DBPapers
DOI: 10.5593/sgem2017/51/S20.008

AM-241 IN THE DON RIVER SEDIMENT CORE

Y. A. Fedorov, A. N. Kuznetsov, V. M. Yaroslavtsev
Wednesday 13 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-08-9 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 51, 53-60 pp, DOI: 10.5593/sgem2017/51/S20.008

ABSTRACT

The concern about the environmental contamination by 241Am is caused by the fact, that its half-life period is longer and its mobility is much higher than that of parent plutonium. That is why in soils and sediments the specific activity of the radionuclide increases over time. The alpha-decay energy of 241Am and the relatively short lifetime of the isotope create high specific radioactivity and thermal yield. In bottom sediments, the ratio of 241Am to 241Pu increases every year. All these factors result in a high probability of contamination of hydrobiota, food chains and penetration into human body. The present paper examines the results of study of the 241Am specific activity vertical distribution in a relatively long core extracted from the contemporary sediments of the Don River bed. The authors consider this sediment core as parametric, so the results of its study and their correct use in assessing the radionuclide contamination of aquatic ecosystems on a regional scale are of high importance. It is found out that in this one-meter-long sediment core extracted near Manycheskaya village 241Am is present in all the layers. A close correlation was found between the specific activities of 238U and 241Am. The correlation may be explained by their synchronous and asynchronous accumulation in the sediments, that is proved by a model of behavior of 238U, 241Am and 241Pu triad that the authors have developed. According to the first scenario of the model, these radionuclides simultaneously enter the water body as a result of nuclear fuel cycle including processing and storage of radioactive wastes. Moreover, "hot" particles of aerosols could penetrate the Sea of Azov catchment basin with regional and global mass transfer. According to the second scenario, 238U comes as an aerosol component (micro- and nanoparticles of coal dust and ash) and as a component of sediments from coastal and soil erosion, while 241Am coming from nuclear technological cycle and home appliances is sorbed by these 238U-containing particles suspended in the atmosphere and in water column. Then the particles precipitate on the river bed. The sorption of 241Am by the particles of uranium oxide in situ during the diagenesis of bottom sediments is also possible.

Keywords: radionuclides, bottom sediments, the Don River, Americium-241.