Derivation of allometric relationships for radionuclides in marine phyla

An allometric scaling approach has been used to calculate biological half-lives of elimination (TB1/2) and concentration factors (CF) for radionuclides in marine biota. Power functions of organism mass are fitted to a biokinetic database for plankton, seaweed, fish, crustaceans and molluscs, using data generated by us, in combination with reviewed data. Scaling of the CF to M-0.26 ± 0.09 is observed, compatible at ±1σ with metabolic theory predictions that metabolism scales to M0.75. We also observe scaling of TB1/2 to M+0.16 ± 0.03, within the previously reported range +0.15 to +0.30 for biota from various environments and, at < ± 3σ, slightly outside turnover rate scaling predictions to M-0.25. The elements for which the CF scales better allometrically are particle seeking, mainly lanthanides and actinides. Association of the independent term of the allometric power function a with the sediment-water partition coefficient Kd is strongest for these elements, possibly through binding to biological/organic matter. The findings from this study are relevant to extend the range of applicability of our biota dose assessment methodologies where data gaps in transfer exist.

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