Study of sediment characterization at beach sand using radionuclides and the geo-referenced in-situ γ-ray spectrometry

Abstract In this work, an in-situ method is presented for rapid mapping of natural gamma-ray radionuclides in order to study the sediment characterization in beach sand area. The idea of the proposed work is to present demonstration exercises using the underwater low-resolution gamma-ray spectrometer named KATERINA II to evaluate the sediment characterization and its granulometry. The detection system is integrated in mobile platforms for continuous operation to be applied as a manned surface vehicle. The measured data are analyzed after the end of the experiment using an existing algorithm for quantitative analysis providing the total counting rate as well as to the activity concentration of key natural radionuclides ( 40 K, 214 Bi, 208 Tl). The average activity concentration of 40 K varied from 104 to 184 Bqkg −1 while the activity concentration of 214Bi varied from 5.4 to 11 Bqkg −1 . The maximum concentrations were found at the west and east part of the beach and other maximum values were also found close to dunes. As concerns 208Tl, the activity concentration varied from 0.8 to l 11 Bqkg −1 . The low values of the granulometry model reproduced the evaluation of sediment dynamics in the middle of the beach since the coarser beach sands predominate due to the rocky bars appearance that prevent the sediment accumulation, which is expected to be enriched by fine grains. The radionuclides’ signature of the beach sand were also used as proxies to better understand the sediment characterization, such as its average grain size. According to the applied model the average grain size varied from 1 to 1.2 mm. The in-situ gamma-ray spectrometry was proved to be a suitable rapid method to determine the eroded and accumulated areas combined with the grain size of the beach sand.