Study on fallout radioactivity in the Sudanese red sea coastal environment

The activity concentration of fallout radionuclides v.z., 238Pu, 239+240Pu, 241Am, 137Cs and 90Sr has been measured in some species of multicellular marine algae, sea grass, coral fishes and shellfish, and surface sediments collected from the fringing reef at different locations along the Sudanese coast of the red sea.The measurements were carried out using alpha particle spectrometry, high resolution gamma spectrometry, gas flow proportional counter and liquid scintillation. In the sediments analyzed, the activity concentration averaged 2.65±1.3 (238Pu), 47.96±26.3 (239+240Pu), 19.1±6.5 (241Am), 273±157 (137Cs) and 140.8±73.9 (90 Sr) mBq/kg dry weight. Average activity concentrations(mBq/Kg dry weight) in marine algae from different locations were found to be 20.1±14.1, 21.6±13.3 and 8.5±3.8 (239+240Pu), 6.2±4.0, 11.7±6.1 and 5.1±3.5 (241Am) and 688±242, 868±713 and 116±14.8(137Cs) for brown, red and green algae, respectively. High levels of 137Cs observed in brown and red algae seem to confirm that algae are responsive to the soluble phase of constituents in the ambient medium more than the elements associated to particulate matter. From the results obtained in this study, brown algae (cystoseria species) and red algae (lauranthia species) suggested their suitability to be used as a bio indicators. Activity concentrations of both 238Pu, 239+240Pu in fish are close to detection limits, while shellfish show values an order of magnitude higher relative to coral fish species. The lowest concentration for 239+240Pu was met in the molluscs species tridacnica (2.4) and the highest value was met in the coral species favites. Committed effective dose (CED) from 137 Cs and 210Po due to consumption of coral reef fishes was assessed from their respective activity concentration values measured in aforementioned 31 species of coral fishes using dose conversion factors (DRCFs). On the average, CED (μSv/y) values were found to be 0.012 (carnivores), 0.01(omnivores) and 0.01(herbivores) for 137Cs contributing about 0.4% of the total dose. While for 210Po, it was found to be 3.47, 4.81 and 4.14 (μSv/y) in carnivores, omnivores and herbivores, respectively, which represent 99.6% of the total dose