Faculty Profiles - Ryo Kanzaki

Papers - Ryo Kanzaki

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Kanzaki R., Hidaka T., Tokuda Y., Kodamatani H., Tomiyasu T. . Brønsted acidity of bis(trifluoromethanesulfonyl)amide and trifluoromethanesulfonic acid in ionic liquids of ternary ammonium . Journal of Molecular Liquids409 2024.9

Language：Japanese Publisher：Journal of Molecular Liquids

Bis(trifluoromethanesulfonyl)amide (Tf2N−) and triflate (TfO−) are commonly used anions of protic ionic liquids (PILs). They are the conjugate anions of strong acids, Tf2NH and TfOH, whose Brønsted acidities crucially influence the performance of the PILs. In this study, the Brønsted acidity of Tf2NH and TfOH was compared directly through potentiometric titrations carried out in the ionic liquids of ternary ammonium salts. As a result, Tf2NH exhibits stronger Brønsted acidity than TfOH by approximately 2 pH units. Furthermore, calorimetric titrations revealed that this difference originates from differences in their entropy states. This suggests that the solvation state, rather than the properties in their isolated state, has a more significant impact on the acidities of Tf2NH and TfOH. Besides, ionization thermodynamics turned out to be governed by both the constituent cations and anions of the PILs. Therefore, once the acid-base natures of the constituent ions are characterized, the overall acid-base behavior of the PIL may become predictable.

DOI： 10.1016/j.molliq.2024.125433

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Takashi Tomiyasu, Chihiro Nozoe, Wilder Leonardo Gamboa Ruiz, Hitoshi Kodamatani, Ryo Kanzaki . Distribution of selenium and mercury concentrations in sediments of Kagoshima Bay: can submarine volcanic activity affect the distribution of selenium in sediments? . Environmental Earth Sciences82 ( 20 ) 2023.10Reviewed

Takashi Tomiyasu, Hideaki Matsuki, Masanori Oda, Hitoshi Kodamatani, Ryo Kanzaki, Toru Kobari . Impact of mercury discharged from submarine volcano on inner bay ecosystems . Chemosphere339 139748 2023.10Reviewed

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

Organic mercury, inorganic mercury and total mercury concentrations in phytoplankton (<0.1 mm) and zooplankton (>0.1 mm) collected in Kagoshima Bay, Japan were measured from 2017 to 2019 to estimate the impact of mercury discharged from submarine volcanoes on ecosystems; submarine volcanic activity continues at a depth of 200 m in the inner part of Kagoshima Bay. The total mercury concentrations in phyto- and zooplankton collected by vertical hauling at 0–200 m at just above the submarine volcano were in the range of 0.11–2.0 mg kg−1 (avg. 0.67 mg kg−1) and 0.090–0.56 mg kg−1 (avg. 0.21 mg kg−1), respectively. These values were one order of magnitude higher than the values in plankton collected in the central part of Kagoshima Bay. Organic mercury concentrations in phyto- and zooplankton were <0.010–0.071 mg kg−1 (avg. 0.028 mg kg−1) and 0.012–0.25 mg kg−1 (avg. 0.10 mg kg−1), respectively, for the inner part, and <0.010–0.040 mg kg−1 (avg. 0.010 mg kg−1) and <0.010–0.025 mg kg−1 (avg. 0.012 mg kg−1), respectively, for the central part. The values obtained in the inner part of the bay increased in summer and decreased in winter, which was consistent with changes in seawater mercury concentrations affected by volcanic activity. The organic mercury concentration in zooplankton collected just above the submarine volcano showed a size dependency, and a higher value was observed in the larger size, which suggested that the discharged mercury from the volcano was absorbed and concentrated through the ecosystem.

