研究者詳細 - 神﨑　亮

論文 - 神﨑　亮

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Tomiyasu T., Nakagawa M., Kodamatani H., Kanzaki R. . The influence of submarine volcano on seasonal changes in arsenic in the waters of Kagoshima Bay, southwestern Japan . Environmental Earth Sciences80 ( 8 ) 2021年4月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Environmental Earth Sciences

Volcanic activity is one of the primary sources of arsenic in nature, and chemical forms of arsenic discharged by volcanic activity are inorganic. Kagoshima Bay has active submarine volcano located in the 200 m deep basin of its northern part. Since dissolved inorganic arsenic is more toxic than organic arsenic it is important to understand the dispersion of discharged arsenic in seawater. To estimate the influence of arsenic emitted from the bottom vents seasonal changes in As(III) and As(V) concentrations in seawater were studied. There are few studies on the impact of arsenic discharged by submarine volcanos in the inner bay. The total concentrations of As(III) and As(V) (T-As) in seawater at the background site in Kagoshima Bay was 1.71 ± 0.35 μg L−1 (av. ± s.d.), similar to the world average value of 1.7 μg L−1. The highest T-As value at the nearest point to the submarine volcano, 3.48 μg L−1, was observed in summer. Since the vertical mixing of seawater cannot occur in summer due to the formation of the thermocline, the deep water is strongly affected by volcanic activity. The increase in T-As was caused by the increase in As(III) concentration suggesting the discharge of As(III) from the vents.

DOI： 10.1007/s12665-021-09619-1

Kodamatani H, Sugihara K, Tanisue T, Kanzaki R, Tomiyasu T . Contamination, Decomposition, and Formation of N-Nitrosodimethylamine in Water Samples at the ng/L Level of Determination. . Analytical sciences : the international journal of the Japan Society for Analytical Chemistry36 ( 11 ) 1393 - 1399 2020年11月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Analytical Sciences

An ultra-sensitive analytical system that can determine the concentration of N-nitrosamines at the ng/L level without preconcentration was used to investigate the contamination, decomposition, and formation of A-nitrosodimethylamine (NDMA) and other N-nitrosamines in water samples during general analytical procedures. A preliminary experiment was performed to estimate the NDMA concentrations in ambient air. Since the air samples contained NDMA at concentrations in the range of 2.0 - 10.7 ng/m3, ambient air was identified as the source of NDMA contamination in water samples. We directly confirmed that the concentration of aqueous 10-ng/L NDMA samples stored in clear glass bottles decreased upon exposure to sunlight. Thus, to maintain the N-nitrosamine concentration, such samples must always be protected from sunlight during sampling. The existence of N-nitrosamines in experimental reagents, such as ranitidine and sodium hypochlorite solutions, was also confirmed, as was the formation of NDMA on an activated carbon solid-phase extraction cartridge.

DOI： 10.2116/analsci.20P162

Tomiyasu T., Baransano C., Hamada Y.K., Kodamatani H., Kanzaki R., Hidayati N., Rahajoe J.S. . Distribution of total and organic mercury in soils around an artisanal and small-scale gold mining area in West Java, Indonesia . SN Applied Sciences2 ( 7 ) 2020年7月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：SN Applied Sciences

This study was conducted to understand the environmental behavior of mercury released by artisanal and small-scale gold mining (ASGM) activities. For this purpose, we attempted to assess the effect of diffused mercury on mercury concentrations in soil, demonstrate the presence of methylmercury in soil affected by the deposited mercury and determine the reactions associated with methylmercury production. The vertical profiles of mercury were obtained from two sites in the forest of the ASGM village in Pongkor (West Java, Indonesia) and from two sites in Mount Halimun-Salak National Park, which is approximately 12 km from the ASGM village. The highest total mercury concentration, 8.9 mg kg−1, was observed for soil samples collected at the ASGM village. The mercury was concentrated at the surface or in the subsurface layers, and the concentrations were several times to more than ten times higher than the lowest values observed in the deeper layers at each site. Even in the national park, the highest concentration of 1.9 mg kg−1 was observed in the upper soil layer. These results suggest that the primary source of mercury in the forest soil is atmospheric deposition; fallen plant leaves also deliver accumulated mercury to the soil surface. The organic mercury percentages of the total mercury were 0.2 ± 0.1% for the national park and 0.3 ± 0.2% for ASGM sites. The vertical variation in organic mercury concentration did not always match that in total mercury concentration, which suggested that the formation of methylmercury in soil was closely related to the decomposition of organic matter near the surface. The soil surface is an important reaction field for methylmercury production in forested areas.

