Researcher Database

Kazuhiro Toyoda
Faculty of Environmental Earth Science Integrated Environmental Science Environmental Adaptation Science
Associate Professor

Researcher Profile and Settings

Affiliation

  • Faculty of Environmental Earth Science Integrated Environmental Science Environmental Adaptation Science

Job Title

  • Associate Professor

Degree

  • Ph.D., in Chemistry(The University of Tokyo)
  • Ph.D., in Chemistry(The University of Tokyo)

URL

Research funding number

  • 10207649

J-Global ID

Research Interests

  • 環境微生物   地球科学   放射化学   鉱物化学   元素分析   無機地球化学   環境化学   Radiochemistry   Environmental Geochemistry   UV-B effect on soil   Analytical Geochemistry   Environmental Mineralogy   isotope Geochemistry   Inorganic Geochemistry   Paleolimnology   Bioremediation   

Research Areas

  • Natural sciences / Space and planetary science

Academic & Professional Experience

  • 2005 - 2006 大学院地球環境科学研究院環境起学専攻 助教授
  • 2005 - 2006 Associate Professor
  • 2006 - 大学院環境科学院 環境起学専攻 准教授
  • 1995 - 2005 大学院地球環境科学研究科物質環境科学専攻 助教授
  • 1995 - 2005 Associate Professor
  • 1993 - 1995 東京大学助手(大学院理学系研究科鉱物学専攻) 助手
  • 1993 - 1995 Research Associate
  • 1988 - 1993 東京大学助手(理学部鉱物学教室) 助手
  • 1988 - 1993 Research Associate

Education

  •        - 1987  The University of Tokyo
  •        - 1987  The University of Tokyo  Graduate School, Division of Science
  •        - 1984  The University of Tokyo
  •        - 1984  The University of Tokyo  Graduate School, Division of Science
  •        - 1982  The University of Tokyo  Faculty of Science
  •        - 1982  The University of Tokyo  Faculty of Science

Association Memberships

  • THE CLAY SCIENCE SOCIETY OF JAPAN   放射化分析研究会   日本地球化学会   第四紀学会   GEOCHEMICAL SOCIETY   Japan association of Activation Analysis   SIL   Japan association of Quaternary Research   Mineralogical Society of Japan   the Japan Society for Analytical chemistry   The Geochemical Society of Japan   The Geochemical Society   地球環境史学会   

Research Activities

Published Papers

  • Selective Ion Exchange in Supramolecular Channels in the Crystalline State.
    Katsuya Ichihashi, Daisuke Konno, Kseniya Yu. Maryunina, Katsuya Inoue, Kazuhiro Toyoda, Shogo Kawaguchi, Yoshiki Kubota, Yoko Tatewaki, Tomoyuki Akutagawa, Takayoshi Nakamura, Sadafumi Nishihara
    Angew. Chem. Int. Ed. 58 (13) 4169 - 4172 2019 [Refereed][Not invited]
  • Coupled benthic hyporheic responses of macro-invertebrates to surface water pollution in a gravel-bed river. Freshwater Science.
    Junjiro N. Negishi, Aiko Hibino, Kazuki Miura, Ryota Kawanishi, Nozomi Watanabe, Kazuhiro Toyoda
    Freshwater Science 38 (3) 591 - 604 2019 [Refereed][Not invited]
  • Katsuya Ichihashi, Daisuke Konno, Takuya Date, Takumi Nishimura, Kseniya Yu Maryunina, Katsuya Inoue, Toshimi Nakaya, Kazuhiro Toyoda, Yoko Tatewaki, Tomoyuki Akutagawa, Takayoshi Nakamura, Sadafumi Nishihara
    CHEMISTRY OF MATERIALS 30 (20) 7130 - 7137 0897-4756 2018/10 [Refereed][Not invited]
     
    The synthesis of artificial ion channels is one of the core areas of biomimetics and is aimed at achieving control over channel functionality by careful design and selection of the constituent components. However, the optimization of ionic conductivity in the channel in the crystalline state is challenging because of crystal strain, polymorphism, and potentially limited stability. In this study, the pore size of cylindrical channels was controlled with the aim of optimizing ionic conductivity. We prepared two isomorphic salts, Li-2([18]crown-6)(3)[Ni-(dmit)(2)](2)(H2O)(4) (1) and Li-2([15]crown-5)(3)[Ni(dmit)(2)](2)(H2O)(2) (2), both of which possess ion channels formed by a one-dimensional array of crown ethers, Li + ions, and crystalline water molecules. Meanwhile, [Ni(dmit)(2)] - (S = 1/2) molecules formed a ladder configuration with J(rung)/k(B) = -631(5) K, J(l)(eg)/k(B) = -185(5) K for 1, and J(rung)/k(B) = -S17(4) K, J(l)(eg)/k(B) = -109(5) K for 2. For 1, the Li+ ionic conductivity at 293 K in the crystalline state was enhanced from 1.89(18) x 10(-8) S.cm(-1) to 2.46(6) X 10(-7) S.cm(-1) via dehydration. Furthermore, analysis of Li+ ionic conductivities of 2, which incorporated a crown ether with a smaller cavity (the cavity diameters of [18]crown-6 and [15]crown-5 are 2.60-3.20 angstrom and 1.70-2.20 angstrom, respectively) at the same temperature both before and after dehydration revealed conductivities of 1.93(31) X 10(-8) S.cm(-1) and 7.01(21) X 10(-7) S.cm(-1), respectively. This molecular design approach can contribute to increasing the ionic conductivity as well as the development of all-solid-state lithium ion batteries and other electronic device fabrications.
  • Solid Phase Extraction of Thorium and Uranium and their Separation from Lanthanides using Humic Acid Silica Gel as a Low-Cost Adsorbent
    E Prasetyo, TOYODA Kazuhiro
    Journal of Engineering and Technological Sciences 49 (4) 508  2017/10 [Refereed][Not invited]
  • Erik Prasetyo, Kazuhiro Toyoda
    JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY 310 (1) 69 - 80 0236-5731 2016/10 [Refereed][Not invited]
     
    A new humic acid-silica gel composite (HASi) to serve as an adsorbent was synthesized via a single-pot method, and its formation via the sol-gel process was confirmed by FTIR and SEM-EDS characterization. The adsorbent effectively removed Th and U at low pH (2.5-3), and the Langmuir model yielded a maximum sorption capacity of 32.3 and 33.2 mg/g for Th and U, respectively. The removal process was rapid (85 % removal within 5 min) and followed a pseudo-second-order model. The salinity of the solution had little effect on the removal efficiency, which continued throughout the adsorbent's repeated use up to nine times.
  • Kazuhiro Toyoda, Bradley M. Tebo
    GEOCHIMICA ET COSMOCHIMICA ACTA 189 58 - 69 0016-7037 2016/09 [Refereed][Not invited]
     
    The kinetics of Mn(II) oxidation by spores of the marine Bacillus sp. SG-1 was measured under controlled conditions of the initial Mn(II) concentration, spore concentration, chemical speciation, pH, O-2, and temperature. Mn(II) oxidation experiments were performed with spore concentrations ranging from 0.7 to 11 x 10(9) spores/L, a pH range from 5.8 to 8.1, temperatures between 4 and 58 degrees C, a range of dissolved oxygen from 2 to 270 mu M, and initial Mn(II) concentrations from 1 to 200 mu M. The Mn(II) oxidation rates were directly proportional to the spore concentrations over these ranges of concentration. The Mn(II) oxidation rate increased with increasing initial Mn(II) concentration to a critical concentration, as described by the Michaelis-Menten model (Km = ca. 3 mu M). Whereas with starting Mn(II) concentrations above the critical concentration, the rate was almost constant in low ionic solution (I = 0.05, 0.08). At high ionic solution (I = 0.53, 0.68), the rate was inversely correlated with Mn(II) concentration. Increase in the Mn(II) oxidation rate with the dissolved oxygen concentration followed the Michaelis-Menten model (Km = 12-19 mu M DO) in both a HEPES-buffered commercial drinking (soft) water and in artificial and natural seawater. Overall, our results suggest that the mass transport limitations of Mn(II) ions due to secondary Mn oxide products accumulating on the spores cause a significant decrease of the oxidation rate at higher initial Mn (II) concentration on a spore basis, as well as in more concentrated ionic solutions. The optimum pH for Mn(II) oxidation was approximately 7.0 in low ionic solutions (I = 0.08). The high rates at the alkaline side (pH > 7.5) may suggest a contribution by heterogeneous reactions on manganese bio-oxides. The effect of temperature on the Mn(II) oxidation rate was studied in three solutions (500 mM NaCl, ASW, NSW solutions). Thermal denaturation occurred at 58 degrees C and spore germination was evident at 40 degrees C in all three solutions. The activation energies calculated from the Arrhenius plots are consistent with the observation that Ca ions stimulate the Mn(II) oxidation rate. (C) 2016 Elsevier Ltd. All rights reserved.
  • Chungwan Lim, Kazuhiro Toyoda, Ken Ikehara, David W. Peate
    QUATERNARY RESEARCH 80 (1) 76 - 87 0033-5894 2013/07 [Refereed][Not invited]
     
