3D numerical model of ecohydrodynamics for shallow waters

Bezhenar, Roman,Jung, Kyung Tae,Maderich, Vladimir,Kim, Kyeong Ok BioOne (Coastal Education and Research Foundation) 2016 JOURNAL OF COASTAL RESEARCH Vol.75 No.special

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

European Geosciences Union 2016 Biogeosciences Vol.13 No.10

<P>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 Cs-137 still remain in sediments, benthic organisms, and demersal fishes in the coastal zone around the FDNPP. These observations indicate that there are Cs-137 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 Cs-137 released due to the FDNPP accident. The model simulations for activity concentrations of Cs-137 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 (0.45aEuro-yr(-1)) is close to the observed decrease constant in sediments (0.44aEuro-yr(-1)). These results strongly indicate that the gradual decrease of activity in demersal fish (decrease constant is 0.46aEuro-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 Cs-137 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 Cs-137 from contaminated bottom sediments to marine organisms and the potential application of a generic model in different regions of the world's oceans.</P>

Fukushima ¹³⁷Cs releases dispersion modelling over the Pacific Ocean. Comparisons of models with water, sediment and biota data

Periá,ñ,ez, R.,Bezhenar, R.,Brovchenko, I.,Jung, K.T.,Kamidara, Y.,Kim, K.O.,Kobayashi, T.,Liptak, L.,Maderich, V.,Min, B.I.,Suh, K.S. Elsevier Applied Science Publishers 2019 JOURNAL OF ENVIRONMENTAL RADIOACTIVITY Vol.198 No.-

<P><B>Abstract</B></P> <P>A number of marine radionuclide dispersion models (both Eulerian and Lagrangian) were applied to simulate <SUP>137</SUP>Cs releases from Fukushima Daiichi nuclear power plant accident in 2011 over the Pacific at oceanic scale. Simulations extended over two years and both direct releases into the ocean and deposition of atmospheric releases on the ocean surface were considered. Dispersion models included an embedded biological uptake model (BUM). Three types of BUMs were used: equilibrium, dynamic and allometric. Model results were compared with <SUP>137</SUP>Cs measurements in water (surface, intermediate and deep layers), sediment and biota (zooplankton, non-piscivorous and piscivorous fish). A reasonable agreement in model/model and model/data comparisons was obtained.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Marine dispersion models applied to Fukushima releases in the Pacific Ocean. </LI> <LI> Biological uptake model included within physical dispersion models. </LI> <LI> Model results compared with measurements in water, sediments and biota. </LI> <LI> Generally good agreement in model/model and model/data comparisons. </LI> </UL> </P>

Modelling of marine radionuclide dispersion in IAEA MODARIA program: Lessons learnt from the Baltic Sea and Fukushima scenarios

Periá,ñ,ez, R.,Bezhenar, R.,Brovchenko, I.,Duffa, C.,Iosjpe, M.,Jung, K.T.,Kobayashi, T.,Lamego, F.,Maderich, V.,Min, B.I.,Nies, H.,Osvath, I.,Outola, I.,Psaltaki, M.,Suh, K.S.,de With, G. Elsevier 2016 Science of the Total Environment Vol.569 No.-

<P><B>Abstract</B></P> <P>State-of-the art dispersion models were applied to simulate <SUP>137</SUP>Cs dispersion from Chernobyl nuclear power plant disaster fallout in the Baltic Sea and from Fukushima Daiichi nuclear plant releases in the Pacific Ocean after the 2011 tsunami. Models were of different nature, from box to full three-dimensional models, and included water/sediment interactions. Agreement between models was very good in the Baltic. In the case of Fukushima, results from models could be considered to be in acceptable agreement only after a model harmonization process consisting of using exactly the same forcing (water circulation and parameters) in all models. It was found that the dynamics of the considered system (magnitude and variability of currents) was essential in obtaining a good agreement between models. The difficulties in developing operative models for decision-making support in these dynamic environments were highlighted. Three stages which should be considered after an emergency, each of them requiring specific modelling approaches, have been defined. They are the emergency, the post-emergency and the long-term phases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Models applied to simulate <SUP>137</SUP>Cs marine dispersion after nuclear accidents. </LI> <LI> Not good agreement initially found in highly dynamic environments. </LI> <LI> Difficulties in developing models for decision making after emergencies highlighted. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Inter-comparison of dynamic models for radionuclide transfer to marine biota in a Fukushima accident scenario

Vives i Batlle, J.,Beresford, N.A.,Beaugelin-Seiller, K.,Bezhenar, R.,Brown, J.,Cheng, J.-J.,Ć,ujić,, M.,Dragović,, S.,Duffa, C.,Fié,vet, B.,Hosseini, A.,Jung, K.T.,Kamboj, S.,Keu Elsevier 2016 JOURNAL OF ENVIRONMENTAL RADIOACTIVITY Vol.153 No.-

<P><B>Abstract</B></P> <P>We report an inter-comparison of eight models designed to predict the radiological exposure of radionuclides in marine biota. The models were required to simulate dynamically the uptake and turnover of radionuclides by marine organisms.</P> <P>Model predictions of radionuclide uptake and turnover using kinetic calculations based on biological half-life (<I>T</I> <SUB> <I>B1/2</I> </SUB>) and/or more complex metabolic modelling approaches were used to predict activity concentrations and, consequently, dose rates of <SUP>90</SUP>Sr, <SUP>131</SUP>I and <SUP>137</SUP>Cs to fish, crustaceans, macroalgae and molluscs under circumstances where the water concentrations are changing with time. For comparison, the ERICA Tool, a model commonly used in environmental assessment, and which uses equilibrium concentration ratios, was also used. As input to the models we used hydrodynamic forecasts of water and sediment activity concentrations using a simulated scenario reflecting the Fukushima accident releases.</P> <P>Although model variability is important, the intercomparison gives logical results, in that the dynamic models predict consistently a pattern of delayed rise of activity concentration in biota and slow decline instead of the instantaneous equilibrium with the activity concentration in seawater predicted by the ERICA Tool. The differences between ERICA and the dynamic models increase the shorter the <I>T</I> <SUB> <I>B1/2</I> </SUB> becomes; however, there is significant variability between models, underpinned by parameter and methodological differences between them.</P> <P>The need to validate the dynamic models used in this intercomparison has been highlighted, particularly in regards to optimisation of the model biokinetic parameters.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Comparison of 7 dynamic models for radionuclide transfer in marine biota with the ERICA Tool. </LI> <LI> <SUP>90</SUP>Sr, <SUP>131</SUP>I, <SUP>137</SUP>Cs in fish, crustaceans, algae and molluscs in a Fukushima scenario. </LI> <LI> Consistent pattern of delayed uptake and slow turnover by the dynamic models. </LI> <LI> Differences between ERICA and dynamic models increase with biological half-life. </LI> <LI> Significant variability between models linked to parameter and methodology differences. </LI> </UL> </P>

후쿠시마 방사능 오염수의 거동 및 해양생물에의 영향

정경태,김경옥,김미경,Chang, Z,Qiao, F,Maderich, V,Brovchenko, I,Bezhenar, R 한국해양환경·에너지학회 2014 한국해양환경·에너지학회 학술대회논문집 Vol.2014 No.5