TRANSFER-FACTORS OF SOME SELECTED RADIONUCLIDES (RADIOACTIVE CS, SR, MN, CO AND ZN) FROM SOIL TO LEAF VEGETABLES

Transfer factors of radionuclides from soil to leaf vegetables (cabbage, Chinese cabbage, komatsuna, spinach and lettuce) have been studied by radiotracer expeiments using Andosol as a representative of Japanese soils. The transfer factors of radioactive Cs, Sr, Mn, Co and Zn for edible parts of vegetables (average of five vegetables) were 0.11, 0.24, 0.61, 0.05 and 0.52, respectively. These values should be used in safety assessment for Japanese agricultural environment. The transfer factors of Mn, Co and Zn for spinach were higher than those for the other vegetables. The transfer factors of Cs for different organs of the leaf vegetables were rather homogeneous. The transfer factors of Sr and Mn were higher for older (outer) leaves than younger (inner) ones. In contrast to Sr and Mn, transfer factors of Zn for younger leaves were higher than those for older ones. The distribution ratios of the elements between soil-solution and soil were in the order Sr>Mn>Cs>Co>Zn, whereas the distribution ratios of the elements between plant and soil-solution were in the order Zn>Cs>Mn>Co>Sr. These results indicate that the selectivity for Sr by plants from the soil-solution was low and that for Zn was very high.