DOI： 10.1016/j.chemosphere.2023.139748

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Ryo Kanzaki, Tomoya Hidaka, Hitoshi Kodamatani, Takashi Tomiyasu . Determination of autoprotolysis (autoionization) constant according to gran's procedure on potentiometric titrations . Journal of Molecular Liquids384 2023.8Reviewed

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

Gran's plot is an ingenious tool to find endpoints in potentiometric neutralization titrations. It can also be utilized for determining the formal potential of the electrodes, which is required in the case of obtaining the hydrogen ion concentration with pH sensor electrodes involving glass electrodes. Furthermore, autoprotolysis constants can be determined through Gran's plots with high accuracy, even those containing impurities. Gran's plot is thus a fundamental technique for investigating the properties of novel solvents such as protic ionic liquids as acid-base media. However, there are limitations in the autoprotolysis constants of the solvents and the ionization constants of the impurities, and so on, where Gran's plots work well. Hence, we have clarified the reliable range of these constants to be determined through Gran's plot by calculating the titration curves under various conditions and simulating these determination processes.

DOI： 10.1016/j.molliq.2023.122180

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Ryo kanzaki . Deep eutectic solvents for liquid–liquid extraction . Analytical Sciences39 ( 7 ) 1021 - 1022 2023.6Invited

Authorship：Lead author,　Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

DOI： 10.1007/s44211-023-00362-0

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Other Link： https://link.springer.com/article/10.1007/s44211-023-00362-0/fulltext.html

Takashi Tomiyasu, Ryohei Shitauchi, Daigo Kasai, Toshiki Kitagawa, Hitoshi Kodamatani, Ryo Kanzaki . The distribution and dynamics of residual mercury from the Chisso chemical plant in sediments of the Yatsushiro Sea, western Kyushu, Japan: have recent sedimentations lowered surface mercury concentrations? . Environmental science and pollution research international30 ( 28 ) 72769 - 72781 2023.6Reviewed International journal

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

To determine the long-term dynamics of mercury discharged from Chisso chemical plant between 1932 and 1968, the vertical variation in mercury concentrations in Yatsushiro Sea sediments was studied from 2013 to 2020 at 31 locations and compared to the mercury concentration distribution obtained in 1996. The results suggest that new sedimentation occurred after 1996, but the mercury concentrations at the surface ranged from 0.2 to 1.9 mg kg-1, which did not decrease significantly over a 20-year period. It was estimated that approximately 17 t of mercury remained in the southern Yatsushiro Sea sediment, which is equivalent to 10-20% of the total mercury discharged between 1932 and 1968. From results of WD-XRF and TOC measurement, it was suggested that mercury in sediment had been transported with suspended particles derived from sludges from the chemical plant and further suggests that the suspended particles derived from the sediment surface layer are still slowly diffusing.

DOI： 10.1007/s11356-023-27505-0

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Hitoshi Kodamatani, Shotaro Kubo, Akinori Takeuchi, Ryo Kanzaki, Takashi Tomiyasu . Sensitive Detection of Nitrite and Nitrate in Seawater by 222 nm UV-Irradiated Photochemical Conversion to Peroxynitrite and Ion Chromatography-Luminol Chemiluminescence System. . Environmental science & technology57 ( 14 ) 5924 - 5933 2023.4International journal

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

Sensitive detection methods for nitrite (NO2-) and nitrate (NO3-) ions are essential to understand the nitrogen cycle and for environmental protection and public health. Herein, we report a detection method that combines ion-chromatographic separation of NO2- and NO3-, on-line photochemical conversion of these ions to peroxynitrite (ONOO-) by irradiation with a 222 nm excimer lamp, and chemiluminescence from the reaction between luminol and ONOO-. The detection limits for NO2- and NO3- were 0.01 and 0.03 μM, respectively, with linear ranges of 0.010-2.0 and 0.10-3.0 μM, respectively, at an injection volume of 1 μL. The results obtained by the proposed method for seawater analysis corresponded with those of a reference method (AutoAnalyzer based on the Griess reaction). As luminol chemiluminescence can measure ONOO- at picomolar concentrations, our method is expected to be able to detect NO2- and NO3- at picomolar concentrations owing to the high conversion ratio to ONOO- (>60%), assuming that contamination and background chemiluminescence issues can be resolved. This method has the potential to emerge as an innovative technology for NO2- and NO3- detection in various samples.

