%0 Conference Paper %F Oral %T Discriminating the contribution of global fallout and Chernobyl to anthropogenic fallout radionuclide inventories in soils of Europe. %+ Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE) %+ Géochimie Des Impacts (GEDI) %+ Institut Fédéral de Recherches sur la Forêt, la Neige et le Paysage (WSL) %+ Centre Georges Lemaître for Earth and Climate Research [Louvain] (TECLIM) %+ Université de Bâle = University of Basel (Unibas) %+ Metropolitan State University of Denver %+ Soil and Water Management & Crop Nutrition Laboratory (SWMCN Laboratory) %+ JRC Institute for Environment and Sustainability (IES) %A Evrard, O. %A Meusburger, Katrin %A van Oost, Kristof %A Borrelli, Pasquale %A Ketterer, Michael %A Mabit, Lionel %A Lefèvre, Irène %A Alewell, Christine %A Panagos, Panos %Z Université Paris-Saclay - Programme d'Alembert %Z FNRS (Belgium) - grant number J006517F %< avec comité de lecture %B MARC XI (Methods and Application of Radioanalytical Chemistry) Conference %C Kona, Hawaii, United States %8 2018-04-08 %D 2018 %Z Environmental Sciences %Z Sciences of the Universe [physics]/Continental interfaces, environment %Z Sciences of the Universe [physics]/Earth Sciences/Geomorphology %Z Life Sciences [q-bio]/Agricultural sciences/Soil study %Z Chemical Sciences/RadiochemistryConference papers %X Fieldwork was conducted every 6 months between 2011 and 2017 to monitor the dispersion of sediment contaminated with radionuclides in rivers draining the main Fukushima radioactive pollution plume (~500 km²). Fine sediment was systematically collected at the same locations (n=47) and analysed for gamma-emitting radionuclides (including 137Cs and 110mAg). A selection of samples was also analysed for carbon/nitrogen concentrations and isotopes. Organic matter analyses showed that paddy fields provided the main source of contaminated sediment to the rivers shortly after the accident. The spatial variations of the 110mAg:137Cs activity ratio in soils were used to demonstrate the very rapid export of sediment to the Pacific Ocean. However, this tool could only be used during the first campaigns, because of the quick decay of 110mAg. Overall, radiocesium concentrations measured in sediment deposits decreased by ~90% between 2011 and 2017. This may be explained by remediation works, by a massive export of material during typhoons and by the occurrence of landslides or channel bank erosion that supply material sheltered from the Fukushima fallout to the river network. Consequently, 6 years after the accident, most of the residual radioactive contamination is found in forests and in dam reservoirs. The analysis of sediment cores collected in a reservoir confirmed the significant storage of contaminated material in these lakes and that paddy fields provided their main source. Ongoing research focuses on the development of a soil erosion model and on the quantification of the impact of remediation works. %G English %L cea-02674181 %U https://cea.hal.science/cea-02674181 %~ SDE %~ CEA %~ INSU %~ CNRS %~ GIP-BE %~ UVSQ %~ CEA-UPSAY %~ LSCE %~ UNIV-PARIS-SACLAY %~ CEA-UPSAY-SACLAY %~ UVSQ-SACLAY %~ TEST-HALCNRS %~ LSCE-CEA %~ UVSQ-UPSACLAY %~ GS-ENGINEERING %~ GS-GEOSCIENCES %~ GS-BIOSPHERA %~ INSTITUT-SCIENCES-LUMIERE