Modellierung geochemischer Prozesseim Sickerwasser und Grundwasser : Beispiel: Die Pyritverwitterung unddas Problem saurer Grubenwässer

Abstract

Thermodynamic equilibrium models represent an important tool for the description of geochemical processes in natural ground and seepage water systems.In part I of the thesis, interpretation methods are presented and discussed at the example of data from different geochemical environments. Furthermore, the effects of analysis and calculation errors are critically assessed using sensitivity analyses. The investigations show that in natural systems, often kinetic equilibria rather than thermodynamic equilibria have to be assumed. Therefore, the model KINEQ was developed and calculations for a given set of up to three minerals approaching a kinetic equilibrium are presented and compared to the results for natural systems.In part II, labratory experiments and model considerations on the geochemical and kinetic processes accompanied with the formation of acid mine drainage are presented. In column experiments with quartz sand containing 2% pyrite and calcite, feldspar and kaolinite, pyrite weathering rates and the buffering effect of different minerals were investigated. The pH-dependency of pyrite dissolution rates was determined in microbiologically controlled column experiments. Microbially mediated pyrite weathering was found to have a maximum at pH 2-3with dissolution rates in the order of 10**-9 mol· m**-2·s**-1.