DOI： 10.1021/acs.est.3c00273

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Takashi Tomiyasu, Sora Yasumatsu, Hitoshi Kodamatani, Ryo Kanzaki, Chisato Takenaka, Satoshi Murao, Shuichi Miyagawa, Kenichi Nonaka, Akiko Ikeguchi, Ian A Navarrete . The dynamics of mercury around an artisanal and small-scale gold mining area, Camarines Norte, Philippines. . Environmental science and pollution research international30 ( 8 ) 20052 - 20064 2023.2Reviewed International journal

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

To elucidate the dynamics of mercury emitted and released by artisanal and small-scale gold mining (ASGM) activity and to estimate its impact on the ecosystems of the bay, the distribution of mercury in the atmosphere, soil, water, and sediment around Mambulao Bay, Camarines Norte, Philippines, was investigated. The ASGM operations use mercury to extract gold from ore and are located on the east shore side of the bay. Samplings were conducted in August 2017 and September 2018. The samples were used for determination of total mercury (T-Hg) and organic mercury (org-Hg) concentrations, total organic carbon (TOC) content, and chemical composition. The atmospheric mercury concentration on the east shore side, 6.1-25.8 ng m-3, was significantly higher than the value of 1.4-9.9 ng m-3 observed on the west shore side. The average concentrations of T-Hg in the forest soils of the west shore side and those of the east shore side were 0.081 ± 0.028 mg kg-1 and 0.496 ± 0.439 mg kg-1, respectively. In the vertical distribution of T-Hg in the soil of the east shore side, a higher concentration was observed near the surface. For the vertical variations in T-Hg in the marine sediment, higher values were observed near the estuary, and the vertical variations in core samples showed an increase in mercury concentration toward the surface. The highest concentration of T-Hg in sediment, 9.5 mg kg-1, which was 2 orders of magnitude higher than the background levels of this area, was found near the river mouth. The T-Hg, org-Hg, and TOC levels showed a positive correlation, suggesting that the rivers are the main sources of T-Hg and org-Hg in the bay. Although the fish sample containing a mercury content higher than the regulatory level for fish and shellfish of 0.4 mg kg-1 in Japan was only one of 42 samples, the percentage of org-Hg in fish samples was 91 ± 18%. Mercury released into the surroundings by the ASGM activities can be converted into methylmercury and affect the bay's ecosystem.

DOI： 10.1007/s11356-022-23497-5

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Hitoshi Kodamatani, Karin Kubozono, Ryo Kanzaki, Takashi Tomiyasu, Takahiro Fujioka . Reverse osmosis membrane-based pretreatment for the quantification of N-nitrosodimethylamine concentrations in high-matrix water samples . Environmental Science: Water Research and Technology9 ( 10 ) 2553 - 2560 2023Reviewed

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

N-Nitrosodimethylamine (NDMA) is a carcinogenic constituent commonly found in recycled water and pharmaceuticals. Developing an analytical method to continuously monitor changes in NDMA concentrations during water recycling and pharmaceutical manufacturing can mitigate accidents caused by NDMA formation. However, NDMA analysis in high-matrix water samples, such as beverages, wastewater, and pharmaceutical ingredients, is difficult. In this study, we adapted reverse osmosis (RO) membrane treatment as a pretreatment for NDMA analysis by isolating NDMA from interfering substances in high-matrix water samples. Subsequently, high-performance liquid chromatography-chemiluminescence detection was used for NDMA analysis. In a pure water matrix, 95% of NDMA can pass through at a low permeate flux of 1 L m−2 h−1. The method was then validated using beer, which is known to contain high concentrations of NDMA, as a representative high-matrix water sample. We found that RO pretreatment leads to clean chromatograms in which NDMA peaks are clearly visible while other peaks are mostly absent. Analysis of six different beer samples showed a maximum NDMA concentration of 315 ng L−1, and an average NDMA concentration of 138 ± 83 ng L−1 (n = 6), which fall within the regulation limits for NDMA in beer in the United States of America. The proposed pretreatment method has the potential to provide a platform for developing technologies for continuous monitoring of NDMA in aqueous solutions.

