Ljudmila Benedik, Polona Vreček

Jožef Stefan Institute, Department of Environmental Sciences, Jamova 39, 1000 Ljubljana, Slovenia
 
 

ABSTRACT

The naturally-occurring radionuclides 210Pb and 210Po (22.3 y and 138.4 d half-lives, respectively), are important because of  their contributions to the natural radiation dose and release into the environment from technologically-enhanced sources. Methods for determination of 210Pb and of 210Po are described. Both radionuclides were determined in waters and in air filter samples. The procedure for determination of 210Pb includes dithizone extraction for the separation of lead from the matrix and precipitation of PbCrO4 with K2Cr2O7 from weak acetic acid media. After waiting for radiochemical equilibrium to be re-established between 210Pb and its daughter 210Bi (at least 20 days), the activity of 210Bi was measured on a gas flow proportional beta counter. The method for determination of 210Po is based on spontaneous deposition of polonium radioisotopes on a copper planchet and measurement by alpha spectrometry. Both methods were optimised using 208Po and 212Pb tracers. A procedure for preparation of 212Pb tracer that involves purging of thorium nitrate solution with nitrogen was developed.