CHAI, CF (reprint author), ACAD SINICA,INST HIGH ENERGY PHYS,POB 2732,BEIJING 100080,PEOPLES R CHINA.
Article; Proceedings Paper
The neutron activation analysis, gamma coincidence spectroscopy, nondispersive hydrogen flame atomic fluorescence spectroscopy, and Mossbauer spectrometry were used to study the low-selenium environment of the Exi Autonomous Prefecture, a well-known Keshan disease region. The Se contents in the soil samples there range from 0.075-0.18 mg/kg with the average of 0.13 mg/kg, whereas in the maize from 0.001-0.018 mg/kg with the average of 0.0099 mg/kg. The Fe-57 Mossbauer spectrum of the soil indicates an anoxic environment. In addition to the Fe3+ species, the compounds containing low-valence iron, e.g., goethite, and so forth, also exist. The rare earth element (REE) pattern obtained by NAA further confirms the reductive soil environment, which causes the selenium deficiency.