Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scientific Research Publishing, Inc.  

DOI： 10.4236/jep.2021.1211055

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Scientific Research Publishing, Inc.  

DOI： 10.4236/jep.2021.129040

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

In this study, we investigated the removal of Cs from aqueous solutions using geomaterials. Adsorption was chosen as an effective method to develop for the removal of Cs from radioactive waste liquids. Geomaterials, including fly ash and slag as raw materials, were prepared as adsorbents using an alkali activator. The materials were characterized by X-ray diffraction (XRD); scanning electron microscopy with energy dispersive spectrometer (SEM-EDS); and BET surface area, pore volume, and pore size analysis. The effects of various parameters, such as pH, contact time, and adsorbent dosage on the adsorption of the Cs were studied. The partition coefficient (PC) as well as the adsorption capacity were evaluated to assess the true performance of the adsorbent in this work. The fly ash-based geomaterials showed a maximum Cs adsorption capacity of 89.32 mg·g−1 and a high PC of 31.02 mg·g−1·mM−1 for the Cs under our experimental conditions. From this work, this method can be regarded being practical for use as a potential adsorbent for treating Cs in wastewater. Furthermore, the immobilization of Cs in geomaterials was explored from a chemical perspective. In conclusion, fly ash-based geomaterials may be a promising option for the treatment and disposal of nuclear-contaminated waste.

DOI： 10.3390/app11188407

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Chitosan (CS) modified with ethylenediamine tetraacetic acid (EDTA) was further modified with the zeolite imidazole framework (ZIF-8) by in situ growth method and was employed as adsorbent for the removal of rare-earth elements (REEs). The material (EDTA–CS@ZIF-8) and ZIF-8 and CS were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and nitrogen adsorption/desorption experiments (N2- Brunauer–Emmet–Teller (BET)). The effects of adsorbent dosage, temperature, the pH of the aqueous solution, contact time on the adsorption of REEs (La(III), Eu(III), and Yb(III)) by EDTA–CS@ZIF-8 were studied. Typical adsorption isotherms (Langmuir, Freundlich, and Dubinin–Radushkevich (D-R)) were determined for the adsorption process, and the maximal adsorption capacity was estimated as 256.4 mg g−1 for La(III), 270.3 mg g−1 for Eu(III), and 294.1 mg g−1 for Yb(III). The adsorption kinetics results were consistent with the pseudo-second-order equation, indicating that the adsorption process was mainly chemical adsorption. The influence of competing ions on REE adsorption was also investigated. After multiple cycles of adsorption/desorption behavior, EDTA–CS@ZIF-8 still maintained high adsorption capacity for REEs. As a result, EDTA–CS@ZIF-8 possessed good adsorption properties such as stability and reusability, which have potential application in wastewater treatment.

DOI： 10.3390/ijms22073447

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The removal of cadmium (Cd) and zinc (Zn) from soil by phytoremediation was investigated using Taraxacum officinale and Gazania. A plant environmental control system was used to cultivate the plants. The effects of different biodegradable chelating agents (i.e., EDDS, HIDS, and GLDA), relative humidity, and other competitive metals on the adsorption of Cd and Zn were also studied. In addition, the approach for metal recovery was explored by extraction of metals from plants after phytoremediation using Gazania. The concentrations of Cd and Zn were determined by inductively coupled plasma mass spectrometry (ICP-MS). In addition, one-way analysis of variance (ANOVA) tests were performed.to determine significant differences between the experimental treatments adopted in this work. Consequently, the following main conclusions were obtained: (1) In the case of Taraxacum officinale, Cd and Zn could be removed even under the presence of other heavy metals. (2) By adding a chelating agent, the amount absorbed by the shoot generally increased. (3) In the case of Gazania, the concentration of Cd was higher in root than that in shoot, whereas the concentration of Zn was higher in the shoot than that in the root. (4) Taraxacum officinale was more suitable for phytoremediation of Cd than Gazania. (5) Cd and Zn could be extracted from plants by adding a low concentration of nitric acid. (6) The one-way ANOVA tests showed no statistically significant differences among the experimental treatments.

DOI： 10.3390/app11041557

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Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

DOI： 10.3769/radioisotopes.69.299

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In this study, chitosan beads modified with sodium dodecyl sulfate (SDS) were successfully synthesized and employed for the removal of chromium(VI) (Cr(VI)). The adsorption performance of the adsorbent (SDS-chitosan beads) was examined by batch experiments. The partition coefficient (PC) as well as the adsorption capacity were evaluated to assess the true performance of the adsorbent in this work. The adsorbent (SDS-chitosan beads) showed a maximum Cr(VI) adsorption capacity of 3.23 mg·g−1 and PC of 9.5 mg·g−1·mM−1 for Cr(VI). The prepared adsorbent was characterized by different techniques such as scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Fourier transform-infrared spectroscopy (FT-IR). We used inductively coupled plasma mass spectrometry (ICP-MS) for the determination of Cr(VI) in solution. The experimental data could be well-fitted by pseudo-second-order kinetic and Langmuir isotherm models. The thermodynamic studies indicated that the adsorption process was favorable under the higher temperature condition. The SDS-modified chitosan beads synthesized in this work represent a promising adsorbent for removing Cr(VI).

DOI： 10.3390/app10144745

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotopes Association  

DOI： 10.3769/radioisotopes.69.217

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In order to obtain the adsorption mechanism and adsorption structures of Rare Earth Elements (REEs) ions adsorbed onto layered double hydroxides (LDH), the adsorption performance of LDH and ethylenediaminetetraacetic acid (EDTA) intercalated LDH for REEs was investigated by batch experiments and regeneration studies. In addition to adsorption capacity, the partition coefficient (PC) was also evaluated to assess their true performance metrics. The adsorption capacity of LDH increases from 24.9 μg·g−1 to 145 μg·g−1 for Eu, and from 20.8 μg·g−1 to 124 μg·g−1 for La by intercalating EDTA in this work; and PC increases from 45.5 μg·g−1·uM−1 to 834 μg·g−1·uM−1 for Eu, and from 33.6 μg·g−1·μM−1 to 405 μg·g−1·μM−1 for La. Comparison of the data indicates that the adsorption affinity of EDTA-intercalated LDH is better than that of precursor LDH no matter whether the concept of adsorption capacity or that of the PC was used. The prepared adsorbent was characterized by XRD, SEM-EDS and FT-IR techniques. Moreover, quantum chemistry calculations were also performed using the GAUSSIAN09 program package. In this calculation, the molecular locally stable state structures were optimized by density functional theory (DFT). Both the quantum chemistry calculations and the experimental data showed that REEs ions adsorbed by EDTA-intercalated LDH are more stable than those adsorbed by precursor LDH. Furthermore, the calculation results of adsorption and desorption rates show that adsorption rates are larger for Eu(III) than for La(III), which agrees with the experimental result that Eu(III) has a higher adsorption ability under the same conditions. The LDHs synthesized in this work have a high affinity for removing REEs ions.

DOI： 10.3390/app9224805

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DOI： 10.3390/jfb9030049

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DOI： 10.3390/jfb8040051

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

Stable hydrogen and oxygen isotopic compositions (delta D and delta O-18 values, respectively) were analyzed for "sake," a traditional Japanese alcohol beverage, to assess these values for the identification of its geographic origin. We collected sake (Junmai-shu; made of only rice, water, and koji) and its source water (i.e., brewing water) from breweries in Niigata Prefecture, Japan, and measured the isotopic compositions of water in these samples. The delta D and delta O-18 values for the sake are well correlated with their respective values for the corresponding brewing water (delta D; r = 0.92, delta O-18; r = 0.80). Furthermore, based on the delta D-delta O-18 cross plot, sake brewed in Niigata Prefecture is distinguishable from that brewed in countries other than Japan. These results imply that this dual isotope (delta D and delta O-18) analysis is potentially useful in identifying the geographic origin of sake.

