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| 1.
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Hasegawa, Hiroshi ; Barua, Suman ; Wakabayashi, Tomoya ; Mashio, Asami ; Maki, Teruya ; Furusho, Yoshiaki ; Rahman, Ismail M.M. ; 長谷川, 浩 ; 牧, 輝弥
概要:
金沢大学理工研究域物質化学系<br />End-of-life electrical and electronic equipment is the potential secondary resource for economically
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-viable precious metals (PMs), e.g., gold (Au), palladium (Pd), or platinum (Pt). The hydrometallurgical processes produce acidic leachates during the recovery of PMs from waste sources, while the selective recovery of Au, Pd, or Pt from such a matrix is challenging either due to the chemical similarities of elements or complexities in the sources and matrices. A total of nine solid-phase extraction (SPE) systems, all claimed to designed for separation of PMs from complex matrices, was evaluated at varying solution pH (≤2 to 10) based on the selectivity towards Au, Pd, or Pt. The observation was used to develop a technique for selective Au, Pd, or Pt separation from acidic waste solutions using a macrocycle-equipped SPE. The feed solution flow-rates, eluent-type or compositions has been optimized to achieve maximum separation efficiency of the target analytes. The relative affinity of the macrocycles in solid-phase towards the ions (Pd > Au > Pt) is the core phenomenon of the proposed technique, and the host-guest type interaction is expected to be more stable than the resin-based separation processes. Furthermore, application of the macrocycle-equipped SPE system is advantageous regarding economics as it minimizes the impact of coexisting ions in the matrix and provides unaltered separation performance for several loading-elution cycles. © 2018 Elsevier B.V.<br />Embargo Period 12 months
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| 2.
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Maki, Teruya ; Hirota, Wakana ; Motojima, Hiroyuki ; Hasegawa, Hiroshi ; Rahman, Mohammad Azizur
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金沢大学理工研究域物質化学系<br />Aquatic arsenic cycles mainly depend on microbial activities that change the arsenic chemical forms
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and influence human health and organism activities. The microbial aggregates degrading organic matter are significantly related to the turnover between inorganic arsenic and organoarsenic compounds. We investigated the effects of microbial aggregates on organoarsenic mineralization in Lake Kahokugata using lake water samples spiked with dimethylarsinic acid (DMA). The lake water samples converted 1μmolL-1 of DMA to inorganic arsenic for 28d only under anaerobic and dark conditions in the presence of microbial activities. During the DMA mineralization process, organic aggregates >5.0μm with bacterial colonization increased the densities. When the organic aggregates >5.0μm were eliminated from the lake water samples using filters, the degradation activities were reduced. DMA in the lake water would be mineralized by the microbial aggregates under anaerobic and dark conditions. Moreover, DMA amendment enhanced the degradation activities in the lake water samples, which mineralized 50μmolL-1 of DMA. The DMA-amended aggregates >5.0μm completely degraded 1μmolL-1 of DMA with a shorter incubation time of 7d. The supplement of KNO3 and NaHCO3 to lake water samples also shortened the DMA-degradation period. Presumably, the bacterial aggregates involved in the chemical heterotrophic process would contribute to the DMA-biodegradation process in Lake Kahokugata, which is induced by the DMA amendment. © 2011 Elsevier Ltd.
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| 3.
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Azizur Rahman, Mohammad ; Mamunur, Rahman ; Kadohashi, K. ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
This study was conducted to investigate the effect of external iron status and arsenic species on chelant-enhanced iron
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bioavailability and arsenic uptake. Rice seedlings (Oryza sativa L.) were used as model plant, and were grown in artificially contaminated sandy soils irrigated with Murashige and Skoog (MS) culture solution. Arsenate uptake in roots and shoots of rice seedlings were affected significantly (p > 0.05) while dimethylarsinic acid (DMAA) was not by the additional iron and chelating ligand treatments. Regardless of iron concentrations in the soil solution, HIDS increased arsenic uptake for roots more than EDTA and EDDS. Chelating ligands and arsenic species also influenced iron uptake in rice roots. Irrespective of arsenic species, HIDS was found to be more effective in the increase of iron bioavailability and uptake in rice roots compared to other chelants. There was a significant positive correlation (r = 0.78, p < 0.05) between arsenate and iron concentrations in the roots of rice seedlings grown with or without additional iron indicating that arsenate inhibit iron uptake. In contrast, there was no correlation between iron and DMAA uptake in roots. Poor correlation between iron and arsenic in shoots indicated that iron uptake in shoots was neither affected by additional iron nor by arsenic species. Compared to the control, chelating ligands increased iron uptake in shoots of rice seedlings significantly (p < 0.05). Regardless of additional iron and arsenic species, iron uptake in rice shoots did not differed among EDTA, EDDS, and HIDS treatments. © 2011 Elsevier Ltd. All rights reserved.
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| 4.
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Rahman, Ismail M. M. ; Furusho, Yoshiaki ; Begum, Zinnat A. ; Sabarudin, Akhmad ; Motomizu, Shoji ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
A simple flow-based method was developed for the simultaneous separation of certain transition metal ions (Co, Ni, Cu, Z
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n, Cd) from aqueous systems, which ions show ecotoxic effects when present at elevated concentrations. A silica-gel-bonded macrocycle system, commonly known as molecular recognition technology (MRT) gel, was used for solid phase extraction (SPE) of the target analytes. The collection behavior of the MRT-SPE system was studied based on pH. Fortified deionized water samples containing 250 μg L-1 of each of the elements were treated at the flow rate of 1 mL min-1. The collected analytes were then eluted by 3 M HNO3 and analyzed using inductively coupled plasma spectrometry. Detection limits of the proposed technique were in the range of 0.004-0.040 μg L-1 for the studied metal ions. The validity of this separation technique was checked with spiked 'real' water samples, which produced satisfactory recoveries of 96-102%. The non-destructive nature and highly selective ion-extraction capability of the SPE material are the most important aspects of the proposed method and they are the main focus of this paper. © 2011 © Versita Warsaw and Springer-Verlag Wien.
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| 5.
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Nakano, Masayoshi ; Begum, Zinnat A. ; Egawa, Yuji ; Maki, Teruya ; Furusho, Yoshiaki ; Mizutani, Satoshi
概要:
Aminopolycarboxylate chelants (APCs) are extremely useful for a variety of industrial applications, including the treatm
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ent of toxic metal-contaminated solid waste materials. Because non-toxic matrix elements compete with toxic metals for the binding sites of APCs, an excess of chelant is commonly added to ensure the adequate sequestration of toxic metal contaminants during waste treatment operations. The major environmental impacts of APCs are related to their ability to solubilize toxic heavy metals. If APCs are not sufficiently eliminated from the effluent, the aqueous transport of metals can occur through the introduction of APCs into the natural environment, increasing the magnitude of associated toxicity. Although several techniques that focus primarily on the degradation of APCs at the pre-release step have been proposed, methods that recycle not only the processed water, but also provide the option to recover and reuse the metals, might be economically feasible, considering the high costs involved due to the chelants used in metal ion sequestration. In this paper, we propose a separation process for the recovery of metals from effluents that contain an excess of APCs. Additionally, the option of recycling the processed water using a solid phase extraction (SPE) system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel, is presented. Simulated effluents containing As(V), Cd(II), Cr(III), Pb(II) or Se(IV) in the presence of APCs at molar ratios of 1:50 in H2O were studied with a flow rate of 0.2mL min-1. The 'captured' ions in the SPE system were quantitatively eluted with HNO3. The effects of solution pH, metal-chelant stability constants and matrix elements were assessed. Better separation performance for the metals was achieved with the MRT-SPE compared to other SPE materials. Our proposed technique offers the advantage of a non-destructive separation of both metal ions and chelants compared to conventional treatment options for such effluents. © 2011 Elsevier Ltd.
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| 6.
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Hasegawa, Hiroshi ; Rahman, Ismail M.M. ; Nakano, Masayoshi ; Begum, Zinnat A. ; Egawa, Yuji ; Maki, Teruya ; Furusho, Yoshiaki ; Mizutani, Satoshi
概要:
Aminopolycarboxylate chelants (APCs) are extremely useful for a variety of industrial applications, including the treatm
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ent of toxic metal-contaminated solid waste materials. Because non-toxic matrix elements compete with toxic metals for the binding sites of APCs, an excess of chelant is commonly added to ensure the adequate sequestration of toxic metal contaminants during waste treatment operations. The major environmental impacts of APCs are related to their ability to solubilize toxic heavy metals. If APCs are not sufficiently eliminated from the effluent, the aqueous transport of metals can occur through the introduction of APCs into the natural environment, increasing the magnitude of associated toxicity. Although several techniques that focus primarily on the degradation of APCs at the pre-release step have been proposed, methods that recycle not only the processed water, but also provide the option to recover and reuse the metals, might be economically feasible, considering the high costs involved due to the chelants used in metal ion sequestration. In this paper, we propose a separation process for the recovery of metals from effluents that contain an excess of APCs. Additionally, the option of recycling the processed water using a solid phase extraction (SPE) system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel, is presented. Simulated effluents containing As(V), Cd(II), Cr(III), Pb(II) or Se(IV) in the presence of APCs at molar ratios of 1:50 in H2O were studied with a flow rate of 0.2mL min-1. The 'captured' ions in the SPE system were quantitatively eluted with HNO3. The effects of solution pH, metal-chelant stability constants and matrix elements were assessed. Better separation performance for the metals was achieved with the MRT-SPE compared to other SPE materials. Our proposed technique offers the advantage of a non-destructive separation of both metal ions and chelants compared to conventional treatment options for such effluents. © 2011 Elsevier Ltd.
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| 7.
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Rahman, Ismail M. M. ; Furusho, Yoshiaki ; Begum, Zinnat A. ; Sabarudin, Akhmad ; Motomizu, Shoji ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
A simple flow-based method was developed for the simultaneous separation of certain transition metal ions (Co, Ni, Cu, Z
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n, Cd) from aqueous systems, which ions show ecotoxic effects when present at elevated concentrations. A silica-gel-bonded macrocycle system, commonly known as molecular recognition technology (MRT) gel, was used for solid phase extraction (SPE) of the target analytes. The collection behavior of the MRT-SPE system was studied based on pH. Fortified deionized water samples containing 250 ìg L-1 of each of the elements were treated at the flow rate of 1 mL min-1. The collected analytes were then eluted by 3 M HNO3 and analyzed using inductively coupled plasma spectrometry. Detection limits of the proposed technique were in the range of 0.004-0.040 ìg L-1 for the studied metal ions. The validity of this separation technique was checked with spiked 'real' water samples, which produced satisfactory recoveries of 96-102%. The non-destructive nature and highly selective ion-extraction capability of the SPE material are the most important aspects of the proposed method and they are the main focus of this paper. © Versita Sp. z o.o.
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| 8.
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Maki, Teruya ; Aoki, Kazuma ; Kobayashi, Fumihisa ; Kakikawa, Makiko ; Tobo, Yutaka ; Matsuki, Atsushi ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
金沢大学理工研究域物質化学系<br />Microbial particles transported by Asian desert dust (KOSA) possibly impact ecosystems and human hea
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lth in downwind environments and are commonly called "bioaerosols." The microbial communities associated with KOSA mineral particles (KOSA bioaerosol), which were collected from the snow cover on Mt. Tateyama, were investigated by means of a culture-amendment technique combined with denaturing gradient gel electrophoresis (DGGE) analysis using 16S rRNA genes. After the stratigraphy of the snow layer formed on the walls of a snow pit on Mt. Tateyama, samples were collected from 2 layers, which included KOSA particles and one which did not. The snow samples with KOSA particles indicated microbial growth in the 100 and 10-1 dilution media and in the medium with NaCl below 10%, while the snow sample without KOSA particles showed no microbial growth in the culture media. The PCR-DGGE analysis revealed that the bacterial compositions in the snow samples including KOSA mineral particles were mainly composed of the members of the phyla Actinobacteria, Firmicutus, and Proteobacteria. In particular, the 2 phylotypes appeared in the microbial cultures were similar to the members of the B. subtilis group, which has been detected in bioaerosol samples collected from the atmosphere over KOSA arrival (Suzu City) and source (Dunhuang City) regions. Presumably, halotolerant and oligotrophic bacterial communities are associated with the KOSA particles that descend to the snow cover on Mt. Tateyama. © 2011 Springer Science+Business Media B.V.
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| 9.
