Factors influencing the distribution of weapon-test plutonium alpha-emitters on the whole-basin of a lake

Abstract

By analysing the 239+240Pu and 238Pu content in a total of 32 sediment gravity cores, it has been possible to obtain quite rich information about the accumulation pattern of these radioactive pollutants on the basin of a small lake located in southwest Sweden. In fact, it has been observedthat the traditional lacustrine models reflecting as expectations higher accumulation of pollutants at deeper water depths are not appropriate for describing the specific processes controlling the distribution of the Pu alpha-emitters isotopes in the analysed whole basin. Additionally, and knowing the primary weapon-test atmospheric origin of the Pu-isotopes in the region where the lake is located, it has been possible to evaluate the magnitudeof the Pu incorporated to the lake basin from the surrounding drainage area. This evaluation was based in the analysis of the Pu-isotopes profile in a twelve layers sediment core collected from the deepest part of the basin and in the comparison between the Pu cumulative depositions determined in the gravity cores and the expected direct-atmospheric inputs.