DOI： 10.2116/analsci.33.979

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In this study, a new adsorbent material was synthesized by using carboxymethyl chitosan and silicon dioxide. The hybrid membrane was used as an adsorbent for the removal of Cr(VI) from aqueous solutions. The adsorption potential of Cr(VI) by the hybrid materials was investigated by varying experimental conditions such as pH, contact time, and the dosage of the hybrid membrane. Adsorption isotherms of Cr(VI) onto the hybrid membrane were studied with varying initial concentrations under optimum experiment conditions. The surface property of the hybrid membrane was characterized by SEM (scanning electron microscope) and Fourier transform infrared spectrometer (FTIR). The concentrations of Cr(VI) in solution are determined by ICP-AES (inductively coupled plasma atomic emission spectrometry). The present study investigates the adsorption mechanisms of Cr(VI) onto the hybrid membrane. The results provide new insight, demonstrating that the modified hybrid membrane can be an efficient adsorbent for Cr(VI) from the aqueous solution.

DOI： 10.1155/2017/3426923

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DOI： 10.3769/radioisotopes.65.409

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

In the present work, the hydrotalcite-like compound [Mg6Al2(OH)(16)]CO3 center dot nH(2)O (shorted as MgAl-CO3) is synthesized and the adsorption of phosphorous anions, their adsorption performance on the surface of hydrotalcites, and its mechanism are analyzed. To theoretically clarify the adsorption mechanism and adsorption structures, we perform quantum chemistry calculations of reactants, locally stable states, transition states, and products among phosphorous anion, water, and hydrotalcite in a variety of pH ranges. The experimental result shows that the efficiency of phosphate removal does not depend on pH of the solution, with which the numerical results are consistent. In particular, we identify the factors of influencing the adsorption ratio in different pH ranges from the quantum chemistry calculations: the stability of locally stable states, and the energies and locations of potential barriers along the reaction pathway relative to those of the locally stable states. The results suggest that hydrotalcites synthesized in this work are suitable as sorbent materials for the adsorption and removal of phosphorous anions from aqueous solutions.

DOI： 10.1142/S1793604716500612

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DOI： 10.17265/1934-7375/2016.02.002

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DOI： 10.17265/2162-5298/2016.11.001

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DOI： 10.3769/radioisotopes.64.717

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

<i>Hydrogen explosion occurred at Fukushima Dai-ichi nuclear power plants in Japan on 12―15^th March, 2011. At the same time, lots of radioactive materials have been released including tritium(</i>T<i>), and caused serious environmental impacts. In order to investigate the effect of the accident of Fukushima Dai-ichi nuclear power plant on environment, we collected the short precipitation(hourly collected precipitation) and spring water for several years after the accident. As to the precipitation collected, </i>T<i> and radiocaesium were measured by using liquid scintillation counter and high-purity germanium detector, respectively. Furthermore, we also measured the concentration of ions(</i>Na^＋<i>,</i> Cl^－<i>,</i> Ca^2＋<i>, and</i> SO₄^2－<i>) in spring water. From the above-mentioned matters, the following points have been obtained:(1)The variation of </i>T<i> concentration in recent three years(2012, 2013 and 2014) can be clarified. (2)The effect of the accident on spring water in mountains around the Fukushima prefecture is so small. (3)As to the short precipitation on 15^th March, 2011, the activity of radiocaesium was not detected, but the activity of </i>T<i> was detected significantly.</i>

DOI： 10.3769/radioisotopes.64.553

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：David Publishing Company  

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DOI： 10.3769/radioisotopes.64.455

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：化学工業社  

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DOI： 10.17265/2162-5298/2015.03.001

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DOI： 10.17265/1934-7375/2014.11.005

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DOI： 10.3769/radioisotopes.63.429

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DOI： 10.3769/radioisotopes.63.283

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC CHEMICAL ENG JAPAN  

This study investigated the adsorption of lead ions (Pb2+) by activated carbon modified with potassium permanganate (KMnO4). Activated carbon was chemically modified through impregnation with solutions of KMnO4 (0.01 mol/L and 0.03 mol/L). Adsorption experiments from aqueous solutions containing known amounts of Pb2+ were explored in a batch system. The amount of Pb2+ adsorbed at different pH values, initial concentrations, sorbent dosages, contact times, and temperature were determined by atomic absorption spectrometry (AAS) in order to determine the optimum conditions for Pb2+ adsorption. Moreover, the effects of common ions like sodium, potassium, calcium, and magnesium on the adsorption capacity were also studied. The Pb2+ adsorption on modified and unmodified activated carbon conformed to the Langmuir isothermal adsorption equation. Overall the modified activated carbon exhibited a higher adsorption capacity and stronger chemical affinity than pristine activated carbon. The rates of adsorption were found to conform to pseudo-second order kinetics.

DOI： 10.1252/jcej.13we208

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Adsorption of uranium (VI) from aqueous solution onto Yukitsubaki carbon (YKC) modified with nitric acid (10% and 30%) has been investigated in a batch system. Adsorption parameters such as contact time, carbon dosage, pH of solution and temperature onto the modified carbon have been determined with ICP-MS in order to obtain the optimum conditions for the U(VI) adsorption process. Adsorption isotherms of U(VI) onto the modified and pristine carbon were measured at varying initial concentrations under optimized condition. The surface properties of the modified carbon as well as the pristine carbon were characterized using N-2-BET, SEM and FT-IR. The results show that the U(VI) adsorption capacity of YKC is increased after the modification with nitric acid, and that the Langmuir isotherm model fits the experimental data better than the Freundlich isotherm.

DOI： 10.1252/jcej.13we207

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The hydrotalcite-like compound [Mg2Al(OH)(6)]NO3 center dot nH(2)O (shorted as MgAl-NO3) was intercalated with the chelating agent ethylenediaminetetraacetic acid (EDTA) and N,N'-1,2-ethanediylbis-1-aspartic acid (EDDS) by anion exchange to uptake heavy metal ions (Cu2+ , Pb2+) from aqueous solutions. These layered double hydroxides (LDHs) synthesized in this work were used to adsorb Cu2+ and Pb2+. The amount of Cu2+ or Pb2+ adsorbed at different pH, temperature, and the dosage of adsorbent was determined by atomic absorption spectrometry (AAS). The structure, the composition and the surface properties of precursor-LDHs and intercalated-LDHs (intercalated with the chelating agents) were characterized by chemical analysis, Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD) and a physical adsorption analyzer. Comparative experiments were carried out with commercially available LDH adsorbent (i.e., Kyowa DHT-4A). The adsorption behaviors of the MgAl-LDHs for Cu2+ and Pb2+ in aqueous were investigated by applying the adsorption results to the Freundlich isotherms model, and the data were well fitted by the model. The results suggested that MgAl-LDHs synthesized in this work could be suitable as sorbent materials for the adsorption and removal of heavy metal ions from aqueous solutions.

DOI： 10.1252/jcej.13we210

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In order to reveal the quality and isotopic characteristics of lagoon waters in Niigata Prefecture in recent years, the nutrients concentrations of nitrogen (N) and phosphorus (P) as well as oxygen stable isotope ratios(i.e., δ¹⁸O) in water samples of Sakata and Toyanogata were measured.<br>Samples were regularly taken at the fixed sampling points from these lagoons, and depth distribution was surveyed at one point in Toyanogata. In addition, δ¹⁸O and nutrients concentrations of water samples in Zhalong Wetland at Heilongjiang Province in China were also determined.<br>Consequently, the following matters have been mainly clarified. (1) δ¹⁸O values of sample waters in Zhalong Wetland are generally large probably because of the effect of evaporation, whereas those of Sakata lagoon are large which may be due to the biological process such as the activity of plankton. (2) Considering the results of nutrients concentrations, the water quality of lagoon (Sakata and Toyanogata) waters in Niigata Prefecture is better than that of Zhalong Wetland in China.

