Determination of uranium, thorium and polonium radioisotopes in algae samples from El Hierro island by using alpha spectrometry

Abstract

A first radioactivity study of algae species from El Hierro island has been carried out in this final degree work. The radionuclide content of 238U, 235U, 234U, 210Po, 228Th, 230Th and 232Th were analysed by alpha-spectrometry technique and this methodology was checked when a proficiency test was applied. For this purpose, activity concentration, concentration factor and its ratios have been calculated for each alga sample. The coastal environment was found to be enriched with 210Po and 228Th for brown algae species, with an average activity concentration of 311 ± 15 and 65 ± 3 Bq/kg respectively. For the same nuclides, the ratios approved their affinity to organic matter and a radiological risk assessment showed an exceed dose of 210Po to these samples (747 ± 37 μSv/y). Significant differences were found between type of algae and geographical location in a statistical analysis for each radionuclide. This study also proposed a continuation of radiological characterization to assess the future impacts on the marine environment of this region.