福島で放射性セシウムを吸着・固定している鉱物は何か

抄録

Mineral species that really retain radioactive cesium in Fukushima soil have been investigated by analyzing actual contaminated soil samples in Fukushima using IP autoradiography, electron microscopy and X-ray diffraction. Weathered biotite originated from granitic body in Fukushima was frequently found as radioactive fine particles. The weathered biotite is mineralogically a biotite-vermiculite mixed-layer mineral. Besides, smectite-like clay mineral was identified in biotite-free particles using X-ray diffraction. A new cesium-sorption experiment was conducted, in which various clay minerals were immersed together in dilute ¹³⁷Cs radioisotope solutions and the amount of ¹³⁷Cs adsorbed in each mineral was measured by IP autoradiography to reproduce the sorption at actual concentration level in the radioactive particles. It was found that ¹³⁷Cs was sorbed predominantly by the weathered biotite collected in Fuku shima, confirming the results from the investigation of the actual contaminated soil mentioned above.