Study of a Low-Selenium Environment in China by INAA and Mössbauer Spectrometry

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.