1. Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
2. Helmholtz Zentrum München, Institute of Groundwater Ecology, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany
3. Environment Canada, 11 Innovation Blvd., Saskatoon, SK S7N 3H5, Canada