1. Institute of Groundwater Ecology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
2. Department of Chemistry, Mwenge Catholic University, P.O. Box 1226, Moshi, Tanzania
3. Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, Wisconsin 53706, United States
4. Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
5. Departments of Soil Science and Civil & Environmental Chemistry, University of Wisconsin, Madison, Wisconsin 53706, United States
6. Institute of Hydrochemistry, Chair for Analytical Chemistry and Water Chemistry, Technical University of Munich, Marchioninistrasse 17, 81377 Munich, Germany