DOI： 10.1039/d3ew00222e

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Takashi Tomiyasu, Akihiro Mitsui, Mai Mitarai, Hitoshi Kodamatani, Ryo Kanzaki . Seasonal variation in mercury species in seawater of Kagoshima Bay, southern Kyushu, Japan: The impact of active submarine volcanos on the inner bay . Marine Chemistry244 2022.7Reviewed

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

Wakamiko Proto-Caldera, a submarine volcano, is located at the bottom of the sea in the bay head area of Kagoshima Bay. In Kagoshima Bay, several species of fish with total mercury exceeding the provisional regulation value of 0.40 mg kg−1 were found in the 1970s. The effects of mercury released from submarine volcanoes are suspected. However, the path from volcanic mercury to the broader ecosystem has not yet been clarified. In this study, as the first step to elucidate the impact of volcanic activity on the ecosystems of Kagoshima Bay, seasonal changes in the concentrations of dissolved gaseous mercury (DGM), Hg(II), filtered total mercury (FT-Hg), particulate mercury (P-Hg), and mercury in suspended particulate matter (Hg in SPM) in seawater of Kagoshima Bay were tracked every two months from Feb. 2014 to Dec. 2017. The dissolved total mercury (DT-Hg) concentration was calculated by summing the DGM and FT-Hg concentrations. The DT-Hg at the location in the caldera ranged from 0.09 to 6.83 ng L−1 showing higher values in summer compared to winter, that is, in the stratified period. The P-Hg showed similar periodic variation as DT-Hg, and the highest Hg in SPM was 2.15 mg kg−1, which is one order of magnitude higher than that observed at the reference site. The high mercury concentration in SPM suggests the accumulation of dissolved mercury discharged from volcanic activity on SPM. Since mercury loaded on SPM can be taken up by suspension feeders and enter the food chain, the Hg in SPM may be a key factor affecting Hg in fishes in Kagoshima Bay.

DOI： 10.1016/j.marchem.2022.104133

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Hitoshi Kodamatani, Azusa Shigetomi, Junna Akama, Ryo Kanzaki, Takashi Tomiyasu . Distribution, alkylation, and migration of mercury in soil discharged from the Itomuka mercury mine. . The Science of the total environment815 152492 - 152492 2022.4Reviewed International journal

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

The purpose of this study was to investigate the behavior of previously discharged mercury (Hg) released from the Itomuka Hg mine into the surrounding environment, especially into soil. Total-Hg (T-Hg), methylmercury (MeHg), and ethylmercury (EtHg) concentrations in the surface soil at eight sample sites around the mine were 3.8-64.2 mg/kg, 6.0-54.7 μg/kg, and undetected to 4.5 μg/kg, respectively. Core samples collected from seven of the eight sample sites showed that the vertical distribution of T-Hg was the highest in the surface soil layer and decreased rapidly in the lower layers. A strong positive correlation was observed between T-Hg and MeHg concentrations in the core samples; however, the slope of the regression line varied considerably for each core. This suggests that Hg and MeHg were not supplied from the atmosphere simultaneously, but rather that MeHg was produced on-site. Further, the formation of MeHg and EtHg in soil was considered in terms of the total organic carbon/total nitrogen ratio, which is a decomposition index of soil organic matter. The strong positive correlation between T-Hg and MeHg can be attributed to the migration of organic matter containing Hg species to the lower layers. There was no relationship between T-Hg and MeHg at the riverbed sample site because of the high T-Hg in the lower soil layers, suggesting that Hg was supplied by ore at this sample site. These assumptions of the formation change and migration of Hg in soil were supported by the results of the fractionation experiment and the elution test. To understand the current conditions in this area, measurements of Hg in the water, sediment, atmosphere, and plants were also conducted.

