Comparison of beta (LSC) and gamma (HPGe) spectrometric methods for lead-210 in chronological study

The sediments of two lakes located in the Baltic Uplands, the western part of the East European Plain (East Lithuania and North East Poland), were studied. Activity concentration of ²¹⁰Pb was determined using two nuclear analytical techniques: determination of ²¹⁰Pb in equilibrium with its beta emitting daughter ²¹⁰Bi using liquid scintillation counter (LSC), and direct determination of ²¹⁰Pb (and other radionuclides) by low-background gamma-ray spectrometer with a well type HPGe detector. For the ²¹⁰Pb determination by LSC the methodology of lead separation based on the anion exchange resin in Cl^– form (Eichrom) was used. Several steps of radiochemical procedures and respective parameters were investigated additionally. The optimized procedures for LSC method were used for case study with two lake cores. The activity concentration of ²¹⁰Pb in lake sediment samples based on both nuclear analytical techniques (LSC and HPGe) were compared. ²¹⁰Pb dating of cores was performed according to Constant Rate of ²¹⁰Pb Supply (CRS) model with some modifications. Both techniques in the range of uncertainties gave similar results. From two considered lakes, the more eutrophic one exhibited higher sediment mass accumulation rate (MAR) values.