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Rahman M., Mamunur ; Rahman M., Azizur ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
Arsenic (As) contamination is an important environmental consequence in some parts of salinity-affected South (S) and So
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uth-East (SE) Asia. In this study, we investigated the individual and combined phytotoxicity of arsenic (As) [arsenate; As(V)] and salinity (NaCl) on early seedling growth (ESG) of saline-tolerant and non-tolerant rice varieties. Germination percentage (GP), germination speed (GS) and vigor index (VI) of both saline-tolerant and non-tolerant rice varieties decreased significantly (p > 0.01) with increasing As(V) and NaCl concentrations. The highest GP (91%) was observed for saline non-tolerant BRRI dhan28 and BRRI dhan49, while the lowest (62%) was for saline-tolerant BRRI dhan47. The ESG parameters, such as weights and relative lengths of plumule and radicle, also decreased significantly (p < 0.01) with increasing As(V) and NaCl concentrations. Relative radicle length was more affected than plumule length by As(V) and NaCl. Although VI of saline-tolerant and non-tolerant rice seedlings showed significant variation (p < 0.05), weights and lengths of plumule and radicle of different rice varieties did not show significant variation for As(V) and NaCl treatments. Results reveal that the combined phytotoxicity of As(V) and NaCl on rice seed germination and ESG are greater than their individual toxicities, and some saline-tolerant rice varieties are more resistant to the combined phytotoxicity of As(V) and NaCl than the saline non-tolerant varieties. © 2012 Springer Science+Business Media, LLC.
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| 10.
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Hasegawa, Hiroshi ; Rahman M., Azizur ; Luan, Nguyen Trong ; Maki, Teruya ; Iwasaki, Nozumu
概要:
Precious corals have been commercially exploited for many centuries around the world. The skeletons of these corals cons
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ist of calcium carbonate, and have been used as amulets or gemstones since ancient times. Different Corallium species of Coralidae family (e.g., Corallium rubrum, Corallium elatus, Corallium konojoi, and Paracorellium japonicum) were collected from different locations of the Mediterranean Sea (off Italy) and Pacific Ocean (off Japan and off Midway Island), and trace elements in their skeletons were analyzed. Results show that trace element concentrations in the skeletons of Corallium spp. were attributable to their habitat and origin. In particular, Mg/Ca and Ba/Ca ratios in the skeletons of Corallium spp. from the Mediterranean Sea and Japanese and the Midway Islands' waters were found to be habitat-specific. This study also reveals that trace elements in the skeletons can be used as ecological indicator of the coral's origin, and are expected to play an important part in the cultural study and sustainable management of precious corals. Findings of this study will also be of great relevance to the coral industry to authenticate and identify the habitat and origin of the corals. © 2012 Elsevier B.V.
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| 11.
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Begum, Zinnat A. ; Rahman, Ismail M. M. ; Tate, Yousuke ; Sawai, Hikaru ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
Ex situ soil washing with synthetic extractants such as, aminopolycarboxylate chelants (APCs) is a viable treatment alte
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rnative for metal-contaminated site remediation. EDTA and its homologs are widely used among the APCs in the ex situ soil washing processes. These APCs are merely biodegradable and highly persistent in the aquatic environments leading to the post-use toxic effects. Therefore, an increasing interest is focused on the development and use of the eco-friendly APCs having better biodegradability and less environmental toxicity. The paper deals with the results from the lab-scale washing treatments of a real sample of metal-contaminated soil for the removal of the ecotoxic metal ions (Cd, Cu, Ni, Pb, and Zn) using five biodegradable APCs, namely [S,S]-ethylenediaminedisuccinic acid, imminodisuccinic acid, methylglycinediacetic acid, DL-2-(2-carboxymethyl) nitrilotriacetic acid (GLDA), and 3-hydroxy-2,2'-iminodisuccinic acid. The performance of those biodegradable APCs was evaluated for their interaction with the soil mineral constituents in terms of the solution pH and metal-chelant stability constants, and compared with that of EDTA. Speciation calculations were performed to identify the optimal conditions for the washing process in terms of the metal-chelant interactions as well as to understand the selectivity in the separation ability of the biodegradable chelants towards the metal ions. A linear relationship between the metal extraction capacity of the individual chelants towards each of the metal ions from the soil matrix and metal-chelant conditional stability constants for a solution pH greater than 6 was observed. Additional considerations were derived from the behavior of the major potentially interfering cations (Al, Ca, Fe, Mg, and Mn), and it was hypothesized that use of an excess of chelant may minimize the possible competition effects during the single-step washing treatments. Sequential extraction procedure was used to determine the metal distribution in the soil before and after the extractive decontamination using biodegradable APCs, and the capability of the APCs in removing the metal ions even from the theoretically immobilized fraction of the contaminated soil was observed. GLDA appeared to possess the greatest potential to decontaminate the soil through ex situ washing treatment compared to the other biodegradable chelants used in the study. © 2012 Elsevier Ltd.
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| 12.
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Azizur Rahman, Mohammad ; Rahman, Mahboob Mamunur ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
Arsenic (As) contamination is an important environmental consequence in some parts of salinity-affected South (S) and So
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uth-East (SE) Asia. In this study, we investigated the individual and combined phytotoxicity of arsenic (As) [arsenate; As(V)] and salinity (NaCl) on early seedling growth (ESG) of saline-tolerant and non-tolerant rice varieties. Germination percentage (GP), germination speed (GS) and vigor index (VI) of both saline-tolerant and non-tolerant rice varieties decreased significantly (p[0.01) with increasing As(V) and NaCl concentrations. The highest GP(91%) was observed for saline non-tolerant BRRI dhan28 and BRRI dhan49, while the lowest (62%) was for salinetolerant BRRI dhan47. The ESG parameters, such as weights and relative lengths of plumule and radicle, also decreased significantly (p\0.01) with increasing As(V) and NaCl concentrations. Relative radicle length was more affected than plumule length by As(V) and NaCl. Although VI of saline-tolerant and non-tolerant rice seedlings showed significant variation (p\0.05), weights and lengths of plumule and radicle of different rice varieties did not show significant variation for As(V) and NaCl treatments. Results reveal that the combined phytotoxicity of As(V) and NaCl on rice seed germination and ESG are greater than their individual toxicities, and some saline-tolerant rice varieties are more resistant to the combined phytotoxicity of As(V) and NaCl than the saline non-tolerant varieties. © Springer Science+Business Media, LLC 2012.
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| 13.
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Maki, Teruya ; Kakikawa, Makiko ; Kobayashi, Fumihisa ; Yamada, Maromu ; Matsuki, Atsushi ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Long-range transport of airborne microorganisms through the free troposphere significantly impacts biological ecosystems
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, human life, and atmospheric processes in downwind areas. However, microbial communities in the free troposphere have rarely been investigated because the direct collection of microbial cells at high altitudes requires sophisticated sampling techniques. In this study, tropospheric air sampling was performed using a balloon and an aircraft at 800 m and 3000 m, respectively, over the Noto Peninsula in Japan (37.5°N, 137.4°E) where free tropospheric winds carry aerosols from continental areas. The air samples were collected during four different sampling periods when air masses came from desert regions of Asian continent (west samples) and from Siberia of Russia North Asia (north samples). The west samples contained higher levels of aerosols, and bacteria from the west samples grew in culture media containing up to 15% NaCl. In contrast, bacteria from the north samples could not be cultured in the same media. All isolates obtained from the NaCl-amended cultures were similar to Bacillus subtilis and classified as Firmicutes. A 16S rDNA clone library prepared from the west samples was mainly composed of one phylotype of Firmicutes that corresponded to the cultured B. subtilis sequence. A clone library prepared from the north samples consisted primarily of two phyla, i.e., Actinobacteria and Proteobacteria, which are known to dominantly inhabit low-temperature environments of North Asia. Our results suggest that airborne bacterial communities at high altitudes include several species that vary by the direction and interaction of free tropospheric winds. •Aerosol samples were collected at high altitudes using an aircraft and a balloon.•During four sampling periods, the air masses came from the Gobi Desert and North Asia.•Airborne bacterial species were investigated using a 16S rDNA clone library technique.•Bacterial species at high altitudes varied by the direction of free tropospheric winds. © 2013 Elsevier Ltd.
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| 14.
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Egawa, Yuji ; Sawai, Hikaru ; Begum, Zinnat A. ; Maki, Teruya ; Mizutani, Satoshi
概要:
The metal indium termed as 'rare' in recent days due to its increasing demand in the formulations of electronic and ener
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gy-related gadgets and scarce supply resources. Hence, the attempts to recover indium from the secondary resources, such as recycling of the indium abundant waste materials, received increasing research focus. The major indium consumption happens in the form of indium tin oxide (ITO) that used for the fabrication of liquid-crystal displays (LCD). The end-of-life LCD screens, termed as ITO-glass hereafter, are an emerging contributor to the global e-waste load and can be an impending secondary source of indium. The present work introduces a new technique for the treatment of waste ITO-glass using aminopolycarboxylate chelants (APCs) in combination with a mechanochemical treatment process. APCs are capable of forming stable complexes with the indium deposited on the ITO-glass, whereas the rate of recovery was not substantial. The mechanochemical treatment induces the destruction of crystalline structure with which the ITO fragments are attached and facilitate the increased indium dissolution with the chelants. The increase was more prominent followed by a decrease in the cumulative processing time from 24 to 6. h when the vitrified ITO-glass was simultaneously crushed and washed with the chelants. The extraction of indium was better at the acidic pH condition, and it was further intensified when the operating temperature was raised to ≥ 120°C. © 2012 Elsevier B.V.
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| 15.
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Begum, Zinnat A. ; Rahman, Ismail M. M. ; Tate, Yousuke ; Egawa, Yuji ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
The protonation and complex formation equilibria of two biodegradable aminopolycarboxylate chelants {dl-2-(2-carboxymeth
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yl)nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2′-iminodisuccinic acid (HIDS)} with Ni 2+, Cu 2+, Zn 2+, Cd 2+ and Pb 2+ ions were investigated using the potentiometric method at a constant ionic strength of I = 0.10 mol·dm -3 (KCl) in aqueous solutions at 25 ± 0.1 °C. The stability constants of the proton-chelant and metal-chelant species for each metal ion were determined, and the concentration distributions of various complex species in solution were evaluated for each ion. The stability constants (log 10K ML) of the complexes containing Ni 2+, Cu 2+, Zn 2+, Cd 2+ and Pb 2+ ions followed the identical order of log 10K CuL > log 10K NiL > log 10K PbL > log 10K ZnL > log 10K CdL for either GLDA (13.03 > 12.74 > 11.60 > 11.52 > 10.31) or HIDS (12.63 > 11.30 > 10.21 > 9.76 > 7.58). In each case, the constants obtained for metal-GLDA complexes were larger than the corresponding constants for metal-HIDS complexes. The conditional stability constants (log 10 {Mathematical expression}) of the metal-chelant complexes containing GLDA and HIDS were calculated in terms of pH, and compared with the stability constants for EDTA and other biodegradable chelants. © 2012 Springer Science+Business Media New York.
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| 16.
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Maki, Teruya ; Kobayashi, Fumihisa ; Yamada, Maromu ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Bioaerosol particles including bacteria, fungi, and virus are originated from marine and terrestrial environments. The a
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irborne microorganisms are transported for long distance through the free troposphere and are thought to influence the downwind ecosystems and human life. However, microbial communities in the free troposphere have not been understood in detail because the direct sampling of microbial cells at high altitude requires sophisticated sampling techniques. In this study, for the investigation of microbial species compositions in the free troposphere, air sampling using an aircraft was performed over the Noto Peninsula in Japan, where the tropospheric winds carry aerosol particles from continental areas. Two air samples were collected at 3,000 m on March 27, 2010, when air mass was carried from the Gobi Desert to Japan area. Microorganisms from one air sample grew in culture media containing up to 15 % NaCl, suggesting that halotolerant bacteria maintain their viabilities in the free troposphere. DGGE analysis revealed that the amended cultures were dominated by Bacillus subtilis, and the isolates obtained from the amended cultures were identical to B. subtilis. Furthermore, the 16S rDNA clone library (culture-independent survey) of the other air sample grew was composed of three phylotypes belonging to Firmicutes, Bacteroidetes, and Proteobacteria with the sequences of Firmicutes phylotype corresponding to that of the cultured B. subtilis sequence. Microscopic observation using FISH method indicated that B. subtilis particles occupied 80 % of total eubacterial particles on the mineral particles. The halotolerant bacteria identical to B. subtilis would dominate at high altitudes over Noto Peninsula where the prevailing westerly wind was blowing. © 2012 Springer Science+Business Media Dordrecht.
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| 17.
