Ljudmila Benedik, Polona Vreček
Jožef Stefan Institute, Department of Environmental Sciences, Jamova
39, 1000 Ljubljana, Slovenia
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.