1. Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
2. Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092 Zürich, Switzerland
3. Department of Chemistry, University of Zurich, 8057 Zürich, Switzerland
4. Department Ecohydrology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, 12587 Berlin, Germany
5. Geography Department, Humboldt University of Berlin, 12489 Berlin, Germany