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Radionuclide Transport and Uptake in Coastal Aquatic Ecosystems: A Comparison of a 3D Dynamic Model and a Compartment Model
Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
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2013 (English)In: Ambio, ISSN 0044-7447, Vol. 42, no 4, 464-475 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2013. Vol. 42, no 4, 464-475 p.
Keyword [en]
Steady state, Biosphere, Process modeling, Bioaccumulation, Point source
National Category
Environmental Sciences
URN: urn:nbn:se:su:diva-90772DOI: 10.1007/s13280-013-0398-2ISI: 000318285100010OAI: diva2:628724


Available from: 2013-06-14 Created: 2013-06-11 Last updated: 2014-12-05Bibliographically approved
In thesis
1. Element transport in aquatic ecosystems – Modelling general and element-specific mechanisms
Open this publication in new window or tab >>Element transport in aquatic ecosystems – Modelling general and element-specific mechanisms
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Radionuclides are widely used in energy production and medical, military and industrial applications. Thus, understanding the behaviour of radionuclides which have been or may be released into ecosystems is important for human and environmental risk assessment. Modelling of radionuclides or their stable element analogues is the only tool that can predict the consequences of accidental release.

In this thesis, two dynamic stochastic compartment models for radionuclide/element transfer in a marine coastal ecosystem and a freshwater lake were developed and implemented (Paper I and III), in order to model a hypothetical future release of multiple radionuclides from a nuclear waste disposal site. Element-specific mechanisms such as element uptake via diet and adsorption of elements to organic surfaces were connected to ecosystem carbon models. Element transport in two specific coastal and lake ecosystems were simulated for 26 and 13 elements, respectively (Papers I and III). Using the models, the concentration ratios (CR: the ratio of the element or radionuclide concentration in an organism to the concentration in water) were estimated for different groups of aquatic organisms. The coastal model was also compared with a 3D hydrodynamic spatial model (Paper II) for Cs, Ni and Th, and estimated confidence limits for their modelled CRs. In the absence of site-specific CR data, being able to estimate a range of CR values with such models is an alternative to relying on literature CR values that are not always relevant to the site of interest.

Water chemistry was also found to influence uptake of contaminants by aquatic organisms. Empirical inverse relationships were derived between CRs of fish for stable Sr (CRSr) and Cs (CRCs) and water concentrations of their biochemical analogues Ca and K, respectively (Paper IV), illustrating how such relationships could be used in the prediction of more site-specific CRCs and CRSr in fish simply from water chemistry measurements. 

Place, publisher, year, edition, pages
Stockholm: Department of Ecology, Environment and Plant Sciences, Stockholm University, 2014. 34 p.
radionuclides, elements, concentration ratio, bioaccumulation, biomagnification, fish, modelling, aquatic food web, ecosystem, Cs, Sr, environmental risk assessment
National Category
Environmental Sciences
Research subject
Marine Ecotoxicology
urn:nbn:se:su:diva-110064 (URN)978-91-7649-026-6 (ISBN)
Public defence
2015-01-21, föreläsningssalen, Institutionen för ekologi, miljö och botanik, Lilla Frescativägen 5, Stockholm, 09:30 (English)

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2014-12-28 Created: 2014-12-05 Last updated: 2014-12-30Bibliographically approved

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Konovalenko, LenaBradshaw, Clare
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