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Maki, Teruya ; Yoshinaga, Ikuo ; Katanozaka, Noriaki ; Imai, Ichiro
概要:
金沢大学大学院自然科学研究科物質情報解析<br />Heterocapsa circularisquama, a noxious marine dinoflagellate, has frequently caused red tides
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and killed cultured bivalves in western Japanese embayments. Observations by electron and epifluorescence microscopy revealed that many bacterial particles were detected inside the H. circularisquama cells. To elucidate the identity and origin of the intracellular bacteria associated with H. circularisquama, bacterial 16S ribosomal RNA genes (16S rDNA) were directly amplified by polymerase chain reaction from 5 clonal cultures of the algal strains that had been isolated from different localities. After cloning, randomly selected clones including the bacterial 16S rDNA fragments were sequenced. The results showed that intracellular bacterial populations consisted of only 2 ribotypes of bacteria, even though the algal strains were established from different localities. One ribotype (bac-G), which was dominant in the intracellular bacterial population, belonged to the gamma-proteobacteria group, and the other (bac-F) clustered with the Flexibacter-Cytophaga-Bacteroides group. Both of these are novel species of endosymbiotic bacteria because of their unique 16S rDNA sequences. Furthermore, the populations of extracellularly associated bacteria were also composed of bac-G and bac-F, indicating that they originated from the intracellular bacteria. Fluorescence in situ hybridization targeting 16S rRNA indicated that bac-G appeared to localize on the algal nuclear surface, while bac-F was distributed in the cytoplasmic space of algal cells. These results strongly suggest that only a few species of specific bacteria reside and share their habitat in the H. circularisquama cells as endosymbionts.
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| 18.
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Maki, Teruya ; Takeda, Noriko ; Hasegawa, Hiroshi ; Ueda, Kazumasa
概要:
金沢大学大学院自然科学研究科物質情報解析<br />Chemical warfare agents, composed of harmful organoarsenic compounds have contaminated the soi
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ls of Ohkunoshima Island with high levels of arsenic. As a basic research establishing useful bioremediation techniques, environmental factors such as arsenic concentrations and bacterial biomass in the soils were investigated. Among the five stations of Ohkunoshima Island, the soils of four stations were contaminated by high levels of arsenic compounds at concentrations of 125,12.7, 3.29 and 0.504 g/kg soil, while the other station with low arsenic concentrations of 0.007 g/kg soil was considered an uncontaminated area. The distribution of arsenic compounds originating from the chemical weapon agent differs among the various areas of Ohkunoshima Island. The cell densities of arsenate-resistant bacteria also varied among the five stations, ranging from 106 to 108 cells/g soil. In an attempt to isolate bacteria that strongly mineralize the organoarsenic compounds, the mineralization activities for monomethylarsonic acid [MMAA(V)] of 48 isolates of arsenate-resistant bacteria were determined. Only nine isolates reduced 140 μg/1 of MMAA(V), giving decreasing percentages ranging from 5 to 100% within 14 days. Among the nine isolates, two remarkably converted 140 μg/1 of MMAA to more than 71 μg/1 of inorganic arsenic. Presumably only specific members of the environmental bacterial population have strong mineralization activities for MMAA. Phylogenetic analysis using 16S rDNA sequences showed that the two isolates belonged to the Pseudomonas putida strains, which are known to have strong mineralization activity for various organic compounds. In the soil contaminated by arsenic at a high level, few bacteria in the arsenate-resistant bacterial group would significantly mineralize organoarsenic compounds. Copyright © 2006 John Wiley & Sons, Ltd.
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| 19.
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Rahman, M. Azizur ; Hasegawa, Hiroshi ; Ueda, Kazumasa ; Maki, Teruya ; Rahman, M. Mahfuzur
概要:
金沢大学理工研究域物質化学系<br />In the present study, the effect of phosphate ion and iron hydroxides (Fe-plaques) on the selective
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uptake of arsenic species by water fern (Salvinia natans L.) was investigated. The plants were grown for 5 days in aqueous Murashige and Skoog (MS) culture media modified in arsenic and phosphate concentrations. Arsenic accumulations in S. natans L. increased with the increase of arsenate and DMAA concentrations in the culture solutions. Compared to the control treatment, S. natans L. accumulated significantly higher amount of arsenic from phosphate-deficient solutions, when the source was arsenate. However, arsenic uptake was not affected significantly by phosphate, when the source was dimethylarsinic acid (DMAA). From solutions containing 100 μM of phosphate and 4.0 μM of either arsenate or DMAA, the S. natans L. accumulated 0.14 ± 0.02 and 0.02 ± 0.00 μmol (g dry weight)-1 of arsenic, respectively. In contrast, plants accumulated 0.24 ± 0.06 and 0.03 ± 0.00 μmol (g dry weight)-1 of arsenic from solutions containing 4.0 μM of either arsenate and DMAA in phosphate deficient conditions, respectively. Thus, it is reasonable to state that increasing phosphate concentration in culture solutions decreased the arsenic uptake into the water fern significantly, when the source was arsenate. Moreover, arsenic and phosphate content in plant tissue correlated significantly (r = -0.66; p < 0.05), when initial source was arsenate while there were no correlation between arsenic and phosphate, when initial source was DMAA (r = -0.077; p > 0.05). Similarly, significant correlation was observed between arsenic and iron content in plant tissues (r = 0.66; p < 0.05), when initial source was arsenate while the correlation was not significant (r = 0.23; p < 0.05), when initial source was DMAA. The results indicate the adsorption of arsenate on Fe-plaques of aquatic plant surfaces. Furthermore, the study demonstrates that the DMAA uptake mechanisms into the water fern are deferent from those of arsenate. © 2008 Elsevier B.V. All rights reserved.<br />This article has not been published yet.
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| 20.
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Rahman, Mustafizur Azizur ; Hasegawa, Hiroshi ; Ueda, Kazumasa ; Maki, Teruya ; Rahman, M. Mahfuzur
概要:
金沢大学理工研究域物質化学系<br />The uptake of arsenate (As(V)) and dimethylarsinic acid (DMAA) by aquatic macrophyte Spirodela polyr
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hiza L. was investigated to determine the influence of arsenic interaction with PO43- and Fe ions. Plants were grown hydroponically on standard Murashige and Skoog (MS) culture solutions. Arsenic concentrations in Fe-oxide (Fe-plaque) on plant surfaces were determined by citrate-bicarbonate-ethylenediaminetetraacetic acid (CBE) technique. S. polyrhiza L. accumulated 51-fold arsenic from arsenate solution compared to that from DMAA solution with initial concentrations of 4.0 and 0.02 μM of arsenic and phosphate, respectively. The arsenate uptake was negatively (p < 0.001) correlated with phosphate uptake and positively (p < 0.05) correlated with iron uptake. About 56% of the total arsenic was accumulated into the plant tissues while 44% was adsorbed on Fe-plaque (CBE-extract), when the plants were grown on arsenate solution. The DMAA uptake into the plant was neither affected by the phosphate concentrations nor correlated (p > 0.05) with iron accumulation. The results suggest that adsorption of arsenate on Fe-plaque of the surface of S. polyrhiza L. contributes to the arsenic uptake significantly. Thus, arsenate uptake in S. polyrhiza L. occurred through the phosphate uptake pathway and by physico-chemical adsorption on Fe-plaques of plant surfaces as well. The S. polyrhiza L. uses different mechanisms for DMAA uptake. © 2008 Elsevier B.V. All rights reserved.
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| 21.
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論文
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Hasegawa, Hiroshi ; Rahman, Mustafizur Azizur ; Matsuda, T. ; Kitahara, T. ; Maki, Teruya ; Ueda, Kazumasa
概要:
金沢大学理工研究域物質化学系<br />Effects of eutrophication on arsenic speciation were studied in eutrophic Lake Kiba and mesotrophic
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Lake Biwa, Japan. By combining hydride generation atomic absorption spectrometry with ultraviolet irradiation, inorganic, methyl and ultraviolet-labile fractions of arsenic were determined. In both Lakes, inorganic species (As(V + III)) dominated over other forms of arsenic all the year round. Most of methylarsenic fraction was dimethylarsinic acid (DMAA), and the concentration of monomethylarsonic acid (MMAA) was below the detection limit. Measurements of size-fractioned arsenic concentrations in water column indicate that most of the DMAA was distributed in truly dissolved fraction (< 10 kDa), while ultraviolet-labile fractions were distributed in particulate (> 0.45 μm) and colloidal (10 kDa-0.45 μm) fractions. Arsenic speciation in eutrophic Lake Kiba fluctuated greatly with season. The ultraviolet-labile fractions were observed with the increase of DMAA from May to October, and they disappeared with the decrease of DMAA in January. In mesotrophic Lake Biwa, the ultraviolet-labile fractions of arsenic were not influenced as much as those in eutrophic Lake Kiba. On the other hand DMAA concentration was higher in Lake Biwa compared to that in Lake Kiba. The results suggest that the biosynthesis of complex organoarsenicals was enhanced by eutrophication, and the arsenic speciation would be influenced by the balance of biological processes in natural waters. © 2008 Elsevier B.V. All rights reserved.
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| 22.
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Rahman, M.A. ; Kadohashi, K. ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
金沢大学理工研究域物質化学系<br />Arsenate (As(V)) transport into plant cells has been well studied. A study on rice (Oryza sativa L.)
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showed that arsenite is transported across the plasma membrane via glycerol transporting channels. Previous studies reported that the dimethylarsinic acid (DMAA) and monomethylarsonic acid (MMAA) uptake in duckweed (Spirodela polyrhiza L.) differed from that of As(V), and was unaffected by phosphate (H2PO4). This article reports the transport mechanisms of DMAA and MMAA in rice roots. Linear regression analysis showed that the DMAA and MMAA uptake in rice roots increased significantly (p ≤ 0.0002 and ≤0.0001 for DMAA and MMAA, respectively) with the increase of exposure time. Concentration-dependent influx of DMAA and MMAA showed that the uptake data were well described by Michaelis-Menten kinetics. The MMAA influx was higher than that of DMAA. The DMAA and MMAA uptake in rice roots were decreased significantly (p ≤ 0.0001 and ≤0.0077 for DMAA and MMAA, respectively) with the increase of glycerol concentration indicating that DMAA and MMAA were transported into rice roots using the same mechanisms of glycerol. Glycerol is transported into plant cells by aquaporins, and DMAA and MMAA are transported in a dose-dependent manner of glycerol which reveals that DMAA and MMAA are transported into rice roots through glycerol transporting channels. The DMAA and MMAA concentration in the solution did not affect the inhibition of their uptake rate by glycerol. © 2010.
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| 23.
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論文
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Hasegawa, Hiroshi ; Rahman, Ismail M.M. ; Kinoshita, Sanae ; Maki, Teruya ; Furusho, Yoshiaki
概要:
金沢大学理工研究域物質化学系<br />Although the excellent metal-binding capacities of aminopolycarboxylate chelants (APCs) facilitate t
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heir extensive use, pre- and post-toxicity of APCs and their high persistence in aquatic environments evoke concerns. Several treatment techniques with a principal focus on the degradation of APCs at the pre-release step have been proposed. Here, we report a technique for the separation of metal ions from waste solution containing excess APCs using a solid phase extraction system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel. Synthetic metal solutions with 100-fold chelant content housed in H2O matrices were used as samples. The MRT gel showed a higher recovery rate compared with other SPE materials at 20 °C using a flow rate of 0.2 mL min-1. The effects of solution pH, metal-chelant stability constants and ionic radii were assessed for 32 metals. Compared to the conventional treatment options for such waste solutions, our proposed technique has the advantage of non-destructive separation of both metal ions and chelants. © 2010 Elsevier Ltd. All rights reserved.
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| 24.
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論文
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Rahman, M. Azizur ; Hasegawa, Hiroshi ; Kadohashi, K. ; Maki, Teruya ; Ueda, K.
概要:
金沢大学理工研究域物質化学系<br />The influence of biodegradable chelating ligands on arsenic and iron uptake by hydroponically grown
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rice seedlings (Oryza sativa L.) was investigated. Even though the growth solution contained sufficient Fe, the growth of rice seedlings gradually decreased up to 76% with the increase of pH of the solution from 7 to 11. Iron forms insoluble ferric hydroxide complexes at neutral or alkaline pH in oxic condition. Chelating ligands produce soluble 'Fe-ligand complex' which assist Fe uptake in plants. The biodegradable chelating ligand hydroxyiminodisuccinic acid (HIDS) was more efficient then those of ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), and iminodisuccinic acid (IDS) in the increase of Fe uptake and growth of rice seedling. A total of 79 ± 20, 87 ± 6, 116 ± 15, and 63 ± 18 mg dry biomass of rice seedlings were produced with the addition of 0.5 mM of EDDS, EDTA, HIDS, and IDS in the nutrient solution, respectively. The Fe concentrations in rice tissues were 117 ± 15, 82 ± 8, 167 ± 25, and 118 ± 22 μmol g-1 dry weights when 0.25 mM of EDDS, EDTA, HIDS, and IDS were added to the nutrient solution, respectively. Most of the Fe accumulated in rice tissues was stored in roots after the addition of chelating ligands in the solution. The results indicate that the HIDS would be a potential alternative to environmentally persistent EDTA for the increase of Fe uptake and plant growth. The HIDS also increased As uptake in rice root though its translocation from root to shoot was not augmented. This study reports HIDS for the first time as a promising chelating ligand for the enhancement of Fe bioavailability and As phytoextraction. © 2009.