DOI： 10.1007/s42452-020-3008-5

Kodamatani H, Daiba Y, Morisaki S, Ichitani K, Kanzaki R, Tomiyasu T . Detailed investigation of methylmercury accumulation in rice grain from Hg<sup>2+</sup>-spiked non-contaminated paddy field soils. . Chemosphere247 125827 2020年5月査読

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Chemosphere

Total-Hg (T-Hg) and methylmercury (MeHg) concentrations in rice grains were measured to understand the MeHg accumulation process. Rice plants were cultivated in Hg2+-spiked non-contaminated soils in experimental pots at three different places. Although soil MeHg concentrations in the pots changed significantly and individually during the rice-growing season, T-Hg concentration of brown rice grain was high at high soil MeHg concentration. In addition, there was no significant variation in T-Hg concentration in brown rice grains from individual panicles or among panicles obtained from the same pot, although the period of growth for each panicle was different. The highest T-Hg concentration of brown rice grains recorded for a panicle was 1.4 ± 0.1 mg kg−1 (n = 8), and the corresponding MeHg ratio was 76%. In addition, the T-Hg and MeHg concentrations in various parts of the brown rice grain—white rice (endosperm), bran, and embryo—were measured. Among the parts of the brown rice grain, the embryo had the highest Hg concentration. Furthermore, Hg concentration in the grain was constant during grain filling. These findings suggest that MeHg formed in soil accumulates in the rice plant during growth and is supplied to the rice grains continuously for the entire duration of the grain development period.

DOI： 10.1016/j.chemosphere.2020.125827

Kamiyama Y, Shibata M, Kanzaki R, Fujii K . Lithium-ion coordination-induced conformational change of PEG chains in ionic-liquid-based electrolytes. . Physical chemistry chemical physics : PCCP22 ( 10 ) 5561 - 5567 2020年3月

神﨑亮 . 新・分析化学者のための熱力学 . 熱測定46 ( 4 ) 195 - 201 2019年10月招待査読

Ryo Kanzaki, Hitoshi Kodamatani, and Takashi Tomiyasu . Proton Thermodynamics in a Protic Ionic Liquid, Ethylammonium Nitrate . Chemistry - A European Journal25 ( 59 ) 13500 - 13503 2019年査読

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Wiley

In order to investigate the proton solvation state in protic ionic liquids (PILs), ten acid dissociation enthalpies and entropies of eight compounds were determined in ethylammonium nitrate (EAN). Regardless of the nature of the compound, 24 kJ mol−1 larger enthalpy and 65 J mol−1 K−1 larger entropy than those in water, respectively, were observed. These values were reasonably explained by the differences in the proton solvation structure in EAN and water. Namely, protons in EAN exist as HNO3, having a higher reaction energy than that of H3O+ in water, undergo entropic stabilization as a result of the less-structured solvation. As such, the entropic effect of the proton solvation structure on the acid–base property is possibly applicable to all PILs. In addition, based on these proton thermodynamics, enthalpy and entropy windows were proposed as a novel perspective for the characterization of solvents. Use of this concept enabled the visualization of similarities and differences between EAN and water.

