Collation of strontium concentration ratios from water to aquatic biota species in freshwater and marine environments and factors affecting the ratios

The fate of strontium-90 (90Sr) from water to aquatic biota is of concern since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, because of continuing small 90Sr releases to the seawater from the FDNPP site. The Japanese diet includes many edible marine and freshwater species, and the environmental parameter, that is, the concentration ratio (CR) from water to biota is useful to estimate the potential 90Sr intake, especially from frequently consumed seafoods. However, widely used CR data for radiation dose assessment only have provided values for biota types such as fish, crustaceans, macroalgae etc. and thus it is difficult to identify specific data for each species. In this study, therefore, we collated CR data of Sr for aquatic biota by surveying available open data sources from the 1950’s to 2019, not only for edible parts but also whole and inedible parts. In total, we obtained 3800 CR data: 3013 data for marine biota, 28 data for brackish water biota, and 759 data for freshwater biota. The results showed that species-specific CRs may decrease the uncertainties compared to those published in IAEA documents; however, different diets and living areas by species may lead to different uncertainties for different species.