1. Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, United
States
2. Department of Chemistry, Trent University, Peterborough, Ontario K9J 7B8, Canada
3. Department of Anthropology, Yale University, New Haven, Connecticut 06520, United
States
4. Institute for Geoecology, Technical University-Braunschweig, Langer Kamp 19c,
38106 Braunschweig, Germany
5. School
of Oceanography, University of Washington, Seattle, Washington 98195,
United States
6. St . Croix
Watershed Research
Station, Science Museum of Minnesota, Marine-on-St.
Croix, Minnesota 55047, United States