Natural radioactivity in algae arrivals on the Canary coast and dosimetry assessment

Abstract

Nowadays, the use of wild and culture harvest seaweed in food industry is a booming productive sector. In this context, a radiological characterization of five globally common seaweed species that were collected in arrival on Gran Canaria coast was carried out. The studied algae species were Cymopolia barbata, Lobophora variegata, Sargassum vulgare, Dictyota dichotoma and Haliptilon virgatum. Radionuclides analysed by alpha and gamma spectrometry were 238U, 234U, 235U, 210Po, 234Th, 226Ra, 210Pb, 228Th, 224Ra, 40K and 7Be. Activity concentrations, ratios, and concentration factors (CF) were determined for all samples collected. The CF in algae was higher for reactive-particle radionuclides (210Po, 234Th, 228Th and 210Pb) than for conservative ones (40K and the uranium isotopes). 210Po, 228Th and 234Th CF were one or two orders of magnitude higher than those recommended by the IAEA. L. variegata, C. barbata and S. vulgare showed a clear preference for 210Pb and 210Po, for uranium radioisotopes, and for 40K and 234Th, respectively. A dosimetry assessment due to seaweed ingestion showed considerable values of annual committed effective dose for H. virgatum (605 ± 19 μSv/y), L. variegata (574 ± 17 μSv/y) and D. dichotoma (540 ± 30 μSv/y). Hence, this study suggests that an algae radiological characterization is recommended as part of the product valorising process.