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• Using LSC to measure 226Ra and 228Ra in food samples simultaneously. • Overall efficiencies of 226Ra and 228Ra were 68.4–79.4% and 30.1– 35.8%, respectively. • The MDA of 226Ra and 228Ra were 11.3 mBq/g and 33.4 mBq/g, respectively. • Method was validated by reference materials and compared to data from γ-spectrometry. The 228Ra and 226Ra isotopes of radium are significant contaminants in food, raising public concern because of their radiotoxicity. Several methods are available for determining 228Ra and 226Ra. However, the application of these procedures is not focused on food but only on water and environmental matrices. In this study, a cost-effective method for the simultaneous determination of 226Ra and 228Ra radioactivity in food samples using liquid scintillation counting was developed. The overall efficiencies of 226Ra and 228Ra in the food samples are 69.4–78.4% and 30.1–35.8%, respectively. The minimum detectable activities of 226Ra and 228Ra are 11.3 mBq/g and 33.4 mBq/g, respectively, in our food sample, obtained using a 1.0 g ash sample and 60 min of counting time. The method was validated using IAEA-certified reference materials and compared with data obtained using gamma spectrometry in tea, kelp, and oyster samples. [ABSTRACT FROM AUTHOR]

Knowledge of sedimentation rates in lakes is required to understand and quantify the geochemical processes involved in scavenging and remobilization of contaminants at the Sediment-Water Interface (SWI). The well-known 210 Pb excess ( 210 Pb ex ) method cannot be used for quantifying sedimentation rates in uranium-enriched catchments, as large amounts of 210 Pb produced by weathering and human activities may dilute the atmospheric 210 Pb. As an alternative dating method in these cases, we propose an original method based on 232 Th decay series nuclides. This study focuses on an artificial lake located in a granitic catchment downstream from a former uranium mine site. The exponential decay of 228 Ra excess ( 228 Ra ex ) with depth in two long cores yields sedimentation rates of 2.4 and 5.2 cm yr −1 respectively. These sedimentation rates lead to the attribution of the 137 Cs activity peak observed at depth to the Chernobyl fallout event of 1986. The 228 Ra ex method was also applied to two short cores which did not display the 137 Cs peak, and mean sedimentation rates of 2.1 and 4.0 cm y −1 were deduced. The proposed method may replace the classical radiochronological methods ( 210 Pb ex , 137 Cs) to determine sedimentation rates in granitic catchments. [ABSTRACT FROM AUTHOR]