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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 of210Pb was determined using two nuclear analytical techniques: determination of210Pb in equilibrium with its beta emitting daughter210Bi using liquid scintillation counter (LSC), and direct determination of210Pb (and other radionuclides) by low-background gamma-ray spectrometer with a well type HPGe detector. For the210Pb 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 of210Pb 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 of210Pb 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.

The article deals with an alteration in specific activity and transfer factor of naturally occurring radionuclide 40K from soil with a loamy structure to the segments of root vegetables – an ordinary carrot (Daucus carota L.) and red beet (Beta vulgaris L.). The paper establishes the specific activity of 40K in soil and vegetable segments and evaluates transfer factors (TF). The obtained data show that the transfer factor of naturally occurring radionuclide 40K from soil to the segments of the ordinary carrot (Daucus carota L.) varied from 0,28 to 0,99 while that of the red beet (Beta vulgaris L.) – from 0,53 to 0,96. The results of the study could be used for estimating 40K transfer in the system “soil-plant” and accumulation of radionuclide in composting garden waste. Santrauka Straipsnyje nagrinėjama gamtinės kilmės radionuklido 40K savitojo aktyvumo ir pernašos faktoriaus kaita iš turinčių priemolio struktūrą dirvožemių į šakniavaisinių daržovių – paprastųjų morkų (Daucus carota L.) ir raudonųjų burokėlių (Beta vulgaris L.) – segmentus. Nustatytas savitasis 40K aktyvumas dirvožemyje ir daržovių segmentuose, įvertinti pernašos (PF) faktoriai. Gauti duomenys rodo, kad gamtinės kilmės radionuklido 40K pernašos faktorius iš dirvožemio į paprastosios morkos (Daucus carota L.) segmentus kito nuo 0,28 iki 0,99, o į raudonojo burokėlio (Beta vulgaris L.) – nuo 0,53 iki 0,96. Remiantis eksperimentinių tyrimų duomenimis bei atsižvelgiant į vykdomos veiklos radioaktyviąją dirvožemio užtaršą, galima įvertinti 40K pernašą dirvožemis-augalas sistemoje bei kaupimąsi daržininkystės atliekose.