DOI： 10.1016/j.scitotenv.2021.152492

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Ryo Kanzaki, Mika Sako, Hitoshi Kodamatani, Takashi Tomiyasu, Clément Guibert, Jérôme Fresnais, Véronique Peyre . Enthalpy profile of pH-induced flocculation and redispersion of polyacrylic acid-coated nanoparticles in protic ionic liquid, N,N-diethylethanolammonium trifluoromethanesulfonate . Journal of Molecular Liquids349 2022.3Reviewed

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

Maghemite nanoparticles coated with polyacrylic acid (pAA) were dispersed in the protic ionic liquid, diethylethanolammonium trifluoromethanesulfonate (DEEAH+⋅TfO−), and the thermodynamics of particle dispersion was studied by means of potentiometric and calorimetric titrations over the entire accessible pH range. As previously reported, the domain of colloidal stability is divided into two pH regions, mildly acidic and basic, separated by a flocculation domain at an intermediate pH. In this study, solvent DEEAH+⋅TfO− was first characterized in terms of the thermodynamic parameters of two reference reactions: autoprotolysis and ionization of acetic acid. A negative autoprotolysis entropy is obtained due to hydrogen-bond formation between the neutralized solvent cation, DEEA, and the neighboring cation DEEAH+. This suggests that the solvent structure is reinforced by the formation of neutral species, being an opposite trend to both ethylammonium nitrate and water. Second, the ionization and flocculation of pAA-coated nanoparticles (CNps) in the ionic liquid were examined. The potentiometric results could be modeled using a simple pAA ionization, independent of the aggregation state over the entire pH range. However, the calorimetric titration detected extra heat generation in an acidic condition prior to flocculation, in addition to an ionization enthalpy of pAA of 30 kJ/mol. This exothermic contribution is attributed to a change in the solvation process of CNps in the ionic liquid. Herein, we propose a model in which different types of solvation in the acidic and basic domains are sufficient to ensure colloidal stability, while aggregation unfolds between the switching pH.

DOI： 10.1016/j.molliq.2021.118146

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Hitoshi Kodamatani, Daisuke Yoshimine, Takahiro Fujioka, Ryo Kanzaki, Takashi Tomiyasu . A novel luminol chemiluminescence induced by photoexcited ketones: A selective determination method for acetone in wastewater . Talanta open3 100035 - 100035 2021.8Reviewed

Hitoshi Kodamatani, Taketo Tanisue, Takahiro Fujioka, Ryo Kanzaki, Takashi Tomiyasu . Inhibitory effect of alkyl groups on N-nitrosamine formation from secondary and tertiary alkylamines with monochloramine . Environmental Technology and Innovation22 2021.5Reviewed

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

N-nitrosamines are contaminants of emerging concern, and controlling these chemicals in potable water and recycled water for potable reuse has become important for protecting public health. This study aimed to evaluate the influence of the alkyl chain lengths of N-nitrosamine precursors (secondary and tertiary amines) on the formation of N-nitrosamines via chloramination. The molar conversion efficiency from dimethylamine, an N-nitrosodimethylamine (NDMA) precursor, to NDMA (0.67%) was greater than that from diethylamine, an N-nitrosodiethylamine (NDEA) precursor, to NDEA (0.38%). Similarly, the molar conversion efficiency from trimethylamine to NDMA (0.92%) was greater than from triethylamine to NDEA (0.33%). Interestingly, a considerable difference in molar conversion efficiencies were observed for tertiary amines with the N,N-dialkyl-α-arylamine structure: the molar conversion efficiencies from N,N-dimethylbenzylamine and N,N-diethylbenzylamine to NDMA and NDEA were 50.2% and 1.7%, respectively. These results indicate that amines with ethyl groups have lower potentials for producing the corresponding N-nitrosamines than those with methyl groups. These differences in yields between amines with methyl and ethyl groups can be explained by the difference in electron density in the nitrogen atom of the amine, which influences the protonation of the amine and stabilization of intermediate species. These findings could be useful for enhancing source control of water and wastewater by regulating runoff or industrial wastewater containing high concentrations of specific N-nitrosamine precursors.

