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Nagai, Haruyasu; Terada, Hiroaki
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.126 - 133, 2007/03
As a nuclear emergency response system, SPEEDI and WSPEEDI were developed to predict the atmospheric dispersion of radionuclides. Recently, a numerical simulation system SPEEDI-MP has been constructed to apply for various environmental studies. SPEEDI-MP consists of models for the atmospheric, terrestrial, and oceanic environments, database for model inputs, and system utilities. New WSPEEDI in SPEEDI-MP consists of the atmospheric dynamic model and particle dispersion model and has high performance for diffusion and deposition calculations. It simulated successfully the dispersion of 
Cs released by the Chernobyl accident.
Koarashi, Jun; Takeishi, Minoru; Kobayashi, Hirohide
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.223 - 230, 2007/03
no abstracts in English
Tanaka, Tadao; Mukai, Masayuki; Bamba, Tsunetaka
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.275 - 278, 2007/03
Migration behavior of Ce, one of redox-sensitive elements, was studied in natural aquifer loess zone in P.R.China. Migration parameters such as distribution coefficient were obtained by column migration and batch sorption tests. The batch sorption test indicates Ce is irreversibly incorporated near loess surface as Ce(IV). Cerium showed large retardation in migration in the aquifer loess zone. Predicted migratory mobility of Ce in the aquifer, which was calculated by using the distribution coefficient determined by the batch and column tests, could reproduce that in the field test conservatively.
Tsuneyama, Teppei; Ito, Toshimichi; Otosaka, Shigeyoshi
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.236 - 239, 2007/03
The purpose of this study is to investigate the balance of the radionuclides in the Japan Sea by examining the all available data. In order to investigate the balance of the radionuclides in the Japan Sea, we examine the temporal changes of existing, incoming and outgoing amounts. The incoming amount is estimated as the sum of the amounts supplied from the atmosphere by global fallout and from the East China Sea by the Tsushima Warm Current. The outgoing amount is estimated as the sum of the amounts discharged from the Japan Sea and to seabed sediment. The existing amount is estimated by integrating the inventories over a whole surface of the Japan Sea. So, the temporal change of inventories must be elucidated in examining the temporal change of the existing amount. From the result, it is suggested that the rapid vertical transport exists in the Japan Sea as well as the slow transport. In our presentation, the balance of the radionuclides in seawater of the Japan Sea will be elucidated.
Matsunaga, Takeshi; Tsuzuki, Katsunori; Yanase, Nobuyuki; Hanzawa, Yukiko; Naganawa, Hirochika; Inoue, Takanobu*; Yamada, Toshiro*; Miyata, Akifumi*
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.243 - 246, 2007/03
The aim of this work is to obtain a fundamental scheme of stream discharge of inorganic toxic materials derived from Characteristics of the stream discharge of metallic elements were investigated in two forested catchments in the Oda River and the Ijira River watersheds. Precipitations, stream water and soil water samples were collected in raining events and were analyzed for inorganic elements, dissolved organic carbon and isotopic abundance of deuterium. Results revealed an accelerated discharge of specific metals of Cu, Sb and Cr and all the studied REE in dissolved form. This feature was commonly found in the two catchments. The specific metals are strongly suspected to be of anthropogenic origin. An analysis of hydrological discharge, using chemical and isotopic tracers, suggested that the increased discharge of the metals originate from their deposits on the ground surface and/or instantaneous resuspension of stream sediment. Contrary, REE discharge was tightly coupled with that of dissolved humic substances.
Tsuzuki, Katsunori; Matsunaga, Takeshi
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.65 - 72, 2007/03
no abstracts in English
Kimura, Masanori; Matsubara, Takeshi; Ishikawa, Jun; Homma, Toshimitsu
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.348 - 351, 2007/03
no abstracts in English
Cs in the Irish Sea by using ocean environment assessment systemKobayashi, Takuya; Otosaka, Shigeyoshi; Togawa, Orihiko; Hayashi, Keisuke
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.51 - 57, 2007/03
An ocean environment assessment system that forecasts the detailed migration processes of radionuclides in the ocean has been developed. This system consists of an ocean current model and a particle random-walk model. The ocean current model is the modified Princeton Ocean Model (POM). The POM calculates tidal currents by giving tide levels at the open boundary. The particle random-walk model, SEA-GEARN, calculates the radionuclides migration in the ocean. Radionuclides that exist in the ocean are modeled in three phases, such as dissolved in seawater, adsorbed with suspended solids and adsorbed with active bottom sediment. As model validation, the system has been applied to the Irish Sea to simulate the long-term dispersion of Cs actually released from the BNFL spent nuclear fuel reprocessing plant at Sellafield in UK. The calculation well reproduces the main characteristic of migration of dissolved surface Cs concentration in the Irish Sea.
In, Teiji*; Nakayama, Tomoharu*; Matsuura, Yasutaka*; Shima, Shigeki*; Ishikawa, Yoichi*; Awaji, Toshiyuki*; Kobayashi, Takuya; Kawamura, Hideyuki; Togawa, Orihiko; Toyoda, Takahiro*
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.58 - 64, 2007/03
The northwestern part of the Pacific Ocean off the Shimokita Peninsula assumes a complex water mass structure. It is necessary to accurately reproduce the striking circulation patterns and the complicated water mass structures in this area with an ocean general circulation model. We have planned to make use of a one-way nesting method. To initialize the forecast system, we use a 4-dimensional variational method of data assimilation. The assimilated data consist of hydrographic observations collected through the Global Temperature-Salinity Profile Program, sea surface temperature and sea surface height data observed by satellites. A forecast experiment on the basis of oceanographic observations made in 2003 illustrates the good performance of our system. We shall focus, in particular, on the shift from the coastal mode to the gyre mode and vice versa.
Homma, Toshimitsu; Matsubara, Takeshi; Tomita, Kenichi*
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.196 - 203, 2007/03
This paper presents the results obtained from the application of OSCAAR to the Iput dose reconstruction scenario of BIOMASS and also to the Chernobyl 
I fallout scenario of EMRAS, both organized by International Atomic Energy Agency. The Iput Scenario deals with Cs contamination of the catchment basin and agricultural area in the Bryansk Region of Russia, which was heavily contaminated after the Chernobyl accident. This exercise was used to test the chronic exposure pathway models in OSCAAR with actual measurements and to identify the most important sources of uncertainty with respect to each part of the assessment. The OSCAAR chronic exposure pathway models almost successfully reconstructed the whole 10-year time course of Cs activity concentrations in most requested types of agricultural products and natural foodstuffs. The Plavsk scenario provides an good opportunity to test not only the food chain transfer model of I but also the method of assessing I thyroid burden. OSCAAR showed in general good capabilities for assessing the important I exposure pathways, but also limitations using constant isotopic ratio I /Cs provided by the scenario to estimate I deposition for whole Plavsk district.
Kato, Tomoko; Suzuki, Yuji*
Proceedings of International Symposium on Environmental Modeling and Radioecology, p.336 - 339, 2007/03
no abstracts in English