1. Department of Earth and Environmental Sciences Michigan State University 206 Natural Sciences Building, 288 Farm Lane, East Lansing MI 48824 USA
2. British Geological Survey Nicker Hill, Keyworth, Nottingham NG12 5GG UK
3. U.S. Geological Survey 215 Limekiln Road, New Cumberland PA 17070 USA
4. Geology and Geophysics Section Naval Research Laboratory NRL Code 7432, John C. Stennis Space Center MS 39529 USA
5. Program for Isotope and Hydrochemistry Geological Survey of Brazil (CPRM‐SGB) Rua Costa, 55—Cerqueira César, São Paulo CEP 01304‐010 Brazil
6. Morwick G360 Institute for Groundwater Research University of Guelph 50 Stone Road East, Thornbrough Building, Guelph Ontario N1G 2W1 Canada