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Anan M.,Takasaki Sogo Consultant Co. | Yuge K.,Kyushu University | Oohira Y.,Kyushu Environmental Evaluation Association
Paddy and Water Environment | Year: 2012

The subject of this study is water management in low-lying paddy fields. The objective of this study is to quantify the water requirement, and estimate an appropriate volume and facilitate management of irrigation water in areas where it is difficult to estimate the flow rate continuously. A field observation was conducted at a 14-ha study site located in the Kuwabara area, Fukuoka City, southwest of Japan, to evaluate water management conditions in the command area of the reservoir. This site near the reservoir was selected, because it was impossible to understand the water supply situation in the entire command area. The farmers in this region have been unable to retain sufficient irrigation water. The observation results indicate that the water depth fluctuates widely in every irrigation canal. The canals are frequently empty because rotational irrigation is conducted by water managers; this makes quantifying the flow rate in the irrigation canal very difficult. To quantify the water requirement, an improved tank model was introduced. The accuracy of the model was examined by comparing the observed and calculated ponding depths at a paddy field. The simulation results agreed with the observed data. Using this model, water management for the reduction of water managers' labor was simulated. Simulation results indicated that rotational irrigation effectively reduces labor and saves irrigation water. © 2011 Springer-Verlag. Source

Park J.-I.,Kuwait Institute for Scientific Research | Al-Mutairi A.,Kuwait Institute for Scientific Research | Marafi A.M.J.,Kuwait Institute for Scientific Research | Mochida I.,Kyushu Environmental Evaluation Association | And 2 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2016

Behaviors of vanadium and nickel species during hydrodemetallization (HDM) were studied. A Kuwait atmospheric residue and its hydrodemetallized products from a pilot plant at mild and severe reaction conditions were characterized by using GPC coupled with ICP-MS and high temperature GC-AED after separation of them into saturates, aromatics, resins, and asphaltenes. It was found that the HDM reactivity of the vanadium species, especially those with lower molecular weight, was higher than that of Ni species, probably due to the higher polarity of the former than the latter. HDM of the vanadium species in the asphaltene was more difficult than that in the resin. The average molecular weight of metal species through higher temperature HDM was higher than that through the lower temperature HDM, although the metal removal at the higher temperature is higher. © 2016 The Korean Society of Industrial and Engineering Chemistry. Source

Kakiuchi H.,Intituefor Environmental science | Hasegawa H.,Intituefor Environmental science | Akata N.,Intituefor Environmental science | Tamari T.,Kyushu Environmental Evaluation Association | And 5 more authors.
Fusion Science and Technology | Year: 2011

We adeveloped an analytical method for organically bound 3T) in biological environmental samples by using noble gas mass spectrometry of 3He produced from 3 . Three environmental samples with background level OBT concentrations were analyzed, and the results agreed well with those by the conventional liquid scintillation counting of electrolyzed combustion water of the samples. This showed that the method is practical and effective. We also developed an analytical method for nonexchangeable OBT as a combination of pre-treatment of dried samples with free water 3H and our newly developed analytical method for OBT. The repeated analysis of a grass sample with moderate 3H concentration had smaller variance of results for non-exchangeable OBT than for OBT. The sum of non-exchangeable and exchangeable OBT agreed well with OBT measured in the samples. The developed method was successfully applied to terrestrial and marine environmental samples with background 3H levels. Source

Akata N.,Japan National Institute for Fusion Science | Kakiuchi H.,Japan Institute for Environmental Sciences | Tamari T.,Kyushu Environmental Evaluation Association | Tanaka M.,Japan National Institute for Fusion Science | And 4 more authors.
Radiation Protection Dosimetry | Year: 2015

Free water tritium (FWT) and organically bound tritium (OBT) concentrations in pine needles have been investigated to understand the regional background tritium concentration in Toki City. Samples were regularly collected from pine trees on the National Institute for Fusion Science campus (1998-2012) and the nearby Shiomi Park (SP; 2002-12). FWTand OBTconcentrations of the former samples ranged from 0.33 to 0.92 and 0.41 to 1.10 Bq l-1, respectively, while those of the latter samples ranged from 0.32 to 0.86 and 0.33 to 0.79 Bq l-1, respectively. Results of both sampling sites were almost the same, and they have been gradually decreased year by year. Concentration level of tritium for Toki City was close to the average background level in Japan. The OBT/FWT ratios were almost 1.0. The apparent half-life of FWT in this period was estimated as almost 10 y, and that of OBT was estimated as almost 12 y; these values were almost the same as the physical half-life. © The Author 2015. Published by Oxford University Press. All rights reserved. Source

Ueda S.,Japan Institute for Environmental Sciences | Kakiuchi H.,Japan Institute for Environmental Sciences | Hasegawa H.,Japan Institute for Environmental Sciences | Akata N.,Japan Institute for Environmental Sciences | And 2 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2014

The spent nuclear fuel reprocessing plant in Rokkasho, Japan, has been undergoing final testing since March 2006. The concentrations of 129I in environmental water samples collected around the reprocessing plant were measured from 2005 to 2012. The 129I concentrations in water samples of the brackish lake adjacent to a plant from 2006 to 2008 which the spent fuel rods were cut and chemically processed, was higher than the background level. The major source of 129I in the lake was dominated by the direct deposition of 129I from the atmosphere than that from the ocean. © 2014 Akadémiai Kiadó, Budapest, Hungary. Source

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