もみ殻等を用いる環境水中の放射性セシウムの除染

概要

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Deposition of radioactive cesium isotopes, known as 137Cs and 134Cs, from the Fukushima Daiichi Nuclear Power Station (FDNPS) causes great concern due to their long half lives. Decontamination of radioactive cesium in the environment is not easy. Deposited radioactive cesium moves slowly in the soil, and remains in the surface region unless physically disturbed. However, a selective extraction of cesium from soil particles is impossible, because cesium has been strongly absorbed on clay minerals. This study demonstrated a method for the effective decontamination of radioactive cesium by using rice chaff and straw as an adsorbent at drains for rainwater in Moriya city, Japan. After 58 days of soaking, rice chaff and straw have captured radioactive cesium from 2990 Bq kg−1 (chaff) to 13610 Bq kg−1 (straw). Moreover, it was revealed that microorgasisms on the surface of rice chaff strongly captured radioactive cesium from soil particles in water. Therefore, rice chaff and straw are effective, low-cost and safe adsorbents for the decontamination of radioactive cesium.