A comparison of marine radionuclide dispersion models for the Baltic Sea in the frame of IAEA MODARIA program

Periáñez, R.; Bezhenar, Roman; Iøsjpe, M.; Maderich, Vladіmir; Nies, H.; Osvath, I.; Outola, Iisa; With, G. de

doi:10.1016/j.jenvrad.2014.09.013

Cited by 20 publications

(15 citation statements)

References 29 publications

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“…[35]). However, as follows from (27), the transition time to the equilibrium state (28) of contamination of multi-fraction sediment $ a À1 ds h À1 is on the order of 10 6 s (10 days), i.e., activity is redistributed between different fractions of sediments far slower than between water and the total concentration in the sediment. Additionally, the transfer of activity due to diffusion and/or bioturbation can also lead to a deviation from the equilibrium approximation (28).…”

Section: Model Comparison With the Laboratory Experimentsmentioning

confidence: 99%

“…The exchange processes between water and solids in most models are described in the frame of a one-step reversible reaction of sorption/ desorption on the surface of particles (e.g. [18,26,27]); however, the mobility of radionuclides can be affected by a slow sorption process which ''fixes'' the ion to the solids due to the penetration of ions into the structure of sediment particles and interlattice spacing [20,22,33,35]. These processes were taken into account using two-step fast and slow reversible reactions [9,20,25,36].…”

Section: Introductionmentioning

confidence: 99%

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Migration of radioactivity in multi-fraction sediments

et al. 2017

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A new 3D radioactivity transport model coupled with multiscale circulation and multi-fractional sediment transport modules is presented. The sediment transport module simulates the transport of a mixture of one cohesive sediment fraction and a number of fractions of non-cohesive sediments of different sizes and densities. The model of radionuclide transport describes the key transport and exchange processes in the system of water-suspended and bottom multi-fraction sediments. Two-step kinetics with two successive reversible fast and slow reactions is used in the model. A noticeable feature of the model is approximation of the sediment and contamination profiles in the bed by multiple well-mixed layers to describe the vertical migration of radioactivity within bottom sediments due to erosion/deposition, molecular diffusion and bioturbation. The model accurately reproduced a laboratory experiment on the uptake of radiocesium by lake sediments. An analytical solution describing mutual adjustment of the concentrations of radioactivity in the pore water and in the multi-fraction sediment showed that activity was redistributed between different fractions of sediments far slower than between water and the total concentration in the sediment. The extended one-layer model of bottom contamination of multi-fraction sediments was derived from a general model and compared with a multilayer model. It was found, however, that the one-layer approximation was not capable of correctly predicting the inventory due to the fact that one-layer averaged concentration can essentially differ from the near-surface value in the multi-layer model. Radionuclide 123Environ Fluid Mech (2017) 17:1207-1231 DOI 10.1007 transport in channel with bottom depression was simulated to estimate the effects of erosion/deposition and the multi-fractionality of sediments on the transport process. It was shown that these factors affect the distribution of sediments by forming local maxima and minima of activity at the beginning and end of the depression, respectively, due to the redistribution of contaminated bottom sediments by flow. The developed model can also be used to simulate the transport of a wide class of toxic substances sorbed on sediments.

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Section: Model Comparison With the Laboratory Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Migration of radioactivity in multi-fraction sediments

et al. 2017

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“…Within HELCOM (Helsinki Convention on the Protection of the Marine Environment of the Baltic Sea Area, http://www.helcom.fi) the group MORS (Monitoring of Radioactive Substances) established an internationally agreed monitoring network in 1986 and deposited all the data in a common database (MORS, 2015). Therefore, this event also represents a good test case to validate models and study the benthopelagic coupling effects on radionuclide dynamics (Periañez et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Transfer of radiocaesium from contaminated bottom sediments to marine organisms through benthic food chains in post-Fukushima and post-Chernobyl periods