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| 25.
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25. Seasonal dynamics of biodegradation activities for dimethylarsinic acid (DMA) in Lake Kahokugata
Maki, Teruya ; Hirota, Wakana ; Ueda, Kaori ; Hasegawa, Hiroshi ; Rahman, Mohammad Azizur
概要:
金沢大学理工研究域物質化学系<br />The microbial activities in aquatic environments significantly influence arsenic cycles such as the
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turnover between inorganic arsenic and organoarsenic compounds. In Lake Kahokugata, inorganic arsenic was detected at concentrations ranging from 2.8 to 23 nM in all seasons, while the concentrations of dimethylarsinic acid (DMA) produced by microorganisms such as phytoplankton changed seasonally and showed a peak in winter. The changes in the concentrations of methylarsenic species did not correlate with the changes in phytoplankton abundance (chlorophyll a contents), suggesting that DMA-degradation is related to this inconsistency. DMA (1 μM) added into the lake water was converted to inorganic arsenic at 20 °C only under anaerobic and dark conditions, while DMA degradation was diminished under aerobic or light conditions. Moreover, DMA added to the lake water samples collected through four seasons was degraded at the same rates under anaerobic and dark conditions at 20 °C. However, at 30 °C, 1 μM of DMA in the summer lake water samples was rapidly degraded in 7 and 21 d. In contrast, DMA degradation was diminished in the winter lake water samples at 4 °C of incubation. Presumably, DMA-biodegradation activities are mainly controlled by changes in the water temperature in Lake Kahokugata, where the arsenic concentrations change seasonally. © 2009 Elsevier Ltd. All rights reserved.
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| 26.
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論文
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Rahman, M. Azizur ; Hasegawa, Hiroshi ; Kadohashi, K. ; Maki, Teruya ; Ueda, Kazumasa
概要:
金沢大学理工研究域物質化学系<br />The influence of biodegradable chelating ligands on arsenic and iron uptake by hydroponically grown
…
rice seedlings (Oryza sativa L.) was investigated. Even though the growth solution contained sufficient Fe, the growth of rice seedlings gradually decreased up to 76% with the increase of pH of the solution from 7 to 11. Iron forms insoluble ferric hydroxide complexes at neutral or alkaline pH in oxic condition. Chelating ligands produce soluble 'Fe-ligand complex' which assist Fe uptake in plants. The biodegradable chelating ligand hydroxyiminodisuccinic acid (HIDS) was more efficient then those of ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), and iminodisuccinic acid (IDS) in the increase of Fe uptake and growth of rice seedling. A total of 79 ± 20, 87 ± 6, 116 ± 15, and 63 ± 18 mg dry biomass of rice seedlings were produced with the addition of 0.5 mM of EDDS, EDTA, HIDS, and IDS in the nutrient solution, respectively. The Fe concentrations in rice tissues were 117 ± 15, 82 ± 8, 167 ± 25, and 118 ± 22 μmol g-1 dry weights when 0.25 mM of EDDS, EDTA, HIDS, and IDS were added to the nutrient solution, respectively. Most of the Fe accumulated in rice tissues was stored in roots after the addition of chelating ligands in the solution. The results indicate that the HIDS would be a potential alternative to environmentally persistent EDTA for the increase of Fe uptake and plant growth. The HIDS also increased As uptake in rice root though its translocation from root to shoot was not augmented. This study reports HIDS for the first time as a promising chelating ligand for the enhancement of Fe bioavailability and As phytoextraction. © 2009 Elsevier Ltd. All rights reserved.
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| 27.
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Maki, Teruya ; Hirota, Wakana ; Motojima, Hiroyuki ; Hasegawa, Hiroshi ; Rahman, Mohammad Azizur
概要:
金沢大学理工研究域物質化学系<br />Aquatic arsenic cycles mainly depend on microbial activities that change the arsenic chemical forms
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and influence human health and organism activities. The microbial aggregates degrading organic matter are significantly related to the turnover between inorganic arsenic and organoarsenic compounds. We investigated the effects of microbial aggregates on organoarsenic mineralization in Lake Kahokugata using lake water samples spiked with dimethylarsinic acid (DMA). The lake water samples converted 1 μmol L-1 of DMA to inorganic arsenic for 28 d only under anaerobic and dark conditions in the presence of microbial activities. During the DMA mineralization process, organic aggregates >5.0 μm with bacterial colonization increased the densities. When the organic aggregates >5.0 μm were eliminated from the lake water samples using filters, the degradation activities were reduced. DMA in the lake water would be mineralized by the microbial aggregates under anaerobic and dark conditions. Moreover, DMA amendment enhanced the degradation activities in the lake water samples, which mineralized 50 μmol L-1 of DMA. The DMA-amended aggregates >5.0 μm completely degraded 1 μmol L-1 of DMA with a shorter incubation time of 7 d. The supplement of KNO3 and NaHCO3 to lake water samples also shortened the DMA-degradation period. Presumably, the bacterial aggregates involved in the chemical heterotrophic process would contribute to the DMA-biodegradation process in Lake Kahokugata, which is induced by the DMA amendment. © 2011 Elsevier Ltd. All rights reserved.
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| 28.
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Hasegawa, Hiroshi ; Rahman, M. Azizur ; Kitahara, K. ; Itaya, Y. ; Maki, Teruya ; Ueda, K.
概要:
金沢大学理工研究域物質化学系<br />In this study, the influence of eutrophication on arsenic speciation in lake waters was investigated
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. Surface water samples (n=1-10) were collected from 18 lakes in Japan during July 2007 and February 2008. The lakes were classified into mesotrophic (7 lakes) and eutrophic (11 lakes) based on the total phosphate (T-P) and chlorophyll-a (Chl-a) concentrations in water column. Inorganic, methylated and ultraviolet-labile fractions of arsenic species were determined by combining hydride generation atomic absorption spectrometry with ultraviolet irradiation. Organoarsenicals (mainly methylated and ultraviolet-labile fractions) comprised 30-60% of the total arsenic in most lakes during summer. On the other hand, inorganic arsenic species (As(III+V)) dominates (about 60-85%) during winter. The occurrence of ultraviolet-labile fractions of arsenic was higher in eutrophic lakes than those in mesotrophic lakes in both seasons. The concentration of dimethyl arsenic (DMAA) was high in eutrophic lakes during winter; and in mesotrophic lakes during summer. The results suggest that the conversion of As(III+V) to more complicated organoarsenicals occurred frequently in eutrophic lakes compared to that in mesotrophic lakes, which is thought to be the influence of biological activity in the water column. The distribution of arsenic species were well correlated with phosphate concentrations than those of Chl-a. This might be due to the competitive uptake of As(V) and phosphate by phytoplankton. The organoarsenicals (OrgAs)/As(V) ratio was higher at low phosphate concentration indicating that conversion of As(V) to OrgAs species was more active in phosphate-exhausted lakes with high phytoplankton density.
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| 29.
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論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Kinoshita, Sanae ; Maki, Teruya ; Furusho, Yoshiaki
概要:
金沢大学理工研究域物質化学系<br />A new technique for the separation and pre-concentration of dissolved Fe(III) from the ligand-rich a
…
queous system is proposed. A solid phase extraction (SPE) system with an immobilized macrocyclic material, commonly known as molecular recognition technology (MRT) gel and available commercially, was used. Synthetic Fe(III) solution in aqueous matrices spiked with a 100-fold concentration of EDTA was used. Dissolved iron that was 'captured' by the MRT gel was eluted using hydrochloric acid and subsequently determined by graphite furnace atomic absorption spectrometry. The effect of different variables, such as pH, reagent concentration, flow rate and interfering ions, on the recovery of analyte was investigated. Quantitative maximum separation (~100%) of the dissolved Fe(III) from synthetic aqueous solutions at a natural pH range was observed at a flow rate of 0.2mLmin-1. The extraction efficiency of the MRT gel is largely unaltered by the coexisting ions commonly found in natural water. When compared with different SPE materials, the separation performance of MRT gel is also much higher. © 2010 Elsevier Ltd.
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| 30.
論文 |
論文
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Rahman, Mustafizur Azizur ; Hasegawa, Hiroshi ; Ueda, Kazumasa ; Maki, Teruya ; Rahman, M. Mahfuzur
概要:
金沢大学理工研究域物質化学系<br />In the present study, the effect of phosphate ion and iron hydroxides (Fe-plaques) on the selective
…
uptake of arsenic species by water fern (Salvinia natans L.) was investigated. The plants were grown for 5 days in aqueous Murashige and Skoog (MS) culture media modified in arsenic and phosphate concentrations. Arsenic accumulations in S. natans L. increased with the increase of arsenate and DMAA concentrations in the culture solutions. Compared to the control treatment, S. natans L. accumulated significantly higher amount of arsenic from phosphate-deficient solutions, when the source was arsenate. However, arsenic uptake was not affected significantly by phosphate, when the source was dimethylarsinic acid (DMAA). From solutions containing 100 μM of phosphate and 4.0 μM of either arsenate or DMAA, the S. natans L. accumulated 0.14 ± 0.02 and 0.02 ± 0.00 μmol (g dry weight)-1 of arsenic, respectively. In contrast, plants accumulated 0.24 ± 0.06 and 0.03 ± 0.00 μmol (g dry weight)-1 of arsenic from solutions containing 4.0 μM of either arsenate and DMAA in phosphate deficient conditions, respectively. Thus, it is reasonable to state that increasing phosphate concentration in culture solutions decreased the arsenic uptake into the water fern significantly, when the source was arsenate. Moreover, arsenic and phosphate content in plant tissue correlated significantly (r = -0.66; p < 0.05), when initial source was arsenate while there were no correlation between arsenic and phosphate, when initial source was DMAA (r = -0.077; p > 0.05). Similarly, significant correlation was observed between arsenic and iron content in plant tissues (r = 0.66; p < 0.05), when initial source was arsenate while the correlation was not significant (r = 0.23; p < 0.05), when initial source was DMAA. The results indicate the adsorption of arsenate on Fe-plaques of aquatic plant surfaces. Furthermore, the study demonstrates that the DMAA uptake mechanisms into the water fern are deferent from those of arsenate. © 2008 Elsevier B.V. All rights reserved.
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| 31.
論文 |
論文
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Rahman, M.A. ; Hasegawa, Hiroshi ; Ueda, Kazumasa ; Maki, Teruya ; Rahman, M.M.
概要:
金沢大学理工研究域物質化学系 金沢大学工学部<br />The uptake of arsenate (As(V)) and dimethylarsinic acid (DMAA) by aquatic macrophyte Spirode
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la polyrhiza L. was investigated to determine the influence of arsenic interaction with PO43- and Fe ions. Plants were grown hydroponically on standard Murashige and Skoog (MS) culture solutions. Arsenic concentrations in Fe-oxide (Fe-plaque) on plant surfaces were determined by citrate-bicarbonate-ethylenediaminetetraacetic acid (CBE) technique. S. polyrhiza L. accumulated 51-fold arsenic from arsenate solution compared to that from DMAA solution with initial concentrations of 4.0 and 0.02 μM of arsenic and phosphate, respectively. The arsenate uptake was negatively (p < 0.001) correlated with phosphate uptake and positively (p < 0.05) correlated with iron uptake. About 56% of the total arsenic was accumulated into the plant tissues while 44% was adsorbed on Fe-plaque (CBE-extract), when the plants were grown on arsenate solution. The DMAA uptake into the plant was neither affected by the phosphate concentrations nor correlated (p > 0.05) with iron accumulation. The results suggest that adsorption of arsenate on Fe-plaque of the surface of S. polyrhiza L. contributes to the arsenic uptake significantly. Thus, arsenate uptake in S. polyrhiza L. occurred through the phosphate uptake pathway and by physico-chemical adsorption on Fe-plaques of plant surfaces as well. The S. polyrhiza L. uses different mechanisms for DMAA uptake. © 2008 Elsevier B.V. All rights reserved.<br />This article has not been published yet.
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| 32.
