Assessment of the measures for the extraction or fixation of radiocesium in soil

- Extraction behavior of Cs from soil varies with soil type.
- Lime remediation is effective for acid washed soil.
- Cs mobility in soil can be suppressed by mixing Prussian blue nanoparticles.
- Extraction or suppression of r-Cs are remediation alternatives.

Methods for the remediation of radioactive cesium contaminated soil and for controlling the transfer of 137Cs to plants were assessed in reference to two abundant soil groups in Fukushima region, brown forest soil (BFS) and andosol. The hot acid treatment method, which is found to be effective on extracting substantial amount of Cs from BFS was not effective for andosol. For the remediation of acid treated soil, Komatsuna germination test was performed. Although no successful germination was observed with 100% acid washed soil, the productivity could be improved by lime treatment and mixing with the untreated soil. Targeting the soils like andosol, soils with moderate contamination, or the contaminated soil storage areas, Cs transfer suppression test was performed between 2011 and 2014. In the first planting of sunflower, high concentration of 137Cs is transferred to the plant. It could be successfully suppressed by mixing zeolite or Prussian blue adsorbents onto the soil. Results with nano-Prussian blue mixed soils showed high suppression rate with lowest transfer factor in the first harvest and constantly minimum concentration of exchangeable 137Cs in soil throughout the study.

By fixation or extraction followed by remediation, the risk of transfer of radiocesium into the harvest can be largely reduced.164