    Only Ulleung and Baegdusan volcanoes have produced alkaline tephras in the japan Sea/East Sea during the Quaternary. Little is known about their detailed tephrostratigraphy, except for the U-Old and B-Tm tephras. Trace element analysis of bulk sediments can be used to identify alkaline cryptotephra because of the large compositional contrast Five sediment cores spanning the interval between the rhyolitic AT (29.4 ka) and Aso-4 (87 ka) tephras were analyzed using an INAA scanning method. Source volcanoes for the five detected alkaline cryptotephra were identified from major element analyses of hand-picked glass shards: Ulleung (U-Ym, and the newly identified U-Sado), and Baegdusan (B-J, and the newly identified B-Sado and B-Ym). The eruption ages of the U-Ym, U-Sado, B-J, B-Sado, and B-Ym tephras are estimated to be 38 ka, 61 ka, 26 ka, 51 ka, 68-69 ka, and 86 ka, respectively, based on correlations with regional-scale TL (thinly laminated) layer stratigraphy (produced by basin-wide changes in bottom-water oxygen levels in response to millennium-scale paleoclimate variations). This study has allowed construction of an alkaline tephrostratigraphical framework for the late Quaternary linked to global environmental changes in the Japan Sea/East Sea, and improves our knowledge of the eruptive histories of Ulleung and Baegdusan volcanoes. Crown Copyright (C) 2013 Published by Elsevier Inc. on behalf of University of Washington. All rights reserved.
  • Kazuhiro Toyoda, Bradley M. Tebo
    GEOCHIMICA ET COSMOCHIMICA ACTA 101 1 - 11 0016-7037 2013/01 [Refereed][Not invited]
     
    Manganese(IV) oxides, believed to form primarily through microbial activities, are extremely important mineral phases in marine environments where they scavenge a variety of trace elements and thereby control their distributions. The presence of various ions common in seawater are known to influence Mn oxide mineralogy yet little is known about the effect of these ions on the kinetics of bacterial Mn(II) oxidation and Mn oxide formation. We examined factors affecting bacterial Mn(II) oxidation by spores of the marine Bacillus sp. strain SG-1 in natural and artificial seawater of varying ionic conditions. Ca2+ concentration dramatically affected Mn(II) oxidation, while Mg2+, Sr2+, K+, Na+ and NO3- ions had no effect. The rate of Mn(II) oxidation at 10 mM Ca2+ (seawater composition) was four or five times that without Ca2+. The relationship between Ca2+ content and oxidation rate demonstrates that the equilibrium constant is small (on the order of 0.1) and the binding coefficient is 0.5. The pH optimum for Mn(II) oxidation changed depending on the amount of Ca2+ present, suggesting that Ca2+ exerts a direct effect on the enzyme perhaps as a stabilizing bridge between polypeptide components. We also examined the effect of varying concentrations of NaCl or KNO3 (0-2000 mM) on the kinetics of Mn(II) oxidation in solutions containing 10 mM Ca2+. Mn(II) oxidation was unaffected by changes in ionic strength (I) below 0.2, but it was inhibited by increasing salt concentrations above this value. Our results suggest that the critical coagulation concentration is around 200 mM of salt (I = ca. 0.2), and that the ionic strength of seawater (I > 0.2) accelerates the precipitation of Mn oxides around the spores. Under these conditions, the aggregation of Mn oxides reduces the supply of dissolved O-2 and/or Mn2+ and inhibits the Mn(II) -> Mn(III) step controlling the enzymatic oxidation of Mn(II). Our results suggest that the hardness and ionic strength of the aquatic environment at circumneutral pH strongly influences the rate of biologically mediated Mn(II) oxidation. (C) 2012 Elsevier Ltd. All rights reserved.
  • Michinobu Kuwae, Narumi K. Tsugeki, Tetsuro Agusa, Kazuhiro Toyoda, Yukinori Tani, Shingo Ueda, Shinsuke Tanabe, Jotaro Urabe
    Science of The Total Environment 442 189 - 197 0048-9697 2013/01/01 [Refereed][Not invited]
  • New technique for the determination of trace elements using multiparameter coincidence spectrometry.
    Hatsukawa, Yuichi, Toh, Yosuke, Oshima, Masumi, Hayakawa, Takehito, Shinohara, Nobuo, Kushita, Kohei, Ueno, Takashi, Toyoda, Kazuhiro
    Journal of Radioanalytical and Nuclear Chemistry 255 (1) 111 - 113 2013 [Refereed][Not invited]
  • Narumi K. Tsugeki, Tetsuro Agusa, Shingo Ueda, Michinobu Kuwae, Hirotaka Oda, Shinsuke Tanabe, Yukinori Tani, Kazuhiro Toyoda, Wan-lin Wang, Jotaro Urabe
    ECOLOGICAL RESEARCH 27 (6) 1041 - 1052 0912-3814 2012/11 [Refereed][Not invited]
     
    Atmospheric dust has wide-reaching effects, not only influencing climate conditions, but also ecosystems. The eastern region of the Asian continent is one of the largest emitters of dust in the world, and recent economic growth in the region has been accompanied by an increase in anthropogenic emissions. However, the effects of increased Asian dusts on aquatic ecosystems are not well understood. We examined fossil pigments and zooplankton remains from Pb-210-dated sediments taken from high mountain lakes of Hourai-Numa and Hachiman-Numa, located in the Towada-Hachimantai National Park of Japan Islands, to uncover historical changes in the phyto-and zooplankton community over the past 100 years. Simultaneously, we measured the geochemical variables of TOC, TN, TP, delta C-13, delta N-15, and lead isotopes (Pb-207/Pb-206, Pb-208/Pb-206) in the sediments to identify environmental factors causing such changes. As a result, despite few anthropogenic activities in the watersheds, alpine lakes in Japan had increased algal and herbivore plankton biomasses by 3-6 fold for recent years depending on the surrounding terrestrial vegetation and landscape conditions. Biological and biogeochemical proxies recorded from the lake sediments showed that this eutrophication occurred after the 1990s when P deposition increased as a result of atmospheric loading of dust transported from the Asian continent. The continued increase of anthropogenically produced dust may therefore impart damaging impacts on mountain ecosystems even if they are protected from direct anthropogenic disturbances.
  • Hiroyuki Imai, Tomoyuki Akutagawa, Fumito Kudo, Mitsuhiro Ito, Kazuhiro Toyoda, Shin-ichiro Noro, Leroy Cronin, Takayoshi Nakamura
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 131 (38) 13578 - + 0002-7863 2009/09 [Refereed][Not invited]
     
    Single crystals of the nanoscale polyoxomolybdate wheel, Na15Fe3Co16[Mo176O528(H2O)(80)]Cl-27 center dot 450H(2)O, was synthesized by the condensation reaction of Na0.4Co0.8[MoO4]center dot 1.5H(2)O at low pH and in the presence of an iron-based reducing agent, and these crystals were characterized by the synchrotron-based X-ray single crystal analysis, magnetic susceptibility, and ionic conductivity measurements.
  • Chungwan Lim, Ken Ikehara, Kazuhiro Toyoda
    GEOCHIMICA ET COSMOCHIMICA ACTA 72 (20) 5022 - 5036 0016-7037 2008/10 [Refereed][Not invited]
     
    Detection techniques for invisible tephra, known as cryptotephra, have been exploited to construct precise and high-resolution correlations for a broad range of sedimentary sequences. We demonstrate that continuous trace-element profiles are an effective means for detecting probable positions of distal cryptotephra in Holocene hemipelagic sediments. Instrumental neutron activation analyses were performed on specimens of bulk sediments from five piston and gravity cores (water depths: 300-1500 m) taken from the southern Japan/East Sea. The down-core variations in the Ta/Sc ratio identify the positions of one to three alkaline cryptotephra in four of these cores. The Cr/Sc profiles show the position of one rhyolitic cryptotephra in three of the cores. The existence of tephra-derived components (glass +/- crystals) was confirmed by microscopic observation, SEM-EPMA analysis and refractive index measurement on grains extracted from these layers. Based on microscopic observation and the stratigraphic correlations between cores, we identified eruption ages of the cryptotephras at 6.3, 7.5 and 9.3 C-14 kyr BP, and two source volcanoes around 800 and 400 km from the study area. The tephra layers visible to the naked eye contained volcanic grains coarser than 200 mu m, and the alkaline and rhyolitic tephra component comprised >20% and >33% of the sediment on weight basis, respectively. In contrast, the range of particle sizes of the cryptotephras detected in this study is finer than 125 mu m, and almost all of the glass shards were finer than 40 Pm. The alkaline and rhyolitic cryptotephras made up only 2-17% and 22-24%, respectively, of the sediment on weigh basis. The high sensitivity of this method stems from the significant difference in trace-element contents between the tephras and enclosing hemipelagic sediments in the core. Alkaline U-Oki tephra was enriched in Ta by one order of magnitude over that of the sediment, and depleted in Sc by one order. The rhyolitic tephra, K-Ah, was depleted by about one order in Cr relative to that of enclosing the sediment. The differences in chemical composition between within-plate alkaline tephras and hemipelagic sediments are usually so large that trace-element geochemical method is likely to be useful for alkaline cryptotephra detection in other areas with similar tectonic characteristics. (C) 2008 Elsevier Ltd. All rights reserved.
  • Michiyo Shimamura, Tomohisa Irino, Tadamichi Oba, Guoqiang Xu, Bingquan Lu, Luejiang Wang, Kazuhiro Toyoda
    GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS 9 (Q04024) 1525-2027 2008/04 [Refereed][Not invited]
     
