National Institute for Environmental StudiesIbaraki


National Institute for Environmental StudiesIbaraki

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Misawa K.,Tokyo Metroplitan University | Misawa K.,National Institute for Environmental StudiesIbaraki | Yoshino A.,National Institute for Environmental StudiesIbaraki | Takami A.,National Institute for Environmental StudiesIbaraki | And 4 more authors.
Aerosol and Air Quality Research | Year: 2017

Due to economic growth in China, emissions of gaseous components from factories and automobiles have been increasing, which has resulted in severe air pollution. During the winter and spring seasons, Japan, which is on the leeward side of the Asian continent, is on the receiving end of this increasingly problematic transboundary air pollution. In this study, the mass concentration and chemical components of the particulate PM2.5 were continuously observed using an automatic analyzer at Kumamoto on the west coast of Japan from October 2014 to March 2015. A greater number of high PM2.5 days were observed in winter than in autumn. This seasonal change in concentrations was believed to be due to transboundary air pollution traveling from the Asian continent due to seasonal monsoons. The analysis of the chemical composition of PM2.5 supported this idea. The factors leading to high PM2.5 concentrations were investigated and categorized into transboundary air pollution, local air pollution, and volcanic activity based on the analysis of sulfate (SO4 2-) and sulfur dioxide (SO2) concentrations and model simulations. The average concentration of chemical components showed that local air pollution also influenced air quality in Kumamoto. © Taiwan Association for Aerosol Research.

Shimotori K.,National Institute for Environmental StudiesIbaraki | Satou T.,National Institute for Environmental StudiesIbaraki | Imai A.,National Institute for Environmental StudiesIbaraki | Kawasaki N.,University of Selangor | And 5 more authors.
Limnology and Oceanography: Methods | Year: 2016

Molecular size and dissolved organic carbon (DOC) distributions of dissolved organic matter (DOM) in seawater were determined qualitatively and quantitatively by high-performance size exclusion chromatography (HPSEC). To estimate the relationship between molecular size distribution and the DOC concentration of seawater DOM, seawater was desalinated with an electric dialyzer. The recent technological advancements of desalination make us possible to recover a high percentage of seawater DOM. Surface coastal seawater samples were collected from three locations in Japan: Tokyo Bay, Kashima Port, and Cape Inubo. Samples were evaluated by a chromatography system coupled with ultraviolet (UV) absorbance, fluorescence, and nondispersive infrared total organic carbon detectors in series. Two peaks, 1 (1.24 × 105-1.54 × 105 Da) and 2 (9.48 × 102-1.81 × 103 Da), were detected in all sample chromatograms. Peak 1 showed little fluorescence and UV absorption in all samples. It has been shown that carbohydrates, one of the main components of seawater DOM, exhibit almost no fluorescence or UV absorption; thus, Peak 1 could mainly consist of carbohydrates which are usually labile DOM. Total DOC concentrations of the Tokyo Bay, Kashima Port, and Cape Inubo were 1.38, 0.92, and 0.80 mg C L-1, respectively. Peak 2 accounted for 75-80% of the total DOC and showed a substantial humic-like fluorescence and UV absorption in all samples. These results indicate that the photochemical characteristics of seawater DOM significantly differ depending on its molecular size. Thus, analysis of molecular size with our HPSEC provides a new approach for quantitative and qualitative characterization of seawater DOM. © 2016 The Authors Limnology and Oceanography.

