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Contamination of Alpine snow and ice at Colle Gnifetti, Swizz/Italian Alps, from nuclear weapons tests

Publication: Research - peer-reviewJournal article

Jacopo Gabrieli, Giulio Cozzi, Paul Travis Vallelonga, Margit Schwikowski, Michael Sigl, J Eickenberg, L Wacker, Claude Boutron, Heinz Gaggeler, Paolo Cescon, Carlo Barbante

Plutonium is present in the environment as a consequence of atmospheric nuclear tests, nuclear weapons production and industrial releases over the past 50 years. To study temporal trends, a high resolution Pu record was obtained by analyzing 52 discrete samples of an alpine firn/ice core from Colle Gnifetti (Monte Rosa, 4450 m a.s.l.), dating from 1945 to 1990. The 239Pu signal was recorded directly, without previous decontamination or preconcentration steps, using an Inductively Coupled Plasma - Sector Field Mass Spectrometer (ICP-SFMS) equipped with a desolvation system, thus requiring much less sample preparation than previously used methods. The 239Pu profile reflects the three main periods of atmospheric nuclear weapons testing: the earliest peak lasted from 1954/55 to 1958 and was caused by the first testing period reaching a maximum in 1958. Despite a temporary halt of testing in 1959/60, the Pu concentration decreased only by half with respect to the 1958 peak due to long atmospheric residence times. In 1961/62 Pu concentrations rapidly increased reaching a maximum in 1963, which was about 40% more intense than the 1958 peak. After the signing of the “Limited Test Ban Treaty” between USA and USSR in 1964, Pu deposition decreased very sharply reaching a minimum in 1967. The third period (1967-1975) is characterized by irregular Pu concentrations with smaller peaks (about 20-30% of the 1964 peak) which might be related to the deposition of Saharan dust contaminated by the French nuclear tests of the 1960s. The data presented are in very good agreement with Pu profiles previously obtained from the Col du Dome (multi-collector ICP-mass spectrometry) and Belukha ice cores by Accelerator Mass Spectrometry (AMS). Although a semi-quantitative method was employed here, the results are quantitatively comparable to previously published results.
Original languageEnglish
JournalAtmospheric Environment
Pages (from-to)587-593
Number of pages6
StatePublished - 2011
Externally publishedYes

ID: 32399194