論文 |
論文
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Azizur Rahman, Mohammad ; Kadohashi, K. ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
Arsenate (As(V)) transport into plant cells has been well studied. A study on rice (Oryza sativa L.) showed that arsenit
…
e is transported across the plasma membrane via glycerol transporting channels. Previous studies reported that the dimethylarsinic acid (DMAA) and monomethylarsonic acid (MMAA) uptake in duckweed (Spirodela polyrhiza L.) differed from that of As(V), and was unaffected by phosphate (H2PO4). This article reports the transport mechanisms of DMAA and MMAA in rice roots. Linear regression analysis showed that the DMAA and MMAA uptake in rice roots increased significantly (p竕､0.0002 and 竕､0.0001 for DMAA and MMAA, respectively) with the increase of exposure time. Concentration-dependent influx of DMAA and MMAA showed that the uptake data were well described by Michaelis-Menten kinetics. The MMAA influx was higher than that of DMAA. The DMAA and MMAA uptake in rice roots were decreased significantly (p竕､0.0001 and 竕､0.0077 for DMAA and MMAA, respectively) with the increase of glycerol concentration indicating that DMAA and MMAA were transported into rice roots using the same mechanisms of glycerol. Glycerol is transported into plant cells by aquaporins, and DMAA and MMAA are transported in a dose-dependent manner of glycerol which reveals that DMAA and MMAA are transported into rice roots through glycerol transporting channels. The DMAA and MMAA concentration in the solution did not affect the inhibition of their uptake rate by glycerol.. © 2010 Elsevier B.V.
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| 33.
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論文
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33. Seasonal dynamics of biodegradation activities for dimethylarsinic acid (DMA) in Lake Kahokugata
Maki, Teruya ; Hirota, W. ; Ueda, Kazumasa ; Hasegawa, Hiroshi ; Rahman, Mohammad Azizur
概要:
金沢大学理工研究域物質化学系<br />The microbial activities in aquatic environments significantly influence arsenic cycles such as the
…
turnover between inorganic arsenic and organoarsenic compounds. In Lake Kahokugata, inorganic arsenic was detected at concentrations ranging from 2.8 to 23 nM in all seasons, while the concentrations of dimethylarsinic acid (DMA) produced by microorganisms such as phytoplankton changed seasonally and showed a peak in winter. The changes in the concentrations of methylarsenic species did not correlate with the changes in phytoplankton abundance (chlorophyll a contents), suggesting that DMA-degradation is related to this inconsistency. DMA (1 μM) added into the lake water was converted to inorganic arsenic at 20 °C only under anaerobic and dark conditions, while DMA degradation was diminished under aerobic or light conditions. Moreover, DMA added to the lake water samples collected through four seasons was degraded at the same rates under anaerobic and dark conditions at 20 °C. However, at 30 °C, 1 μM of DMA in the summer lake water samples was rapidly degraded in 7 and 21 d. In contrast, DMA degradation was diminished in the winter lake water samples at 4 °C of incubation. Presumably, DMA-biodegradation activities are mainly controlled by changes in the water temperature in Lake Kahokugata, where the arsenic concentrations change seasonally. © 2009 Elsevier Ltd. All rights reserved.
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| 34.
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論文
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Maki, Teruya ; Susuki, Shinzi ; Kobayashi, Fumihisa ; Kakikawa, Makiko ; Tobo, Yutaka ; Yamada, Maromu ; Higashi, Tomomi ; Matsuki, Atsushi ; Hong, Chunsang ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
金沢大学理工研究域物質化学系<br />The microbial communities transported by Asian desert dust (KOSA) events have attracted much attenti
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on as bioaerosols because the transported microorganisms are thought to influence the downwind ecosystems in Korea and Japan. However, the atmospheric microbial community has not been investigated at high altitude in the KOSA arrival area. In this study, to estimate the viability and diversity of atmospheric halotolerant bacteria, which are expected to resist to various environmental stresses as well as high salinities, bioaerosol samples were collected at 10 and 600. m above the ground within the KOSA arrival area, Suzu City, Japan, during KOSA events. During the sampling period, the particle numbers at 600. m were higher than those at 10. m, suggesting that large particles of aerosol fall from the high altitude of 600. m to the ground surface. The microorganisms in bioaerosol samples grew in media containing up to 15% NaCl concentrations demonstrating the viability of the halotolerant bacteria in bioaerosol samples. The PCR-DGGE analysis using 16S rDNA revealed that the bacterial species in NaCl-amended cultures were similar to the bacteria detected from the genomic DNA directly extracted from the bioaerosol samples. The 16S rDNA sequences of bacterial communities in bioaerosol samples were classified into 4 phylotypes belonging to the Bacillus cereus or Bacillus subtilis group. The bioaerosol samples collected at 600. m included 2 phylotypes belonging to B. subtilis, and one phylotype among all 4 phylotypes was identical between the samples at 10 and 600. m. In the atmosphere at 600. m, the halotolerant bacterial community was expected to remain viable, and the species composition was expected to include a few species of the genus Bacillus. During this investigation period, these atmospheric bacteria may have been vertically transported to the ground surface, where the long-range KOSA particle transport from China is frequently observed. © 2010 Elsevier B.V.
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| 35.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Kinoshita, Sanae ; Maki, Teruya ; Furusho, Yoshiaki
概要:
金沢大学理工研究域物質化学系<br />A new technique for the separation and pre-concentration of dissolved Fe(III) from the ligand-rich a
…
queous system is proposed. A solid phase extraction (SPE) system with an immobilized macrocyclic material, commonly known as molecular recognition technology (MRT) gel and available commercially, was used. Synthetic Fe(III) solution in aqueous matrices spiked with a 100-fold concentration of EDTA was used. Dissolved iron that was 'captured' by the MRT gel was eluted using hydrochloric acid and subsequently determined by graphite furnace atomic absorption spectrometry. The effect of different variables, such as pH, reagent concentration, flow rate and interfering ions, on the recovery of analyte was investigated. Quantitative maximum separation (~100%) of the dissolved Fe(III) from synthetic aqueous solutions at a natural pH range was observed at a flow rate of 0.2mLmin-1. The extraction efficiency of the MRT gel is largely unaltered by the coexisting ions commonly found in natural water. When compared with different SPE materials, the separation performance of MRT gel is also much higher. © 2010 Elsevier Ltd.
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| 36.
論文 |
論文
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Rahman, Ismail M. M. ; Begum, Zinnat A. ; Nakano, Masayoshi ; Furusho, Yoshiaki ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
金沢大学理工研究域物質化学系<br />A combination of solid phase extraction (SPE) columns was used for selective separation of water-sol
…
uble arsenic species: arsenite, arsenate, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The SPE columns, namely AnaLig TE-01 (TE-01), AnaLig AN-01 Si (AN-01) and AnaLig As-01 PA (As-01), contain immobilized macrocyclic material as the sorbent and commonly known as molecular recognition technology (MRT) gel. The retention, extraction and recovery behavior of the MRT gel SPE columns were studied at pH 4-10. Fortified deionized water spiked with 100μM of arsenic species were treated at the flow rate of 0.2mLmin-1. HNO3 (1.0 and 6.0M) was used as eluent to recover the retained arsenic species from TE-01 and AN-01 SPE columns. Arsenic species retained in the As-01 column were eluted with HNO3 (0.1M) followed by NaOH (2.0M). Likely interference from the various coexisting ions (Na+, K+, Ca2+, Mg2+, Cl-, NO3-, CH3COO-, PO43-, SO42-, ClO4-) (10mM) were negligible. Quantitative separation of As(III), As(V), MMA and DMA was achieved based on the differences in extraction and recovery behavior of the MRT gel SPE columns with pH for different arsenic species. Complexation between arsenic species and MRT gel is the core phenomenon of the proposed technique as the complexation of MRT gels is expected to be stronger than the resin-based separation processes. MRT gel SPE columns are advantageous as compared with other reported SPE columns in terms of its performance with As(III). Effortless regeneration and unaltered separation performance of the sorbent materials for more than 100 loading and elution cycles are other sturdy characteristics to consider the MRT gel SPE columns for sensitive and selective arsenic species separation. © 2010 Elsevier Ltd.
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| 37.
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論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Kinoshita, Sanae ; Maki, Teruya ; Furusho, Yoshiaki
概要:
金沢大学理工研究域物質化学系<br />A new technique for the separation and pre-concentration of dissolved Fe(III) from the ligand-rich a
…
queous system is proposed. A solid phase extraction (SPE) system with an immobilized macrocyclic material, commonly known as molecular recognition technology (MRT) gel and available commercially, was used. Synthetic Fe(III) solution in aqueous matrices spiked with a 100-fold concentration of EDTA was used. Dissolved iron that was 'captured' by the MRT gel was eluted using hydrochloric acid and subsequently determined by graphite furnace atomic absorption spectrometry. The effect of different variables, such as pH, reagent concentration, flow rate and interfering ions, on the recovery of analyte was investigated. Quantitative maximum separation (~100%) of the dissolved Fe(III) from synthetic aqueous solutions at a natural pH range was observed at a flow rate of 0.2mLmin-1. The extraction efficiency of the MRT gel is largely unaltered by the coexisting ions commonly found in natural water. When compared with different SPE materials, the separation performance of MRT gel is also much higher. © 2010 Elsevier Ltd.
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| 38.
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論文
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Rahman, Ismail M.M. ; Begum, Zinnat A. ; Nakano, Masayoshi ; Furusho, Yoshiaki ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
金沢大学理工研究域物質化学系<br />A combination of solid phase extraction (SPE) columns was used for selective separation of water-sol
…
uble arsenic species: arsenite, arsenate, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The SPE columns, namely AnaLig TE-01 (TE-01), AnaLig AN-01 Si (AN-01) and AnaLig As-01 PA (As-01), contain immobilized macrocyclic material as the sorbent and commonly known as molecular recognition technology (MRT) gel. The retention, extraction and recovery behavior of the MRT gel SPE columns were studied at pH 4-10. Fortified deionized water spiked with 100 μM of arsenic species were treated at the flow rate of 0.2 mL min-1. HNO3 (1.0 and 6.0 M) was used as eluent to recover the retained arsenic species from TE-01 and AN-01 SPE columns. Arsenic species retained in the As-01 column were eluted with HNO3 (0.1 M) followed by NaOH (2.0 M). Likely interference from the various coexisting ions (Na+, K+, Ca2+, Mg2+, Cl-, NO3-, CH3COO-, PO43 -, SO42 -, ClO4-) (10 mM) were negligible. Quantitative separation of As(III), As(V), MMA and DMA was achieved based on the differences in extraction and recovery behavior of the MRT gel SPE columns with pH for different arsenic species. Complexation between arsenic species and MRT gel is the core phenomenon of the proposed technique as the complexation of MRT gels is expected to be stronger than the resin-based separation processes. MRT gel SPE columns are advantageous as compared with other reported SPE columns in terms of its performance with As(III). Effortless regeneration and unaltered separation performance of the sorbent materials for more than 100 loading and elution cycles are other sturdy characteristics to consider the MRT gel SPE columns for sensitive and selective arsenic species separation. © 2010 Elsevier Ltd. All rights reserved.
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| 39.
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論文
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Hasegawa, Hiroshi ; Rahman, M. Azizur ; Kitahara, K. ; Itaya, Y. ; Maki, Teruya ; Ueda, K.
概要:
金沢大学理工研究域物質化学系<br />In this study, the influence of eutrophication on arsenic speciation in lake waters was investigated
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. Surface water samples (n = 1-10) were collected from 18 lakes in Japan during July 2007 and February 2008. The lakes were classified into mesotrophic (7 lakes) and eutrophic (11 lakes) based on the total phosphate (T-P) and chlorophyll-a (Chl-a) concentrations in water column. Inorganic, methylated and ultraviolet-labile fractions of arsenic species were determined by combining hydride generation atomic absorption spectrometry with ultraviolet irradiation. Organoarsenicals (mainly methylated and ultraviolet-labile fractions) comprised 30-60% of the total arsenic in most lakes during summer. On the other hand, inorganic arsenic species (As(III + V)) dominates (about 60-85%) during winter. The occurrence of ultraviolet-labile fractions of arsenic was higher in eutrophic lakes than those in mesotrophic lakes in both seasons. The concentration of dimethyl arsenic (DMAA) was high in eutrophic lakes during winter; and in mesotrophic lakes during summer. The results suggest that the conversion of As(III + V) to more complicated organoarsenicals occurred frequently in eutrophic lakes compared to that in mesotrophic lakes, which is thought to be the influence of biological activity in the water column. The distribution of arsenic species were well correlated with phosphate concentrations than those of Chl-a. This might be due to the competitive uptake of As(V) and phosphate by phytoplankton. The organoarsenicals (OrgAs)/As(V) ratio was higher at low phosphate concentration indicating that conversion of As(V) to OrgAs species was more active in phosphate-exhausted lakes with high phytoplankton density. © 2009 Elsevier B.V. All rights reserved.
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| 40.
