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A new analytical technique using inductively coupled plasma mass spectrometry (ICP-MS) was applied to the determination of 99Tc in some environmental samples. The accuracy and precision of the new method were assessed by comparison with those of the liquid scintillation counting method. The results obtained by ICP-MS were in good agreement with those by liquid scintillation counting at a relative deviation of 3%. The detection limit is 1.1 mBq/mL (1.73 pg/mL).

The distribution of radioiodine (131I) species in rain water collected at Tsukuba in May 1986 was studied using the isotopic exchange method. Organic-soluble forms of radioiodine were not observed. Iodide (I∗−) was the predominant species, and the concentration of iodate (I∗O3−) was less than half of I∗−. The results were compared with those for 131I produced by neutron-irradiation of uranyl nitrate.

The adsorption behaviour of trace amounts of tellurate, tellurite, iodide and iodate on active charcoal has been studied by a radioactive-tracer method; on the basis of the results, a column chromatographic separation of these ions from each other was devised. By passing the sample solution (at pH 5.6) through an active charcoal column, all but tellurate are retained, lodate, tellurite and iodide are then eluted successively with water (pH 7.0), 0.1 N hydrochloric acid and 1 N sodium hydroxide, respectively. The method can be applied to the preparation of radioiodine from a neutron-irradiated tellurate target.

The radioactivity released by the reactor accident at Chernobyl was detected in surface air at Tsukuba, Japan. Gamma-spectrometry of airborne dust collected using aerodynamic separation showed higher concentrations of radionuclides in fine particles. The particle-size distribution of radionuclides changed with time.