DOI： 10.3769/radioisotopes.62.409

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Other Link： http://hdl.handle.net/10191/30806

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The hydrogen isotope exchange reaction between HTO vapor and each amino acid has been observed in order to establish a method of estimation of the internal exposure of organically bound tritium in a heterogeneous system at 25 similar to 70 degrees C. Rate constants (k) for the amino acids have been obtained by applying the A ''-McKay plot method. Using these k values, Arrhenius plots for both the COOH and NH2 groups are drawn, and linearity was obtained over the range of 25 similar to 70 degrees C. Comparing the rate constants, the following four statements can be made regarding the T-for-H exchange reaction. (1) The reactivity of the functional groups in amino acids increases with increasing temperature. (2) Applying Taft's equation, the ratio of polar effect to steric effect is 2:8 in the COOH group and 9:1 in the NH2 group at 25 degrees C. (3) The A ''-McKay plot method is useful for studying the reactivity of materials, not only with one (or the same kind of) functional group(s) but also with two different kinds of functional groups. (4) The method used in this work may be useful to investigate the behavior of organically bound tritium, quantitatively.

DOI： 10.1080/00223131.2012.693882

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In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90-100% using a precipitation method with alkaline solution.

DOI： 10.1155/2012/173819

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TRANS TECH PUBLICATIONS LTD  

Effect of EDTA and EDDS on phytoremediation of Pb- and Zn- contaminated soil by Brassica Juncea was investigated in this work. Especially, the effect of the kind and the method of adding chelating agent was investigated during the plant growth. Plants were grown in an environmental control system. The biomass of the whole plant was weighed, and the uptake of Pb and Zn in shoot and root were determined using ICP-AES. Consequently, the following matters have been obtained: (1) Both EDTA and EDDS significantly enhanced the translocation of metals (Pb and Zn) in soil from root to shoot. Furthermore, the two chelating agents resulted in a sharply biomass loss for more than 30% of the control. As a result, the total uptake amount of metals by Brassica Juncea was decreased (except the uptake of Pb with the addition of 3.0 mmol.kg(-1) EDTA). (2) EDDS showed the higher inhibition for the growth of Brassica Juncea than EDTA. (3) The method for adding EDTA and EDDS at several times separately did not necessarily increase the uptake of heavy metals.

DOI： 10.4028/www.scientific.net/AMR.518-523.5040

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DOI： 10.3769/radioisotopes.60.443

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DOI： 10.3769/radioisotopes.60.363

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DOI： 10.3769/radioisotopes.60.215

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

In order to evaluate the efficiency of seaweed biomass as sorbent for rare earth elements(REEs), sorption experiment from aqueous solutions containing known amount of lanthanide(La, Eu or Yb) using three kinds of Ca-loaded dried seaweeds(brown algae:Sargassum hemiphyllum, green algae:Ulva pertusa and red algae:Schizymenia dubyi) in single component system was explored. Furthermore, the sorption mechanism of these elements was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, to confirm the characteristics of the seaweed biomasses, the surface morphology of the biomass before and after metal adsorption was determined by Scanning Electron Microscope(SEM).<br>Consequently, the following matters have been mainly clarified. (1)The morphology of Sargassum hemiphyllum and Ulva pertusa surface has hardly changed even after exposing to metals. On the other hand, the change of the surface condition on Schizymenia dubyi after adsorption was observed. (2)Adsorption isotherms using the seaweed biomass can be described by Langmuir and Freundlich isotherms satisfactorily for lanthanide. These adsorption may have occurred mainly by monolayer reaction because of better-fitting for Langmuir model. (3)The seaweed biomasses could be an efficient sorbent for REEs. Particularly, Ulva pertusa is found to be a promising biosorbent for removing La. (4)Ion-exchange process is considered to be the main mechanism responsible for the sorption of lanthanide ion onto the seaweed biomass.

DOI： 10.3769/radioisotopes.59.623

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DOI： 10.3769/radioisotopes.59.549

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DOI： 10.3769/radioisotopes.59.379

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In order to clarify the effect of tritium(<SUP>3</SUP>H or T)on both the ecosystem and the reactivity of compounds including H atom(s), the hydrogen-isotope exchange reaction (T-for-H exchange reaction) between each benzaldehyde derivative and tritium-labeled poly (vinyl alcohol) was observed in the range of 50 to 90°C. As a result, the radioactivity of the compounds increased with the reaction time. Applying the A"-McKay plot method to the observed data, the rate constants(k) of the functional group in each compound were obtained. Comparing these k with each other, the following six matters have been clarified in the reaction. (1)The reactivity of benzaldehyde derivatives depends on temperature. (2)The order of the temperature dependence in the reactivity of the fluorobenzaldehyde tends to o-substitute > m-substitute > p-substitute, and that in the reactivity of the chlorobenzaldehyde tends to m-substitute > o-substitute > p-substitute. (3)The order of reactivity in each chlorobenzaldehyde derivatives tends to o-position > m-position > p-position. (4)The reactivity of the formyl group in the benzaldehyde derivative can be estimated by applying both the A"-McKay plot method and the Hammett rule. (5)The method used in this work is useful for evaluating the influence of T on environment.

DOI： 10.3769/radioisotopes.59.311

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DOI： 10.3769/radioisotopes.59.93

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Biosorption experiment from aqueous solutions containing known amount of rare earth elements (REEs) using pre-treated Buccinum tenuissimum shell was explored to evaluate the efficiency of shell biomass as sorbent for REEs. In this work, four kinds of sieved shell samples: (a) "Ground original sample", (b) "Heat-treatment (480 degrees C, 6 hours) sample", (c) "Heat-treatment (950 degrees C, 6 hours) sample" and (d) "Heat-treatment (950 degrees C, 6 hours) and water added sample" were used. Furthermore, to confirm the characteristics of the shell biomass, the crystal structure, the surface morphology, and the specific surface area of these shell samples were determined. Consequently, the following matters have been mainly clarified. (1) The crystal structure of the shell biomass was transformed from aragonite (CaCO(3)) into calcite (CaCO(3)) phase by heat-treatment (480 degrees C, 6 hours); then mainly transformed into calcium oxide (CaO) by heat-treatment (950 degrees C, 6 hours), and calcium hydroxide (Ca(OH)(2)) by heat-treatment (950 degrees C, 6 hours) and adding water. (2) The shell biomass showed excellent sorption capacity for lanthanides. (3) Adsorption isotherms using the shell biomass can be described by Langmuir and Freundlich isotherms satisfactorily for lanthanides except "heat-treatment (950 degrees C, 6 hours) sample". (4) Shell biomass (usually treated as waste material) can be an efficient sorbent for lanthanides in future.

DOI： 10.1155/2010/804854

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DOI： 10.3769/radioisotopes.58.727

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DOI： 10.3769/radioisotopes.58.469

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Association of Ecotechnology Research  

Speciation analysis of Cr in some environmental waters in Niigata Prefecture was performed by applying size fractionation and ion-exchange methods. Moreover, the concentration of humic substances was also determined for investigating the relationship between the concentration of humic substances and the speciation of Cr in environmental waters. The experiments yielded the following results: (1) Roughly 50-80 % of total Cr is present in the "dissolved" in normal weather condition. (2) In case of lagoon water samples, the distribution percentage of Cr in the "suspended" (the fraction left on 0.45μm filter when filtrating sample water) or "colloidal" (the fraction left on 0.1μm filter, although passing through 0.45μm filter) is generally large compared to that of river water samples. (3) For all of the investigated water samples, the concentration of Cr (III) species is higher than that of Cr (VI) species. (4) The concentration of total Cr and the distribution percentage of "suspended" remarkably increases after rainfall event. (5) The order of the amount of humic substances in Sakata is LS1 (downstream point of Lower Lagoon (Shitakata)) › LS2 (conflux point of Lower Lagoon (Shitakata) and Upper Lagoon (Uwakata)) ›LS3 (spring water at shore of south area in Lower Lagoon (Shitakata)); and the average concentration of humic substances is about 10ppm.

