title: Plutonium release from Fukushima Daiichi fosters the need for more detailed investigations.
abstract: The contamination of Japan after the Fukushima accident has been investigated mainly for volatile fission products, but only sparsely for actinides such as plutonium. Only small releases of actinides were estimated in Fukushima. Plutonium is still omnipresent in the environment from previous atmospheric nuclear weapons tests. We investigated soil and plants sampled at different hot spots in Japan, searching for reactor-borne plutonium using its isotopic ratio ²⁴⁰Pu/²³⁹Pu. By using accelerator mass spectrometry, we clearly demonstrated the release of Pu from the Fukushima Daiichi power plant: While most samples contained only the radionuclide signature of fallout plutonium, there is at least one vegetation sample whose isotope ratio (0.381 ± 0.046) evidences that the Pu originates from a nuclear reactor (²³⁹⁺²⁴⁰Pu activity concentration 0.49 Bq/kg). Plutonium content and isotope ratios differ considerably even for very close sampling locations, e.g. the soil and the plants growing on it. This strong localization indicates a particulate Pu release, which is of high radiological risk if incorporated.
authors.affiliation: Leibniz Universität Hannover, Institut für Radioökologie und Strahlenschutz, D-30419 Hannover, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schneider
authors.forename: Clemens
authors.initials: C
authors.lastname: Walther
authors.forename: Stefan
authors.initials: S
authors.lastname: Bister
authors.forename: Viktoria
authors.initials: V
authors.lastname: Schauer
authors.forename: Marcus
authors.initials: M
authors.lastname: Christl
authors.forename: Hans-Arno
authors.initials: HA
authors.lastname: Synal
authors.forename: Katsumi
authors.initials: K
authors.lastname: Shozugawa
authors.forename: Georg
authors.initials: G
authors.lastname: Steinhauser
mesh_terms: D062406:Fukushima Nuclear Accident; D005843:Geography; D006801:Humans; D011005:Plutonium / Q000032:analysis*; D011834:Radiation Monitoring / Q000379:methods; D011848:Radioactive Pollutants / Q000032:analysis*
chemical_list: D011848:Radioactive Pollutants; D011005:Plutonium