Evidence of the radioactive fallout in France due to the Fukushima nuclear accident

Radioactive fallout due to the Fukushima reactor explosion in Japan was detected in environmental samples collected in France. The presence of 131I in aerosols (200 ± 6 μBq m−3) collected at the Pic du Midi observatory, located at 2877 m altitude in the French Pyrénées, indicated that the Japanese radioactive cloud reached France between 22 and 29 March, i.e. less than two weeks after the initial emissions, as suggested by a 137Cs/134Cs ratio of 1.4. Cesium radioisotopes (134Cs and 137Cs) were not detected in this sample but they were present in the aerosol sample collected the next week, i.e. between 29 March and 05 April (about 10 μBq m−3). We also report 131I activities measured in grass (1.1–11 Bq kg−1; fresh weight) and soil samples (0.4 Bq kg−1) collected in the Seine River basin between 30 March and 10 April. The 134Cs from the damaged Fukushima power plant was also detected in grass collected in the Seine River basin between 31 March and 10 April (0.2–1.6 Bq kg−1 fresh weight, with a 137Cs/134Cs ratio close to 1, which is consistent with Fukushima radioactive release). Despite the installation of a network of nested stations to collect suspended matter in the upstream part of the Seine River basin, 131I was only detected in suspended matter (4.5–60 Bq kg−1) collected at the most upstream stations between 30 March and 12 April. Neither 131I nor 134Cs has been detected in environmental samples since the end of April 2011, because of the rapid decay of 131I and the very low activities of 134Cs (about 400 times lower than after Chernobyl accident).

► Artificial radionuclides emitted by Fukushima power plant accident were detected in environmental samples collected in France.
► Radioactivity measurements on air filters obtained at the highest altitude in France.
► 131I detected in grass, soil and sediment collected between 30 March and 12 April.
► 134Cs detected in grass collected between 31 March and 10 April.
► Total 134Cs input to grass of 2 Bq m−2 (∼400 times lower than Chernobyl input).