Web Release Date: October 27,
Plutonium from Global Fallout Recorded in an Ice Core from the Belukha Glacier, Siberian Altai
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Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland, Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland, Australian National University, ACT 0200, Australia, Institute for Water and Environmental Problems, 656099 Barnaul, Russia, Texas A&M University, Galveston, Texas 77551, and Division of Climate and Environmental Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
Received for review May 12, 2004
Revised manuscript received August 9, 2004
Accepted August 26, 2004
Abstract:
Ice cores from glaciers situated near anthropogenic sources of air pollution provide important archives of the emissions of species with short atmospheric lifetimes. Here we present the history of atmospheric Pu fallout reconstructed from an ice core from the Belukha glacier in the Siberian Altai. Fourteen ice core samples covering the time period 1941-1986 were selected for Pu analysis, chemically processed, and measured using accelerator mass spectrometry. The Pu concentration peaks in 1963, coinciding with the maximum of the nuclear weapons tests and in concordance with the 3H activity concentration peak. The shapes of the 239Pu and 3H profiles reflect two main periods of atmospheric nuclear test activity: premoratorium testing before 1958 and postmoratorium testing in 1961 and 1962. Premoratorium tests contribute about 45% of the integrated Pu inventory. The average 240Pu/239Pu isotopic ratio is 0.18 ± 0.05, indicating that a large majority of the Pu in the Belukha glacier originates from global stratospheric fallout rather than from direct tropospheric input.
