Radionuclide transfer to wildlife at a ‘Reference site’ in the Chernobyl Exclusion Zone and resultant radiation exposures

N.A Beresford,C.L Barnett,S Gashchak,A Maksimenko,E Guliaichenko,M.D Wood,M Izquierdo

doi:10.1016/j.jenvrad.2018.02.007

Abstract

This study addresses a significant data deficiency in the developing environmental protection framework of the International Commission on Radiological Protection, namely a lack of radionuclide transfer data for some of the Reference Animals and Plants (RAPs). It is also the first study that has sampled such a wide range of species (invertebrates, plants, amphibians and small mammals) from a single terrestrial site in the Chernobyl Exclusion Zone (CEZ). Samples were collected in 2014 from the 0.4 km2 sampling site, located 5 km west of the Chernobyl Nuclear Power complex. We report radionuclide (137Cs, 90Sr, 241Am and Pu-isotopes) and stable element concentrations in wildlife and soil samples and use these to determine whole organism-soil concentration ratios and absorbed dose rates.Increasingly, stable element analyses are used to provide transfer parameters for radiological models. The study described here found that for both Cs and Sr the transfer of the stable element tended to be lower than that of the radionuclide; this is the first time that this has been demonstrated for Sr, though it is in agreement with limited evidence previously reported for Cs.Studies reporting radiation effects on wildlife in the CEZ generally relate observations to ambient dose rates determined using handheld dose meters. For the first time, we demonstrate that ambient dose rates may underestimate the actual dose rate for some organisms by more than an order of magnitude. When reporting effects studies from the CEZ, it has previously been suggested that the area has comparatively low natural background dose rates. However, on the basis of data reported here, dose rates to wildlife from natural background radionuclides within the CEZ are similar to those in many areas of Europe.

Highlights

In environmental radiation protection, the estimation of activity concentrations in organisms is one of the largest uncertainties in the prediction of dose rates received by wildlife (e.g. Vives i Batlle et al, 2007; Beresford et al, 2008a; Johansen et al, 2012)
Results for wildlife are presented on a fresh matter (FM) basis and those for soil on a dry matter (DM) basis
Radionuclide activity concentrations in soils collected in the vicinity of the sampled pine trees were in the range of those collected from the inner sampling area, with the exception of higher Pu-isotope concentrations

Summary

Introduction

The estimation of activity concentrations in organisms is one of the largest uncertainties in the prediction of dose rates received by wildlife (e.g. Vives i Batlle et al, 2007; Beresford et al, 2008a; Johansen et al, 2012). Transfer parameters are not available for many radionuclide-organism combinations (ICRP, 2009; IAEA, 2014; Brown et al, 2016) To address this lack of data, the International Commission on Radiological Protection (ICRP) (2009) suggested identifying a series of sites where each of the ‘Reference Animals and Plants’ (RAPs) considered in the ICRP assessment framework (ICRP, 2008) could be collected and analysed. To date such sites, in the terrestrial environment, have been sampled in Norway (Thørring et al, 2016), Spain (Guillén et al, 2018) and England (Barnett et al, 2014); the Norwegian study sampled marine and freshwater RAPs. The RAPs are defined at the taxonomic level of family and for terrestrial ecosystems they are: Reference Wild grass (Poaceae); Reference Pine tree (Pinaceace); Reference Earthworm (Lumbricidae); Reference Bee (Apidae); Reference Rat (Muridae); Reference Deer (Cervidae); Reference Duck (Anatidae); and Reference Frog (Ranidae).

Methods

Results

Discussion

Conclusion