An improved dynamic metabolic model for application to biota

Area of Science:

• Environmental Science
• Radiological Science
• Ecology

Background:

• Nuclear facilities require robust radiation protection for biodiversity.
• Tritium (3H) and radiocarbon (14C) are key elements in biological tissues, necessitating study of their transfer in wild animals.
• Existing models need refinement to accurately assess risks to wildlife.

Purpose of the Study:

• To improve the scientific basis of a model for tritium and radiocarbon transfer in wild mammals, birds, and reptiles.
• To analyze model uncertainties and test its applicability across a broader range of species.
• To link biological/metabolic half-times of organically bound tritium (OBT) and 14C with energy metabolism and metabolic scaling.

Main Methods:

• Utilized a large database of basal metabolic rate (BMR), field metabolic rate (FMR), and organ mass for model inputs.
• Incorporated brain as a distinct compartment in the metabolic model.
• Analyzed experimental data on carbon turnover rates, assessing their suitability for wild animals and linking 13,14C with 134,137Cs turnover.

Main Results:

• Biological and metabolic half-times for OBT and 14C were linked to energy metabolism and metabolic scaling.
• The model successfully accounted for metabolic energy partitioning and factors influencing metabolic rate (temperature, diet, habitat, phylogeny).
• The refined metabolic approach was validated for mammals and reptiles, highlighting limitations of current experimental data for wild populations.

Conclusions:

• The improved model provides a stronger scientific foundation for assessing tritium and radiocarbon transfer in wildlife.
• Understanding metabolic scaling and adaptation is crucial for accurate radiological impact assessments.
• Future research should focus on the radiological impact of accidental releases of 3H and 14C on biota, utilizing the developed model and extensive 134,137Cs data.