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Rahman, M. Azizur ; Hasegawa, Hiroshi ; Ueda, Kazumasa ; Maki, Teruya ; Rahman, M. Mahfuzur
概要:
金沢大学理工研究域物質化学系<br />Ferric (oxyhydro-)oxides (FeOx) precipitate in the rhizosphere at neutral or alkaline pH and are ads
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orbed on the plant root surfaces. Consequently, the higher binding affinity of arsenate to FeOx and the low iron phytoavailability of the precipitated FeOx make the phytoremediation of arsenic difficult. In the present study, the influence of chelating ligands on arsenic and iron uptake by hydroponically grown rice seedlings (Oryza sativa L.) was investigated. When chelating ligands were not treated to the growth medium, about 63 and 71% of the total arsenic and iron were distributed in the root extract (outer root surfaces) of rice, respectively. On the other hand, ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS) and hydroxyiminodisuccinic acid (HIDS) desorbed a significant amount of arsenic from FeOx of the outer root surfaces. Therefore, the uptake of arsenic and iron into the roots and their subsequent translocation to the shoots of the rice seedlings increased significantly. The order of increasing arsenic uptake by chelating ligands was HIDS > EDTA > EDDS. Methylglycinediacetic acid (MGDA) and iminodisuccinic acid (IDS) might not be effective in arsenic solubilization from FeOx. The results suggest that EDDS and HIDS would be a good and environmentally safe choice to accelerate arsenic phytoavailability in the phytoremediation process because of their biodegradability and would be a competent alternative to the widely used non-biodegradable and environmentally persistent EDTA. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 41.
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Maki, Teruya ; Hasegawa, Hiroshi ; Watarai, Hiroshi ; Ueda, Kazumasa
概要:
金沢大学大学院自然科学研究科物質情報解析<br />金沢大学工学部
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| 42.
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Hasegawa, Hiroshi ; Maki, Teruya ; Asano, Khonosuke ; Ueda, Kentaro ; Ueda, Kazumasa
概要:
金沢大学大学院自然科学研究科物質情報解析<br />金沢大学工学部
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| 43.
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論文
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Kobayashi, Fumihisa ; Maki, Teruya ; Nakamura, Yoshitoshi ; Ueda, Kazumasa
概要:
金沢大学自然計測応用研究センターエコテクノロジー研究部門<br />金沢大学工学部<br />Phytoremediation is an innovative technology that utilizes the natural pr
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operties of plants to remediate hazardous waste sites. For more cost-effective phytoremediation, it is important to utilize a hyperaccumulating plant after phytoremediation, i.e. the recovery of valuable metals and the production of useful materials. In this work, the determination of metals in plant component polymers in a fern, Athyrium yokoscense, as a hyper-accumulating plant was established using steam explosion, Wayman's extraction method, and ICP emission spectrometry. After A. yokoscense plants were treated by steam explosion, the steam-exploded A. yokoscense were separated into four plant component polymers, i.e. water-soluble material fraction, holocellulose fraction, methanol-soluble lignin fraction, and residual lignin fraction. The concentrations of Cu, Pb, Fe, and Zn in these plant component polymers and the dry weights of plant component polymers were measured. These analytical process determining metals in the plants will contribute to not only the evaluation and the efforts of phytoremediation using a hyperaccumulating plant, but also to the development of more effective phytoremediation. 2005 © The Japan Society for Analytical Chemistry.
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| 44.
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論文
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Rahman M., Mamunur ; Rahman M., Azizur ; Maki, Teruya ; Nishiuchi, Takumi ; Asano, T. ; Hasegawa, Hiroshi
概要:
Iron (Fe) is one of the vital limiting factors for phytoplankton in vast regions of the contemporary oceans, notably the
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high nutrient low chlorophyll regions. Therefore, it is apparent to be acquainted with the Fe uptake strategy of marine phytoplankton under Fe-limited condition. In the present study, marine phytoplankton Prymnesium parvum was grown under Fe-deplete (0.0025 μM) and Fe-rich (0.05 μM) conditions, and proteomic responses of the organism to Fe conditions were compared. In sodium dodecyl sulfate (SDS) gel electrophoresis, 7 proteins (16, 18, 32, 34, 75, 82, and 116 kDa) were highly expressed under Fe-deplete condition, while one protein (23 kDa) was highly expressed under Fe-rich condition. These proteins were subjected to 2-dimensional gel electrophoresis (2-D DIGE) to differentiate individual proteins, and were identified by matrix-assisted laser desorption-ionization-time of flight-mass spectrometer (MALDI-TOF-MS) analysis. The results showed that under Fe-deplete condition P. parvum increases the biosynthesis of ATP binding cassette (ABC) transporters, flagellar associated protein (FAP), and Phosphoribosylaminoimidazole-succinocarboxamide synthase. These proteins are assumed to be involved in a number of cellular biochemical processes that facilitate Fe acquisition in phytoplankton. Under Fe-deplete condition, P. parvum increases the synthesis of ribulose biphosphate carboxylase (RuBisCo), malate dehydrogenase, and two Fe-independent oxidative stress response proteins, manganese superoxide dismutase (MnSOD) and Serine threonine kinase (STK). Thus, marine phytoplankton may change their Fe acquisition strategy by altering the biosynthesis of several proteins in order to cope with Fe-limitation. © 2013 Elsevier Ltd. All rights reserved.
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| 45.
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論文
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Begum, Zinnat A. ; Rahman, Ismail M. M. ; Sawai, Hikaru ; Tate, Yousuke ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
The complex formation equilibria of Cr3+ and Fe3+ ions in aqueous solution with two biodegradable aminopolycarboxylate c
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helants (dl-2-(2-carboxymethyl)nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2'- iminodisuccinic acid (HIDS)) were investigated. The potentiometric data obtained at the constant ionic strengths (I) of (0.1 and 1.0) mol·dm-3 KCl and at (25 ± 0.1) °C was processed with the aid of the computer program HYPERQUAD 2008. The formation constants of the proton-chelant and metal-chelant (log KML) species (M = Fe3+ or Cr 3+; L = GLDA or HIDS) were determined, and the concentration distributions of complex species in solution were evaluated for both metal ions. In various pH conditions, the interaction between the chelants (L = GLDA or HIDS) and the metal ions (M = Fe3+ or Cr3+) leads to the formation of different complexes formulated as MH2L+, MHL, ML-, M(OH)L2-, and M(OH)2L3-. The log KML values at I = 0.1 mol·dm-3 KCl (T = (25 ± 0.1) °C) were 15.27 (log KFe-GLDA), 14.96 (log K Fe-HIDS), 13.77 (log KCr-GLDA), 12.67 (log K Cr-HIDS), and at I = 1.0 mol·dm-3 KCl (T = (25 ± 0.1) °C) were 14.79 (log KFe-GLDA), 14.34 (log K Fe-HIDS), 12.90 (log KCr-GLDA), 12.09 (log K Cr-HIDS). The conditional stability constants (log K'ML) of the ML complexes were calculated in terms of pH in the range of 2 to 12 and compared with the same for EDTA and other biodegradable chelants (NTA and EDDS). © 2012 American Chemical Society.
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| 46.
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論文
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Begum, Zinnat A. ; Rahman, Ismail M. M. ; Sawai, Hikaru ; Mizutani, Satoshi ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
Development of aminopolycarboxylate chelants (APCs) having enhanced biodegradability is gaining increasing focus to repl
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ace the EDTA and its homologs with those used widely for the ex situ treatment of contaminated soils and are potential eco-threats. The paper reports the chelant-assisted extraction of the toxic metals (Cd, Cu, Pb, and Zn) from the metal-spiked European reference soils (Eurosoil 1 and Eurosoil 4) using biodegradable APCs, namely EDDS, GLDA, and HIDS. The effects of chelant-to-metal molar ratio, solution pH, and metal/chelant stability constants were evaluated, and compared with that of EDTA. The selectivity aptitude of the biodegradable chelants towards the toxic metals was assumed from the speciation calculations, and a proportionate correlation was observed at neutral pH. Pre- and post-extractive solid phase distributions of the target metals were defined using the sequential extraction procedure and dissolution of metals from the theoretically immobilized fraction was witnessed. The effect of competing species (Al, Ca, Fe, Mg, and Mn) concentrations was proven to be minimized with an excess of chelant in solution. The highlight of the outcomes is the superior decontamination ability of GLDA, a biodegradable APC, at minimum chelant concentration in solution and applicability at a wide range of pH environments. © 2012 Springer Science+Business Media Dordrecht.
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| 47.
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論文
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Begum, Zinnat A. ; Rahman, Ismail M. M. ; Tate, Yousuke ; Egawa, Yuji ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
The protonation and complex formation equilibria of two biodegradable aminopolycarboxylate chelants {dl-2-(2-carboxymeth
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yl)nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2′-iminodisuccinic acid (HIDS)} with Ni 2+, Cu2+, Zn2+, Cd2+ and Pb 2+ ions were investigated using the potentiometric method at a constant ionic strength of I = 0.10 mol·dm-3 (KCl) in aqueous solutions at 25 ± 0.1 C. The stability constants of the proton-chelant and metal-chelant species for each metal ion were determined, and the concentration distributions of various complex species in solution were evaluated for each ion. The stability constants (log10 K ML) of the complexes containing Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+ ions followed the identical order of log10 K CuL > log10 K NiL > log10 K PbL > log10 K ZnL > log10 K CdL for either GLDA (13.03 > 12.74 > 11.60 > 11.52 > 10.31) or HIDS (12.63 > 11.30 > 10.21 > 9.76 > 7.58). In each case, the constants obtained for metal-GLDA complexes were larger than the corresponding constants for metal-HIDS complexes. The conditional stability constants (log10 $$ K-{\text{ML}}^{'} $$) of the metal-chelant complexes containing GLDA and HIDS were calculated in terms of pH, and compared with the stability constants for EDTA and other biodegradable chelants. © 2012 Springer Science+Business Media New York.
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| 48.
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論文
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Hasegawa, Hiroshi ; Ismail M. M. Rahman ; Zinnat A. Begum ; Umehara, Yoshihiro ; Maki, Teruya ; Furusho, Yoshiaki ; Mizutani, Satoshi
概要:
Selective separation of cadmium(II) on a macrocycle immobilized solid phase extraction (SPE) system namely AnaLig Cd-01,
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and commonly known as molecular recognition technology (MRT) gel, have been examined. The MRT-SPE able to retain the cadmium from the metal-affluent aqueous matrix at the pH range of 2 to 8, and the captured species can be recovered via elution with 1 and 6 M HNO3. Besides the effects of solution pH and eluent concentration, the impacts of sample loading flow rates and coexisting matrix ions were also investigated and optimized. The Cd(II) retention capacity of the MRT-SPE was 0.26 mmol g-1, and it can be reused for more than 100 loading and elution cycles. The Cd(II) recovery attained from the metal-spiked natural waters was satisfactory (95.3-98.1%). However, the Cd(II) retention ability of the MRT-SPE was significantly decreased when excess of chelant remain in the aqueous waste matrix. © 2012 Versita Warsaw and Springer-Verlag Wien.
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| 49.
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論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Egawa, Yuji ; Sawai, Hikaru ; Begum, Zinnat A. ; Maki, Teruya ; Mizutani, Satoshi
概要:
The metal indium termed as 'rare' in recent days due to its increasing demand in the formulations of electronic and ener
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gy-related gadgets and scarce supply resources. Hence, the attempts to recover indium from the secondary resources, such as recycling of the indium abundant waste materials, received increasing research focus. The major indium consumption happens in the form of indium tin oxide (ITO) that used for the fabrication of liquid-crystal displays (LCD). The end-of-life LCD screens, termed as ITO-glass hereafter, are an emerging contributor to the global e-waste load and can be an impending secondary source of indium. The present work introduces a new technique for the treatment of waste ITO-glass using aminopolycarboxylate chelants (APCs) in combination with a mechanochemical treatment process. APCs are capable of forming stable complexes with the indium deposited on the ITO-glass, whereas the rate of recovery was not substantial. The mechanochemical treatment induces the destruction of crystalline structure with which the ITO fragments are attached and facilitate the increased indium dissolution with the chelants. The increase was more prominent followed by a decrease in the cumulative processing time from 24 to 6 h when the vitrified ITO-glass was simultaneously crushed and washed with the chelants. The extraction of indium was better at the acidic pH condition, and it was further intensified when the operating temperature was raised to ≥ 120 °C. © 2012 Elsevier B.V. All rights reserved.
