[1] Univ Lausanne, Inst Radiat Phys, CH-1007 Lausanne, Switzerland
[2] CHU Vaudois, CH-1007 Lausanne, Switzerland
[3] Univ Bern, Inst Phys, CH-3012 Bern, Switzerland
[4] Univ Bern, Oeschger Ctr Climate Change Res, CH-3012 Bern, Switzerland
[5] Swiss Fed Inst Aquat Sci & Technol, Dept Water Resources & Drinking Water, EAWAG, CH-8600 Dubendorf, Switzerland
[6] ETH, Inst Geochem & Petr, Swiss Fed Inst Technol, CH-8092 Zurich, Switzerland
[7] Czech Geol Survey, Prague 11821 1, Czech Republic