MEASUREMENTS OF U-ISOTOPES AND RA-ISOTOPES IN RAINWATER SAMPLES

Concentrations of U- and Ra-isotopes in rainwater samples taken in the South Spanish atmospheric environment during the years 1986, 1987 and 1988 are presented. Such data have been obtained by applying a simple method for the simultaneous determination of such radionuclides from the same rainwater sample. Ra is firstly coprecipitated as Ba-Ra sulfate. Then two alternatives can be used for U analysis: a coprecipitation of U with Fe, followed by a selective redissolution of the precipitate with ammonium carbonate, or a solvent extraction technique by using tributyl phosphate. Levels of 0.99 to 1.81-mu-g/l, 3.4 to 17.9 mBq/l and 0.5 to 5.5 mBq/l, respectively for U, Ra226 and Ra224 are found during the studied time period. The dependence of such concentration variability on meteorological parameters is discussed.