STUDY OF A LOW-SELENIUM ENVIRONMENT IN CHINA BY INAA AND MOSSBAUER SPECTROMETRY

The neutron activation analysis, gamma coincidence spectroscopy, nondi spersive hydrogen flame atomic fluorescence spectroscopy, and Mossbaue r 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 th e average of 0.13 mg/kg, whereas in the maize from 0.001-0.018 mg/kg w ith the average of 0.0099 mg/kg. The Fe-57 Mossbauer spectrum of the s oil indicates an anoxic environment. In addition to the Fe3+ species, the compounds containing low-valence iron, e.g., goethite, and so fort h, also exist. The rare earth element (REE) pattern obtained by NAA fu rther confirms the reductive soil environment, which causes the seleni um deficiency.