DOI： 10.1002/chem.201903485

北川俊輝, 河西大悟, 下内良平, 児玉谷仁, 神﨑亮, 冨安卓滋 . 水俣湾周辺底質中残留水銀濃度分布と底質化学組成 . 日本地球化学会年会要旨集66 ( 0 ) 259 2019年

記述言語：日本語出版者・発行元：一般社団法人日本地球化学会

<p>水俣湾は1977年～1990年にかけて25 mg kg⁻¹以上の水銀を含む底質は浚渫・埋め立てが行われたが、未だにバックグラウンドの数十倍の水銀を含む底質が存在する。本研究では2013年～2018年に採取された底質中の総水銀濃度及び底質化学組成の測定を行い、排出された水銀の拡散について検討を試みた。八代海表層底質中総水銀濃度は、水俣湾に近いほど高く、遠ざかるほど低くなる傾向が見られた。底質化学組成を見ると主要成分はSiO₂、Fe₂O₃、Al₂O₃であった。SiO₂に対しFe₂O₃及びAl₂O₃をプロットすると、八代海底質ではともに正の相関が見られ、水俣湾沿岸に近い程それらの割合が高くなる傾向が見られた。水俣湾、袋湾の底質では、SiO₂に対するFe₂O₃、Al₂O₃の割合は八代海底質に比べて高く、SiO₂に対するこれらの値は八代海底質とは明らかに異なる領域にプロットされた。</p>

DOI： 10.14862/geochemproc.66.0_259

野添千裕, 児玉谷仁, 神﨑亮, 冨安卓滋 . 鹿児島湾海底質中水銀及びセレン濃度分布と海底熱水噴気活動の影響 . 日本地球化学会年会要旨集66 ( 0 ) 126 2019年

記述言語：日本語出版者・発行元：一般社団法人日本地球化学会

<p>1973年鹿児島湾で漁獲された魚から暫定規制値を超える水銀を含むものが見つかり、その水銀の起源は湾奥の海底熱水噴気孔であると考えられている。セレンは生体内で水銀と共存することで、その毒性を軽減する作用を持つことから、本研究では海底熱水噴気孔から放出される水銀とセレンの挙動を追跡することを目的とし、鹿児島湾の海底質中の水銀とセレンの定量を行った。その結果、湾奥の熱水噴気域であるSt.2と、St.2から北西方向に位置するSt.8の総水銀濃度とセレン濃度の鉛直分布の間にそれぞれ有意な正の相関が見られた。(St.2 R<sup>2</sup>= 0.65,St.8 R<sup>2</sup>= 0.85)対照地点のSt.12では鉛直変動は見られず、St.2,8で観察されたセレンの濃度変動は、海底熱水噴気孔の影響である可能性が示唆された。</p>

DOI： 10.14862/geochemproc.66.0_126

Ryo Kanzaki, Hikaru Daiba, Hitoshi Kodamatani, Takashi Tomiyasu . Validation of pH Standards and Estimation of the Activity Coefficients of Hydrogen and Chloride Ions in an Ionic Liquid, Ethylammonium Nitrate . The Journal of Physical Chemistry B122 ( 46 ) 10593 - 10599 2018年11月査読

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：American Chemical Society (ACS)

We selected and validated the pH values of three standard materials that function in the protic ionic liquid, ethylammonium nitrate (EAN). The pH values of 0.05 mol kg-1 phthalate, oxalate, and phosphate buffers were 4.93 (0.04), 2.12 (0.04), and 7.13 (0.06), respectively (the values in the parentheses denote the standard deviation). Because the pH of EAN ranges from 0 to 10, with a neutral pH of 5, these materials are usable as acidic, basic, or neutral standards. The standard electrode potential of silver-silver chloride in EAN was 127.2 (1.7) mV. The activity coefficients of hydrogen and chloride ions remain equal to unity in EAN of a wide concentration range, which indicates that the effective ionic strength is independent of the solute ion concentration. In addition, the estimated value of the transfer activity coefficient of chloride ion suggests a weaker solvation in EAN compared with water in spite of a ubiquitous cation (C2H5NH3+). These behaviors of ions in EAN can be explained by the unique solvation in the ionic liquid through direct ion-ion electrostatic interactions.