    To understand the main controlling factors of coral skeletal carbon isotope ratio (delta(13)Cc), we undertook high-temporal- resolution (similar to 1.5 d) measurements of delta(13)Cc for Porites lutea collected from the east coast of Hainan Island, China. The results were compared with factors that have previously been proposed to control coral delta(13)Cc: skeletal extension rate, carbon isotope composition of dissolved inorganic carbon in seawater (delta(13)Cw), and light availability to the coral colony. Hainan Island is characterized by strong summer and winter monsoons that result in distinctive seasonal variations in environmental and coral growth conditions. Compared with other tropical/ subtropical areas, this climate is advantageous in evaluating the effects of different environmental factors on delta(13)Cc. We found that delta(13)Cc varied in phase with solar radiation. Increased total suspended matter (TSM) in the water column was found to reduce delta(13)Cc. These data suggest that light availability, the interplay between solar intensity and attenuation of light by TSM in the water column, is the main controlling factor of delta(13)Cc in the studied coral. In addition, slower skeletal extension was found during periods of lower solar radiation and high turbidity than other periods of similar temperature conditions, suggesting that both factors influence skeletal growth. Seasonal variations in delta(13)Cw were not only too narrow in range to explain the observed delta(13)Cc, but also showed an opposite trend to that of delta(13)Cc. We also failed to detect delta(13)Cc variations due to the kinetic isotope effect (i.e., the discrimination of heavier isotopes during CO2 hydration and hydroxylation and the resulting simultaneous negative shifts of delta(13)Cc and delta(18)Oc from equilibrium values), despite large variations in the measured skeletal extension rate. This outcome probably reflects the high skeletal extension rates of the studied coral (average, 15 mm/a; minimum, 4 mm/a).
  • Y. Hatsukawa, Y. Miyamoto, Y. Toh, M. Oshima, M. Hosein Mahmudy Gharaie, K. Goto, K. Toyoda
    JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY 272 (2) 273 - 276 0236-5731 2007/05 [Refereed][Not invited]
     
    In this study, using neutron activation analysis with multi-parameter coincidence method which was developed at Japan Atomic Energy Agency (JAEA), a non-destructive, ultra-high sensitive multi-elemental determination has been realized. The multi-parameter coincidence method is carried out with an array of 19 germanium detectors, GEMINI-II. Using this system, very weak gamma-rays emitted from trace amounts of elements can be detected. The iridium concentration has been determined by means of neutron activation analysis with multi-parameter coincidence method for Cuban sediment samples across the K/T boundary strata.
  • T Sagawa, K Toyoda, A Tadamichi
    JOURNAL OF QUATERNARY SCIENCE 21 (1) 63 - 73 0267-8179 2006/01 [Refereed][Not invited]
     
    We conducted paired measurements of the Mg/Ca ratio and delta O-18 of planktonic foraminifera, Globigerina bulloides, from a sediment core (MD01-2420) off central Japan in the northwest Pacific, to reconstruct Current movements since the Last Glacial Maximum (LGM). These methods make it possible to determine the magnitude and timing of the sea Surface temperature (SST) changes and to reconstruct the variations of the past seawater delta O-18 (delta(18)Ow) off central Japan. The amplitude of Mg/Ca-based SST changes between the Holocene and the LGM was about 10 degrees C. The strong resemblance of the SSTs estimated from both methods, Mg/Ca-based and delta O-18-based, Suggests that the SST changes were caused primarily by latitudinal displacement of the Kuroshio-Oyashio currents and no distinct change in the carbonate dissolution of the core. The southward migration of the water mass was 5-6 degrees in latitude at the LGM. The values for regional delta(18)Ow changes, which were obtained by subtracting the ice volume contribution from the calculated delta(18)Ow, describe the millennial-scale water mass migration over the last 30 kyr. Copyright (c) 2005 John Wiley & Sons, Ltd.
  • M Shimamura, T Oba, GQ Xu, BQ Lu, LJ Wang, M Murayama, K Toyoda, A Winter
    GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS 6 (Q09017) 1525-2027 2005/09 [Refereed][Not invited]
     
    [1] The extremely high temporal resolution ( nearly daily interval) measurement was conducted on the coral (Porites lutea) oxygen isotope compositions (delta(18)Oc) to examine the detailed relationship between delta(18)Oc and sea surface temperature (SST) and seawater oxygen isotope composition (delta(18)Ow) from Hainan Island, China. Although SST and sea surface salinity (SSS) or delta(18)Ow varied in a wide range at the studied site, the dynamic range of delta(18)Oc recorded in coral was much smaller than expected from SST and SSS (delta(18)Ow) changes. The extremely high (> 30 degrees C) and low (< 22 degrees C) SST and low (< 27) SSS are not suitable for coral calcification, and coral could not record the information as their skeletal delta(18)O. Estimated coral extension rates ( the overall rate is 15 mm/year) varied by a factor of about 18 within one year, from very slow in winter to very fast in spring. Light availability could affect the extension rate of coral skeleton through the activity of photosynthesis of symbiont algae. Such cessation and acceleration of calcification cause a serious distortion of the delta(18)O profile, which makes it difficult to make a correlation between delta(18)O and SST. Because high and low extension rates correspond to low- and high-density bands, respectively, a detailed examination of the density structure may assist the correction for distortion of the delta(18)O profile.
  • Fidelity of δ18O as a proxy for sea surface temperature: Influence of variable coral growth rates on the coral Porites lutea from Hainan Island, China,
    Shimamura, M, T. Oba, G. Xu, B. Lu, L. Wang, M. Murayama, K. Toyoda, A. Winter
    Geochem. Geophys. Geosyst., 6 (9) 09017  2005 [Refereed][Not invited]
  • K Toyoda, Y Shinozuka
    QUATERNARY INTERNATIONAL 123 51 - 61 1040-6182 2004 [Refereed][Not invited]
     
    Lake Biwa is the largest lake in Japan. It is a semi-closed lake surrounded by active faults, and was oxygen-rich prior to the Industrial Revolution. In this lake, arsenic concentration in core sediments was proposed as a proxy for lake-level change, due to a strong correlation between As concentration in recent sediments and water depth. Detailed elemental variations from two piston cores from water depths of 76 and 67 m were obtained from the center of the lake to examine the possible correspondence between As concentrations and paleo-environmental change during the past 40,000 years. The vertical Fe distribution pattern indicates that precipitated Fe hydroxide, the adsorbent of As ions from lake water, has been preserved in buried sediment due to oxic conditions. The change in the Ti/Al ratio suggests that the rapid drop of As content through the last several centuries is due to the increasing inflow of clayey materials generated by human activity, diluting the hydrogenous component. The As contents are fairly constant between 2000 and 9000 yr BP, and the fluctuation of equivalent water depth was 10 m at most. The increase of As content and equivalent water depth during the last two millennia should be coincident with the lake-level rise event at about 2000 yr BP, as suggested by previous investigations. However, during the last 40 kyr the extent of change of equivalent water depth is too large to explain only by tectonic movement. From about 40 cal. kyr BP to 30 cal. kyr BP, As contents significantly increased, and then gradually decreased until mid-Holocene. The change at 30 cal. kyr BP should correspond with climatic change, from wet to dry, at the marine oxygen stage 2/3 transition, with some time lag. Increases of As content are synchronized with events marked by abrupt increases in precipitation. Arsenic was dissolved in lake water as a consequence of rock and soil weathering around Lake Biwa, and then immediately precipitated with iron hydroxide into the take sediment. Our results revealed that the historical change of As contents in core samples was influenced by the amount of As inflow to the lake from the watershed area, as well as by lake-level change. Chemical analysis of the extracts of the hydrogenous component of the samples confirmed this hypothesis. (C) 2004 Elsevier Ltd and INQUA. All rights reserved.
  • K Toyoda
    QUATERNARY INTERNATIONAL 105 57 - 69 1040-6182 2003 [Refereed][Not invited]
     
    Neutron activation analysis was performed on sediments taken from the 250 in thick sediment bed of Lake Biwa, which is composed entirely of lacustrine clay and records palco-environmental change over the past 430,000 years. A comparison is made between the geochemical compositions of cores from the center of Lake Biwa, and lacustrine surface and terrestrial sediments from around Lake Biwa, to estimate past changes in sediment sources. Time series of Th/Sc ratios are synchronized with glacial-interglacial climatic change and also correlated with the reported aeolian quartz flux data. Th/Sc ratios during the delta(18)O stages 1, 5, 7, 9 and 11 are approximately 1.1-1.2, whereas Th/Sc ratios during the 6180 stages 2, 4, 6, 8 and 10 are approximately 1.0-1.1. The possibility of a contribution from the mafic area in the northwestern shore of Lake Biwa, which has low Th/Sc ratios (ca. 0.8), is excluded by the Ti/Al ratio data. As aeolian dust flux to the downwind area from the Asian desert area is higher during glacial times, this data suggests that aeolian dust reaching Japan has an unexpectedly low Th/Sc ratio of source material, and/or that there was a large shift in the amount of dust flux. This assumption remains to be tested by future studies. Th/Sc ratios apparently lag ca. 5000 years behind the marine delta(18)O record during the stage 1/2, 3/4, and 5/6 transitions, which coincides 214, 6 with the aeolian quartz flux variation. Continuous increase of Hf contents from ca. 200,000 years BP could be mainly related to upheaval of the Hf rich and high Th/Sc ratio granite block on the west shore of drilling site by active fault movement. The variations in delivery of high Th/Sc granitic debris has damped the oscillation between Th/Sc ratios of sediments and aeolian dust flux during oxygen isotopic stages 2-3. Both the intermittent increase of Na contents from ca. 430,000 years BP to present, and the abrupt increase of Na content at ca. 140,000 years BP are probably due to the subsidence of the northern basin, as the result of tectonic movement around Lake Biwa. (C) 2002 Elsevier Science Ltd and INQUA. All rights reserved.
  • Y Hatsukawa, Y Toh, M Oshima, T Hayakawa, N Shinohara, K Kushita, T Ueno, K Toyoda
    JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY 255 (1) 111 - 113 0236-5731 2003 [Refereed][Not invited]
     
