Radionuclide Transport and Uptake in Coastal Aquatic Ecosystems: A Comparison of a 3D Dynamic Model and a Compartment Model

Abstract

In safety assessments of underground radioactive waste repositories, understanding radionuclide fate in ecosystems is necessary to determine the impacts of potential releases. Here, the reliability of two mechanistic models (the compartmental K-model and the 3D dynamic D-model) in describing the fate of radionuclides released into a Baltic Sea bay is tested. Both are based on ecosystem models that simulate the cycling of organic matter (carbon). Radionuclide transfer is linked to adsorption and flows of carbon in food chains. Accumulation of Th-230, Cs-135, and Ni-59 in biological compartments was comparable between the models and site measurements despite differences in temporal resolution, biological state variables, and partition coefficients. Both models provided confidence limits for their modeled concentration ratios, an improvement over models that only estimate means. The D-model enables estimates at high spatio-temporal resolution. The K-model, being coarser but faster, allows estimates centuries ahead. Future developments could integrate the two models to take advantage of their respective strengths.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-013-0398-2) contains supplementary material, which is available to authorized users.

Difference in Particle Transport Between Two Coastal Areas in the Baltic Sea Investigated with High-Resolution Trajectory Modeling

“…For a discussion of the reactiveness of the radionuclides in this safety-assessment study, see Erichsen et al (2013) and Piqué et al (2013). In Simpevarp, a larger proportion of a potential discharge would be transported out to open water than in Forsmark, and the site-specific differences in residence times and distribution of settled particles will increase over time as land uplift will make the Forsmark area more secluded from the Baltic Sea (Lindborg 2010; Lindborg et al 2013).…”

Model of the Long-Term Transport and Accumulation of Radionuclides in Future Landscapes

“…Further, we assume that equilibrium is established between the concentration of radionuclides in newly produced biomass and the corresponding environmental media (upper regolith for terrestrial primary producers and water for aquatic primary producers) and use CR values to estimate radionuclide concentrations in this newly produced biomass. This is an improvement over traditional equilibrium plant uptake models, as we represent plant uptake dynamically as a function of growth, while at the same time ensuring that mass balance is maintained (Avila 2006a, b; Andersson 2010; Erichsen et al 2013). …”

“…Results of dose assessments for other biota than humans are provided by Torudd and Saetre (2013). There are also alternative models for the marine ecosystems (Erichsen et al 2013). …”

Ecosystem model-based approach for modeling the dynamics of <sup>137</sup>Cs transfer to marine plankton populations: application to the western North Pacific Ocean after the Fukushima nuclear power plant accident

“…Consequently, the effective consideration of all these factors implies that the modeling approach of radionuclide transfer to marine biota should be driven by an ecosystem model describing different ecological and physical processes and transfers between organisms in the food web (Erichsen et al, 2013;Koulikov and Meili, 2003;Kryshev and Ryabov, 2000;Kumblad et al, 2006;Sandberg et al, 2007).…”