DOI： 10.1021/acs.jpcb.8b08870

Kodamatani Hitoshi, Katsuma Souta, Shigetomi Azusa, Hokazono Toshimune, Imura Ryusuke, Kanzaki Ryo, Tomiyasu Takashi . Behavior of mercury from the fumarolic activity of Mt. Myoko, Japan: production of methylmercury and ethylmercury in forest soil . ENVIRONMENTAL EARTH SCIENCES77 ( 13 ) 2018年7月査読

記述言語：日本語出版者・発行元：Environmental Earth Sciences

The behavior of mercury (Hg) in water, sediments, air, dwarf bamboo leaves, and soils around the fumarolic area of Mt. Myoko, Japan, was investigated. Although some of the hot spring water samples contained over 1 µg/L total-Hg, overall, the total-Hg concentrations in the water samples decreased rapidly as the water flowed into a river. The total-Hg concentrations decreased not only due to simple dilution, but also to co-precipitation of Hg2+ with Fe(OH)3. The highest atmospheric Hg concentration, 91.7 ng/m3, was detected near the fumarole, and the concentrations decreased with distance from the fumarolic area. This tendency was also confirmed in the total-Hg concentrations of plant leaf samples. Total-Hg, methylmercury (MeHg), and ethylmercury (EtHg) concentrations in the soil surface layer (n = 13) ranged from 0.19 to 21.7 mg/kg, 0.3 to 9.3 µg/kg, and undetected to 7.7 µg/kg, respectively. The total-Hg concentrations in the surface layer soil samples decreased with distance from the fumarolic area, while the vertical distribution of total-Hg concentrations in the core and outcrop samples showed no clear trends. However, the MeHg and EtHg concentrations had no relationship with the total-Hg concentrations and were higher in the upper layer soils. The results suggest that MeHg and EtHg not only migrate with other Hg species from the volcanic gases, but are also generated on site. It was also confirmed that EtHg occurs in soil at the same level as MeHg in the study area.

DOI： 10.1007/s12665-018-7616-y

Kanzaki R, Guibert C, Fresnais J, Peyre V . Dispersion mechanism of polyacrylic acid-coated nanoparticle in protic ionic liquid, N,N-diethylethanolammonium trifluoromethanesulfonate. . Journal of colloid and interface science516 248 - 253 2018年4月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Colloid and Interface Science

Hypothesis: Ionic liquids (ILs) are extremely concentrated electrolyte solutions. The ubiquitous presence of ions induces specific behaviors for chemical reactions compared to reactions in water solutions. This is also the case for the stability of colloidal dispersions, for which the DLVO model cannot be applied as the ionic strength is out of the model range. In a previous work, in the protic IL ethylammonium nitrate (doi: https://doi.org//10.1016/j.jcis.2015.04.059), we observed an unexpected influence of the pH on the stability of dispersion of maghemite nanoparticles coated with poly(acrylic acid) (pAA). Experiments: To clarify and generalize these observations, we investigated here the pH response of the dispersion in a second protic ionic liquid with a different acid-base nature, diethylethanolammonium trifluoromethanesulfonate. pH titrations of the dispersions were achieved with an IS-FET electrode and the associated thermodynamic constants determined. The colloid structural properties were examined by small angle X-ray scattering. Findings: Under acidic or mildly basic condition, a stable dispersion was obtained, i.e., when the degree of dissociation of pAA, α was α < 0.1 or α > 0.7. Dispersions form quite dense but reversible aggregates in the intermediate α range. A model for the solvation layer around the particles is proposed and generalizes the former findings.

DOI： 10.1016/j.jcis.2018.01.004

Kanzaki R, Uchida S, Kodamatani H, Tomiyasu T . Copper(II) Chloro Complex Formation Thermodynamics and Structure in Ionic Liquid, 1-Butyl-3-Methylimidazolium Trifluoromethanesulfonate. . The journal of physical chemistry. B121 ( 41 ) 9659 - 9665 2017年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：American Chemical Society (ACS)