    Multiparameter coincidence gamma-ray spectrometry based on gamma-gamma coincidence is widely used in the field of nuclear structure studies, and has produced many succesful results. In this paper, feasibility of the method for neutron activation analysis of trace elements was studied. Particularly, a long-lived radioisotope I-129 (T-1/2 = 1.57.10(7) y) in algae samples and iridium in geological samples has been determined.
  • K/T boundary deposit in the proto-Caribbean basin.
    H. Takayama, S. Yamamoto, S. Kiyokawa, K. Toyoda, D. Garcia-Delgado, C. Diaz-Otero, R. Rojas-Consuegra
    American association of petroleum Geologists Memoir, 79 582 - 604 2003 [Refereed][Not invited]
  • Paleo-phosphorus loading to Lake Biwa in Japan anterior to the urban-industrial activity.
    TOYODA Kazuhiro
    GEOCHIMICA ET COSMOCHIMICA ACTA 67 (18) A489 - A489 2003 [Refereed][Not invited]
  • Complex tsunami waves suggested br the Cretaceous/Tertiary boundary deposit at Moncada section, west Cuba in Catastrophic Events and Mass Extinctions
    Geological Society of America Special Paper 356 109 - 124 2002 [Not refereed][Not invited]
  • SHINOZUKA Yoshitsugu, TOYODA Kazuhiro
    Japan analyst The Japan Society for Analytical Chemistry 50 (4) 229 - 235 0525-1931 2001/04/05 [Refereed][Not invited]
     
    We investigated the mass-determination method of As content in soil samples. Both HG (hydride generation)/ICP-AES and HG/AAS combined with the procedure of acid digestion in open vessels are commonly used for As determination in soil and sediment samples, which should shorten the dissolution times. We examined two commercial microwave digestion (MWD) systems to evaluate the possibility for the MWD of soil and sediment samples. They yielded poor results compared to the recommended values from the literature. This is probably because the resistant organic matter found after MWD contains a sig...
  • Origin of the Penalver Formation in northwestern Cuba and its relation to K/T boundary impact event.
    H. Takayama, R. Tada, T. Matsui, M. A. Iturralde-Vinent, T. Oji, E. Tajika, S. Kiyokawa, D. Garcia, H. Okada, T. Hasegawa, K. Toyoda
    Sedimentary Geology 135 (1-4) 295 - 236 2001 [Refereed][Not invited]
  • H Takayama, R Tada, T Matsui, MA Iturralde-Vinent, T Oji, E Tajika, S Kiyokawa, D Garcia, H Okada, T Hasegawa, K Toyoda
    SEDIMENTARY GEOLOGY 135 (1-4) 295 - 320 0037-0738 2000/09 [Refereed][Not invited]
     
    The uppermost Maastrichtian Penalver Formation and its equivalents in northwestern Cuba are characterized by thick, normal-graded calcarenite with distinct basal conglomerate, and have been suspected as deposits related to the Cretaceous-Tertiary boundary (K/T) impact. However, its depositional mechanism is not well understood and clear evidence for its association with the impact has never been presented. In this study, detailed field survey and petrographic observations were carried out on the Penalver Formation in order to clarify its sedimentary processes and to test its relation to the K/T impact. The Penalver Formation at the type locality near Havana is approximately 180 m thick and is subdivided into the Basal, Lower, Middle, Upper and Uppermost Members based on its lithology. The Basal Member consists of massive, poorly sorted, calcirudite with grain-supported fabric, which contains abundant macrofossils of shallow-marine origin and occasional large intraclasts of the underlying strata, suggesting that it was formed by a grain flow from a carbonate platform on the Cretaceous Cuban Are. The Lower to Uppermost Members consist of massive calcarenite and calcilutite that show upward fining. Composition of the calcarenite is distinctly different from that of the Basal Member. The homogeneous appearance, coarse-tail normal grading, abundant water escape structures, and abundant reworked fossils in these members are consistent with those of the Mediterranean "homogenite", a deep sea tsunami-induced deposit that was formed by settling from a high density suspension. Repetition of thin conglomerate beds in the Lower Member that contain well-sorted, well-rounded mud clasts and shallow marine fossils is considered to reflect intermittent lateral dow possibly induced by a series of tsunami waves during an early stage of settling of grains from a high density suspension. Altered vesicular glass of probable impact origin and shocked quartz are discovered in the Basal and the Lower to Upper Members, respectively. Together with the biostratigraphically constrained age of the Penalver Formation, this evidence suggests that the Penalver Formation has a genetic relation to the K/T impact. Distribution of altered vesicular glass and shocked quartz grains can explain the sequence of the initial grain flow and the following tsunami waves. (C) 2000 Published by Elsevier Science B.V.
  • M Kawasaki, T Kakizaki, WH Hu, K Toyota, K Hasebe
    ELECTROANALYSIS 10 (4) 276 - 278 1040-0397 1998/04 [Refereed][Not invited]
     
    In the presence of cysteine, osmium(VIII) in hydrochloric acid exhibits a will-defined maximum wave at -0.85 V (vs. SCE). Effects of the osmium's valence states and the coexisting anions on the reduction wave have been studied polarographically in acidic solution. The high oxidation states (e.g., osmium(VIII) and (VI)) in comparison with low oxidation states have an influence on the height of the hydrogen wave.
  • A catalytic hydrogen wave of the osmium-cysteine system. Electroanalysis
    M. Kawasaki, T. Kakizaki, W. Hu, K. Toyota, K. Haseb
    Electroanalysis 10 (4) 276 - 278 1998 [Refereed][Not invited]
  • S. Colman, M. Grachev, P. Hearn, S. Horie, T. Kawai, N. Logachov, V. Antipin, V. Fialkov, A. Gorigljad, B. Tomilov, B. Khakhaev, S. Kochikov, V. Lykov, L. Pevzner, A. Bucharov, N. Logachev, V. Mats, A. Bardardinov, E. Karabanov, E. Baranova, O. Khlystov, V. Khrachenko, M. Shimaraeva, E. Kornakova, S. Efremova, E. Stolbova, A. Gvozdkov, V. Kravchinski, T. Fileva, S. Kashik, T. Khramtsova, I. Kalashnikova, T. Rasskazova, V. Tatarnikova, R. Yuretich, V. Mazilov, K. Takemura, V. Bobrov, T. Gunicheva, H. Haraguchi, S. Ito, T. Kocho, M. Kuzmin, M. Markova, V. Pampura, O. Proidakova, H. Sawatari, A. Takeuchi, K. Toyoda, S. Vorobieva, A. Ikeda, A. Marui, T. Nakamura, K. Ogura, T. Ohta, J. King, J. Peck, H. Sakai, T. Yokoyama, A. Hayashida, E. Bezrukova, S. Fowell, N. Fuji, P. Letunova, V. Misharina, N. Miyoshi, G. Chernyaeva, I. Ignatova, E. Likhoshvai, E. Stoermer, L. Granina, O. Levina, P. Dolgikh, R. Ishiwatari, F. Lazo, N. Lutskaia, W. Orem, E. Wada, D. Williams, K. Yamada, S. Yamada, E. Callander, L. Golobokoval, L. Granina, P. Shanks, R. Dorofeeva, A. Duchkov
    Quaternary International 37 3 - 17 1040-6182 1997 [Refereed][Not invited]
     
    The Baikal Drilling Project (BDP) is a multinational effort to investigate the paleoclimatic history and tectonic evolution of the Baikal sedimentary basin during the Late Neogene. In March 1993 the Baikal drilling system was successfuly deployed from a barge frozen into position over a topographic high, termed the Buguldeika saddle, in the southern basin of Lake Baikal. The BDP-93 scientific team, made up of Russian, American and Japanese scientists, successfully recovered the first long (>100 m) hydraulic piston cores from two holes in 354 m of water. High quality cores of 98 m (Hole 1) and 102 m (Hole 2), representing sedimentation over the last 500,000 years, were collected in 78 mm diameter plastic liners with an average recovery of 72% and 90%, respectively. Magnetic susceptibility logging reveals an excellent hole-to-hole correlation. In this report the scientific team describes the preliminary analytical results from BDP-93 hole 1 cores. Radiocarbon dating by accelerator mass spectrometry provides an accurate chronology for the upper portion of Hole 1. Detailed lithologic characteristics, rock magnetic properties and inorganic element distributions show a significant change to the depositional environment occuring at 50 m subbottom depth, approximately 250,000 BP. This change may be due to uplift and rotation of the horst block in the Buguldeika saddle. The sedimentary section above 50 m is pelitic with varve-like laminae, whereas the section below 50 m contains a high proportion of sand and gravel horizons often organized into turbidite sequences. Accordingly, high resolution seismic records reveal a change in sonic velocity at this depth. It is inferred that sedimentation prior to 250 ka BP was from the west via the Buguldeika river system. After 250 ka BP the Buguldeika saddle reflects an increase in hemipelagic sediments admixed with fine-grained material from the Selenga River drainage basin, east of Lake Baikal. Variations in the spore-pollen assemblage, diatoms, biogenic silica content, rock magnetic properties, clay mineralogy and organic carbon in the upper 50 m of BDP-93-1 reveal a detailed record of climate change over approximately the last 250,000 years. These variables alternate in a pattern characteristic of glacial/interglacial climatic fluctuations. The present age model suggests that the climate signal recorded in Lake Baikal sediments is similar to Late Quaternary signals recorded in Chinese loess sections and in marine sediments. Copyright © 1996 INQUA/ Elsevier Science Ltd.
  • A MASUDA, K SUGINO, K TOYODA
    APPLIED GEOCHEMISTRY 10 (4) 437 - 446 0883-2927 1995/07 [Refereed][Not invited]
     
