1. Institute of Environment and Resources DTU, Technical University of Denmark, Bygningstorvet B115, DTU, DK-2800 Kgs. Lyngby, Denmark, Center for Applied Geoscience, University of Tübingen, Sigwartstrasse 10, D-72076 Tübingen, Germany, Department of Chemical Engineering, Technical University of Denmark, IVC-SEP, Søltofts Plads, DTU, DK-2800 Kgs. Lyngby, Denmark, and Laboratoire de Chimie et Environnement, Université de Provence, Case 29, 3, Place Victor Hugo, F-13331 Marseille Cedex 3, France