Metal ions in ionic liquids are laid under an unprecedented reaction field. In order to assess the reaction thermodynamics of metal ions in such a situation, Cu2+-chloro complex formation was examined with spectroscopic and calorimetric titrations in an ionic liquid, 1-buthyl-3-methylimidazolium trifluoromethanesulfonate (C4mimTfO). In addition, the effect of the structure of the solvated complexes on the complexation mechanism was investigated with the aid of DFT calculations. Chloro complexation successively proceeded and finally provided a [CuCl4]2- species, which is also the final product in conventional molecular solvents. Their stability constants were comparable to those in molecular solvents. Interestingly, in spite of the charged solvent in the ionic liquid, the entropy profile of the complexation resembled that in the conventional molecular liquids. This indicates that the entropy gain of the released solvent species from the complexes is the main driving force of the chloro complexation in the ionic liquid. In contrast, unlike the major molecular solvents, the total coordination number of Cu2+ is saturated to 4 in the ionic liquid, and the Cl- complexation tends to be accompanied by a 1:1 exchange of the solvent TfO- from the complex. In addition, this ligand exchange was almost athermal. This possibly indicates that the coordination number is dominated by the electrostatic hindrance among the ligands including the solvent ions in the primary coordination sphere.

DOI： 10.1021/acs.jpcb.7b06287

Kodamatani H, Maeda C, Balogh SJ, Nollet YH, Kanzaki R, Tomiyasu T . The influence of sample drying and storage conditions on methylmercury determination in soils and sediments. . Chemosphere173 380 - 386 2017年4月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Chemosphere

The separate influences of drying and storage conditions on methylmercury (MeHg) concentrations in soil and sediment samples were investigated. Concentrations of MeHg and total Hg were determined in various soil and sediment samples that had been stored or dried under differing conditions. The influence of drying conditions (oven-drying (40 °C) versus freeze-drying) on MeHg concentrations in marine sediments, river sediments, soils, and paddy field soils was investigated (n = 43). The ratio of the MeHg concentration in oven-dried sub-samples divided by the concentration in freeze-dried sub-samples ranged from 0 to 336%. In order to confirm the production of MeHg during storage in some samples, Hg2+was added at 15 mg kg−1to a paddy soil, and the sample was then stored at 30 °C. The concentrations of MeHg at 1-h, 1-day, 4-days and 7-days after Hg2+spiking were 2.0 ± 0.1, 13.8 ± 1.0, 36.0 ± 5.0, and 24.9 ± 1.6 μg kg−1(n = 3), respectively. The concentration of MeHg at 4-days after Hg spiking and sterilizing (121 °C, 30 min) was 1.8 μg kg−1, similar to the original value. These results indicate that bacterial Hg methylation and MeHg demethylation occurred within days in the soil. In addition, tests of the stability of MeHg in wet and dry samples during storage were also performed. Overall, our results indicate that the best way to preserve MeHg in soil and sediment samples is to freeze the samples immediately after collection, followed subsequently by freeze-drying, grinding, homogenization, and storage of the dry material in cool, dark conditions until analysis.

DOI： 10.1016/j.chemosphere.2017.01.053

Kodamatani H, Iwaya Y, Saga M, Saito K, Fujioka T, Yamazaki S, Kanzaki R, Tomiyasu T . Ultra-sensitive HPLC-photochemical reaction-luminol chemiluminescence method for the measurement of secondary amines after nitrosation. . Analytica chimica acta952 50 - 58 2017年2月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Analytica Chimica Acta

A novel method for the determination of secondary amines at the nanomolar level was developed. The method is based on the nitrosation reaction of secondary amines, with the generated N-nitrosamines being measured using an HPLC separation, photochemical reaction, and chemiluminescence detection system. The efficient nitrosation of secondary amines was performed using sodium nitrite (200 mM) and acetic acid (0.8 M) at 80 °C over 60 min. Although compounds bearing OH and SH functional groups also underwent the nitrosation reaction, the sensitivity of these compounds was 1000 times lower than that of the secondary amines. Our method was applied to the determination of low molecular weight secondary amines, including dimethylamine, morpholine, pyrrolidine, diethylamine, and piperidine, giving method detection limits of 0.7 nM, 0.2 nM, 0.4 nM, 0.7 nM, and 1.5 nM, respectively. The calibration curves were linear in the range of 5–100 nM. We then applied this method for the detection and quantification of these secondary amines in samples of tap water, river water, treated wastewater, and sea water. Dimethylamine was detected at concentrations up to 15.4 nM, <0.7 nM, and 48.5 nM in tap water, river water, and treated wastewater samples, respectively, with recoveries ranging from 94 to 103%. Other amines were also detected at nanomolar levels. These results indicate that our proposed method can be applied to the analysis of secondary amines in various environmental water samples. To the best of our knowledge, the proposed method is one of the most sensitive and selective methods for the determination of secondary amines without pre-concentration steps.