    This is the first study on Pb stable isotopes in fault gouges and their parent rocks. We analyzed the composition of Pb isotopes and contents of U and Pb in 10 pairs of fault gouges and their parent rocks collected along several active faults in central Japan. Thorium-232-Pb-208 ages of two fault systems were determined as pre-Tertiary, which are consistent with the data from K-Ar ages and geological considerations. Naturally, the U-235-Pb-207 system is of little use for dating because the magnitude of difference in Pb-207/Pb-204 between gouges and parent rocks is too small. It is found that the Pb-206/Pb-204 can indicate the contribution of Pb-206 resulting from excess supplies of Ra-226 and Rn-222 along the fault. The excess Pb-206 accumulation rate corresponds to the average Rn-222 concentration in soil gas or groundwater through geological time since the gouge formation. A comparison of Quaternary fault activity and estimated Tertiary activity reveals the characteristics of each fault system.
  • K FUKUDA, MAKI, I, S ITO, K TOYODA
    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 103 (5) 444 - 448 1882-0743 1995/05 [Refereed][Not invited]
     
    The cell dimensions for a series of beta-Ca2SiO4 solid solutions were determined as a function of concentration of foreign oxides (Na2O, Al2O3 and Fe2O3). The angle beta varied most sensitively with the Na/(Na+Ca) ratio (=x) according to beta (degrees) = 94.55-8.86 x (0 less than or equal to x less than or equal to 0.03). The decrease in x that accompanies the remelting reaction was therefore defectable by the increase in beta. When the crystals were cooled at a constant rate r (degrees C/s) over the temperature range in which the remelting reaction occurred, the fraction remelted was expressed by 1-exp(-1.33 r(-0.25)).
  • Kintics of the a-to-a’ H polymorphic Phase Transition of Ca2SiO4 solid solutions.
    K.Fukuda, I.Maki, K.Toyoda, S.Ito
    Journal of the American Ceramic Society 76 1821 - 1824 1995 [Refereed][Not invited]
  • K TOYODA, H HORIUCHI, M TOKONAMI
    EARTH AND PLANETARY SCIENCE LETTERS 126 (4) 315 - 331 0012-821X 1994/09 [Refereed][Not invited]
     
    Geochemical and Sr, Pb, O and C isotopic data are reported for carbonatite samples from five locations in southeast Brazil. Elemental abundances and delta(13)C(PDB) data (between -5.8 and -7.2 parts per thousand) prove that all the samples are derived from the mantle. Dupal isotopic characteristics in the all carbonatite samples from five locations in southeast Brazil are found in this study, characteristics that have not previously been recognized in carbonatites. Brazilian carbonatites possess average Delta 8/4 values of between 101 and 145, average Delta 7/4 values of between 5.2 and 10.3, and initial Sr isotopic compositions of between 0.7046 and 0.7062. The Brazilian carbonatites comprise two groups: The northern group is coincident with the passage of the Trindade non-Dupal hotspot at ca. 80 Ma, while the southern group mainly corresponds to the passage of the Tristan de Cunha Dupal hotspot at ca. 130 Ma. Although we expected a geochemical correlation between the Brazilian carbonatites and the South Atlantic hotspots, the enriched isotopic signature (EM1) of all the carbonatite samples is similar to that of alkali basalts on Tristan de Cunha. The combined O-Sr isotopic diagram indicates that the southern group carbonatites have negligible or only slight crustal contamination. The northern group samples show significantly higher delta(18)O(SMOW) values of 9-14 parts per thousand, more radiogenic Pb isotopic ratios, and a Sr-87/Sr-86 value of 0.705. Even if these signatures are derived from the contamination of a lower crustal component with mantle sources, it is clear that the parental magma also has inherent EM1 isotopic characteristics. The interpretation of the origin of EM1 in the Brazilian carbonatites (subcontinental lithospheric mantle vs. asthenosphere) is dependent on the model of Parana volcanism at ca. 130 Ma, which remains controversial. One possibility is that both the northern and southern carbonatites came from enriched SCLM under a part of Gondwanaland. In this case, a hotspot would provide the thermal energy to melt the lithospheric source region for both the Parana flood basalts and the alkali carbonatitic volcanism. Another possibility is that the source of the northern carbonatites is also the Tristan plume carbonate-rich material which had once been trapped under the crust and reactivated by the Trindade hotspot, on the assumption that Parana volcanism at ca. 130 Ma was mainly triggered by the huge Tristan plume activity. If anything, we favour the latter and believe an asthenospheric mantle plume origin for bath the ultimate carbonate source and the Dupal anomaly in the Brazilian carbonatites.
  • DUPAL ANOMALY OF BRAZILIAN CARBONATITES - GEOCHEMICAL CORRELATIONS WITH HOTSPOTS IN THE SOUTH-ATLANTIC AND IMPLICATIONS FOR THE MANTLE SOURCE
    K TOYODA, H HORIUCHI, M TOKONAMI
    EARTH AND PLANETARY SCIENCE LETTERS 126 (4) 315 - 331 0012-821X 1994/09 [Refereed][Not invited]
     
    Geochemical and Sr, Pb, O and C isotopic data are reported for carbonatite samples from five locations in southeast Brazil. Elemental abundances and delta(13)C(PDB) data (between -5.8 and -7.2 parts per thousand) prove that all the samples are derived from the mantle. Dupal isotopic characteristics in the all carbonatite samples from five locations in southeast Brazil are found in this study, characteristics that have not previously been recognized in carbonatites. Brazilian carbonatites possess average Delta 8/4 values of between 101 and 145, average Delta 7/4 values of between 5.2 and 10.3, and initial Sr isotopic compositions of between 0.7046 and 0.7062. The Brazilian carbonatites comprise two groups: The northern group is coincident with the passage of the Trindade non-Dupal hotspot at ca. 80 Ma, while the southern group mainly corresponds to the passage of the Tristan de Cunha Dupal hotspot at ca. 130 Ma. Although we expected a geochemical correlation between the Brazilian carbonatites and the South Atlantic hotspots, the enriched isotopic signature (EM1) of all the carbonatite samples is similar to that of alkali basalts on Tristan de Cunha. The combined O-Sr isotopic diagram indicates that the southern group carbonatites have negligible or only slight crustal contamination. The northern group samples show significantly higher delta(18)O(SMOW) values of 9-14 parts per thousand, more radiogenic Pb isotopic ratios, and a Sr-87/Sr-86 value of 0.705. Even if these signatures are derived from the contamination of a lower crustal component with mantle sources, it is clear that the parental magma also has inherent EM1 isotopic characteristics. The interpretation of the origin of EM1 in the Brazilian carbonatites (subcontinental lithospheric mantle vs. asthenosphere) is dependent on the model of Parana volcanism at ca. 130 Ma, which remains controversial. One possibility is that both the northern and southern carbonatites came from enriched SCLM under a part of Gondwanaland. In this case, a hotspot would provide the thermal energy to melt the lithospheric source region for both the Parana flood basalts and the alkali carbonatitic volcanism. Another possibility is that the source of the northern carbonatites is also the Tristan plume carbonate-rich material which had once been trapped under the crust and reactivated by the Trindade hotspot, on the assumption that Parana volcanism at ca. 130 Ma was mainly triggered by the huge Tristan plume activity. If anything, we favour the latter and believe an asthenospheric mantle plume origin for bath the ultimate carbonate source and the Dupal anomaly in the Brazilian carbonatites.
  • TOYODA Kazuhiro
    PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY 101 (1-2) 169 - 184 1993/03 [Refereed][Not invited]
  • GEOCHEMICAL HISTORY OF ANCIENT LAKE BIWA IN JAPAN - CHEMICAL INDICATORS OF SEDIMENTARY PALEO-ENVIRONMENTS IN A DRILLED CORE
    K TOYODA
    PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY 101 (1-2) 169 - 184 0031-0182 1993/03 [Refereed][Not invited]
     
    A comparison is made between the geochemical compositions of drilled sediment core samples from Lake Biwa and samples of surface sediments and from land around Lake Biwa to estimate paleo-water depth, spatial variability and past changes in sediment sources. The Al-Fe-Mn x 10 diagram indicates that Lake Biwa has been an oligotrophic lake since its formation. An investigation of the origin of a positive correlation between water-depth and the Mn/Al ratio in surface sediments is made and the historical change of paleo-water depth in Lake Biwa proposed by Koyama et al. (1985) verified. Demonstrated are the usefulness of both Ti/Al ratio and REE pattern to detect changes in sediment sources and geochemical discontinuities in four layers which should indicate unconformities are found. My data could be supporting evidence for the chronological assignment of Takemura (1990). An explanation is given for the historical changes of source materials in drilled core samples associated with tectonic changes on the basis of the historical basin development postulated by Yokoyama (1984).
  • Comprehensive investigation of lake Baikal core 323-PC1
    K.Toyoda, K.Takemura, R.Ishiwatari
    Russian Geology and Geophysics. 34 (11) 101 - 110 1993 [Refereed][Not invited]
     
    K.Toyoda, K.Takemura and R.Ishiwatari: "Comprehensive investigation of lake Baikal core 323-PC1" Russian Geology and Geophysics. 34. 101-110 (1993). Тойеда К., Такемура К., Ишиватари Р.Комплексное исследование колонки 323-PC1 донных осадков оз. Байкал. // Геология и геофизика; 1993; 34(10-11):124-135.
  • K TOYODA, A MASUDA
    GEOCHEMICAL JOURNAL 25 (2) 95 - 119 0016-7002 1991 [Refereed][Not invited]
     
