Bachelor Thesis

Uranium in Bavarian Groundwater

Theresa Dittmann (11/2010-08/2011)

Support: Britta Planer-Friedrich

Uranium occurs ubiquitously in the environment and is a metal toxic for humans particularly be-cause of its chemotoxicity. The objective of this Bachelor thesis was to continue the Bavarian Environment Agency’s (LfU) investigations about the occurrence of uranium contents in Bavar-ian groundwater with a larger number of samples. Therefore, 15183 groundwater analyses from 11163 wells were made available by the LfU. These were to be analysed in hydrogeological classes. While altogether the groundwater contents had a median of 0,40 µg/L and an arithmetic mean of 1,32 µg/L, the higher values were located particularly in the Keuper and in fluvial Quaternary depositions. Apart from few exceptions no evidence for anthropogenically caused uranium content was found, whereas the often assumed geogenic origin was proved to be true. Especially in the fluvial Quaternary depositions there are many indications for uranium adsorbed to organic substance. In the Keuper the high uranium levels concentrate mainly on the Burg-sandstein, which includes arkoses with greatly enhanced uranium concentrations. The multiple sampled wells show mostly small fluctuations of the uranium contents. Nevertheless, single measurements aren’t always reliable. The correlations, which were performed in some classes, never resulted in correlation coefficients higher than 0,6. This indicates the diversity of influences on the uranium contents. The performed assessment of uranium contents from some private wells in the Keuper on the basis of the surrounding concentrations turned out to mainly be correct compared to actual sampling data. The wrong assessments might be due to the het-erogeneity of the Keuper or insufficient information about the aquifer.