Application of α and γ Spectrometry in the ²¹⁰Pb Method to Model Sedimentation in Artificial Retention Reservoir

The paper describes the application of the ²¹⁰Pb method for creating a comprehensive model of sedimentation in the retention reservoir Kozłowa Góra 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 ²¹⁰Pb 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 ²¹⁰Pb with the application of alpha spectrometry because even the oldest sediments contain allochthonous ²¹⁰Pb. The determination of the activity of authigenic ²¹⁰Pb 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 ²¹⁰Pb, ²¹⁴Pb and ²¹⁴Bi isotopes. Analysis of the ²¹⁰Pb gamma spectrum line yields information about total activity of ²¹⁰Pb, while the assessed activity of ²¹⁴Pb and ²¹⁴Bi equals to the activity of authigenic ²¹⁰Pb.