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

Abstract

A Lagrangian model which simulates the transport of radionuclides released from nuclear accidents in the western Mediterranean Sea was recently described. This model was developed in spherical coordinates and includes three-dimensional mixing due to turbulence, advection by currents, radioactive decay, and radionuclide exchanges between water and bed sediments. Water circulation was downloaded from the HYCOM global ocean model. Water–sediment interactions were described using a dynamic model based on kinetic transfer coefficients. Mixing, decay, and water–sediment interactions were solved using a stochastic method. Now, a dynamic biological uptake model consisting of four species (phytoplankton, zooplankton, non-piscivorous fish, and piscivorous fish) has been integrated within the transport model to be able to assess the effects of a potential accident in biota and fishery regions. The model has been set up for ¹³⁷Cs and ⁹⁰Sr due to the radiological relevance of these radionuclides. Several hypothetical accidents were simulated, resulting in ¹³⁷Cs concentrations in biota significantly higher than background levels. In contrast, ⁹⁰Sr accumulates in the food chain to a considerably weaker extent.