DOI： 10.11190/jer.14.239

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DOI： 10.3769/radioisotopes.58.121

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SCIENCE PRESS BEIJING  

In the present work, the papermaking wastewater was treated by combing fluidized bed biological reactor (FBBR) with sequential batch reactor technology (SBR). Particular attention was paid to the acclimation process, then confirmed the optimal operation, which consisted of 6 h cycle including an inflow process, 6 h aeration process, 2 h settling process, 2 h drainage process and 6h idle process. Under these conditions, COD(Cr) removal efficiency reached 94.4%, NH(3)-N concentration were reduced to 5 mg/L from 30 mg/L,maximal removal efficiencies of color and SS were obtained as 91.7% and 86.0%, respectively. Most of toxic organic substances were eliminated at shorter operational time. The study suggests that the combined sequential batch reactor technology with fluidized bed biological reactor is a potential alternative for papermaking wastewater treatment.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The determination of rare earth elements (REEs), Th and U in seaweeds of various species and in ambient surface seawater were performed by inductively coupled plasma mass spectrometry. The seaweeds and the seawater samples were collected at 10 different coastal areas of Niigata Prefecture in Japan twice a year (spring and autumn) in 2004 and 2005. Results showed that concentration of REEs in seaweed species from Niigata Prefecture were about 103 times higher than those in seawater, and the enrichment factors of REEs were larger in heavy REE than light REE. A significant concentration difference of REEs, Th and U was found among species even in the same phylum. Undaria pinnatifida had the highest concentration of U. Considering that U. pinnatifida has low concentrations of REEs among typical brown algae, different REEs and U uptake mechanisms are suggested. The concentration of REEs, Th and U did not vary remarkably between sampling points and/or seasons. (c) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apgeochem.2008.04.011

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DOI： 10.3769/radioisotopes.57.405

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DOI： 10.3769/radioisotopes.57.375

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DOI： 10.3769/radioisotopes.57.233

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：HINDAWI PUBLISHING CORPORATION  

In order to investigate the behavior of rare earth elements (REEs) and uranium (U) in marine organism, the concentrations of REEs and U in some brown algae samples taken on the coast of Niigata Prefecture were determined. In addition, laboratory model experiment to uptake these elements using living and dried algae (Undaria pinnatifida and Sargassum hemiphyllum) was also carried out to survey the uptake and bioaccumulation mechanism of REEs and U in algae. Consequently, the following matters have been mainly clarified. (1) The order of the concentration of REEs for each organ in Sargassum hemiphyllum is "main branch" &gt; "leaf" &gt; "vesicle," however for U, the order is "leaf " &gt; "vesicle" &gt; " main branch." (2) The concentration of REEs in Sargassum hemiphyllum may be strongly affected by suspended solid in seawater. (3) The uptake and/or accumulate mechanism of REEs in brown algae may be different from that of U. Copyright (C) 2008 Nobuo Sakamoto et al.

DOI： 10.1155/2008/706240

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

<I>In order to quantitatively evaluate the influence of tritium </I> (<SUP>3</SUP>H <I>or</I> T) <I>on various functional groups in environment, the hydrogen isotope exchange reaction</I> (T<I> for</I>-H<I> exchange reaction) between tritium-labeled poly (vinyl alcohol) and each aliphatic cyclic alcohol (or carboxylic acid) has been dynamically observed in the range of 50 to 90°C. Consequently, the activities of the aliphatic cyclic alcohol and carboxylic acid increased with increasing reaction time. Applying the A″-McKay plot method to the observed data, the rate constants (k) for these materials were obtained. Using the k, the relation between the number of carbon atoms in the ring in each alcohol and the reactivity of the alcohol was quantitatively compared. Then, to clarify the effect of relative atomic charge of</I> O <I>atom (connected with the </I>H <I>atom in the hydroxy (or carboxy) group in the material) on the reactivity of the material, the </I>MOPAC<I> method was used.</I><BR><I>From both the above-mentioned and the obtained previously, the following nine items were found as to aliphatic cyclic alcohols (and carboxylic acids) in the </I>T<I>-for-</I>H <I>exchange reaction. (1) The reactivity of aliphatic cyclic alcohols (and carboxylic acids) depends on the temperature. (2) The reactivity of the cyclic materials decreases with increasing number of carbon atoms in the ring. (3) The reactivity of the aliphatic cyclic carboxylic acid seems to be smaller than that of aliphatic cyclic alcohol, and be larger than that of aliphatic cyclic amine. (4) For aliphatic cyclic alcohols, correlation exists between k and relative atomic charges of</I> O<I> atom obtained by the </I>MOPAC<I> method, but the tendency for aliphatic cyclic carboxylic acid is not clear. (5) As to having the same number of carbon atoms in each ring, the reactivity of the aliphatic cyclic carboxylic acid including the side chain is smaller than of the aliphatic cyclic carboxylic acid including no side chain. (6) The reactivity of aliphatic cyclic carboxylic acid is larger than that of aliphatic normal carboxylic acid. (7) The reactivity of these materials dissolved in 1, 4-dioxane is smaller than that in p-xylene. (8) Using both the </I>MOPAC<I> and the A″-McKay plot methods, the actual analysis of aliphatic cyclic alcohols can be more possible. (9) The method used in this work is useful for evaluating influence of</I> T<I> on environment.</I>

DOI： 10.3769/radioisotopes.56.593

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Association of Ecotechnology Research  

In this study, laboratory model experiments on the interactions of Cr with natural ecological restoration substances were carried out to estimate optimum conditions for the reduction of Cr in soils and/or waters. For natural ecological restoration substances, humic substances (humic acid and fulvic acid) and clay minerals (bentonite and imogolite) were used. The experiments, performed at pH 4-8, yielded the following results: (1) Cr(VI) was reduced to Cr(III) by the humic substances; moreover, the reduction ability of the humic substances decreased with increasing pH. (2) The complexation of Cr(III) proceeded faster than the reduction of Cr(VI) and reached a maximum at pH 5. (3) Cr(III) was best removed at pH 4 and 5 by bentonite, but the removal ratio decreased with increasing pH. Furthermore, the removal effect of bentonite decreased with the addition of a humic substance. (4) While Cr(VI) was never removed by bentonite, the removal was slightly improved by the addition of a humic substance and an increase in pH. (5) An effect of imogolite on the removal of Cr(VI) was observed at pH 4 and 5. Reaching a maximum at pH 4, the effect was not indicated at pH 6-8.