    Several chemical leaching experiments were carried out to characterize the REE distribution in four pelagic sediments which have negative Ce anomaly collected in Central Pacific. Extraction experiments indicate that the carrier of the negative Ce anomaly is phosphate phase. This result supports our hypothesis that a negative Ce anomaly is mainly due to fish bone debris in the Pacific equatorial pelagic sediments, in case of pelagic sediments far from the areas of hydrothermal activity. Furthermore, a positive Ce anomaly in pelagic sediments was confirmed by leaching experiment to be due to hydrogenous components (Mn-Fe oxides). The terrigenous component (silicate phase) has a low REE content and a flat shale-normalized REE pattern.
  • Chemical Leaching of Pelagic Sediments having Ce anomaly.
    K.Toyoda, A.Masuda
    Geochemical Journal, 25 95 - 119 1991 [Refereed][Not invited]
  • SEDIMENTARY ENVIRONMENTS AND CHEMICAL-COMPOSITION OF PACIFIC PELAGIC SEDIMENTS
    K TOYODA, A MASUDA
    CHEMICAL GEOLOGY 88 (1-2) 127 - 141 0009-2541 1990/10 [Refereed][Not invited]
  • K TOYODA, M TOKONAMI
    NATURE 345 (6276) 607 - 609 0028-0836 1990/06 [Refereed][Not invited]
  • K TOYODA, Y NAKAMURA, A MASUDA
    GEOCHIMICA ET COSMOCHIMICA ACTA 54 (4) 1093 - 1103 0016-7037 1990/04 [Refereed][Not invited]
  • K TOYODA, H HARAGUCHI
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 60 (3) 933 - 939 0009-2673 1987/03 [Refereed][Not invited]
  • GEOCHEMICAL CHARACTERIZATION OF GEOLOGICAL STANDARD ROCK SAMPLES FROM RARE-EARTH ELEMENT DISTRIBUTION PATTERNS MEASURED BY INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY
    K TOYODA, H HARAGUCHI
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 60 (3) 933 - 939 0009-2673 1987/03 [Refereed][Not invited]
  • K TOYODA, H HARAGUCHI
    GEOSTANDARDS NEWSLETTER 10 (2) 173 - 175 0150-5505 1986/10 [Refereed][Not invited]
  • Rare earth Elements in Six New GSJ Standard Rock Samples as determined by Inductively Coupled Plasma Atomic Emission Spectrometry
    K.Toyoda, H.Haraguchi
    Geostandard Newsletter 10 173 - 175 1986 [Refereed][Not invited]
  • Y SANO, K TOYODA, H WAKITA
    NATURE 317 (6037) 518 - 520 0028-0836 1985 [Refereed][Not invited]
  • K TOYODA, H HARAGUCHI
    CHEMISTRY LETTERS (7) 981 - 984 0366-7022 1985 [Refereed][Not invited]
  • HE-3-HE-4 RATIOS OF MARINE FERROMANGANESE NODULES
    Y SANO, K TOYODA, H WAKITA
    NATURE 317 (6037) 518 - 520 0028-0836 1985 [Refereed][Not invited]
  • Determination of Rare Earth Elements in Geological Standard Rock Samples as determined by Inductively Coupled Plasma Atomic Emission Spectrometry. Chemistry Letters
    TOYODA Kazuhiro
    1985 [Refereed][Not invited]
  • 深海底堆積物とマンガンノジュールの地球化学的研究」
    豊田 和弘
    東京大学大学院理学系研究科 [Refereed][Not invited]

Books etc

  • 地球と宇宙の化学辞典
    豊田 和弘 (Contributorテフラによる火山活動履歴)
    朝倉書店 2012/09 (ISBN: 9784254160574)
  • オゾン層破壊の科学
    北海道大学出版会 2007
  • 放射化分析ハンドブック—確度の高い多元素同時微量分析への実践
    日本アイソトープ協会 2004

Conference Activities & Talks

  • Airborne radioactive contamination in urban areas from the nuclear accident in Fukushima  [Invited]
    TOYODA Kazuhiro
    the Second International Conference on Sustainable Built Environment (ICSBE) 2012 Universitas Islam Indonesia, Yogyakarta, Indonesia  2012/07
  • Environmental purification by manganese-oxidizing bacteria.  [Invited]
    TOYODA Kazuhiro, TEBO Bradley
    Annual meeting of Japan Society for Bioscience, Biotechnology, and Agrochemistry 2011 Kyoto  2011/03

MISC

Research Grants & Projects

  • 文部科学省:科学研究費補助金(挑戦的萌芽研究)
    Date (from‐to) : 2012 -2012 
    Author : 豊田 和弘
  • 文部科学省:科学研究費補助金(新学術領域研究(研究領域提案型))
    Date (from‐to) : 2009 -2012 
    Author : 米延 仁志, 奥野 充, 五反田 克也, 豊田 和弘, 守田 益宗, 安田 喜憲
     
    本年度(H22)は調査と試料の分析を重点的に実施した。(調査)南西諸島(奄美大島,沖縄本島,西表島),長野県深見池,グアテマラ・ペテン県の湖・河川(ラス・ポサス湖,ケシル湖等)でボーリング調査,周辺植生調査を実施し,堆積物コア試料を採取した。またペルーでは花粉分析試料を採取した。また秋田県一の目潟の表層堆積物をミニアイスフィンガー法で採取した。グアテマラ調査では年縞を含む欠損の無い堆積物試料が得られた。さらに鹿児島県・藺牟田池で機械ボーリングによる調査を実施し,約20m×2本のコアで欠損の無い試料得られた。これは東アジア地域の高精度年代決定の示準となる火山灰層を多数含むため,今後の高精度編年に貴重な資料となる。(分析)H21年度に引き続き秋田県・一の目潟,青森県小川原湖,エジプト・カルーン湖試料の分析を実施し,試料の基礎物性(比重・含水率,色),帯磁率,花粉分析等の低時間分解分析を完了した。その結果,両者とも確実に年縞を有しており,高時間分解分析により精度の高い古環境復元が可能であることが判明した。現在はμRF分析等の詳細な分析を継続している。また長野県・深見池では基盤までの完全なコアを含む12本の試料と5本のアイスフィンガー試料を採取,年縞幅を用いて年輪年代学的手法による暦年代決定に成功した。これは世界初の成果である。さらに年縞単位での花粉分析に着手した。本年度採取した南西...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 2007 -2009 
    Author : Keiji TAKEMURA, 北川 浩之, 奥田 昌明, 公文 富士夫, Akira HAYASHIDA, Naoto ISHIKAWA, Tsuyoshi HARAGUCHI, Takehiko SATOMURA, Masahiro CHIGIRA, Hiroki KAMATA, Takahiro TAGAMI, Tomoyuki SHIBATA, Kazuhiro TOYODA, Masaaki OKUDA, Fujio KUMON, Hiroyuki KITAGAWA, Fujio MASUDA, Masayuki TORII
     
    Six piston core samples and two drilling samples from Lake Biwa were obtained in 2007 and 2008. Those core sediments have a potential which is clarified the precise environmental change during past 300,000 years on the basis of tephrochronologial data and 14C dating. Paleomagnetic information and paleotemperature information also were obtained. Shallow seismic survey of total 300km revealed the sediment stratigraphy in whole North Lake region of Lake Biwa.
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2006 -2008 
    Author : Harutaka SAKAI, 藤井 理恵, 豊田 和弘, Yutaka TAKIGAMI, Yoshihiro TANIMURA, Yoshihiro KUWAHARA, Hideo SAKAI, Toshiro YAMANAKA, Rie FUJII, Kazuhiro TOYODA, Arata MOMOHARA
     
    ヒマラヤ山脈上昇史の鍵を握る変成岩ナップは, 約1440万年前に地表に露出・急冷し, 年間3-4cm の速度で南南西に前進し, 約1100 万年前に運動を停止した.冷却は先端から北方へ向け年間約1-1.5cm の速度で進行した.古カトマンズ湖の泥質湖成堆積物の堆積開始は約100 万年前まで遡り, 寒冷期には化学的風化が進まず, 堆積速度が遅く, 温暖期には化学的風化が促進され, 堆積速度が速かったことが判明した.
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2005 -2008 
    Author : Kazuhiro TOYODA, Ken IKEHARA, Hiroshi MACHIDA, Jonghwa CHUN
     
    地球温暖化の将来予測に有用な古環境復元の精密年代軸として注目されるクリプトテフラ(肉眼では検出不可な希薄な火山灰層)の高感度な検出法として、放射化分析法による地層の高密度な微量元素分析が有効であると実証した。十数本の日本海海底コア中の最大過去十五万年間の堆積物を走査し、5つの新しい指標となるテフラを検出し年代推定を行い、欝陵島(韓国)と白頭山(中朝国境)から飛来する降下火山灰の履歴を構築にした。
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2005 -2007 
    Author : Takafumi MATSUI, 多田 隆治, 田近 英一, 後藤 和久, 長谷川 卓, 豊田 和弘
     
    We conducted field survey near the impact site at the Cretaceous/Tertiary (K/T) boundary at Fomento area, Cuba and Lajilla area, Mexico in order to investigate the magnitude and duration of the impact-induced tsunami. As a result, we found that the evidence of the crater-ward first tsunami wave is observed at Fomento area as well as the impactite in and out of the Chicxulub crater. These observations support the hypothesis that the tsunami was generated by the ocean water invasion into the crater and overflow from the crater.We also studied K/T boundary deposits and their adjacent deposits ...
  • 文部科学省:科学研究費補助金(萌芽研究)
    Date (from‐to) : 2003 -2004 
    Author : 豊田 和弘
     