DOI： 10.1016/j.aca.2016.11.045

Kodamatani H., Yamasaki H., Sakaguchi T., Itoh S., Iwaya Y., Saga M., Saito K., Kanzaki R., Tomiyasu T. . Rapid method for monitoring N-nitrosodimethylamine in drinking water at the ng/L level without pre-concentration using high-performance liquid chromatography-chemiluminescence detection . Journal of Chromatography A1460 202 - 206 2016年8月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Chromatography A

As a contaminant in drinking water, N-nitrosodimethylamine (NDMA) is of great concern because of its carcinogenicity; it has been limited to levels of ng/L by regulatory bodies worldwide. Consequently, a rapid and sensitive method for monitoring NDMA in drinking water is urgently required. In this study, we report an improvement of our previously proposed HPLC-based system for NDMA determination. The approach consists of the HPLC separation of NDMA, followed by NDMA photolysis to form peroxynitrite and detection with a luminol chemiluminescence reaction. The detection limit for the improved HPLC method was 0.2 ng/L, which is 10 times more sensitive than our previously reported system. For tap water measurements, only the addition of an ascorbic acid solution to eliminate residual chlorine and passage through an Oasis MAX solid-phase extraction cartridge are needed. The proposed NDMA determination method requires a sample volume of less than 2 mL and a complete analysis time of less than 15 min per sample. The method was utilized for the long-term monitoring of NDMA in tap water. The NDMA level measured in the municipal water survey was 4.9 ng/L, and a seasonal change of the NDMA concentration in tap water was confirmed. The proposed method should constitute a useful NDMA monitoring method for protecting drinking water quality.

DOI： 10.1016/j.chroma.2016.07.014

Ryo Kanzaki, Hitoshi Kodamatani, Takashi Tomiyasu, Hikari Watanabe, Yasuhiro Umebayashi . A pH Scale for the Protic Ionic Liquid Ethylammonium Nitrate . Angewandte Chemie International Edition2016 ( 21 ) 6266 - 6269 2016年査読

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Wiley

To quantify the properties of protic ionic liquids (PILs) as acid-base reaction media, potentiometric titrations were carried out in a neat PIL, ethylammonium nitrate (EAN). A linear relationship was found between the 14 pKa values of 12 compounds in EAN and in water. In other words, the pKa value in EAN was found to be roughly one unit greater than that in water regardless of the charge and hydrophobicity of the compounds. It is possible that this could be explained by the stronger acidity of HNO3 in EAN than that of H3O+ in water and not by the difference in the solvation state of the ions. The pH value in EAN ranges from -1 to 9 on the pH scale based on the pH value in water. Tipping the pH scale: By using potentiometric acid-base titrations, a pH scale applicable to the protic ionic liquid ethylammonium nitrate (EAN) was determined. This water-based pH scale can be employed to directly compare the differences in H+ activity between EAN and water. For example, the H+ activity in the neutral EAN corresponds to the aqueous solution with pH=4.

DOI： 10.1002/anie.201511328

Hikari Watanabe, Hiroyuki Doi, Soshi Saito, Koichiro Sadakane, Kenta Fujii, Ryo Kanzaki, Yasuo Kameda, Yasuhiro Umebayashi . Raman Spectroscopic Speciation Analyses and Liquid Structures by High-Energy X-ray Total Scattering and Molecular Dynamics Simulations for N-methylimidazolium-Based Protic Ionic Liquids . Bulletin of the Chemical Society of Japan89 ( 8 ) 965 - 972 2016年査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Bulletin of the Chemical Society of Japan