DOI： 10.11190/jer.13.79

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DOI： 10.5985/jec.17.205

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

<I>In order to clarify both the effect of tritium</I> (<SUP>3</SUP>H <I>or</I> T) <I>on the ecosystem and the reactivity of materials having</I> H <I>atoms, the reactivity of L-cysteic acid (or L-cysteine) having three different kinds of functional groups was studied. The hydrogen-isotope exchange reaction between each compound and</I> HTO <I>vapor</I> (T-<I>for</I>-H <I>exchange reaction) was observed at 50-70°C, and the reaction was analyzed with both the A″-McKay plot method and the data obtained from the exchange reaction. The following seven matters have been consequently found in the</I> T-<I>for</I>-H <I>exchange reaction. (1) The reactivity of the functional groups in each compound increases with increasing temperature. (2) As to L-cysteic acid, the reactivity of</I> SO<SUB>3</SUB>H <I>group is 2.6 times greater than that of</I> COOH <I>one, and is 5.6 times greater than that of</I> NH<SUB>2</SUB> <I>one. (3) As to L-cysteine, the reactivity of</I> SH <I>group is 1.4 times greater than that of</I> COOH <I>one, and 3.5 times greater than that of</I> NH<SUB>2</SUB> <I>one. (4) The reactivity of</I> NH<SUB>2</SUB> <I>group progressed by the substituent having large electron-attractive effect, however, the reactivity of</I> COOH <I>group does not so progress by such a substituent. (5) Applying the A″-McKay plot method, the reactivity of the three functional groups in each aliphatic compound can be nondestructively and simultaneously clarified under the condition of non-masking reagent. (6) Degree of</I> T-<I>incorporation in a certain material can be nondestructively and quantitatively clarified. (7) The results obtained in this work is useful to prevent</I> T <I>contamination in the environment and to clarify the reactivity of the materials having plural functional groups, and the method used in this work can be also useful as a analytical method to obtain the reactivity of multi-functional groups in a certain compound.</I>

DOI： 10.3769/radioisotopes.55.709

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DOI： 10.3769/radioisotopes.55.307

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DOI： 10.3769/radioisotopes.55.183

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In order to reveal the quality and characteristics of lagoon waters in Niigata Prefecture in recent years, and to investigate the behavior of the pollutants in lagoon waters, dissolved organic carbon (DOC), complexing capacity, the concentration of major ions and oxygen stable isotopic ratios (i.e., delta O-18) in some lagoon water samples in Niigata Prefecture were measured. Moreover, pH and electric conductivity (EC), dissolved oxygen (DO) and water temperature were measured in the field. Lagoon water samples were usually monthly taken from 2004 to 2006 at the fixed sampling point from 2 lagoons (i. e. Sakata and Toyanogata) in Niigata Prefecture.
Consequently, the following matters have been mainly clarified. (1) 6180 values of lagoon water samples is generally larger than that of river water samples. In particular, delta 1(8)O values in Sakata lagoon increase remarkably in summer. It can be closely related to the activity of Crustacea plankton as well as due to the effect of the supply of groundwater. (2) The values of DO and DOC of water samples in Sakata increase in summer. It might be attributable to the photosynthesis of aquatic plants. For the same reason, it can be considered that the complexing capacity of the samples in Sakata also increases in summer. (3) The relationship between delta O-18 values and the concentration of HCO3- can be a good indicator for the degree of the inflow from groudwaters to lagoon under the same geological condition. (4) The relationship between delta O-18 values and the DOC was relatively good in the water samples in Sakata.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEMISTRY  

The monitoring and determination of pollutants in environmental water is very significant from the viewpoint of environmental protection. In this study, the objective was to reveal the quality and characteristics of environmental water samples from Niigata Prefecture in recent years, and to establish a new evaluation method for the behavior of environmental water. For the above-mentioned purpose, the total organic carbon (TOC), chemical oxygen demand (COD), the concentration of major ions and oxygen stable isotopic ratios (i.e., delta(18)O) in some river water, lagoon water and groundwater samples in Niigata Prefecture were measured. Moreover, the water temperature, pH, electric conductivity (EC) and dissolved oxygen (DO) were measured in the field. River water, circumjacent groundwater (located near the river), and lagoon water samples were taken monthly at fixed sampling points from 4 rivers (i.e. Shinano River and its two branch streams, Agano River) and 2 lagoons (i.e. Sakata and Toyanogata) in Niigata Prefecture. Consequently, the following matters have been mainly clarified: (1) The relationship between TOC and COD serve as a useful tool for estimating the effect of mixing from other kinds of river-water systems. (2) The concentration of NO3- in water samples from Sakata was larger than those in other environmental water samples. Particularly, those of spring water in Sakata were 30 to 60 ppm throughout the year. (3) The relationship between the delta(18)O values and the TOC was relatively good in the water samples from Sakata. In a lagoon, such as Sakata (not suffering from the inflow of river waters), investigating delta(18)O values are of interest as one of the indices of organic pollutants (originated from plankton), as well as for characterizing the origin of local water. (4) The pH values of lagoon water samples were 8 to 9, and those of groundwater samples were 5 to 6. It is considered that lagoon water is supersaturated with oxygen, and groundwater is unsaturated.

DOI： 10.2116/bunsekikagaku.54.789

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

<I>The hydrogen-isotope exchange reaction</I> (T-<I>for</I>-H <I>exchange reaction) between tritium-labeled poly (vinyl alcohol) and each cycloamine dissolved in 1, 4-dioxane has been observed at 50-90°C. Consequently, the quantitative relation was obtained between the reaction time and the increase in the tritium activity of the cycloamine. The reaction was dynamically analyzed with both the A''-McKay plot method and data observed. Moreover, in order to clarify the effect of the relative atomic charge of the</I> N <I>atom (in the amino group) on the reactivity of the cycloamine, the</I> MOPAC <I>method was introduced. As to cycloamine, the following three matters have been consequently found in the</I> T-<I>for</I>-H <I>exchange reaction: (1) the reactivity of each cycloamine decreases with increasing the number of carbon atoms in the ring of cycloamine, (2) the rate constant (k) for each cycloamine depends on the reaction temperature, (3) the correlation is found between the relative atomic charge of the</I> N <I>atom in the</I> NH<SUB>2</SUB> <I>group and k for the cycloamine.</I>

DOI： 10.3769/radioisotopes.54.139

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A simple and an efficient preconcentration method for the separate determination of each species of chromium {i.e., Cr(III) and Cr(VI)} in environmental water samples has been investigated, followed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). This method is based on the following ion-exchange method. Cr(III) was adsorbed on cation-exchange resin, and Cr(VI) on anion-exchange resin. The retained Cr(III) and Cr(VI) were quantitatively eluted with 2 mol dm(-3) hydrochloric acid (HCl) and 2 mol dm(-3) potassium chloride (KCl), respectively. The preconcentration factor was 100 for Cr(III) and 300 for Cr(VI) in this work, and the detection limits were 0.03 mug dm in Cr(III) and 0.01 mug dm(-3) in Cr(VI). The method has been applied to environmental water samples from Niigata Prefecture. The recoveries of Cr(III) and Cr(VI) in environmental water samples were all 94similar to98%, and the effect of interference from the coexistence ion was not detected. Therefore, the above-mentioned method is applicable to environmental water samples.

DOI： 10.2116/bunsekikagaku.53.1015

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<I>To reveal the characteristics of environmental water in</I> Niigata Prefecture <I>in recent years, and to establish a new evaluation method for the behavior of the environmental water, oxygen stable isotopic ratios (i.e., </I> δ<SUP>18</SUP>O), <I>concentrations of major ions, </I> pH <I>and</I> EC <I> (electric conductivity) in water samples from several rivers and those from groundwater in</I> Niigata Prefecture <I>were measured. Isotopic measurements were performed with a stable isotope ratio mass spectrometer</I> (Micromass PRISM) . <I>Consequently, the following matters have been found. (1) The</I> δ<SUP>18</SUP>O <I>values of river waters in</I> Niigata Prefecture <I>are generally -11 ‰ to 10‰. (2) The</I> δ<SUP>18</SUP>O <I>values of groundwater in</I> Niigata Prefecture <I>are generally 1.5‰ higher than that of river waters and the variation is about ± 1 ‰ throughout the year. (3) The</I> δ<SUP>18</SUP>O <I>values and the conductivity of groundwater located in the downstream area are higher than those in the upstream throughout the year. (4) The concentrations of major ions of river waters were almost higher in summer and winter than those in spring. (5) The concentrations of major ions in groundwater were higher than those in river water. (6) The concentrations of major ions in river water tend to increase with the downstream from the upstream. (7) The relationship between the conductivity and</I> δ<SUP>18</SUP>O <I>values in river water was relatively close (i.e. The correlation coefficient between them is large) in the upstream area (by comparing with that in the downstream) .</I>

