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Characterisation of222Rn concentrations in Lithuanian spa waters and comparison of the measured radon concentrations in spa waters with those in ground waters with a small content of mineral salts and in waters from private wells were the objectives of this study. The measurements were performed in 34 spa water sources in four different places of Lithuania using the liquid scintillation method with a Packard Liquid Scintillation Analyser Tri-Carb 2770 TR/SL and the Packard BioScience cocktail. Techniques of222Rn extraction from water samples with a high mineralization to toluene in order to exclude precipitation in a mixture with organic scintillation cocktail are discussed. Results of comparison of the two methods—liquid scintillation counting and that using E-PERMS® system electrets—are also presented. [ABSTRACT FROM AUTHOR]

The impact of low-dose ionizing radiation on the electrical signalling pattern and membrane properties of the characea Nitellopsis obtusa was examined using conventional glass-microelectrode and voltage-clamp techniques. The giant cell was exposed to a ubiquitous radionuclide of high biological importance - tritium - for low-dose irradiation. Tritium was applied as tritiated water with an activity concentration of 15 kBq L(-1) (an external dose rate that is approximately 0.05 μGy h(-1) above the background radiation level); experiments indicated that this was the lowest effective concentration. Investigating the dynamics of electrical excitation of the plasma membrane (action potential) showed that exposing Characeae to tritium for half an hour prolonged the repolarization phase of the action potential by approximately 35%: the repolarization rate decreased from 39.2 ± 3.1 mV s(-1) to 25.5 ± 1,8 mV s(-1) due to tritium. Voltage-clamp measurements showed that the tritium exposure decreased the Cl(-) efflux and Ca(2+) influx involved in generating an action potential by approximately 27% (Δ = 12.4 ± 1.1 μA cm(-2)) and 64% (Δ = -5.3 ± 0.4 μA cm(-2)), respectively. The measured alterations in the action potential dynamics and in the chloride and calcium ion transport due to the exogenous low-dose tritium exposure provide the basis for predicting possible further impairments of plasma membrane regulatory functions, which subsequently disturb essential physiological processes of the plant cell., (Copyright © 2014 Elsevier Ltd. All rights reserved.)