Participants: Poul L. Bjerg, Peter Engesgaard (ISVA), Thomas H Christensen. The distribution of cations, including iron and manganese being important in relation to redox processes, in anaerobic leachate plumes is greatly affected by cation exchange although the cation exchange in leachate plumes by determining base saturation, selectivity constants (very few constants are available for Fe2+ and Mn2+) and comparing predictions with actual distribution in the plumes.