Dr. Montserrat Filella
Institute F.-A. Forel
University of Geneva
Route de Suisse 10
CH-1290 Versoix
SWITZERLAND
e-mail: montserrat.filella at unige.ch
Dr. Wolfgang Hummel
Geochemical Modelling Group
Paul Scherrer Institut
LES OFLA/208
CH-5232 Villigen PSI
SWITZERLAND
e-mail: wolfgang.hummel at psi.ch