[1] Paul Scherrer Inst, Lab Environm Chem, CH-5232 Villigen, Switzerland
[2] Univ Bern, Oeschger Ctr Climate Change Res, CH-3012 Bern, Switzerland
[3] Univ Bern, Dept Chem & Biochem, CH-3012 Bern, Switzerland
[4] UCL Inst Archaeol, 31-34 Gordon Sq, London WC1H 0PY, England
[5] HBKU Doha, Coll Humanities & Social Sci, Doha, Qatar