Distribution of technetium-99 in surface soils

Technetium-99 (99Tc) is an important fission product which has been widely distributed in the environment as a result of fallout from nuclear weapons testing. In order to improve our understanding of the behavior of 99Tc in the environment, it is essential that we obtain more reliable information on the levels, distribution and fate of 99Tc in the environment. In this study, the concentration of global fallout 99Tc, in several surface soil samples (0 - 20 cm) collected in Japan, were determined by ICP-MS.The range of 99Tc in rice paddy field, upland field and other soils determined in this study were 0.006 - 0.11, 0.004 - 0.008 and 0.007 - 0.02 Bq kg-1 dry, respectively. 137Cs was used as a comparative indicator for the source of 99Tc, because the fission yields from 235U and 239Pu were about the same (ca. 6%) for the two isotopes, and the behavior and distribution of 137Cs in the environment is reasonably well understood. The 137Cs contents in rice paddy field, upland field and other soils range between 1.7 - 28, 1.4 - 9.2 and