Radiation doses to aquatic organisms from natural radionuclides

Abstract

A framework for protection of the environment is likely to require a methodology forassessing dose rates arising from naturally occurring radionuclides. This paper addressesthis issue for European aquatic environments through a process of (a) data collation,mainly with respect to levels of radioactivity in water sediments and aquatic flora andfauna, (b) the use of suitable distribution coefficients, concentration factors and global datawhere data gaps are present and (c) the utilisation of a reference organism approachwhereby a finite number of suitable geometries are selected to allow dose per unitconcentration factors to be derived and subsequent absorbed dose calculations (weighted orunweighted) to be made. The majority of the calculated absorbed dose, for both marineand freshwater organisms, arises from internally incorporated alpha emitters, with210Po and 226Ra being the major contributors. Calculated doses are somewhat higher for freshwatercompared to marine organisms, and the range of doses is also much greater. This reflectsboth the much greater variability of radionuclide concentrations in freshwater as comparedto seawater, and also variability or uncertainty in concentration factor values. This workhas revealed a number of substantial gaps in published empirical data especially forEuropean aquatic environments.