Changes in the occurrence of heavy metals in the tropical atmosphere during the past 22,000 years as recorded in Bolivian ice core S. Hong, J.K. Park, L.G. Thompson, C.F. Boutron, C.P. Ferrari, B. Franco and L. Maurice-Bourgoin J. Phys. IV France, 107 (2003) 633-636 DOI: 10.1051/jp4:20030383