¹⁴C and tritium dynamics in wild mammals: A metabolic model

¹ National Institute for Physics and Nuclear Engineering “Horia Hulubei", Life and Environmental Physics Department, 407 Atomistilor St., Bucharest-Magurele, POB MG-6, 077125, Romania
² Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP, UK
³ University of Nottingham, School of Life and Environmental Sciences, University Park, Nottingham NG7 2RD, UK
⁴ National Institute of Radiological Sciences, Environmental and Toxicological Sciences Research Group, 4-9-1, Anagawa, Inage-ku, Chiba-shi 263-8555,Japan

Abstract

The protection of biota from ionising radiations needs reliable predictions of radionuclide dynamics in wild animals. Data specific for many wild animal - radionuclide combinations is lacking and a number of approaches including allometry have been proposed to address this. However, for ¹⁴C and ³H, which are integral components of animal tissues and their diets, a different approach is needed. Here we propose a metabolically based model which can be parameterised predominantly on the basis of published metabolic data. We begin with a metabolic definition of the ¹⁴C and OBT loss rate (assumed to be the same) from the whole body and specific organs. The mammalian body is conceptually partitioned into compartments (body water, viscera, adipose, muscle, blood and remainder) and a simple model defined using net maintenance and growth needs of mammals. The model is tested with data from studies using rats and sheep. It provides a reliable prediction for whole body and muscle activity concentrations without the requirement for any calibration specific to ³H and ¹⁴C. Predictions from the model for representative wild mammals) are presented. Potential developments of a metabolic model for birds and the application of our work to human foodchain modelling are also discussed.