1. 1Department of Earth and Environmental Sciences, Michigan State University, 288 Farm Lane, East Lansing, Michigan 48824, USA
2. 2U.S. Geological Survey, 12201 Sunrise Valley Drive, Mail Stop 432, Reston, Virginia 20192, USA
3. 3Morwick G360 Institute for Groundwater Research, University of Guelph, 50 Stone Road East, Thornbrough Building, Guelph, Ontario N1G 2W1, Canada
4. 4Geology and Geophysics Section, U.S. Naval Research Laboratory, NRL Code 7432, John C. Stennis Space Center, Mississippi 39529, USA