Application of nuclear and related analytical techniques in biomonitoring

The mechanisms in which biomonitors survive in an unfavourable environment, such as nuclear weapon testing and nuclear accidents, are still unknown. In order to reveal the nature of these mechanisms, we investigated the uptake of cesium-137 by biomonitor species (mosses, lichens and mushrooms) as well as localization and cellular distribution of this radionuclide in their tissues. Three different nuclear and related analytical techniques were used: gamma spectrometry (HPGe, NaI detectors), X ray fluorescence spectrometry and energy dispersive X ray fluorescence spectrometry. From the obtained results it can be concluded that (i) radiocesium is found in both organic and inorganic molecules, (ii) it is present in all cellular compartments, but predominantly in membranes and (iii) only part of its initial amount is exchangeable with homologous cations. The experimental evidence obtained using a combination of the mentioned techniques implies that transmembrane proteins serving as potassium channels may be cesium-binding sites in the investigated biomonitors. In this study cesium compounds have not been fully characterized, but it was evident that cesium is not associated with essential biomacromolecules. This could be a reason for the tolerance of biomonitor species towards long term retention of radionuclides in their tissues. (author)