DOI： 10.1016/j.eti.2021.101520

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Takashi Tomiyasu, Misato Nakagawa, Hitoshi Kodamatani, Ryo Kanzaki . The influence of submarine volcano on seasonal changes in arsenic in the waters of Kagoshima Bay, southwestern Japan . ENVIRONMENTAL EARTH SCIENCES80 ( 8 ) 2021.4Reviewed

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：SPRINGER

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 mu g L-1 (av. +/- s.d.), similar to the world average value of 1.7 mu g L-1. The highest T-As value at the nearest point to the submarine volcano, 3.48 mu g 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

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Hitoshi Kodamatani, Kenta Sugihara, Taketo Tanisue, Ryo Kanzaki, Takashi Tomiyasu . Contamination, Decomposition, and Formation of N-Nitrosodimethylamine in Water Samples at the ng/L Level of Determination . ANALYTICAL SCIENCES36 ( 11 ) 1393 - 1399 2020.11Reviewed

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

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 N-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/m(3), 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

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Takashi Tomiyasu, Christine Baransano, Yuriko Kono Hamada, Hitoshi Kodamatani, Ryo Kanzaki, Nuril Hidayati, Joeni Setijo Rahajoe . 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 ) 2020.7Reviewed

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：SPRINGER INTERNATIONAL PUBLISHING AG

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

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Hitoshi Kodamatani, Yuri Daiba, Shintarou Morisaki, Katsuyuki Ichitani, Ryo Kanzaki, Takashi Tomiyasu . Detailed investigation of methylmercury accumulation in rice grain from Hg<sup>2+</sup>-spiked non-contaminated paddy field soils . Chemosphere247 125827 2020.5Reviewed

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

© 2020 Elsevier Ltd 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

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Yuji Kamiyama, Masayuki Shibata, Ryo Kanzaki, Kenta Fujii . Lithium-Ion Coordination-Induced Conformational Change of PEG Chains in Ionic-Liquid-Based Electrolytes . Physical Chemistry Chemical Physics22 ( 10 ) 5561 - 5567 2020.3

Kanzaki Ryo . Chemical Thermodynamics for Analytical Chemist . Netsu Sokutei46 ( 4 ) 195 - 201 2019.10Chemical Thermodynamics for Analytical ChemistInvited Reviewed

Language：Japanese Publisher：The Japan Society of Calorimetry and Thermal Analysis

One of the fundamental roles of analytical chemistry is to provide the information of chemical species distributing in solutions, where chemical equilibria of acid dissociation, dissolving of salts, complex formation, electrode reaction, etc., are considered. This extensively owes to chemical thermodynamics, however, the relationship is rarely taught in detail in the class of physical chemistry nor analytical chemistry. It will be a great loss in both fields. In this article, with beginning from the usual equilibria in analytical chemistry, its groundwork of chemical thermodynamics will be explained. First, chemical potential is introduced as the determining factor of equilibrium constant, then Gibbs energy is defined. Although this is inverted from the ordinary way of instruction, possibly more convenient for the field of analytical chemistry. Then, activity coefficient and the standard state are explained, followed by the derivation of chemical potential from the work for changing concentration of solute in solution for clarifying its physical meaning. Turning to the solvent, the solvent transfer is considered by both transfer Gibbs energy and transfer activity coefficient. Finally, electrochemical potential is outlined. They are described within the word of analytical chemistry. Hopefully, this article will help establishing the energy-based perspective on the chemical equilibria in solutions.

DOI： 10.11311/jscta.46.4_195

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Papers - Ryo Kanzaki