Radiation doses to aquatic organisms from natural radionuclides

Abstract

A framework for protection of the environment is likely to require a methodology for assessing dose rates arising from naturally occurring radionuclides. This paper addresses this 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 and fauna, (b) the use of suitable distribution coefficients, concentration factors and global data where data gaps are present and (c) the utilisation of a reference organism approach whereby a finite number of suitable geometries are selected to allow dose per unit concentration factors to be derived and subsequent absorbed dose calculations (weighted or unweighted) to be made. The majority of the calculated absorbed dose, for both marine and freshwater organisms, arises from internally incorporated alpha emitters, with 210Po and 226Ra being the major contributors. Calculated doses are somewhat higher for freshwater compared to marine organisms, and the range of doses is also much greater. This reflects both the much greater variability of radionuclide concentrations in freshwater as compared to seawater, and also variability or uncertainty in concentration factor values. This work has revealed a number of substantial gaps in published empirical data especially for European aquatic environments.

The ERICA Tool

“…These data are derived from published works (Brown et al, 2004;Beresford et al 2007c). The ERICA Integrated Approach should be used to assess incremental doses from human activities only.…”

Application of an environmental impact assessment methodology to a site discharging low levels of radioactivity to a freshwater environment in Norway

“…In this regard, there are some data available. Brown et al (2004) address the issue of assessing dose rates arising from naturally occurring radionuclides for European aquatic environments. The majority of the calculated absorbed doses, for both marine and freshwater organisms, were seen to arise from internally incorporated alpha emitters, with 210 Po and 226 Ra being the major contributors.…”

Embryonic development and skeletogenic gene expression affected by X-rays in the Mediterranean sea urchin Paracentrotus lividus

“…It should be kept in mind that nuclear contamination is caused by unstable isotopes of various elements whose half-life time can be as short as a few days or as long as several centuries. In the marine environment radioactive contamination is mostly caused by discharged nuclear waste which accumulate in the sea bottom sediments (Salbu et al 1997;Brown et al 2004). In addition, ocean seawater currents usually resuspend radionuclides deposited on the ocean floor and distribute them within the water column where some marine organisms or planktonic larvae can migrate vertically and feed on them (Kennish 1997;Aumento et al 2005).…”