Recently, we revealed N-methylimidazole C1Im equimolar mixtures with superacids and strong acids such as trifluoromethanesulfonic acid HTfO (Tf: CF3SO2-), bis-(trifluoro-methanesulfonyl)amide acid HTf2N or trifluoroacetic acid CF3COOH are essentially protic ionic liquids by means of potentiometry of direct pH measurement in such liquids. Here, we demonstrated Raman spectroscopic speciation analysis of [C1hIm+][TfO-] and [C1hIm+][Tf2N-] (C1hIm+: N-methylimidazolium) to elucidate both liquids are spectroscopically protic ionic liquids; much excess ionic species exist in these liquids and the amount of electrically neutral molecular species are practically negligible. In addition, to further insight into the hydrogen bond in the imidazolium-based protic ionic liquids, liquid structure of [C1hIm+][TfO-] were studied by high-energy X-ray total scattering HEXTS experiments with the aid of molecular dynamics simulations. Comparing with the hydrogen bond in [C1hIm+][Tf2N-] previously reported, the hydrogen bond in [C1hIm+][TfO-] is stronger probably due to the narrower negative charge de-localization.

DOI： 10.1246/bcsj.20160130

HikariWatanabe, Hiroyuki Doi, Soshi Saito, Masaru Matsugami, Kenta Fujii, Ryo Kanzaki, Yasuo Kameda, Yasuhiro Umebayashi . Hydrogen bond in imidazolium based protic and aprotic ionic liquids . Journal of Molecular Liquids217 35 - 42 2016年査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Molecular Liquids

Liquid structure of bis-(trifluoromethanesulfonyl)amide TFSA- based protic and aprotic ionic liquids composed of imidazolium [h2Im+], N-methylimidazolium [C1hIm+] and N,N'-dimethylimidazolium [C1mIm+] were investigated by high-energy total scattering (HETS) experiments. The nearest neighboring cation-anon orientation variations by the N-methyl groups substitution to proton were suggested based on the peaks at around 6 and 9 Å in the differential radial distribution functions as the form of r2{GX-ray(r) - 1} for these ionic liquids. It was supposed that the NH · · · O hydrogen bond causes the cation-anion orientation variations. To obtain further insight into the hydrogen bond in the PIL, MD simulations performed and agreed well with the experiments. According to spatial distribution functions (SDF) for the three ionic liquids, the O atom of TFSA- prefers the NH hydrogen of the imidazolium that has the most positive partial atomic charge in the cation, while the F atom locates right above and right below the imidazolium ring plane. In addition, the NH · · · O hydrogen bond has short bond lengths and linear bond angles, while the C2H · ·O interaction is long and bent. The NH · · · O hydrogen bond in the PIL was discussed based on structural aspect accompanied by a thermodynamic viewpoint.

DOI： 10.1016/j.molliq.2015.08.005

Tomiyasu T., Minato T., Ruiz W., Kodamatani H., Kono Y., Hidaka M., Oki K., Kanzaki R., Taniguchi Y., Matsuyama A. . Influence of submarine fumaroles on the seasonal changes in mercury species in the waters of Kagoshima Bay, Japan . Marine Chemistry177 763 - 771 2015年12月査読

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Marine Chemistry

Submarine fumaroles are located in the 200-m deep basin of the northern part of Kagoshima Bay. To estimate the influence of mercury emitted from these fumaroles, the seasonal changes in total mercury (T-Hg), reactive mercury (RM), dissolved gaseous mercury (DGM), and monomethylmercury (MMHg) in water were studied.Seawater samples were collected from five separate locations in the northern part from May, 2011 to May, 2012 using a CTD-Rosette water sampler; the samples were taken every 50 m, starting from the surface.T-Hg, DGM, RM, and MMHg in the seawater columns (n=132) were in the range of 0.05-3.04ngL-1, 0.003-1.08ngL-1, 0.006-1.47ngL-1, 0.02-0.69ngL-1 for an entire sample. Although the average T-Hg values at the surface and middle layers (0-100m) for each sample showed no significant seasonal variation throughout the year, those at the deeper layer (150-200m) were high from summer to autumn and low in winter. The seasonal changes and vertical distributions of DGM, RM, and MMHg concentrations were similar to those of T-Hg. A thermocline was observed from spring to autumn and ceased in winter. Because the thermocline prohibits vertical circulation of seawater, the fumarole impact may increase during those months.

DOI： 10.1016/j.marchem.2015.10.009

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