Evaluating summarised radionuclide concentration ratio datasets for wildlife

Wood, M; Beresford, NA; Howard, BJ; Copplestone, D

Abstract

Concentration ratios (CRwo-media) are used in most radioecological models to predict
whole-body radionuclide activity concentrations in wildlife from those in environmental media. This
simplistic approach amalgamates the various factors influencing transfer within a single generic value
and, as a result, comparisons of model predictions with site-specific measurements can vary by orders
of magnitude. To improve model predictions, the development of 'condition-specific' CRwo-media
values has been proposed (e.g. for a specific habitat). However, the underlying datasets for most
CRwo-media value databases, such as the wildlife transfer database (WTD) developed within the IAEA
EMRAS II programme, include summarised data. This presents challenges for the calculation and
subsequent statistical evaluation of condition-specific CRwo-media values. A further complication is
the common use of arithmetic summary statistics to summarise data in source references, even though
CRwo-media values generally tend towards a lognormal distribution and should, therefore, be
summarised using geometric statistics. In this paper, we propose a statistically-defensible and robust
method for reconstructing underlying datasets to calculate condition-specific CRwo-media values from
summarised data and deriving geometric summary statistics. This method is applied to terrestrial
datasets from the WTD. Statistically significant differences in sub-category CRwo-media values (e.g.
mammals categorised by feeding strategy) were identified, which may justify the use of these CRwomedia
values for specific assessment contexts. However, biases and limitations within the underlying
datasets of the WTD explain some of these differences. Given the uncertainty in the summarised
CRwo-media values, we suggest that the CRwo-media approach to estimating transfer is used with
caution above screening-level assessments.

Citation

Wood, M., Beresford, N., Howard, B., & Copplestone, D. (2013). Evaluating summarised radionuclide concentration ratio datasets for wildlife. Journal of Environmental Radioactivity, 126, 314-325. https://doi.org/10.1016/j.jenvrad.2013.07.022

• Journal Article Type: Article
• Publication Date: Dec 3, 2013
• Deposit Date: Sep 27, 2013
• Publicly Available Date: Apr 5, 2016
• Journal: Journal of Environmental Radioactivity
• Print ISSN: 0265-931X
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 126
• Pages: 314-325
• DOI: https://doi.org/10.1016/j.jenvrad.2013.07.022
• Keywords: Radionuclide transfer, statistical analysis, geometric statistic, lognormal distribution,; environmental assessment, model parameter
• Publisher URL: http://dx.doi.org/10.1016/j.jenvrad.2013.07.022
• Related Public URLs: http://www.journals.elsevier.com/journal-of-environmental-radioactivity/