Determination of Pd-210 and Po-210 in environmental samples

The naturally-occurring radionuclides Pb-210 and Po-210 (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 technolog ically-enchanced sources. Methods for determination of Pb-210 and of Po-210 are described. Both radionuclides were determined in waters and in air fil ter samples. The procedure for determination of Pb-210 includes dithizone e xtraction for the separation of lead from the matrix and precipitation of P bCrO4 with K2Cr2O7 from weak acetic acid media. After waiting for radiochem ical equilibrium to be re-established between Pb-210 and its daughter Bi-21 0 (at least 20 days), the activity of Bi-210 was measured on a gas flow pro portional beta counter. The method of determination of Po-210 is based on s pontaneous disposition of polonium radioisotopes on a copper planchet and m easurement by alpha spectrometry. Both methods were optimised using Po-208 and Pb-212 tracers. A procedure for preparation of 212Pb tracer that involv es purging of thorium nitrate solution with nitrogen was developed.