zone, sorption in a lysimeter, surface complexation of arsenic on iron hydroxides and regeneration of a double porosity aquifer in a former uranium in-situ leaching mine (with WPhast). All exercises will be introduced with some theoretical background and hints for their realization in PhreeqC; afterwards all participants can work on their own computer with fulltime individual supervision.