Application of PIXE analysis to investigation of plants cultivated with contaminated soil of Fukushima

We present a method to research low radioactive cesium contaminated plants by the use of PIXE analysis. Highly contaminated regions still remain in the Fukushima prefecture. We collected wild plants growing in this area, that is, Butterbur, Welsh onion, Alpine leek and White clover and measured their specific activities of 137Cs and 40K. We also measured 137Cs and 40K specific activities of soil under these plants. Soil-to-plant transfer factors of 137Cs were ∼0.02 for 4 wild plants and those of 40K were ∼0.5 except for White clover. Using PIXE analysis, we measured the concentration of mineral elements in these plants. Among mineral elements, we noted the concentrations of additional alkali metal elements such as Na, K and Rb. The experimental results showed that the concentration of Rb was proportional to the specific activities of 137Cs except for Welsh onion and other elements had no strong correlation with 137Cs. These results indicate that there may be correlations between the adsorption of Cs and Rb.