Estimating transfer parameters in the absence of data

Abstract

The calculation of transfer of radionuclides from the abiotic to the biotic environment is a well-established practice in radiological assessments. Concentration ratios provide simple means to estimate radionuclide activity in biota, from measured (or estimated) radionuclide concentrations in either a food source or an abiotic component such as soil or water. They are typically reported by element, and data compilations may include information such as soil type (e.g., sand, loam, clay) and species. The data may be for multiple species at a single location, single species at multiple locations, or represent compilations from multiple sources. Recently published guidance suggests that estimates are best made using data from the same ecosystem. This paper examines this recent guidance, in the context of using measured data from within a single ecosystem and comparing results to more generic values. Results suggest that generic values may be an adequate substitute for site-specific information. It illustrates how ionic potential may be used as an alternative to group chemical properties in estimating transfer factors. Lastly, limited evidence is found to support the concept of allometric scaling functions for elemental concentrations in plants.

Approaches to providing missing transfer parameter values in the ERICA Tool – How well do they work?

“…Sheppard and Evenden (1990) in their analysis of one species of plant concluded that CR values for various elements generally reflected the periodic classification of the elements and that interpolation using periodic classification might therefore be considered justifiable. However, when considered over numerous plant species, CR values as a function of chemical group showed only a limited correlation (Higley, 2010 …”

The transfer of radionuclides to wildlife

“…These techniques can, from a given sample, provide data for a wide range of elements of relevance to radiological assessments many of which are currently poorly understood. Such methodologies are a cost-and resource-effective tool and are also used in the works described by Higley (2010) and Tagami and Uchida (2010).…”

“…Three of the papers in this issue of Radiation Environmental Biophysics evaluate approaches to estimate radionuclide transfer to wildlife when appropriate data are not available (Higley 2010;Tagami and Uchida 2010;Willey 2010). Biological scaling, or allometry, is the consideration of the effect of size on biological variables.…”

“…Higley et al 2003;Vives i Batlle et al 2009). However, Higley (2010) reports that evidence to support the concept of using allometric scaling functions to estimate radionuclide activity concentrations in plants was inconclusive. This is perhaps not surprising as Tagami and Uchida (2010) present an analysis of tree and crop leaf data that suggest that CR values derived for crops [which are relatively numerous (IAEA 2010)] could be applied to predict radionuclide transfer to trees if data for trees were lacking.…”

“…This is perhaps not surprising as Tagami and Uchida (2010) present an analysis of tree and crop leaf data that suggest that CR values derived for crops [which are relatively numerous (IAEA 2010)] could be applied to predict radionuclide transfer to trees if data for trees were lacking. The data presented by Higley (2010) suggest that the ionic potential of an element could be used to predict its CR for plants. Willey (2010) demonstrates that radionuclide transfer to plants can be related to plant evolutionary history (or phylogeny), with, for instance, monocots being shown to have lower CR CR = Radionuclide wholeÀbody activity concentration Bq:kg À1 fresh mass À Á Radionuclide activity concentration in media Bq per unit media mass or volume ð Þ !…”