Fukushima University

About: Fukushima University is a education organization based out in Fukushima, Japan. It is known for research contribution in the topics: Population & Environmental science. The organization has 705 authors who have published 1748 publications receiving 22358 citations.

Erosion as a Factor of Transformation of Soil Radioactive Contamination in the Basin of the Shchekino Reservoir (Tula Region)

Abstract: Redistribution of sediments and Chernobyl-derived 137Сs transported with them were estimated using a set of field methods and erosion model calculations for the Shchekino reservoir (Tula region) catchment, and changes in the contents of 137Сs in soils of various types that occurred over 1986–2018 were determined. The rate of snowmelt soil erosion on arable land during this period has decreased by about a half in comparison with that in 1960–1985 due to a reduction in soil freezing depth in winter. The rainfall erosion rate increased by about a third between 1986–2003 due to an increase in the rainfall erosivity index; after that, it tended to decrease synchronously with a decrease in the rainfall erosivity. The total average annual soil loss related to water erosion varies in the range of 1.3–1.6 t ha–1 depending on the soil type. The erosional loss of 137Сs from arable land averaged 1.5–2% of its total inventory, which decreased by more than a half in comparison with the initial inventory in May 1986 due to natural decay. On 0.4% of the arable land with maximum rates of erosion, the decrease in the 137Сs inventory reached 12–40% from the initial inventory. More than 90% of 137Сs washed away with sediments from arable lands were redeposited along the transportation pathway from arable fields to permanent streams. The total soil 137Сs inventory exceeded its initial inventory at the time of fallout from the atmosphere in May 1986 in the bottoms of hollows in areas from the lower edge of the arable land to the upper reaches of dry first-order valleys due to high sedimentation rates. The 137Сs inventory exceeded the lower threshold of permissible radioactive contamination of soils (37 kBq m–2) also in some other sediment sinks (bottoms of dry valleys, foot of plowed slopes, and a low floodplain of rivers) due to the accumulation of contaminated sediments.

Effects of Particles Blend Ratio on Surface Quality in Surface Polishing Using Magnetic Polishing Liquid (MPL)

Abstract: This paper describes an experimental investigation of the effects of the particle blend ratio on surface quality in surface polishing using magnetic polishing liquid (MPL). MPL is produced by mixing sub-micrometer- or micrometer-size abrasive particles into a Magnetic Compound Fluid (MCF), a functional fluid composed of MF(Magnetic Fluid) and MRF (Magneto-rheological Fluid), that reacts with magnetic fields. As a step toward establishing the new surface finishing technology using MPL, it is essential to clarify the effects of the blend ratio of particles to solvent in MPL. For this purpose, first five kinds of kerosene-based MPLs with different blend ratios of particles were prepared, then polishing operations involving stainless steel workpieces were carried out on an experimental rig developed in-house. During the experiments, steady state magnetic fields with different strengths were applied while the contact force between the workpiece and the polishing pad was kept constant. The experimental results showed that the blend ratio of particles affects the work-surface quality significantly. Following SEM and optical microscopy observations of the polished work-surfaces, an appropriate blend ratio, under which the surface roughness improved from the original value of Ra100nm to a final one of Ra24nm after polishing for 30min, was recommended.

Long-term behavior of 137Cs and 3H activities from TEPCO Fukushima NPP1 accident in the coastal region off Fukushima, Japan.

Abstract: Decreasing trends of both 137Cs and 3H activity concentrations and an increasing trend of 3H/137Cs activity ratio at Fukushima Dai-ichi Nuclear Power Plant, FNPP1, were observed. Homogeneous distribution of 3H were observed off Fukushima and 3H activity concentrations ranged from 60 to 200 Bq m−3 in 2014. Contribution by relatively 3H rich water from surrounding rivers might be larger source of 3H rather than flux of 3H from FNPP1. Possibilities of observed high and variable 3H/137Cs activity ratio close to FNPP1 site may be evaporation of 3H or sporadic release of 3H rich/poor water from the site.

Mechanism of the degradation of Orange G by sodium hypochlorite

Abstract: Products in the degradation of the monoazo dye, Orange G, by sodium hypochlorite in water were investigated. A variety of products, including chlorobenzene, p-dichlorobenzene, biphenyl, 4-chlorobiphenyl and azobenzene, were detected in the diethyl ether extract of the reaction mixture by gas chromatography-mass spectrometry. Three water-soluble products were observed primarily in the reaction mixture by ion-pair chromatography using the cationic surfactant, cetyltrimethylammonium bromide. Two of the three water-soluble products were separated from the reaction mixture and their structures were elucidated. A possible mechanism for the formation of these products is proposed.