    地下水のヒ素汚染は南アジアなどで深刻な問題となっている。その地域の地下水は難分解有機物(フミン物質)に富んでいるためにヒ素の除去は容易ではない。本研究の目的はマンガン酸化バクテリアの1つである桿菌SG-1休眠胞子の環境水中のヒ素の浄化処理能力について確定することである。平成15年度ではマンガンの溶存2価イオンから不溶な4価の酸化物への触媒反応速度とそれに伴う三価と五価のヒ素イオンの変化について実験したが、平成16年度では、有機物や鉄イオンとの共存状態の系について実験を行った。有機物の分解速度を測定するために、フミン物質の分解生成物である一酸化炭素などのガス発生量の定量に必要なガスクロマトグラフィーの検出器を本研究費で購入した。しかし、既に本研究科の専攻に設置済みのガスクロマトグラフィー本体は放射性物質を含むために設置場所の放射線管理区域の移転許可が必要である。ところが、その移転許可申請後3年たった今でもその承認が降りないために購入備品を使用することが出来なかった。そこで、COE経費で捕足部品購入することで使用可能になった有機酸測定用のHPLCシステムを用いて、別のフミン物質分解生成物である低分子有機酸の測定を行う事にした。難分解有機物の標準試料としては泥炭地土壌を原料とした市販のフミン物質をさらに生成してもちいた。無機生成したマンガン酸化物による酸化でフミン物質が分解して直接...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2001 -2003 
    Author : Shin-ichi KAWAKAMI, 豊田 和弘, 大野 照文, 高野 雅夫, 能田 成, 道林 克禎, 可児 智美, 酒井 英男
     
    The purpose of this study is to test the Snowball Earth hypothesis, which suggests that the entire Earth surface was covered with icesheet in several times during Neoproterozoic era. For this purpose, we visited Namibia in winter seasons from 2001 to 2003 and investigated ouccrops of diamictites, cap carbonates, and iron formations associated with diamictites. The rock specimens sampled from Ghaab diamictites near Fransfountain was used for rheological analysis which revealed that the diamicites was compressed by the overburden pressures after deposition. The cap carbonates were used for ge...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 1999 -2001 
    Author : Harutaka SAKAI, 山縣 毅, 折橋 裕二, 瀧上 豊, 桑原 義博, 西 弘嗣, 豊田 和弘, 大野 正夫, 酒井 英男, 山中 寿朗
     
    We carried out geological field investigation and core drilling for academic purpose in the southern part of the Kathmandu Basin, in order to clarify the uplift process of the Himalaya and changes in Indian monsoon during the last 3 myr. Regarding on the drilled cores, we undertook the following studies.1. Paleomagnetic study : we measured natural remanent magnetization and stepwise alternating field demagnetization, and detected two excursions corresponding to Mono Lake and Laschamp excursion.2. 14C age determination : we measured AMS C 14 ages of twelve pieces of carbonized fragment, and ...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 1999 -2001 
    Author : Takafumi UATSUI, 田近 英一, 大路 樹生, 多田 隆治, 豊田 和弘
     
    In order to understand the mode and magnitude of K/T boundary impact and its consequences, field surveys were conducted in Cuba where the proximal deep-sea K/T boundary deposits are well exposed. As a result of the field surveys, the following new informations are obtained :1) The deep-sea K/T boundary deposits, as thick as 700 m, are well exposed in three different geological provinces in western Cuba.2) The K/T boundary deposits are composed of two units such as a lower calcirudite unit and an upper calcarenite/calcilutite unit.3) The lower unit is characterized by breccia derived from th...
  • 文部科学省:科学研究費補助金(萌芽的研究)
    Date (from‐to) : 1999 -2000 
    Author : 豊田 和弘
     
    本研究は、東日本の大規模な破砕帯を伴う活断層中の、既によく調査されたトレンチ路頭から試料を採取して、鉛同位体比と化学組成を精度よく測定することで、断層の年代測定及び活動度の新しい評価法としての研究手法を提示することを目的とする。北海道夕張郡のシューパロ湖周辺のダム計画のために掘削されたコア中の断層、福島県双葉郡の路頭から採取した双葉断層と畑山断層、及び群馬県多野郡上野町の神流川の断層の試料、計13地点から採取した。機器中性子放射化分析、ICP発光分析計及びICP質量分析計を併用して、注目しているウラン、トリウム、鉛以外に主成分元素や希土類元素についても定量を行った。主成分・微量元素から同一起源物質と考えられ、ウラン/鉛比とトリウム/鉛比が大きく異なる母岩とガウジの対試料について選定してから、鉛同位体比を測定する。双葉断層N10地点の隣接した部位から採取した3試料は同一起源物質と考えられ、ウラン/鉛比とトリウム/鉛比が大きく異なった。畑山断層Ht101地点の隣接した部位から採取した3試料は起源の異なると考えられ、本研究には適さない。畑山断層M152地点の隣接した部位から採取した4試料のうち、2試料は起源が同じと推測できるし、ウラン/鉛比とトリウム/鉛比が大きく異なるので、この対試料は本研究に都合がよい。畑山断層Ht132の試料はウラン/鉛比とトリウム/鉛比がほとんど変わらないの...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 1999 -2000 
    Author : Tadamichi OBA, 王 律江, 村山 雅史, 豊田 和弘
     
    We collected one coral drilling core of 2.2 m length in Octorber 1999 from the east coast of Hainan Island, China. The following conclusions were obtained by comparing the in situ temperature-salinity record and the high-resolution oxygen carbon isotopic record (ca 200 samples) of a Hainan Island coral (Porites lutea) for the same one-year period (1999-2000).1. The oxygen isotopic ratios of the coral are clearly affected by both SST and the oxygen isotopic composition of the seawater.2. Minimum oxygen isotopic ratios occurred in December when surface temperatures were the coldest and the ma...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(A))
    Date (from‐to) : 1996 -1999 
    Author : Kazuhiro TOYODA, 田中 俊逸, 長谷部 清
     
    We performed both neutron activation analysis and ICP-AES of sediments taken from the 250 m thick top bed of Lake Biwa at 1.4-2 m intervals, three ca.10 meter long piston cores at 6cm intervals, varved core from the center of Lake Suigetsu at 2 cm intervals during the last glacial/Holocene transition, and the samples from surface sediments and from land around Lake Biwa and Lake Suigetsu for the comparison. The goals in this study are three : (1) Evaluation of As contents as the geochemical proxy of paleo-water-depth ; (2) Quest of geochemical proxy for synchronisation with glacial/-intergl...
  • 文部科学省:科学研究費補助金(萌芽的研究)
    Date (from‐to) : 1996 -1997 
    Author : 豊田 和弘
     
    本研究は、現在問題になっている放射性廃棄物中のアクチノイドの除去材としての生物源リン酸塩の有用性について検討している。ただし、現段階ではアクチノイドと化学的性質が類似している希土類元素を用いている。堆積物中の生物源リン酸塩にはしばしば希土類元素を濃縮しているが、これは堆積物中で有機物が分解後、リン酸塩中のカルシウムが希土類元素に置換されて濃縮されていると考えられる。そこで、本研究では食用の魚の骨片を水酸化カリウム溶液、エチレンジアミン溶液または次亜塩素酸ナトリウム溶液という3つの試薬で処理して有機物を除去した後、吸着剤として使用した。これらの試料片約10〜20mgをそれぞれ0.015〜1.5ppmの希土類元素を含んだ人工海水溶液3mlに3〜7日間室温にて液浸した。各試料を純水中で超音波洗浄後、25℃で乾燥させ、中性子放射化分析を行い、吸着された希土類元素の量を測定した。吸着量はどの吸着剤においても液浸日数に対して増加する傾向にあった。これらの試料はユーロピウム以外の希土類元素についても同様の強い吸着能力を示した。太平化学社製の合成リン酸カルシウム(球形HAP)も生物源リン酸塩と同様に希土類元素に対して強い吸着能力を示し、粒径が小さな試料がより高い吸着能力を示す傾向のあることがわかった。次に、ネオジムについて、球形HAPと球形FAP(合成フロロリン酸カルシウム)の吸着速度と吸着...
  • 文部科学省:科学研究費補助金(重点領域研究)
    Date (from‐to) : 1995 -1995 
    Author : 豊田 和弘
     
    今から二億数千万年前の二畳紀と三畳紀の境界(P/T境界)には地球生物史上最大の大量絶滅が起きたとされている。生物絶滅事件の原因として白亜紀/第三紀においてその境界層にイリジウムの濃集が発見されてから天体衝突説が主張されており、梶原ら(1994)は硫黄の同位体比からP/T境界での天体衝突の可能性を示唆した。私は角和善隆氏(東大教養学部)と共同研究で秩父累帯の天神丸セクション(徳島県)などで採取された、P/T境界の黒色炭質泥岩試料中のイリジウムの中性子放射化分析を行った。黒色炭質泥岩が堆積し始めた時代試料ほどの分析(検出限界は数+ppt)では小天体の衝突を示唆するイリジウムの濃縮は全く見られないことがわかった(角和・豊田、1996)が、路頭での厳密なP/T境界層は確定しておらず、数メートルにも渡る黒色炭質泥岩層からさらに百試料ほど採取して丹念に分析をおこなっている。平成7年10月1日付けで東京大学・大学院理学系研究科から北海道大学・大学院地球環境科学研究科へ転出したために東京大学での研究は不可能になったが、それから一カ月経るうちに環境がある程度整い、北海道大学において研究事業を再開することが可能になったが、こちらでの放射線取り扱いの認可が遅れたためにデータの提出が遅れている。これらの試料中の希土類元素については既に山口大の加藤らがおこなっており、現在化学抽出やその他の微量元素や主...
  • 文部科学省:科学研究費補助金(奨励研究(A))
    Date (from‐to) : 1995 -1995 
    Author : 豊田 和弘
     
