Fig. 1　Read-out images of imaging plates with particles of various minerals onto which radioactive Cs was adsorbed

The read-out images of imaging plates (IPs) when a minute amount of radioactive Cs was absorbed onto various clay minerals (for the initialisms, see the table at the bottom right of the figure). The radioactivity input to the ¹³⁷Cs solution and the reaction time are at the top and left, respectively. The figure at the top right of each image is the percentage of ¹³⁷Cs adsorbed on all the mineral particles. These images show that the adsorbed radioactive Cs was concentrated on weathered biotite.

Fig.2　A model of radioactive-Cs adsorption onto weathered biotite

Weathered biotite has a layered structure. Several examples have been indicated, for example, radioactive Cs entered via a swollen layer called a frayed edge and was strongly fixed by the collapse of the layers when the radioactive Cs was absorbed.

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References

1. Motokawa, R., Endo, H., Yokoyama, S., Nishitsuji, S., Kobayashi, T., Suzuki, S. and Yaita, T. (2014): Collective Structural Changes in Vermiculite Clay Suspensions Induced by Cesium Ions, Scientific Reports, vol. 4, 6585_1-6585_6. https://doi.org/10.1038/srep06585
2. Mukai, H., Hatta, T., Kitazawa, H., Yamada, H., Yaita, T. and Kogure, T. (2014): Speciation of Radioactive Soil Particles in the Fukushima Contaminated Area by IP Autoradiography and Microanalyses, Environmental Science & Technology, vol. 48, no. 22, 13053-13059. https://doi.org/10.1021/es502849e