Presence of 236U and 239,240Pu in soils from Southern Hemisphere

Publication date: December 2018

Source: Journal of Environmental Radioactivity, Volume 192

Author(s): S. Salmani-Ghabeshi, E. Chamizo, M. Christl, C. Miró, E. Pinilla-Gil, F. Cereceda-Balic

Abstract

²³⁶U, ²³⁹Pu and ²⁴⁰Pu are present in soils mainly as a result of the local- and global-fallout from the atmospheric nuclear weapons tests carried out mainly in the 1950's and 1960's. In this work we provide new data on the presence of ²³⁶U and ^239,240Pu in surface soils (i.e. up to 5 cm depth) from Chile and Africa. The results were obtained by low-energy Accelerator Mass Spectrometry (AMS). In the case of the Chilean samples, ²³⁶U/²³⁹Pu atom ratios show a high variability and are in general higher than the reported value for the global fallout in the Northern Hemisphere, ranging from 0.2 to 1.5. The ²³⁶U atomic concentrations range from 3.5 × 10⁶ to 9.1 × 10⁶ atoms/g, and are at least two orders of magnitude lower than the reported values in the Northern Hemisphere. The measured ²⁴⁰Pu/²³⁹Pu atom ratio in soils from South-Africa and Mozambique are of about 0.17, in agreement with the expected one for global-fallout at those coordinates. To best knowledge of the authors the present work is the first publication on ²³⁶U concentrations and ²³⁶U/²³⁹Pu atom ratios in soils from South-America and Africa.

Graphical abstract

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