    私は中部日本の10箇所の代表的な断層のTh-Pb年代測定および断層帯のラドン濃縮による過剰鉛-206からの過去の活動度推定を試みている。ただしこれらの考察には断層粘土とその母岩との鉛、ウラン、トリウムの含有量が断層粘土形成から現在まで変化していないという前提が必要である。断層粘土の形成に伴う微量元素の挙動については不明な点が多く、国内外でも類似の研究は見あたらない。母岩が花崗岩の場合の断層粘土形成時の化学組成の変化を知るために、六甲花崗岩、跡津川断層北東部の船津花崗岩、阿寺断層中央部の苗木一上松花崗岩、中央構造線の両家花崗岩のような地域における、近畿・中部日本の断層の母岩と断層破砕物質について文献調査をおこない、その一部についての試料を入手した。中性子放射化法などの微量元素分析や粉末X線回折装置を併用して鉱物分析および状態分析を併用して母岩と断層破砕物質との化学組成の違い、同一母岩から生成したと考えられる断層破砕物質内での鉱物組成と化学組成の関係、酸化還元状態による鉱物組成と化学組成の差、採取地点の断層からの距離による断層破砕物質、母岩の種類、断層の種類による相違点などについて検討している。平成7年10月1日付けで東京大学・大学院理学系研究科から北海道大学・大学院地球環境科学研究科へ転出したために東京大学での研究は不可能になり、北大での放射線取り扱いの認可が遅れたためにデータ...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(国際学術研究)
    Date (from‐to) : 1994 -1995 
    Author : 原口 紘き, Hiroki HARAGUCHI, Dril S.I, Perepelov A, Kuzmin M, 堀江 正治, 小椋 和子, 石渡 良志, 豊田 和弘, 猿渡 英之, DRIL S.I, PEREPELOV A, KUZMIN M
     
    Lake baikal, the biggest lake in the world, is located in the central Siberia. According to the primary survey, it is known that the 5000-10000 m deep sediment may be accumulated in Lake Baikal during last ca.2000 million years. In the present research project entitled "Geochemical Studies on Sediment Core Samples from Lake Baikal", 2 kinds of the 100 m sediment core samples (BDP-93-1, BDP-93-2) collected in 1993 have been analyzed from the viewpoint of inorganic and organic geochemistry. These sediment core samples were taken and distributed under the BDP (Baikal Drilling Project) internat...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(一般研究(B))
    Date (from‐to) : 1993 -1994 
    Author : 床次 正安, Masayasu TOKOMANI, 豊田 和弘, 小野 洋子, 堀内 弘之, 小澤 徹
     
    Underground disposals of nuclear waste are considered to be indispensable for long-term isolation from the biosphere. The glass waste form will contain the highly radioactive isotopes extracted from spent nuclear fuel. Increasing crystallinity and alteration (metamictization) of waste glass by the effect of alpha-radiolysis and the associated release/retention of radionuclides are problem. Natural analogue is available to estimate the long-term behavior of the radionuclides. The objective is to establish the method of autoradiography of imaging plate (IP) system (R-AXIS-DS III) of block sam...
  • 文部科学省:科学研究費補助金(奨励研究(A))
    Date (from‐to) : 1993 -1994 
    Author : 豊田 和弘
     
    湖の富栄養化は大きな環境問題であるが、そのバックグランドといえる天然状態での湖の栄養状態(酸化還元状態や生物生産性)と気候変動との関係については研究が皆無である。本研究では構造湖で堆積盆の沈降により数十万年以上も現在と同様な水深を保ち続けていた琵琶湖やバイカル湖のボーリングコア試料をもちいて第四紀の氷河期間氷期の繰り返しと湖の栄養状態にどのような因果関係があるか調べることが目的である。当初は過去の琵琶湖の栄養状態の変化は堆積物の水酸化物相中の鉄マンガン比を測定することで推定できると考えていた。琵琶湖の1400mボーリングコアの最上部の120mの80試料について、還元剤で酸化物相中を抽出した後ICP発光分析法で、試料中の水酸化物相中の鉄マンガン比の値をだし、これまでの研究データと比較した。氷期が降水量の少ない時期に、現在のような間氷期が降水量の多い時期に対応すると考えられる。各種分析データの文献値から、降水量の多い時期は約25mから表層面まで、約65-95m、約130-145mであり、鉄マンガン比の値の値にそれに対応した変化があればと期待したが、値は約10-30とかなり変動するが、あまり対応関係はみられない。鉄やマンガンと似た挙動のヒ素についても放射化分析で分析してこの3元素から栄養状態の変化に対応する地球化学的指標を考察するよう現在分析中である。過去の富栄養化状態のもう一つの...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(国際学術研究)
    Date (from‐to) : 1991 -1991 
    Author : Kazuhiro TOYODA, Christian Sc, Michael Kuzm, Louis Scott, 竹村 恵二, 小椋 和子, 石渡 良志, 日比野 紘一郎, 堀江 正治
     
    1. PROGRAM CARRIED OUTIn our joint work on the present theme, we had concentrated our study to South Africa and lake Baikal ; the most distinguished features as tectonic lake are observed in both typical tectonic lakes such as Tanganyika and Baikal. As the first step to study Lake Tanganyika, we started stratigraphic study on the core sample obtained in Verloren Vlei because Lakes Tanganyika and Malauii is regarded as one unit of African tectonism extending to southern coast.On the other hand, paleolimnological study is carried out in Lake Paikal by Russian and American joint work supported...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(国際学術研究)
    Date (from‐to) : 1989 -1990 
    Author : Masayasu TOKONAMI, 湊 秀雄, HASUI Yocite, HIODO Y.Fran, 豊田 和弘, 相川 信之, 芳賀 信彦, 小澤 徹, 堀内 弘之
     
    Research surveys of this project were performed for two years of 1989 and 1990, but have actually been continued since 1987. Main subjects of this project are the surveys of minerals which are closely related to alkaline rocks and carbonatite-alkaline complexes in Brazil and understanding their occurrences, mineral assemblages, textures, chemical compositions and so on. Concentration of rare-earth elements are characteristic in the complexes, and radioactive elements are often accompanied in minerals. Therefore, their minerals are also intersted as a natural analogue for the basic research ...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(一般研究(A))
    Date (from‐to) : 1986 -1989 
    Author : Masayasu TOKONAMI, 山中 高光, 芳賀 信彦, 小澤 徹, 堀内 弘之, 豊田 和弘
     
    High-level radioactive wastes unavoidably remain whenever the used nuclear fuels are reprocessed for the next effective use. These wastes must be kept away from human being and animals in safety for a very long period. Thus, the search of the best way of their disposal is an emergency subject for the use of atomic energy. Most of researches on this problem are performed from technological point of view, however, basic researches of wasted substances are not strongly promoted.In this project, microtextures of minerals which are related to radioactive wastes are mainly investigated because su...
  • レス堆積物及び湖底堆積物コアの無機化学分析と高精度な古環境変動解析、マンガン酸化バクテリアのマンガンイオン酸化反応機構と環境修復、古い活断層の活動履歴の検出法、隠れた火山灰層の検出法

Educational Activities

Teaching Experience

  • Methods of International CommunicationMethods of International Communication GSES, Hokkaido Univ.
  • Exercise on chemistry of the environmentExercise on chemistry of the environment GSES, Hokkaido Univ.
  • Advanced Course of international communication methodsAdvanced Course of international communication methods GSES, Hokkaido Univ.
  • Inter-Graduate School Classes(General Subject):Natural and Applied Sciences
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 大学院共通科目
    キーワード : 環境汚染、環境修復、環境毒性学、資源開発、環境経済
  • Laboratory Work in Environmental Analysis
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 環境汚染物質、環境分析、影響評価  Environmental Contaminants, Environmental Analyses, Biological Assessment for Environmental Contaminants
  • Special lecture in Environmental Science Development III
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 国連の活動、働き方改善、ILO国際労働基準、労働環境、アクションチェックリスト United Nations, Work style improvement, ILO International Labour Standards, Working environment, Action-checklist
  • Advanced Course in Environmental Adaptation
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : environmental remediation, bioremediation, risk assessment, management for chemicals, and monitored natural attenuation
  • Advanced Course in Environmental Adaptation
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 環境適応、環境負荷低減、修復技術、バイオレメディエーション、化学物質のリスク評価と管理、放射性物質、海洋環境、河川環境、必須微量重金属 environmental adaptation, reducing environmental impact, remediation technique, bioremediation, phytoremediation, risk assessment, management for chemicals, ocean environment, river environment, radionuclides in the environment and monitored natural attenuation, roles of essential trace elements
  • Course in Materials Science II
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : Chemical thermodynamics
  • Advanced Course in Environmental Metrology
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 環境計測、水質汚濁、大気汚染、計量法、環境法、統計学、環境分析法、放射線計測、計量管理 environmental measurement, water pollution, air pollution, dosimetry, metrology, environment law, statistics, environmental analytical methods, measuring control
  • Advanced Course of International Science Communication Methods
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : Scientific English, writing, presentation, discussion
  • Advanced Course in Environmental Pollution Comparison
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 鉱害対策、水質汚濁対策、大気汚染対策、公害病、放射性廃棄物、リモートセンシング、GIS (地理情報システム)、環境法 Mine pollution, Water pollution control, air pollution control, pollution disease, radioactive waste, remote sensing, GIS (geographical information system), environmental law
  • Introduction to Environmental Adaptation
    開講年度 : 2018
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 環境適応学、環境と生体、生体システム、重金属、内分泌攪乱物質の生体影響、化学物質のリスクアセスメント、ナノテクノロジーの基礎 Environmental adaptation science, Environment and human beings, Biological system, Effects of heavy metals and endocrine disrupters on the body, Risk assessment of chemicals, Nano-technology for environmental adaptation
  • Chemistry I
    開講年度 : 2018
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 原子の構造、原子軌道、化学結合、混成軌道、物質の三態、電解質溶液


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