The influence of particle size on radionuclide activity concentrations in Tejo River sediments

• Sediment samples were analyzed for 228Ra, 226Ra, 40K and 137Cs by gamma spectrometry.
• Radionuclide activity concentrations are dependent on the sediment particle size.
• Correlation analysis demonstrates the different origins of the radionuclides.
• Cluster analysis has distinguished two different groups: 228Ra, 226Ra and 40K.

Sediment samples from Tejo River were analyzed for 228Ra, 226Ra, 137Cs and 40K by HPGe gamma spectrometry. The activity concentration data were statistically analyzed. The activity concentrations values were in the range of about two orders of magnitude for each radionuclide. The influence of the particle size on the radionuclide concentrations was observed. The different environmental origins of the radionuclides 228Ra, 226Ra, 137Cs and 40K, in the sediments were demonstrated through correlation analysis. Cluster analysis showed a close relationship between 228Ra and 226Ra and a different behavior for 40K. The data obtained in this study provides useful information on the background radioactivity of the studied area and can be further used for radiological mapping of the Tejo River.