Radiocarbon dating of lake sediments

Matas Pocevičius, Radiocarbon dating of lake sediments, bachelor thesis, Vilnius University, Faculty of Physics, Department of General Physics and Spectroscopy, physics, Vilnius, 45 p., 2016. The aim of this study is to evaluate the possibility of radiocarbon dating application for Tapeliai lake bottom sediments. The literature review discusses topics related to accelerator mass spectrometry, principles of radiocarbon formation, importance of nuclear fallout for 14C, possible applications of radiocarbon, methods that are used to date lake bottom sediments using the isotopes: 137Cs, 241Am, 210Pb, 239,240Pu and 14C. In the section about equipment there are described working principles of single stage accelerator mass spectrometer, stable isotope mass spectrometer and automatic graphitisation system. The work tasks were to measure the values of δ13C and modern carbon F14C in Tapeliai lake bottom sediments. To evaluate the amount of organic matter and to determine the correlation between radiocaesium and radiocarbon. To make a conclusion about the possibility to use radiocarbon for dating Tapeliai lake. In conclusion, analysis of δ13C indicated that material transfer takes place in bottom lake sediments. Study of F14C values shown that the lake reservoir effect is dominating over the atmospheric carbon dioxide in the lake bottom sediments. The correlation between radiocaesium and radiocarbon revealed two dominant sources of 14C in sediments: a) the lake reservoir effect; b) radiocarbon in the atmosphere created by the experiments of nuclear weapons. It was also found that bulk fraction is unsuitable for dating such a type of lakes. On the other hand, it is possible to study the processes that are taking place in bottom lake sediments