1. Environmental Science Department, Barnard College, New York, New York 10027
2. Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964
3. Department of Earth and Environmental Science, Columbia University, New York, New York 10027
4. Environmental Health Science, Columbia University, New York, New York 10032
5. Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282
6. Department of Geology, University South Florida, Tampa, Florida 33620-5201
7. Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305
8. Department of Geology, Miami University, Oxford, Ohio 45056
9. Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996