A simple fish physiological model for radioecologists exemplified for 54Mn direct transfer and rainbow trout (Oncorhynchus mykiss W.)

A simple kinetic model for the transfer of radionuclide to freshwater fish was formulated based on physiological (blood and flow rates), anatomical (volume of tissue compartments) and thermodynamic (tissue-to-blood partition coefficients) parameters. The present study describes 54Mn direct transfer to young rainbow trout and exemplifies this new approach for radioecology. The model was calibrated on uptake and depuration kinetics datasets obtained for 14 organs/tissues during a 12-week experiment. Organs were classified into three compartments: an input compartment (gills), a distribution/reservoir compartment (muscles, skeleton and skin) and an excretional function compartment (digestive system and liver). For the three compartments, the partition coefficients and the residence time of the pollutant were, respectively: 161 and 4 h, 87 and 1.5 days, and 1465 and 14 days. As an indirect validation technique, a steady-state concentration factor was calculated for the whole organism from the partition coefficient values and fractional volumes of the compartment. The value of 8 l kg−1 w.w. is similar to those reported in the literature.