et al. 2016

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Abstract. After the earthquake and tsunami on 11 March 2011 damaged the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), an accidental release of a large amount of radioactive isotopes into both the air and the ocean occurred. Measurements provided by the Japanese agencies over the past 5 years show that elevated concentrations of 137Cs still remain in sediments, benthic organisms, and demersal fishes in the coastal zone around the FDNPP. These observations indicate that there are 137Cs transfer pathways from bottom sediments to the marine organisms. To describe the transfer quantitatively, the dynamic food chain biological uptake model of radionuclides (BURN) has been extended to include benthic marine organisms. The extended model takes into account both pelagic and benthic marine organisms grouped into several classes based on their trophic level and type of species: phytoplankton, zooplankton, and fishes (two types: piscivorous and non-piscivorous) for the pelagic food chain; deposit-feeding invertebrates, demersal fishes fed by benthic invertebrates, and bottom omnivorous predators for the benthic food chain; crustaceans, mollusks, and coastal predators feeding on both pelagic and benthic organisms. Bottom invertebrates ingest organic parts of bottom sediments with adsorbed radionuclides which then migrate up through the food chain. All organisms take radionuclides directly from water as well as food. The model was implemented into the compartment model POSEIDON-R and applied to the north-western Pacific for the period of 1945–2010, and then for the period of 2011–2020 to assess the radiological consequences of 137Cs released due to the FDNPP accident. The model simulations for activity concentrations of 137Cs in both pelagic and benthic organisms in the coastal area around the FDNPP agree well with measurements for the period of 2011–2015. The decrease constant in the fitted exponential function of simulated concentration for the deposit-feeding invertebrates (0.45 yr−1) is close to the observed decrease constant in sediments (0.44 yr−1). These results strongly indicate that the gradual decrease of activity in demersal fish (decrease constant is 0.46 yr−1) is caused by the transfer of activity from organic matter deposited in bottom sediment through the deposit-feeding invertebrates. The estimated model transfer coefficient from bulk sediment to demersal fish in the model for 2012–2020 (0.13) is larger than that to the deposit-feeding invertebrates (0.07). In addition, the transfer of 137Cs through food webs for the period of 1945–2020 has been modelled for the Baltic Sea contaminated due to global fallout and from the Chernobyl accident. The model simulation results obtained with generic parameters are also in good agreement with available measurements in the Baltic Sea. Unlike the open coastal system where the FDNPP is located, the dynamics of radionuclide transfer in the Baltic Sea reach a quasi-steady state due to the slow rate in water mass exchange in this semi-enclosed basin. Obtained results indicate a substantial contribution of the benthic food chain in the long-term transfer of 137Cs from contaminated bottom sediments to marine organisms and the potential application of a generic model in different regions of the world's oceans.

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“…In the first instance, it is necessary to optimise tools for dispersion modelling (Min et al, 2013) and perform intercomparisons between different models. For the FDNPP accident, this has successfully been done in the context of the IAEA MODARIA I and II inter-comparisons of radionuclide transfer models for seawater and sediments (Periáñez et al, 2016;Periáñez et al, 2015;Periañez et al, 2015).…”

Section: Are We Well Prepared In Case Of An Accidental Release In Eurmentioning

confidence: 99%

Marine radioecology after the Fukushima Dai-ichi nuclear accident: Are we better positioned to understand the impact of radionuclides in marine ecosystems?

Batlle

Aoyama

Bradshaw

et al. 2018

Science of The Total Environment

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This paper focuses on how a community of researchers under the COMET (CO-ordination and iMplementation of a pan European projecT for radioecology) project has improved the capacity of marine radioecology to understand at the process level the behaviour of radionuclides in the marine environment, uptake by organisms and the resulting doses after the Fukushima Dai-ichi nuclear accident occurred in 2011. We present new radioecological understanding of the processes involved, such as the interaction of waterborne radionuclides with suspended particles and sediments or the biological uptake and turnover of radionuclides, which have been better quantified and mathematically described.We demonstrate that biokinetic models can better represent radionuclide transfer to biota in nonequilibrium situations, bringing more realism to predictions, especially when combining physical, chemical and biological interactions that occur in such an open and dynamic environment as the ocean. As a result, we are readier now than we were before the FDNPP accident in terms of having models that can be applied to dynamic situations.The paper concludes with our vision for marine radioecology as a fundamental research discipline and we present a strategy for our discipline at the European and international levels. The lessons learned 2 are presented along with their possible applicability to assess/reduce the environmental consequences of future accidents to the marine environment and guidance for future research, as well as to assure sustainability of marine radioecology in Europe and globally. This guidance necessarily reflects on why and where further research funding is needed, signalling the way for future investigations.3

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A comparison of marine radionuclide dispersion models for the Baltic Sea in the frame of IAEA MODARIA program

Cited by 20 publications

References 29 publications

Migration of radioactivity in multi-fraction sediments

Migration of radioactivity in multi-fraction sediments

Transfer of radiocaesium from contaminated bottom sediments to marine organisms through benthic food chains in post-Fukushima and post-Chernobyl periods

Marine radioecology after the Fukushima Dai-ichi nuclear accident: Are we better positioned to understand the impact of radionuclides in marine ecosystems?

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