Multi-compartment kinetic–allometric (MCKA) model of radionuclide bioaccumulation in marine fish

Abstract

Abstract. A model of the radionuclide accumulation in fish taking into account the contribution of different tissues and allometry is presented. The basic model assumptions are as follows. (i) A fish organism is represented by several compartments in which radionuclides are homogeneously distributed. (ii) The compartments correspond to three groups of organs or tissues: muscle, bones and organs (kidney, liver, gonads, etc.) differing in metabolic function. (iii) Two input compartments include gills absorbing contamination from water and digestive tract through which contaminated food is absorbed. (iv) The absorbed radionuclide is redistributed between organs or tissues according to their metabolic functions. (v) The elimination of assimilated elements from each group of organs or tissues differs, reflecting differences in specific tissues or organs in which elements were accumulated. (vi) The food and water uptake rates, elimination rate, and growth rate depend on the metabolic rate, which is scaled by fish mass to the 3/4 power. The analytical solutions of the system of model equations describing dynamics of the assimilation and elimination of 134Cs, 57Co, 60Co, 54Mn and 65Zn, which are preferably accumulated in different tissues, exhibited good agreement with the laboratory experiments. The developed multi-compartment kinetic–allometric model was embedded into the box model POSEIDON-R (Maderich et al., 2018b), which describes transport of radionuclides in water, accumulation in the sediment and transfer of radionuclides through the pelagic and benthic food webs. The POSEIDON-R model was applied for the simulation of the transport and fate of 60Co and 54Mn routinely released from Forsmark Nuclear Power Plant (NPP) located on the Baltic Sea coast of Sweden and for calculation of 90Sr concentration in fish after the accident at Fukushima Dai-ichi NPP. Computed concentrations of radionuclides in fish agree with the measurements much better than calculated using standard whole-body model and target tissue model. The model with the defined generic parameters could be used in different marine environments without calibration based on a posteriori information, which is important for emergency decision support systems.

Concentration factors and biological half-lives for the dynamic modelling of radionuclide transfers to marine biota in the English Channel

“…It should be noted that considering only one compartment for the biota was a simplification. This yielded only one kinetic component for depuration though two or three components may be considered (Vives i Batlle et al, 2008;Bezhenar et al, 2021). However, the aim of the present study was to propose recommendation for operational modelling of radionuclide transfer to biota for as many radionuclides and biota as possible based on our available data.…”

A Study on the Transport of 137Cs and 90Sr in Marine Biota in a Hypothetical Scenario of a Nuclear Accident in the Western Mediterranean Sea

“…In the case of 90 Sr, b = 1.0 × 10 −4 for zooplankton and b = 3.0 × 10 −5 for fish [13,29]. Food and water uptakes depend on the metabolic rate of each species [27], thus some parameters are the same for 137 Cs and 90 Sr. As commented in the introduction, these radionuclides were considered due to their high radiological relevance, but BUM parameters for other radionuclides can be seen in [13,27].…”

“…Most models focus on transport processes in the water column and radionuclide interactions with sediments. Nevertheless, the uptake of radionuclides by marine biota is recently being considered and some models already include a biological uptake model (BUM) integrated within the marine transport model [13,[23][24][25][26][27][28][29][30][31].…”