Study of a protected catchment basin: analyses of anthropogenic radionuclides
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Study of a protected catchment basin: analyses of anthropogenic radionuclides Amélie Leclercq1, Violaine Philippini1, Hervé Michel1, Tiina-Leena Lavonen1,2, Eric Ansoborlo3, Christophe Den Auwer1, Vittorio Barci1, Pier Lorenzo Solari4 and Geneviève BarciFunel1 1 Nice Chemistry Institute, University of Nice Sophia-Antipolis, 06100 Nice, France 2 Laboratory of Radiochemistry, Department of Chemistry, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland 3 CEA Nuclear Energy Division, DRCP, Marcoule, 30207 Bagnols sur Cèze, France 4 Synchrotron SOLEIL, MARS beam line, 91108 Gif sur Yvette, France ABSTRACT Natural samples of soil, sediment and natural water were collected in the “Parc National du Mercantour” in France. Soil and sediment samples were studied to better understand the behaviors of radionuclides (RNs) in different natural compartments. Considering 137Cs and 241 Am activities in depth (measured by Į- and Ȗ-spectrometries), two types of sediment profiles can be distinguished depending on the origin (Chernobyl accident or atmospheric nuclear weapon tests). Due to difficulties in modeling the dispersion of those RNs in natural samples, even in a protected area, semi-synthetic studies were conducted. Eu(III) was used as an analogue of Am(III). Eu behavior in water was studied by EXAFS and compared to speciation diagrams drawn in similar chemical conditions. Eu is mainly complexed by carbonate and phosphate ions. The mean Eu-O distance (2.46 Å) obtained by EXAFS is in agreement with predominant solid species determined by speciation diagrams and previous published studies. INTRODUCTION Nuclear weapon tests in the 60’s and industrial accidents (for example: Chernobyl (1986) and Fukushima (2011) nuclear power plant accidents) have released contaminating RNs in the environment. Because of the air fluxes and precipitation, anthropogenic RNs from the Chernobyl accident deposited in France, especially in the eastern part of the country [1]. 137 Cs was widely studied in natural compartments due to its quite long half-life compared to other disseminated RNs (for examples: 131I, 134Cs) [2, 3]. 137Cs is also considered as a good tracer since its behavior in air is quite similar to that of other RNs such as 131I [1]. In 2008, the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) reported that in contaminated areas, only 137Cs will still be relevant over the next decades whereas contamination with other RNs, such as 134,135Cs and I isotopes will be negligible [4]. Nuclear weapon tests also released RNs with rates depending on the weapon type, the meteorological conditions and the surrounding natural media [5]. Many studies have been conducted on natural compartments to measure the anthropogenic radioactivity. Synthetic studies have also been conducted to elucidate the behaviors of the released RNs and to predict their distribution in the natural compartments (soils, plants, animals, human beings, air, etc.) but very few have combined both approaches. The aim of the present study i
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