DOI： 10.3769/radioisotopes.53.415

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<I>In order to clarify the reactivity of normal chain diols, the hydrogen-isotope exchange reaction</I> (T-<I>for</I>-H <I>exchange reaction) between solid poly (vinyl alcohol) labeled with tritium and each normal chain diol dissolved in 1, 4-dioxane has been observed in the range of 30 to 70 °C (or 90 °C) . The observed data was analyzed with the A″-McKay plot method, and the following three matters are consequently found. (1) The greater the number of methylene groups in a diol is, the smaller is the reactivity of the diol. (2) A significant difference in the reactivity is found between diols having even number of methylene groups and those having odd number of ones, and the reactivity of the former is larger than that of the latter. (3) As to the ratio of the decrease of the reactivity of the diols having increasing number of methylene groups, the ratio of diols having even number of methylene groups is greater than the ratio of diols having odd number of ones.</I>

DOI： 10.3769/radioisotopes.53.71

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Environmental Chemistry  

In order to investigate the recent state of marine environment in Niigata Prefecture, to investigate the biological concentration in the ocean, and to investigate the behavior of rare earth elements (REEs) in the ocean, REEs in many kinds of seaweed samples as well as seawater samples in Niigata Prefecture were determined by inductively coupled plasma mass spectrometry (ICP-MS) .<BR>Seaweed and seawater samples were collected at 10 points on the coast in Niigata Prefecture (i.e., Sanpoku Town, Niigata City, Iwamuro Village, Izumozaki Town, Kashiwazaki City, Nou Town, Ryotu City, Aikawa Town, Sawata Town and Akadomari Village) from 2000 to 2002.<BR>The following points have been clarified by the present study. (1) The concentrations of REEs in the seaweed gathered on the coast in Niigata Prefecture were about 10<SUP>3</SUP> to 10<SUP>5</SUP> times higher than those in the seawater; and the enrichment factors of REEs is generally larger in HREE than LREE. (2) A large difference was found between REE pattern of the seaweed samples taken on the coast in Niigata Mainland and that on the coast in Sado Island. (3) The degrees of "positive Ce-anomaly in seaweed samples" and "negative Ce-anomaly in seawater samples" in Niigata Mainland were also larger than those in Sado Island. (4) Positive Gdanomaly (which seems to be an artificial origin) was found in REE patterns of some seawater samples. (5) REE pattern of seaweed and seawater samples may be an useful tracer of investigating the surrounding marine environment.

DOI： 10.5985/jec.13.789

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<I>In order to reveal the reactivity of aliphatic dicarboxylic acids, the hydrogen-isotope exchange reaction </I> (T-<I>for</I>-H <I>exchange reaction) between poly (vinyl alcohol) labeled with tritium at hydroxy group and one of aliphatic dicarboxylic acids in 1, 4-dioxane has been observed in a liquid-solid system in the range from 30 to 90°C. It was consequently found that (1) the greater the number of methylene groups in a aliphatic dicarboxylic acid is, the smaller is the reactivity of the acid; (2) a large difference is found between the reactivity of acids having even numbers of methylene groups and those having odd numbers, and the reactivity of the former is generally larger than that of the latter; (3) relating to the decrease of the reactivity of the acids with increasing number of methylene groups, the rate of the decrease in the case of even numbers is smaller than in the case of odd ones; (4) the reactivity of aliphatic dicarboxylic acids in</I> T-<I>for</I>-H <I>exchange reaction is largely dependent on the configuration (e.g., cisoid or transoid) of the two</I> COOH <I>groups.</I>

DOI： 10.3769/radioisotopes.52.215

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<I>Oxygen stable isotopic ratios </I> (δ<SUP>18</SUP>O) <I>of the precipitation and some river water samples in Niigata prefecture were measured from 1999 to 2002. Isotopic measurements were performed by a stable isotope ratio mass spectrometer. Consequently, the following matters were found. (1) The mean</I> δ<SUP>18</SUP>O <I>value of precipitations was -9‰, and the variation of ±7‰ was shown throughout the year. (2) All of 9 observation points, the seasonal behavior of isotopic ratio was similar to each other. (3) In June and January</I>, δ<SUP>18</SUP>O <I>value o f precipitations was small, and was large in August. (4) In January, the relationship between the temperature of observation points and</I> δ<SUP>18</SUP>O <I> values in precipitation was most remarkably found throughout the year. (5) The variation of</I> δ<SUP>18</SUP>O <I> values in precipitations in winter is smaller than that in the other seasons. (6) The mean</I> δ<SUP>18</SUP>O <I> value of river waters in Niigata prefecture was about -11‰ to -10‰, and the variation was not so large (±2‰) throughout the year. (7) </I> δ<SUP>18</SUP>O <I> values of river waters may vary when the melted snow or the precipitation flow into the rivers. (8) The variation of</I> δ<SUP>18</SUP>O <I> values in groundwater was smaller than that in river waters</I>.

DOI： 10.3769/radioisotopes.52.65

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<I>In order to reveal the reactivity of a functional group in an aromatic compound having two substituents in the aromatic ring, the hydrogen-isotope exchange reaction</I> (T-<I>for</I>-H <I>exchange reaction) between tritiated water vapor</I> (HTO <I>vapor) and 3-amino-4-methoxybenzenesulfonic acid (and 2-aminotoluene-5-sulfonic acid) was dynamically observed at 50°C (and 70°C) in a gas-solid system. Consequently, the specific activity of the acid increased with time, and it showed that the</I> T-<I>for</I>-H <I>exchange reaction occurred. Applying the A″-McKay plot method to the data observed, the rate constant of each functional group for the reaction was obtained. After the additive property of the Hammett's rule was applied to this work; the new substituent constants were obtained. From the above-mentioned, the following four items have been confirmed. (1) The reactivity of the functional groups can be dynamically analyzed, and the A″-McKay plot method is useful to analyze the reactivity. (2) The additive property of the Hammett's rule is applicable to quantitative comparison of the reactivity of the functional groups. (3) The reactivity of the functional groups can be simultaneously analyzed by using the A″-McKay plot method in the</I> T-<I>for</I>-H <I>exchange reaction. (4) The method used in this work is also useful for analyzing the reactivity of a certain material having some kinds of functional groups</I>.

DOI： 10.3769/radioisotopes.52.57

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<I>Hydrogen-isotope exchange reaction</I> (T-<I>for</I>-H <I>exchange reaction) between</I> HTO <I>vapor and aliphatic dicarboxylic acid having different number of methylene groups with each other has been observed at 50°C. Consequently, the quantitative relation was obtained between the reaction time and the increase of the activity of aliphatic dicarboxylic acid. The reaction was dynamically analyzed with both the A″-McKay plot method and data obtained.<BR>As to aliphatic dicarboxylic acids, the following two matters have been consequently found : (1) as the reactivity of each material decreases with increasing the number of methylene groups in the material, the effect of the number of methylene groups per molecule on the reactivity of the material can be quantitatively evaluated, (2) using the A″-McKay plot method, the reactivity of solid organic compounds can be evaluated, nondestructively.</I>

DOI： 10.3769/radioisotopes.51.244

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DOI： 10.3769/radioisotopes.50.9_425

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Environmental Chemistry  

In order to investigate the present state of marine environment in Niigata Prefecture, and to investigate the behavior of rare earth elements (REEs) in the ocean, REEs in many kinds of seaweed samples taken on the coast in Niigata Prefecture were determined by inductively coupled plasma mass spectrometry (ICP-MS) .<BR>Seaweed samples were taken at 10 spots on the coast in Niigata Prefecture including Sado Island on August, 2000. After decomposing the samples, REEs were separated by solvent extraction method.<BR>The following results are obtained. (1) Even in the same phylum (e.g., green algae, brown algae, or red algae), concentrations of REEs vary widely depending on the species of seaweed. (2) A large difference was found between REE patterns of the seaweed samples taken on the coast in Niigata Mainland and those on the coast in Sado Island. It shows that the surrounding marine environment seems to be an important factor for determining REE pattern as well as the species of seaweed. (3) As to REE pattern of some seaweed samples taken on the coast in Niigata Prefecture, Yb-anomaly was found as well as Ce-, and Eu-anomaly. (4) REE pattern of seaweed samples may be an useful tracer of investigating the surrounding marine environments.

