Application of alpha and gamma spectrometry in the Pb-210 method to model sedimentation in artificial retention reservoir

The paper describes the application of the Pb-210 method for creating a comprehensive model of sedimentation in the retention reservoir Kozlowa Gora during the 60 years of its use. The model takes into account the temporal and spatial change in the sedimentation conditions. Because of the specific conditions of the young artificial lake, the techniques available to date are not sufficient and it was necessary to modify the Pb-210 method. The paper describes such modification of the method and its application to dating the sediments in the reservoir. For a young lake it is impossible to estimate the activity of authigenic Pb-210 with the application of alpha spectrometry because even the oldest sediments contain allochthonous Pb-210. The determination of the activity of authigenic Pb-210 in the sediments of the studied reservoir was possible only thank to gamma spectrometry. The gamma ray spectrometry consists of measurements of gamma photons emitted by Pb-210, Pb-214 and Bi-214 isotopes. Analysis of the Pb-210 gamma spectrum line yields information about total activity of Pb-210, while the assessed activity of Pb-214 and Bi-214 equals to the activity of authigenic Pb-210.