1. Earth System Science Research Center, Geographic Institute, Johannes Gutenberg University Mainz, 55099 Mainz, Germany
2. Geographic Institute, University of Berne, Hallerstrasse 12, 3012 Berne, Switzerland
3. Environmental Isotope Geochemistry Group, Department of Geology, University of Illinois at Urbana−Champaign, 245 Natural History Building, 1301 W. Green Street, Urbana, Illinois 61801, United States