A new approach to predicting environmental transfer of radionuclides to wildlife: A demonstration for freshwater fish and caesium

Abstract

The NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. AbstractThe application of the concentration ratio (CR) to predict radionuclide activity concentrations in wildlife from those in soil or water has become the widely accepted approach for environmental assessments. Recently both the ICRP and IAEA have produced compilations of CR values for application in environmental assessment. However, the CR approach has many limitations most notably that transfer of most radionuclides is largely determined by site-specific factors (e.g. water or soil chemistry). Furthermore, there are few, if any, values for many radionuclide-organism combinations. In this paper we propose an alternative approach and, as an example, demonstrate and test this for caesium and freshwater fish. Using a Residual Maximum Likelihood (REML) mixed-model regression we analysed a dataset comprising 597 entries for 53 freshwater fish species from 67 sites. The REML analysis generated a mean value for each species on a common scale after REML adjustment taking account of the effect of the inter-site variation. Using an independent dataset, we subsequently test the hypothesis that the REML model outputs can be used to predict radionuclide, in this case radiocaesium, activity concentrations in unknown species from the results of a species which has been sampled at a specific site. The outputs of the REML analysis accurately predicted 137 Cs activity concentrations in different species of fish from 27 Finnish lakes; these data had not been used in our initial analyses. We recommend that this alternative approach be further investigated for other radionuclides and ecosystems.

Transfer parameters for ICRP reference animals and plants collected from a forest ecosystem

“…Whilst, the CR wo-soil values for stable Cs in Table 6 are considerably lower in all cases than those reported in ICRP (2009) (Copplestone et al in-press) underlying the ICRP (2009) recommendations by Beresford et al (2013) and Wood et al (in-press) have demonstrated differences between stable and radioisotope CR wo-media values although the authors note that there may be a variety of reasons for these observations (e.g. geographical bias in the data).…”

“…How such site specific 'reference' data will be utilised within the ICRP's framework requires further elaboration and we understand that the ICRP are in the process of doing this. Beresford et al (2013) suggest an alternative approach to the CR using a residual maximum likelihood mixed model regression to derive relative values for different taxonomic groups taking into account inter-site variation. They hypothesise that the radionuclide activity concentration in a given species could be estimated from the known concentration in a different species removing the need to base predictions on media concentrations and the consequent effect of site-specific factors such as soil or water chemistry.…”

The transfer of 137 Cs, Pu isotopes and 90 Sr to bird, bat and ground-dwelling small mammal species within the Chernobyl exclusion zone

“…Although there are alternative approaches to predict transfer to wildlife in development, such as the use of taxonomic relationships (e.g. Beresford et al, 2013Beresford et al, , 2015, most of the available tools use concentration ratios (CR wo-media ) relating the activity concentrations in plants and animals to those in the appropriate environmental media (soil, air or water) (Beresford et al, 2008a). Whilst databases of CR wo-media values for wild species have been collated (e.g.…”

Exploring taxonomic and phylogenetic relationships to predict radiocaesium transfer to marine biota

“…The database provides a highly valuable resource with which to explore trends in datasets providing the basis for statistical analyses (e.g. Beresford et al, 2013;Wood et al, 2013). The WTD and the IAEA and ICRP compilations summarise data across all isotopes for a given element (i.e.…”

“…A more analytical means of exploring the validity of this approach by looking at relationships between CRs for various taxa would clearly be advantageous. One potentially useful approach is based upon the hypothesis that some form of underlying taxonomic and/or phylogentic relationship exists in relation to ecological transfer of radionuclides (Beresford et al, 2013).…”