Simultaneous determination of 210Bi and 210Po on pine needles by solvent extraction and liquid scintillation counting

A determination procedure has been developed for 210Bi and 210Po in environmental samples and was applied for pine needles. Bismuth-210 and 210Po separated from the parent nuclide 210Pb as BiOCl precipitate were extracted simultaneously by TOPO/toluene containing PPO and POPOP. The separation of 210Bi and 210Po from 210Pb was almost satisfactory. The activity of 210Bi+210Po in the TOPO/toluene was measured periodically by liquid scintillation counting for about 20 days after separation. The time course of the decreasing pattern of the activity was determined by the initial activity ratio 210Po/210Bi. The decreasing pattern of the activity was compared with theoretical patterns, and best estimates for 210Po and 210Bi were obtained by non-linear least-squares fitting. The activities of 210Bi and 210Po were determined for one-year and two year old pine needles from the same pine tree, a nd weathering half-time and deposition rate of these nuclides was discussed. (author) 11 refs.; 5 figs.; 2 tabs