Pb and Sr isotopes from an ice-core provides evidence for changing atmospheric conditions at the Sajama icecap, South America K.J.R. Roman, S. Hong, G. Bulion, L. Burn, C.F. Boutron, C.P. Ferrari, L.G. Thompson, L. Maurice-Bourgoin and B. Francou J. Phys. IV France, 107 (2003) 1157-1160 DOI: 10.1051/jp4:20030505