Kondo T.,National Institute for Environmental StudiesIbaraki | Ebie Y.,National Institute for Environmental StudiesIbaraki | Kiji M.,Yonden Consultants Co. | Sugiura N.,University of TsukubaIbaraki | And 2 more authors.
Sustainable Environment Research | Year: 2011

The feasibility of the slanted soil chamber system (SSCS) for gray water treatment was conducted. The SSCS treating kitchen- and other-gray water (bath, laundry and hand wash) were installed individually in 3 individual houses in Miho village, Japan. During more than one year operation, water flow patterns of the gray water and pollutants removal efficiency were monitored. From water flow patterns, there were 2 peaks in the gray water: breakfast in the morning and supper time in the evening for kitchen-gray water and other-gray water (laundry in the morning and bath in the evening). The water volume of other-gray water was 3.3-3.8 times higher than kitchen-gray water. Suspended solids (SS) was effectively removed in all SSCSs; however, SS was accumulated on the soil in winter season. Annual renewal or replacement of chambers is necessary. Biochemical oxygen demand, total nitrogen and total phosphorus removal efficiencies were affected not only by water volume but also by ambient temperature. In conclusion, SSCSs used in this study achieved high nutrient removal efficiency when the water volume was set at below 40 L m-2. © 2011, Chinese Institute of Environmental Engineering. All rights reserved.

Kubota K.,National Institute for Environmental StudiesIbaraki | Kubota K.,Nagaoka University | Yoochatchaval W.,National Institute for Environmental StudiesIbaraki | Yamaguchi T.,Nagaoka University | Syutsubo K.,National Institute for Environmental StudiesIbaraki
Sustainable Environment Research | Year: 2010

In the present study, a single-chamber microbial fuel cell (single-chamber MFC) was applied to the treatment of sucrose-based synthetic wastewater at 20 °C in order to evaluate its efficiency for electricity generation and organic removal. A carbon cloth (58 × 160 mm) was used as the anode electrode. The cathode electrode was a carbon cloth (40 × 165 mm, 1 mg Pt cm-2), which was directly exposed to air to supply the oxygen (air cathode). Synthetic wastewater containing sucrose (1 g COD L-1) was used as feed for the MFC. The hydraulic retention time was set to 25 h. In a continuous flow experiment, on 45 d a stable power density of 56 mW m-2 at the anode was obtained. At this time, the coulombic efficiency and COD removal efficiency of the MFC were 21 and 25%, respectively. The coulombic efficiency was reduced to 5% at 220 d, owing to the significant increase in rate of methane conversion. Moreover, this study examined the influence of changes in wastewater composition (including addition of sulfate or electrolyte, and changes in organic composition) on the characteristics of the power generation of the MFC. The maximum power density obtained at the anode was 127 mW m-2 when the wastewater was supplemented with 50 mM PO4 buffer. The organic composition of the wastewater affected methane conversion and power generation. Electron flow from organic matter degradation to electricity or to methane conversion is altered according to the organic composition of the wastewater. © 2010, Chinese Institute of Environmental Engineering. All rights reserved.

Trisomboon J.,Srinakharinwirot University | Trisomboon J.,Tokyo University of Agriculture and Technology | Li C.,Nanjing Agricultural University | Suzuki A.K.,National Institute for Environmental StudiesIbaraki | And 3 more authors.
Journal of Reproduction and Development | Year: 2015

To investigate the effect of endocrine disruption of 4-nitro-3-phenylphenol (PNMPP) on immature male Wistar- Imamichi rats, the rat pituitary was exposed to PNMPP (10–5–10–9 M) for 24 h with or without gonadotropin-releasing hormone (GnRH) in experiment I. In addition, the Leydig cells (10–5–10–9 M) were exposed to PNMPP for 24 h with or without human chronic gonadotropin (hCG) in experiment II. Our results showed that the PNMPP at 10–5–10–7 M suppressed follicle-stimulating hormone (FSH) and luteinizing hormone (LH) productions from GnRH-stimulated pituitary cells. At the same time, PNMPP 10–5–10–7 M induced an increase in testosterone production from the Leydig cells treated with or without hCG. Based on our results, it can be concluded that that PNMPP might have both androgen agonist action by decreasing FSH and LH production in the pituitary and anti-androgenic action by increasing testosterone production in the Leydig cell. © 2015 by the Society for Reproduction and Development.

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