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| 50.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, M. Mamunur ; Kadohashi, Kouta ; Rahman, M. Azizur ; Takasugi, Yui ; Tate, Yousuke ; Maki, Teruya
概要:
Present study investigated the significance of the concentration of chelating ligand on Fe 3+-solubility in growth mediu
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m and its influence on Fe bioavailability and uptake in rice plant. Rice seedlings were grown in modified Murashige and Skoog (MS) hydroponic growth medium with moderate (250 μM) and high (500 μM) concentrations of ethylenediaminetetraacetate (EDTA) and hydroxyiminodisuccinate (HIDS) under sterile and non-sterile conditions. Concentrations of soluble Fe in the growth medium increased with increasing ligand concentrations, and the growth of rice seedlings was higher at moderate ligand concentration than at control (without chelant) and high ligand concentration. This explains the relationship between Fe solubility and bioavailability in the growth medium, and its effect on Fe uptake in rice plant. Fe exists in the growth medium predominantly as particulate (insoluble) forms at low ligand concentration, and as soluble [Fe(OH) 2+, Fe(OH) 2 +, Fe-L complex] and apparently soluble (colloidal) forms at moderate ligand concentration. At high ligand concentration, most of the Fe 3+ in the growth medium forms soluble Fe-L complex, however, the bioavailability of Fe from Fe-L complex decreased due to lopsided complex formation equilibrium reaction (CFER) between Fe and the ligands. Also, Fe is solubilized forming stable and soluble Fe-L complex, which is then detached as less stable, but soluble and bioavailable substance(s) after (time-dependent) biodegradation. Therefore- i) ligand concentration and stability constant of Fe-L complex (K Fe-L) influence Fe bioavailability and uptake in rice plant, and ii) the biodegradable ligands (e.g., HIDS) would be more effective Fe fertilizer than the environmentally persistent and less biodegradable ligands (e.g., EDTA). © 2012 Elsevier Masson SAS.
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| 51.
論文 |
論文
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Mamunur, Rahman M. ; Azizur, Rahman M. ; Maki, Teruya ; Nishiuchi, Takumi ; Asano, Tomoya ; Hasegawa, Hiroshi
概要:
Iron (Fe) is one of the vital limiting factors for phytoplankton in vast regions of the contemporary oceans, notably the
…
high nutrient low chlorophyll regions. Therefore, it is apparent to be acquainted with the Fe uptake strategy of marine phytoplankton under Fe-limited condition. In the present study, marine phytoplankton Prymnesium parvum was grown under Fe-deplete (0.0025 μM) and Fe-rich (0.05 μM) conditions, and proteomic responses of the organism to Fe conditions were compared. In sodium dodecyl sulfate (SDS) gel electrophoresis, 7 proteins (16, 18, 32, 34, 75, 82, and 116. kDa) were highly expressed under Fe-deplete condition, while one protein (23. kDa) was highly expressed under Fe-rich condition. These proteins were subjected to 2-dimensional gel electrophoresis (2-D DIGE) to differentiate individual proteins, and were identified by matrix-assisted laser desorption-ionization-time of flight-mass spectrometer (MALDI-TOF-MS) analysis. The results showed that under Fe-deplete condition P. parvum increases the biosynthesis of ATP binding cassette (ABC) transporters, flagellar associated protein (FAP), and Phosphoribosylaminoimidazole-succinocarboxamide synthase. These proteins are assumed to be involved in a number of cellular biochemical processes that facilitate Fe acquisition in phytoplankton. Under Fe-deplete condition, P. parvum increases the synthesis of ribulose biphosphate carboxylase (RuBisCo), malate dehydrogenase, and two Fe-independent oxidative stress response proteins, manganese superoxide dismutase (MnSOD) and Serine threonine kinase (STK). Thus, marine phytoplankton may change their Fe acquisition strategy by altering the biosynthesis of several proteins in order to cope with Fe-limitation. © 2013 Elsevier Ltd.
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| 52.
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論文
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Rahman, Ismail M. M. ; Begum, Zinnat A. ; Sawai, Hikaru ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
Sand filters devised with iron-rich adsorbents are extensively promoted and deployed in the arsenic-prone south and sout
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h-east Asian countries (e.g., Bangladesh). The approach offers superior performance in removing arsenic while the spent sludge from the sand filters is an issue of concern due to the possibility of toxic releases after being discarded. In this work, a new technique is proposed for the treatment of spent iron-oxide coated sand (IOCS) from filters used in arsenic removal. Chelant-washing of the arsenic-loaded IOCS is combined with the solid phase extraction treatment to accomplish the objective. The unique point of the proposed process is the cost-effective scheme, which includes the option of recycling of the washing solvent beside the decontamination of the spent arsenic-rich sludge. © 2013 Elsevier Ltd.
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| 53.
論文 |
論文
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Rahman, Ismail M. M. ; Begum, Zinnat A. ; Furusho, Yoshiaki ; Mizutani, Satoshi ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
A simple flow-based method was developed for the selective separation of arsenic species (+3 and +5) using a macrocycle-
…
immobilized solid phase extraction (SPE) system, commonly known as molecular recognition technology (MRT) gel. Arsenic species in solution or in the eluent were subsequently quantified with graphite furnace atomic absorption spectrometry. The separation behaviors of As(III) and As(V) on MRT-SPE were investigated. It was found that As(V) can be selectively collected on the SPE system within the range of pH 4 to 9, while As(III) was passed through the MRT-SPE. The retention capacity of the MRT-SPE material for As(V) was found to be 0.25 ± 0.04 mmol g-1. The detection limit of the method for As(V) was 0.06 μg L-1, and the relative standard deviation was 2.9 % (n = 10, C = 1 μmol L-1). Interference from the matrix ions was studied. In order to validate the developed method, certified reference materials of effluent wastewater and groundwater samples were analyzed, and the determined values were in good agreement with the certified values. The proposed method was successfully applied to the speciation analysis of tri- and pentavalent arsenic in natural water samples showing satisfactory recoveries (≥ 98.7 %). © 2013 Springer Science+Business Media Dordrecht.
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| 54.
論文 |
論文
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Egawa, Yuji ; Sawai, Hikaru ; Begum, Zinnat A. ; Maki, Teruya ; Mizutani, Satoshi
概要:
Indium is a rare metal that is mostly consumed as indium tin oxide (ITO) in the fabrication process of liquid crystal di
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splay (LCD) panels. The spent LCD panels, termed as LCD-waste hereafter, is an increasing contributor of electronic waste burden worldwide and can be an impending secondary source of indium. The present work reports a new technique for the reclamation of indium from the unground LCD-waste using aminopolycarboxylate chelants (APCs) as the solvent in a hyperbaric environment and at a high-temperature. Microwave irradiation was used to create the desired system conditions, and a substantial abstraction of indium (≥80%) from the LCD-waste with the APCs (EDTA or NTA) was attained in the acidic pH region (up to pH 5) at the temperature of ≥120. °C and the pressure of ~50. bar. The unique point of the reported process is the almost quantitative recovery of indium from the LCD-waste that ensured via the combination of the reaction facilitatory effect of microwave exposure and the metal extraction capability of APCs. A method for the selective isolation of indium from the extractant solution and recycle of the chelant in solution is also described. © 2013 Elsevier B.V.
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| 55.
論文 |
論文
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Rahman, M. Azizur ; Hasegawa, Hiroshi ; Rahman, M. Mamunur ; Maki, Teruya ; Lim, Richard P.
概要:
Being predominant inorganic arsenicals, methylarsenicals also occur in anaerobic paddy soils. Therefore, this study inve
…
stigated the influence of Fe2+ concentrations and arsenic speciation [arsenate (As(V)) and dimethylarsinate (DMA)] in paddy soils on arsenic uptake in rice plant. Rice seedlings were grown in soil irrigated with a Murashige and Skoog (MS) growth solution containing As(V) or DMA with or without 1.8 mM Fe2+ in excess to the background concentration of total iron (0.03 mM) in the soil. Arsenic concentration in rice roots increased initially and then decreased gradually when the seedlings were grown with excess Fe2+ and As(V). In contrast, arsenic concentration in the roots increased steadily (P < 0.01) when the seedlings were grown without excess Fe2+ and As(V). When the form of the arsenic was DMA, total arsenic (tAs) concentration in rice roots increased gradually (P < 0.01) and was not affected by the addition of excess Fe2+ in the soil. When rice seedlings were grown with As(V), tAs concentration in rice roots and shoots increased steadily (P < 0.01) for gradual increase of Fe2+ concentrations in soil. However, tAs concentration in roots and shoots was independent of Fe2+ concentrations in soil when the form of arsenic was DMA. The tAs concentrations in rice shoots also increased significantly (P < 0.01) with increasing exposure time for both As(V) and DMA. Thus, Fe2+ concentrations in soil affect arsenic uptake in rice plant depending on the speciation of arsenic. © 2013 Springer Science+Business Media Dordrecht.
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| 56.
論文 |
論文
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Maki, Teruya ; Puspitasari, Findya ; Hara, Kazutaka ; Yamada, Maromu ; Kobayashi, Fumihisa ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Asian dust (Kosa) events transport airborne microorganisms that significantly impact biological ecosystems, human health
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, and ice-cloud formation in downwind areas. However, the composition and population dynamics of airborne bacteria have rarely been investigated in downwind areas during Kosa events. In this study, air samplings were sequentially performed at the top of a 10-m high building within the Kosa event arrival area (Kanazawa City, Japan) from May 1 to May 7, 2011, during a Kosa event. The particle concentrations of bacterial cells and mineral particles were ten-fold higher during the Kosa event than on non-Kosa event days. A 16S ribosomal DNA clone library prepared from the air samples primarily contained sequences from three phyla: Cyanobacteria, Firmicutes, and Alphaproteobacteria. The clones from Cyanobacteria were mainly from a marine type of Synechococcus species that was dominant during the first phase of the Kosa event and was continuously detected throughout the Kosa event. The clones from Alphaproteobacteria were mainly detected at the initial and final periods of the Kosa event, and phylogenetic analysis showed that their sequences clustered with those from a marine bacterial clade (the SAR clade) and Sphingomonas spp. During the middle of the Kosa event, the Firmicutes species Bacillus subtilis and Bacillus pumilus were predominant; these species are known to be predominant in the atmosphere above the Chinese desert, which is the source of the dust during Kosa events. The clones obtained after the Kosa event had finished were mainly from Bacillus megaterium, which is thought to originate from local terrestrial areas. Our results suggest that airborne bacterial communities at the ground level in areas affected by Kosa events change their species compositions during a Kosa event toward those containing terrestrial and pelagic bacteria transported from the Sea of Japan and the continental area of China by the Kosa event. © 2014 Elsevier B.V.
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| 57.
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Umehara, Yoshihiro ; Sawai, Hikaru ; Maki, Teruya ; Furusho, Yoshiaki ; Mizutani, Satoshi
概要:
The waste byproducts from the indium-consuming fabrication processes are considered as the viable resource for indium du
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e to the unique preference to the element in designing optoelectronic devices. The present work introduces a new technique for the selective recovery of indium from the etching waste, which produced during the patterning of indium tin oxide (ITO) layer on the flat-panel displays. The process includes the application of a solid phase extraction (SPE) assembly, known as molecular recognition technology (MRT) gel, consisting of a metal-selective ligand immobilized to silica gel or polymer substrates. The samples were the real solution of etching waste from the liquid-crystal display fabrication process, and the simulated waste solution prepared using the commercially available etching solution composition containing ethanedioic acid. The retention and the corresponding indium recovery rate (%) were the key characteristics for the appraisal of MRT-SPE types: AnaLig TE 02 (TE 02), AnaLig TE 03, AnaLig TE 07, AnaLig TE 13 and AnaLig PM 02. The other conclusive factors were the influence of ion intensity in solution and the interfering effects from tin, the co-content element in the ITO-formulation. The TE 02 MRT-SPE came across all the requisite aspects for the selective recovery of indium from the etching effluent. The indium retention or recovery with TE 02 MRT-SPE from the real etching waste solution was in the range of 97 to 99% with the relative standard deviation of <4.4%. The separation of the ITO co-element tin from the waste mixture was successively selective, and thereby minimizes the possibility of interference. A three-step elution with 0.3molL-1 HNO3, 6molL-1 HCl and 1molL-1 HCl/10mmolL-1 EDTA was required to accomplish the sequential selectivity in the process. The indium retention capacity of the TE 02 MRT-SPE was 0.147mmolg-1. © 2013 Elsevier B.V.
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| 58.
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Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Egawa, Yuji ; Sawai, Hikaru ; Begum, Zinnat A. ; Maki, Teruya ; Mizutani, Satoshi
概要:
The incineration fly ash (IFA), molten fly ash (MFA), thermal power plant fly ash (TPP-FA), and nonferrous metal process
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ing plant ash (MMA) have been screened in terms of the following rare-termed metal contents: B, Ce, Co, Dy, Eu, Ga, Gd, Hf, In, Li, Lu, Mn, Nb, Nd, Ni, Pr, Rb, Sb, Se, Sm, Sr, Ta, Tb, Te, Ti, Tm, V, W, Y, and Yb. The pseudo-potential for recycling of the waste ashes, as compared to the cumulative concentration in the crust (mg kg-1), was determined as follows: MMA > IFA > MFA > TPP-FA. The comparison with the crude ore contents indicates that the MMA is the best resource for reprocessing. The recovery of the target metals using aminopolycarboxylate chelants (APCs) has been attempted at varying experimental conditions and ultrasound-induced environment. A better APC-induced extraction yield can be achieved at 0.10 mol L-1 concentration of chelant, or if the system temperature was maintained between 60 to 80 °C. Nevertheless, the mechanochemical reaction induced by the ultrasound irradiation has been, so far, the better option for rare metal dissolution with chelants as it can be conducted at a minimum chelant concentration (0.01 mol L-1) and at room temperature (25 ± 0.5 °C). © 2014 Springer International Publishing Switzerland.
