Dating of sediments from four Swiss prealpine lakes with Pb-210 determined by gamma-spectrometry: progress and problems

摘要

In this paper the most important problems in dating lake sediments with unsupported Pb-210 are summarized and the progress in gamma-spectrometry of the unsupported Pb-210 is discussed. The main topics of these studies concern sediment samples preparation for gamma-spectrometry, measurement techniques and data analysis, as well as understanding of accumulation and sedimentation processes in lakes. The vertical distributions of artificial ((137)cs, Am-241, Pu-239) and natural radionuclides (K-40, (210,214)pb, Bi-214) as well as stable trace elements (Fe, Mn, Pb) in sediment cores from four Swiss lakes were used as examples for the interpretation, inter-comparison and validation of depth-age relations established by three Pb-210-based models (CF-CSR, CRS and SIT). The identification of turbidite layers and the influence of the turbidity flows on the accuracy of sediment dating is demonstrated. Time-dependent mass sedimentation rates in lakes Brienz, Thun, Biel and Lucerne are discussed and compared with published data. (C) 2015 Elsevier Ltd. All rights reserved.