1. Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
2. Oeschger
Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
3. Institute for Water
and Environmental Problems, Siberian Branch of the Russian Academy
of Sciences, 656038 Barnaul, Russia
4. Department
of Chemistry und Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland