Levels of natural and anthropogenic radionuclides in sediments of some Moroccan coastal areas and dose assessment based on ERICA tool

In this work, we considered the concentrations of natural and anthropogenic radionuclides (namely the ⁴⁰K, ²¹⁰Pb, ²²⁶Ra, ¹³⁷Cs, ²³⁴Th, ²²⁸Th and ²²⁸Ra) in sediments from Moroccan coast areas by considering estuaries (Sebou and Loukkos) and marine ecosystems (M'diq Bay and three Lagoons: Moulay Bousselham, Sidi Moussa and Oualidia). Sediment samples were analyzed using Gamma spectrometry. The objective was to establish radioactivity levels in Moroccan coastal areas as well as radiological risk assessment by using the ERICA tool. The software allows the estimation of dose rates to biota (a set of reference organisms by default). The highest activity concentrations were found in sediment samples of Sidi Moussa Lagoon, possibly due to the anthropogenic activities, while the lowest levels were reported in Sebou estuary, attributed most probably to a flooding event that occurred in the same year of sampling. Also, ²¹⁰Pb and ⁴⁰K have the most significant concentrations, while ¹³⁷Cs has the lowest concentrations with a great resemblance with similar works. The World Wide Average concentration of ²²⁶Ra was exceeded in the three lagoons and that of ⁴⁰K only exceeded at Sidi Moussa Lagoon. The application of ERICA tool allowed the assessment of total dose rates that are mainly due to internal exposure with strong contribution of ²²⁶Ra mainly for phytoplankton in the case of marine ecosystems and insect larvae, mollusc-bivalve, mollusc-gastropod and zooplankton for estuary ecosystems. The total dose rates were far lesser than the admissible dose rate proposed by ERICA tool (10 μGy h^-1) and, therefore, unlikely to cause harmful effects to organisms. (authors)