Geochemical and grain-size distribution of radioactive and stable cesium in Fukushima soils; Implications for their long-term behavior

Saito, Takumi; Makino, Hisashi*; Tanaka, Satoru*

Radioactive cesium was predominantly found in the extract obtained by strong-acid dissolution and the extraction residue and was more concentrated in silt and clay grains. X-ray diffraction analyses revealed that micaceous minerals as well as kaolin minerals were predominantly dissolved by the strong-acid treatment. Correlation between the fraction of Cs and the content of micaceous minerals in different grain-size fractions of soil minerals suggests that micaceous minerals are responsible for the fixation of Cs in the soils. The isotopic ratio of Cs and Cs in the extract by strong-acid dissolution was more than three times smaller than those in the extracts by water, ion exchange, and reductive dissolution. This indicates that the distribution of Cs was not in the steady state in 2 y after the accident due to relatively slow fixation by the soil clay minerals.