DOI： 10.5985/jec.11.221

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Other Link： http://hdl.handle.net/10191/21907

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

<I>In order to reveal the reactivity of each functional group in the compound having three functional groups per molecule, the hydrogen-isotope exchange reaction</I> (T-<I>for</I>-H <I>exchange reaction) between disubstituted phenol and tritiated water vapor</I> (HTO <I>vapor) was dynamically observed at 50, 60, and 70°C in a gas-solid system. The data obtained in the observation increased with increasing observed time, and it was found that</I> T-<I>for</I>-H <I>exchange reaction occurred. Applying the A″-McKay plot method to the data obtained, the reaction was dynamically analyzed. The rate constant (k) of each functional group for the reaction was consequently obtained. These k's obtained and k's obtained previously were compared with each other. When the additive property of the Hammett rule was applied to the k's obtained in this work, the new substituent constants were obtained. The new constants were fitted on the Hammett plot obtained previously. From the above-mentioned, the following five matters have been clarified. (1) The reactivity of different functional groups can be compared with each other by applying the method used in this work. (2) The reactivity of the functional groups can be dynamically analyzed, and the A″-McKay plot method is useful to analyze the reactivity. (3) The additive property of the Hammett rule, which is generally used in the field of organic chemistry in order to compare the chemical reactivity of organic materials, is applicable to quantitative comparison of the reactivity of the functional groups. (4) The reactivity of the functional groups can be simultaneously (and unchangeably) analyzed by using the</I> T-<I>for</I>-H <I>exchange reaction. (5) The method used in this work is useful to analyze the reactivity of a material having many kinds of functional groups.</I>

DOI： 10.3769/radioisotopes.49.285

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Other Link： http://hdl.handle.net/10191/29850

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC ANALYTICAL CHEM  

In order to reveal the effect of temperature on (i) the dissociation equilibrium of tritiated water (HTO water) and (ii) the reactivity of each anion-exchange resin, the OT-for-OH exchange reaction between each anion-exchange resin and HTO water was studied within the range of 20 degrees C to 80 degrees C in the equilibrium state. In addition, the apparent dissociation constant (pK') for each resin was estimated by the method of pH-titration. From the observation of the OT-for-OH exchange reaction between each of the following anion-exchange resins and HTO water, the next three items have been found: (1) in the case of acryl-type anion-exchange resin, the effect of temperature on OT-for-OH exchange reaction is larger than that on the reaction in the case of styrene-type one; (2) the radioactivity incorporated into weakly basic anion-exchange resin (OH--form) by the isotope exchange reaction is smaller than that into strongly basic one; (3) in the case of the weakly basic anion-exchange resin, the amount of radioactivity incorporated into Cl--form resin by the hydrolysis is larger than the amount of radioactivity incorporated into OH--form resin by the isotope exchange reaction.

DOI： 10.2116/analsci.15.1071

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Humana Press  

In order to reveal (1) the behavior of the tritium-labeled hydroxyl group (i.e., OT group) and (2) the effect of temperature on the dissociation equilibrium of tritiated water, the OT-for-OH exchange reaction in a homogeneous system was observed (1) using ion-exchange resins and HTO water, and (2) using hydrogen oxides and HTO water. Consequently, the following four conclusions were obtained: (1) The OT-for-OH exchange reaction occurred between each anion-exchange resin (or each metal hydroxide) and HTO water. (2) The higher the temperature is, the smaller the activity of both anion- exchange resin and metal hydroxide will be, and the activity of cation- exchange resin is large when the temperature is high. (3) The larger the degree of crosslinking in each Biorad AG1 resin is, the lower the activity of the resin will be. (4) The exchange rate for the OT-for-OH exchange reaction is small when the electronegativity of the metal ion in the metal hydroxide is large.

DOI： 10.1007/BF02784239

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Language：English   Publishing type：Research paper (scientific journal)  

The hydrogen-isotope exchange reaction (T-for-H exchange reaction) between HTO vapor and an aromatic compound having two different kinds of functional groups has been observed at several temperatures. The rate constant (k) for each functional group in the T-for-H exchange reaction was obtained by using both the A-MCKAY plot method and the data observed. Comparing these k with each other has led to the following four conclusions in the T-for-H exchange reaction. (1) The reactivity of both the COOH and OH groups increases with a rise in temperature. (2) As to the degree of the effect of the COOH group on the reactivity of monosubstituted phenols, the degree in p-hydroxybenzoic acid is greater than that in m-hydroxybenzoic acid. (3) The HAMMETT rule is useful for estimating the reactivity of a certain aromatic compound. (4) The A-MCKAY plot method is also useful not only investigating the reactivity of the compounds having one kind of functional group, but also doing the reactivity of the compounds having two different kinds of functional groups.

DOI： 10.1007/BF02347196

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

<I>In order to reveal whether the</I>H<I>atom (s) directly bonded to carbon atom can participate in</I>T<I>for</I>-H<I>exchange reaction, the</I>T<I>for</I>-H<I>exchange reaction between an ether having normal chain (or cyclic) structure and a</I>T-<I>labeled compound was dynamically observed at the range of 30-80</I>°C<I>in the liquid-solid system. Each ether used includes an atom having lone pairs. In the exchange reaction, polyvinyl (vinyl alcohol) having</I>T-<I>labeled</I>OH<I>groups (i.e., </I>OT<I>group) was used as a solid sample material, and one of three ethers (tetrahydrofuran (THF), dibutylether (DBuEt), and diisopropylether (DIProEt) ) dissolved in p-xylene was used as a liquid sample material. The concentrations of the solutions were set at 2.0, 1.0 and 1.0</I>mol· dm<SUP>-3</SUP>, <I>respectively. Applying the A″-McKay plot method to the data obtained from the exchange reaction, the rate constant (k) for each ether in the reaction was calculated. Comparing the k thus obtained and k obtained previously, the following five have been clarified. (1) The</I>H<I>atom included in each ether can participate in the</I>T<I>for</I>-H<I>exchange reaction in contact with</I>T-<I>labeled compound. (2) Each ether can participate in the exchange reaction as well as the functional groups (e.g., </I>-OH, -SH, -NH<SUB>2</SUB>, -CHO, <I>etc.) included in materials. (3) The decreasing order of the reactivity of the ethers is (THF) > (DBuEt) > (DIProEt) . (4) The temperature dependence of the reactivity of each ether is fairly smaller than that of the compound having a functional group (e.g., phenol, thiophenol, aniline, or benzaldehyde, etc.) . (5) It can be presumed that the</I>H<I>atoms (included in the ethers) participating in the exchange reaction are the</I>H<I>atoms directly bonded to a-carbon in the ethers</I>.

