1. Lamont-Doherty Earth Observatory of Columbia University, Route 9W, Palisades, NY 10964, USA.
2. Heidelberg Academy of Sciences, Institute of Environmental Physics, INF 229, D-69120 Heidelberg, Germany.
3. Eidgenössische Anstalt für Wasserversorgung, Abwasswerreinigung und Gewuässerschutz, Ueberlandstrasse 133, Postfach 611, CH-8600 Duebendorf, Switzerland.
4. Laboratory of Tree-Ring Research, University of Arizona, 105 West Stadium, Tucson, AZ 8572, USA.
5. Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, 1125 Jordan Hall, Raleigh, NC 27695–8208, USA.
6. Accelerator Mass Spectrometry