Keiichi Ohta

University of Shiga Prefecture

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Shafi M. Tareq

Jahangirnagar University

Hiroshi Sakugawa

Heart Life Hospital

Insaf S. Babiker

University of Khartoum

Nobuhiko Handa

Nagoya University Hospital

Masahiro Maruo

University of Shiga Prefecture

NТ

Noriyuki Тanaka

Iwate Prefectural Kamaishi Hospital

Masayoshi Nakawo

Research Institute for Humanity and Nature

Kazuhiko Takeda

Hiroshima University

Mohamed A. A. Mohamed

University of Sheffield

M.I. Venkatesan

University of California, Los Angeles

Cooperative Institutions

Nagoya University

Hiroshima University

The University of Tokyo

Hokkaido University

National Institute of Polar Research

Research Organization of Information and Systems

Okayama University

Chiba University

Kyushu University

Altaiskiy State Nature Biosphere Reserve

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Isolation and characterization of low molecular weight carbohydrates dissolved in seawater

Marine Chemistry (1985)

Hiroshi Sakugawa Nobuhiko Handa Keiichi Ohta

Dinoflagellate

10.1016/0304-4203(85)90007-6

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Citations (19)

Characteristics and role of groundwater dissolved organic matter on arsenic mobilization and poisoning in Bangladesh

Physics and Chemistry of the Earth Parts A/B/C (2013)

Shafi M. Tareq Masahiro Maruo Keiichi Ohta

Mobilization

Arsenic poisoning

10.1016/j.pce.2013.04.014

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Citations (39)

Lignin biomarker and isotopic records of paleovegetation and climate changes from Lake Erhai, southwest China, since 18.5kaBP

Quaternary International (2010)

Shafi M. Tareq Hiroyuki Kitagawa Keiichi Ohta

Stalagmite

East Asian Monsoon

Sedimentary organic matter

Paleoclimatology

Terrestrial ecosystem

10.1016/j.quaint.2010.04.014

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Citations (55)

Assessment of groundwater contamination by nitrate leaching from intensive vegetable cultivation using geographical information system

Environment International (2003)

Insaf S. Babiker Mohamed A. A. Mohamed H. Terao Kikuo Kato Keiichi Ohta

Groundwater Contamination

Thematic map

Agrochemical

10.1016/s0160-4120(03)00095-3

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Citations (271)

Lignin and Isotope Signatures in Pollen: A Caveat of Lignin Phenol Biomarker for Reconstructing Paleovegetation

Asian Journal of Water Environment and Pollution (2015)

Shafi M. Tareq Keiichi Ohta

Lignin phenol and stable isotope have been used as a biomarker to trace the sources of sedimentary organic matter (SOM), reconstruction of paleovegetation and climate changes without considering the possible occurrence of fossil pollen grain in sedimentary matrix. Lignin phenol analysis of modern pollen showed that both gymnosperm and angiosperm pollen yielded very high concentration of cinnamyl (C) phenols as compared to that of vanillyl (V) and syringyl (S) phenols (C/V=3.05–23.67) with variation in isotopic compositions (δ $^{13}$ =−20.2 to −28.3‰ and δ $^{15}$ N =−9.2 to 1.7‰). Therefore the isotopic and lignin phenol signatures in SOM might be distorted to some extent by fossil pollen. This was especially true in the sediments of low altitude and latitude continental lakes and coastal areas where significant amount of fossil pollen might be deposited. Therefore, before using lignin phenol as a biomarker, one should consider a possible distortion derived from lignin of fossil pollen in sedimentary matrix.

10.3233/ajw-2015-12_1_02

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Vertical distribution of iron(II) and its relation to organic substances in Lake Biwa, Japan

SIL Proceedings 1922-2010 (2010)

Masahiro Maruo Keisuke Tate Keiichi Ohta Kazuhide Hayakawa Hajime Obata

(2010). Vertical distribution of iron(II) and its relation to organic substances in Lake Biwa, Japan. SIL Proceedings, 1922-2010: Vol. 30, No. 9, pp. 1379-1383.

10.1080/03680770.2009.11902336

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A Screening Procedure for Repellents against a Sea Snail

Agricultural and Biological Chemistry (1978)

Keiichi Ohta Hideaki Matsumoto Tsutomu Nawamaki

Journal Article A Screening Procedure for Repellents against a Sea Snail Get access Keiichi Ohta, Keiichi Ohta Department of Agricultural Chemistry, Shizuoka University, Shizuoka, Japan Search for other works by this author on: Oxford Academic Google Scholar Hideaki Matsumoto, Hideaki Matsumoto Department of Agricultural Chemistry, Shizuoka University, Shizuoka, Japan Search for other works by this author on: Oxford Academic Google Scholar Tsutomu Nawamaki Tsutomu Nawamaki Department of Agricultural Chemistry, Shizuoka University, Shizuoka, Japan Search for other works by this author on: Oxford Academic Google Scholar Agricultural and Biological Chemistry, Volume 42, Issue 8, 1 August 1978, Pages 1491–1493, https://doi.org/10.1080/00021369.1978.10863192 Published: 01 August 1978 Article history Received: 09 February 1978 Published: 01 August 1978

10.1080/00021369.1978.10863192

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Characterization of Marine Photochemical Processes in the Seto Inland Sea, Japan.

Oceanography in Japan (1999)

Kazuhiko Takeda Hiroshi Sakugawa Keiichi Ohta Shizuko Hirata Akira Takami

Temporal and spatial variations of hydrogen peroxide, organic peroxide, carbon monoxide, Fe(III) and Fe(II), which are crucial species to control the photochemical processes in coastal seawater, are investigated in the western part of the Seto Inland Sea on May 15-19, 1995. Concentrations of hydrogen peroxide and carbon monoxide wee higher at the surface and decreased with depth, while the vertical distributions of organic peroxide and soluble Fe(II) were found to be almost uniform or a little higher at the bottom layer. Soluble Fe(III) increased with depth and the concentrations at the sampling point near the mouse of the river were higher than those far from river and land, suggesting that suspended matter supplied from river and bottom of the sea was the source of soluble Fe(III). Concentrations of hydrogen peroxide, carbon monoxide and soluble Fe(II) in surface water tended to increase with solar radiation. Especially, diurnal variation of carbon monoxide was clearly in accordance with solar radiation. These results strongly suggest the photochemical formation of hydrogen peroxide, carbon monoxide an soluble Fe(II) in the surface and near-surface waters. Diurnal change of organic peroxide was the reverse of that, the concentrations of organic peroxide in the daytime were lower than those during the nighttime.

Peroxide

10.5928/kaiyou.8.323

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Citations (2)

Organic components in size-separated aerosols from the western North Pacific

Journal of Engineering Physics and Thermophysics (1985)

Keiichi Ohta Nobuhiko Handa

Cascade impactor

Carbon fibers

Fraction (chemistry)

10.1007/bf02109928

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