DOI： 10.3769/radioisotopes.47.12_897

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：National Institute of Polar Research  

The Cr isotopic composition of primitive meteorites (acid-residue fractions) was studied. Five chondrites were analyzed in this work [Allende (CV3), Murchison (CM2), Nuevo Mercurio (H5), La Criolla (L6), Qingzhen (EH3)]. Although in most samples, no isotopic anomalies beyond the experimental errors could be detected, an elevated ^<54>Cr/^<52>Cr ratio was found in the acid-soluble fraction from Qingzhen. Moreover, ε^<53>Cr and ε^<54>Cr show an inverse correlation among the meteorites analyzed in this study, and the acid residues have larger ε^<54>Cr and smaller ε^<53>Cr values than do the acid-soluble fractions in Allende and Murchison. The enrichment of ^<54>Cr in the Qingzhen sample suggests that the ^<54>Cr heterogeneity due to stellar nucleosynthesis has remained in enstatite chondrite as well as carbonaceous chondrite. In addition, the inverse correlation of ε^<53>Cr and ε^<54>Cr detected in acid residue samples indicates that the high-temperature condensate contained more exotic ^<54>Cr. It is also suggested that the homogenization of Cr isotopes proceeded with time, and terminated within a relatively short time scale of less than 2-3 Ma.

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Observing the OT-for-OH exchange reaction between iron(II or III) hydroxide and tritiated water (HTO) leads to the following results: (1) isotope exchange as 'atomic group' occurred between the OH group in each iron hydroxide (i.e., Fe(OH)2 or Fe(OH)3) and OT- resulted from the dissociation of HTO
(2) the ratio of the reactivity of the hydroxides is roughly [iron(III) hydroxide] : [iron(II) hydroxide] = 1.2 : 1.0 and the result is related to difference in electronegativity between Fe2+ and Fe3+. (In other words, if the reactivity depends on the number of the charge, the ratio should be 1.5 : 1.0).

DOI： 10.1007/BF02034613

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：R OLDENBOURG VERLAG  

In order to reveal (i) the exchange ability of OT- resulting from the dissociation of HTO, (ii) the effect of temperature on the reactivity of anion-exchange resins, and (iii) the effect of the degree of crosslinking on the reactivity of the resins, the OT- for -OH exchange reaction between each OH--form anion-exchange resin and HTO water was observed in the equilibrium state. The anion-exchange resins used were Amberlite IRA-400, and Biorad AG1-X2, X4, X8. The temperature used was 20, 30, 40, 60, or 80 degrees C. The activity of each resin based on the OT-for-OH exchange reaction was measured with a liquid scintillation counter. Analyzing the data obtained, it was found that: (1) the higher the temperature is, the smaller is the activity of IRA-400 resin within the range of 40 similar to 80 degrees C; (2) the larger the degree of crosslinking in each Biorad AG1 resin, the lower the activity of the resin. Accordingly, it can be concluded that: (1) as for the dissociation of HTO at high temperature, the formula (HTO reversible arrow T+ + OH-) is more predominant than the formula (HTO reversible arrow H+ + OT-); (2) the resin with lower porosity (i.e., the resin having the larger degree of crosslinking) shows a lesser tendency for the OT-for-OH exchange reaction to occur than the resin with a higher porosity.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：R OLDENBOURG VERLAG  

In order to reveal to what extent the number of methylene groups per molecule can have an effect on the reactivity of a material having two different kinds of functional groups, the hydrogen-isotope exchange reaction (T-for-H exchange reaction) between HTO vapor and one of aliphatic compounds having both COOH and NH, groups has been observed in the gas-solid system at a range of 50 similar to 80 degrees C. The rate constants for both COOH and NH2 groups in each material were obtained by applying the A ''-McKay plot method to the data observed. Comparing the rate constants has lead to the following three conclusions. (1) The reactivity of the two groups increases with a rise in temperature. (2) The greater the number of methylene groups is, the smaller the reactivity is of the material (i.e., the smaller the reactivity is of both the COOH and NH2 groups in the material). (3) The reactivity of certain aliphatic materials having two different kinds of functional groups can only be analyzed with the A ''-McKay plot method as well as certain aromatic materials having two different kinds of functional groups.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Kluwer Academic Publishers  

In order to reveal to what extent tritium (3H or T) can be incorporated into hydroxides, the isotope exchange reaction (OT-for-OH exchange reaction) between each alkaline earth metal hydroxide (M(OH)2), where M means alkaline earth metal (M = Ca, Sr or Ba) and HTO water was observed homogeneously at 30 °C under equilibrium after mixing. Consequently, the followings were obtained: (1) a quantitative relation between the electronegativity of each M ion and the ability (of the M ion) incorporating OT- into the M hydroxide can be found and the ability is small when the temperature is high, (2) the exchange rate for the OT-for-OH exchange reaction is small when the electronegativity of the M ion in the M hydroxide is great, (3) as for the dissociation of HTO water, it seems that formula (HTO⇆T+ + OH-) is more predominant than the formula (HTO⇆ + OT-) when the temperature is high and (4) the method used in this work is useful to estimate the reactivity of a certain alkaline material.

DOI： 10.1007/BF02223358

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：R OLDENBOURG VERLAG  

In order to reveal to what extent each substituent of monosubstituted benzyl mercaptan can affect the reactivity of the material, the hydrogen-isotope exchange reaction (T-for-H exchange reaction) between one of monosubstituted benzyl mercaptans in a p-xylene solution and a poly(vinyl alcohol) labeled with tritium has been observed in a liquid-solid system at a range of 50 similar to 90 degrees C. The rate constants for the materials were obtained by applying the A "-McKay plot method to the data observed. Comparing the rate constants and the results obtained previously has led to the following three conclusions. (1) The reactivity of each monosubstituted benzyl mercaptan is somewhat affected by the type of substituent in the material, and by the reaction temperature. (2) The reactivity of monosubstituted benzyl mercaptans follows the Hammett rule, and is enhanced with one of the electron-attractive substituents. (3) The increasing order of the effect of the substituents on the reactivity of monosubstituted aromatic compounds is as follows: (monosubstituted thiophenol) &lt; (monosubstituted aniline) &lt; (monosubstituted benzyl mercaptan) &lt;(monosubstituted benzaldehyde) &lt; (monosubstituted benzylamine) &lt; (monosubstituted phenol).

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

<I>In order to reveal the behavior of hydroxyl group in isotope exchange reaction, </I> OT-<I>for</I>-OH <I>exchange reaction between each anion-exchange resin</I> (OH<SUP>-</SUP> <I>form) and tritiated water (abbreviated as</I> HTO <I>water below) was observed at 80°C under the equilibrium. Anion-exchange resins used were Amberlite IRA-400, IRA-410 (both strongly basic), and IRA-94S (weakly basic) . It can be thought that an</I> HTO <I>molecule dissociates into</I> H<SUP>+</SUP>+OT<SUP>-</SUP> (<I>or</I> T<SUP>+</SUP>+OH<SUP>-</SUP>) . <I>The activity of each resin based on</I> OT-<I>for</I>-OH <I>exchange reaction was measured with a liquid scintillation counter.</I><BR><I>From the above-mentioned, the following five were found. (1) Isotope exchange reaction as "atomic group" occurred between the</I> OH <I>group in each anion-exchange resin and the</I> OT <I>group in</I> HTO <I>water. (2) The reactivity of strongly basic anion-exchange resin is larger than that of weakly basic one. (3) The ratio of the reactivity of these resins can roughly be expressed as follows: (IRA-410) : (IRA-400) : (IRA-94S) =42: 7: 1. (4) The degree of</I> OT-<I>for</I>-OH <I>exchange reaction may be smaller than that of</I> T-<I>for</I>-H <I>exchange reaction. (5) The method used and results obtained in this work may be helpful to obtain the data for the prevention of</I> T-<I>contamination, especially to obtain the data from certain atomic groups including</I> T.

DOI： 10.3769/radioisotopes.45.613

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Kluwer Academic Publishers  

Estimation of burnup in the Oklo natural reactor was based on Ru isotopic abundances determined by thermal ionization mass spectrometry. Nearly all Ru in the samples is fissiogenic, and burnup values calculated from101Ru,102Ru and104Ru isotope abundances are in good agreement with each other. The conversion factor of238U to235U was also determined using Ru isotope abundances. © 1991 Akadémiai Kiadó.

DOI： 10.1007/BF02165064

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