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| 59.
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Hasegawa, Hiroshi ; Mito, Saeko ; Norisuye, Kazuhiro ; Matsui, Masakazu ; Maki, Teruya ; Ueda, Kazumasa
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| 60.
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Sawai, Hikaru ; Rahman, Ismail M. M. ; Lu, Chao ; Tsukagoshi, Yoshinori ; Begum, Zinnat A. ; Maki, Teruya ; Hasegawa, Hiroshi
概要:
The accumulation behaviors and solid phase partitioning patterns of stable cesium, which have been recognized as an indicator of the long-term movement of radioactive cesium (137Cs or 134Cs) in ecosystems, were studied in typical and
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natural soils of Japanese origin, namely, red clay, leaf-mold and andosol soils. The retention and migration of soil-phase cesium have been explained relative to various factors, such as soil organic matter contents, competitive cation concentrations and the adsorption ratio of Cs to the solid phase. Cesium was adsorbed nearly quantitatively in the leaf-mold type soil, and the rate of Cs absorption increased as the particle size decreased in the red clay and andosol soils. The distributions of Cs within the soil solid phases were defined using the selective sequential extraction scheme and were used to explain its relative incorporation in the soil fractions. Solid phase fractionation indicated that nearly half of the total cesium concentrations in the soils were in the 'residual' fraction (representing the metal that was incorporated within the crystalline lattice of the soil and was difficult to extract). These findings are expected to provide information regarding suitable conditions for remediation, immobilization or the recovery of cesium from contaminated soils with excess cesium concentrations.
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| 61.
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Hasegawa, Hiroshi ; Nakagawa, K. ; Rahman, Mohammad Azizur ; Takemura M. ; Maki, Teruya ; Naito, K. ; Rahman, Mahmuda Mamunur
概要:
A new fluorescent-based high-performance liquid chromatography (HPLC) assay using 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-C1) was employed to determine iron (Fe) bioavailability to red tide phytoplankton in seawater. After growing
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four red tide species (Prymnesium parvum, Heterosigma akashiwo, Eutreptiella gymnastica, and Oltmannsiellopsis viridis) in f/2 artificial seawater under different Fe conditions, soluble extracts of the phytoplankton were derivatized using different fluorescent reagents (NBD-C1, 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole; NBD-F, fluorescamine, and ortho-phthalaldehyde; OPA) followed by HPLC assay. Among the four fluorescent reagents, NBD-C1 was most effective for derivatizing the phytoplankton extracts which would consist of proteins and peptides. HPLC chromatograms of the NBD-derivatized extracts showed gradual changes (decrease/increase) of six peaks for different Fe conditions. Four of the peaks decreased, while two peaks increased with the increase of Fe concentrations in the culture medium. Considering the consistency and sensitivity of chromatogram peaks E and A to different Fe, phosphate and nitrate conditions for all phytoplankton studied, the ratio of these two peaks (IE/A) has been proposed as the indicator of Fe bioavailability to red tide phytoplankton.<br />In Press
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| 62.
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Maki, Teruya ; Hara, Kazutaka ; Kobayashi, Fumihisa ; Kurosaki, Yasunori ; Kakikawa, Makiko ; Matsuki, Atsushi ; Chen, Bin ; Shi, Guangyu ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Bacterial populations transported from ground environments to the atmosphere get dispersed throughout downwind areas and
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can influence ecosystem dynamics, human health, and climate change. However, the vertical bacterial distribution in the free troposphere was rarely investigated in detail. We collected aerosols at altitudes of 3000 m, 1000 m, and 10 m over the Noto Peninsula, Japan, where the westerly winds carry aerosols from continental and marine areas. During the sampling period on March 10, 2012, the air mass at 3000 m was transported from the Chinese desert region by the westerly winds, and a boundary layer was formed below 2000 m. Pyrosequencing targeting 16S rRNA genes (16S rDNA) revealed that the bacterial community at 3000 m was predominantly composed of terrestrial bacteria, such as Bacillus and Actinobacterium species. In contrast, those at 1000 m and 10 m included marine bacteria belonging to the classes Cyanobacteria and Alphaproteobacteria. The entire 16S rDNA sequences in the clone libraries were identical to those of the terrestrial and marine bacterial species, which originated from the Chinese desert region and the Sea of Japan, respectively. The origins of air masses and meteorological conditions contribute to vertical variations in the bacterial communities in downwind atmosphere. © 2015 Elsevier Ltd. All rights reserved.<br />Embargo Period 24 months
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| 63.
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Maki, Teruya ; Ishikawa, Akira ; Mastunaga, Tomoki ; Pointing, Stephen B. ; Saito, Yuuki ; Kasai, Tomoaki ; Watanabe, Koichi ; Aoki, Kazuma ; Horiuchi, Amane ; Lee, Kevin C. ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Atmospheric aerosols contain particulates that are deposited to oceanic surface waters. These can represent a major sour
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ce of nutrients, trace metals, and organic compounds for the marine environment. The Japan Sea and the western Pacific Ocean are particularly affected by aerosols due to the transport of desert dust and industrially derived particulate matter with aerodynamic diameter less than 2.5 µm (PM2.5) from continental Asia. We hypothesized that supplementing seawater with aerosol particulates would lead to measurable changes in surface water nutrient composition as well as shifts in the marine microbial community. Shipboard experiments in the Pacific Ocean involved the recovery of oligotrophic oceanic surface water and subsequent supplementation with aerosol particulates obtained from the nearby coastal mountains, to simulate marine particulate input in this region. Initial increases in nitrates due to the addition of aerosol particulates were followed by a decrease correlated with the increase in phytoplankton biomass, which was composed largely of Bacillariophyta (diatoms), including Pseudo-nitzschia and Chaetoceros species. This shift was accompanied by changes in the bacterial community, with apparent increases in the relative abundance of heterotrophic Rhodobacteraceae and Colwelliaceae in aerosol particulate treated seawater. Our findings provide empirical evidence revealing the impact of aerosol particulates on oceanic surface water microbiology by alleviating nitrogen limitation in the organisms. © 2016 Elsevier Ltd<br />Embargo Perion 12 months
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| 64.
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Puspitasari, Findya ; Maki, Teruya ; Shi, Guangyu ; Bin, Chen ; Kobayashi, Fumihisa ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Airborne microorganisms (bioaerosol) from the China desert region, which are released into the atmosphere, disperse by t
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he Asian dust event and affect ecosystems, human life, and atmospheric processes in downwind areas. However, the dynamics of airborne bacteria over the China desert regions have rarely been investigated. In this study, we analyzed bacterial communities in aerosols of the Asian dust source region (Taklimakan Desert) and compared them with the bacterial communities in sand dunes, for evaluating the mixtures from sand area to atmosphere. Air samples were collected at 10 m above the ground level from Dunhuang City during a dust event. The cell densities of airborne bacteria during a dust event were ten times more than that in non-dust periods. The 16S rDNA clone libraries from four air samples mainly belonged to two phyla, Firmicutes and Proteobacteria. During a dust event, the proportion of Proteobacteria clones decreased, whereas that of Firmicutes clones increased. Sand samples were collected from the sand dunes in four sampling sites of the Taklimakan Desert. The bacterial communities in sand samples comprised of the members of Firmicutes and Actinobacteria. The clones of Firmicutes in both air and sand samples included Bacillus species, constituting more than 10 % of total clones. Airborne bacterial communities would be carried by the dust events from sand dunes. Propionibacterium species from the class Actinobacteria that were dominant in sand samples were not detected in the air samples, suggesting that atmospheric stressors eliminate some bacterial species. Presumably, airborne bacterial communities in the Asian dust source region are composed of local environmental bacteria, and their dynamics depend on the occurrence of a dust event. © 2015 Springer Science+Business Media Dordrecht<br />Embargo Period 12 months
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| 65.
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Hasegawa, Hiroshi ; Tate, Yousuke ; Ogino, Masashi ; Maki, Teruya ; Begum, Zinnat A. ; Ichijo, Toshiharu ; Rahman, Ismail M. M.
概要:
The major fractions of dissolved iron in seawater exist as a complex with organic ligands. A high bioavailability of iro
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n bound to humic acid (HA) compared to the other model ligands, such as desferrioxamine B or ferrichrome, has been reported, which implies the importance of HA to control the geochemical behavior and the transfer of Fe to marine phytoplankton, particularly in estuarine and coastal waters. In the current work, the effect of different HA fractions (>100, 100–30, 30–10, 10–5, and 5–3 kDa), which were extracted from lignite, on the comparative solubility of iron in seawater and the corresponding influence on iron uptake and growth rate of the phytoplankton Prymnesium parvum (Haptophyta) was studied using laboratory cultures. The lower-molecular-weight (MW) HA fractions, such as 30–10, 10–5, and 5–3 kDa, remained soluble in the simulated seawater medium for a longer time span compared to the higher MW fractions. The lower MW fractions facilitated higher iron solubility and assisted in achieving a better phytoplankton growth rate. However, a reciprocal impact on phytoplankton growth rates was observed when the HA concentration increased to a higher range (0.18 to 18 mg-C L−1). The highest intracellular Fe uptake in phytoplankton occurred with 30–10 kDa HA in seawater, and the extracellular dissolved Fe concentrations were higher for smaller-sized HA fractions. In summary, our study showed that the controlled addition of lower MW fractions of HA (up to 30–10 kDa) in estuarine waters could ensure the accelerated uptake of Fe in phytoplankton as well as a better growth rate. © 2016 Springer Science+Business Media Dordrecht<br />Embargo Period 12 months
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| 66.
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Hasegawa, Hiroshi ; Nakagawa, K. ; Rahman, Mohammad Azizur ; Takemura, M. ; Maki, Teruya ; Naito, K. ; Rahman, Mahmuda Mamunur
概要:
A new fluorescent-based high-performance liquid chromatography (HPLC) assay using 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-C1) was employed to determine iron (Fe) bioavailability to red tide phytoplankton in seawater. After growing
…
four red tide species (Prymnesium parvum, Heterosigma akashiwo, Eutreptiella gymnastica, and Oltmannsiellopsis viridis) in f/2 artificial seawater under different Fe conditions, soluble extracts of the phytoplankton were derivatized using different fluorescent reagents (NBD-C1, 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole; NBD-F, fluorescamine, and ortho-phthalaldehyde; OPA) followed by HPLC assay. Among the four fluorescent reagents, NBD-C1 was most effective for derivatizing the phytoplankton extracts which would consist of proteins and peptides. HPLC chromatograms of the NBD-derivatized extracts showed gradual changes (decrease/increase) of six peaks for different Fe conditions. Four of the peaks decreased, while two peaks increased with the increase of Fe concentrations in the culture medium. Considering the consistency and sensitivity of chromatogram peaks E and A to different Fe, phosphate and nitrate conditions for all phytoplankton studied, the ratio of these two peaks (IE/A) has been proposed as the indicator of Fe bioavailability to red tide phytoplankton.
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| 67.
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Sawai, Hikaru ; Rahman, Ismail M.M. ; Tsukagoshi, Yoshinori ; Wakabayashi, Tomoya ; Maki, Teruya ; Mizutanai, Satoshi ; Hasegawa, Hiroshi
概要:
Non-ferrous smelting dust, especially lead-smelting dust (LSD), contains percent levels of indium and thus constitutes a
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novel indium resource. The main difficulty in recovering indium from LSD is the coexisting presence of lead and zinc. In this study, a unique indium separation process was designed, combining techniques that involve washing with a chelant, leaching with acid and precipitation as hydroxide. The majority of the Pb in the LSD was selectively separated during chelant-assisted washing with ethylenediaminedisuccinate (EDDS), while the residual Pb was diminished through an acid leaching treatment with a mixed solution of sulfuric acid and hydrochloric acid. The chelant washing step also ensures a decrease in the raw LSD weight at a ratio of approximately 82% due to the removal of lead and counterions such as sulfate, and the washing step also minimizes the consumption of corrosive acids in the subsequent step. Selective indium separation from LSD is further complicated by the similarity of the behavior of zinc during the acid leaching step. Therefore, hydroxide precipitation at pH 5 has been introduced as the final step, ensuring the maintenance of zinc as a soluble species in the supernatant and the selective separation of indium (~88%) as a hydroxide precipitate. © 2015 Elsevier B.V.<br />Embargo Period 48mouths
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| 68.
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Sawai, Hikaru ; Rahman, Ismail M.M. ; Fujita, Mayuko ; Jii, Naoyuki ; Wakabayashi, Tomoya ; Begum, Zinnat A. ; Maki, Teruya ; Mizutani, Satoshi ; Hasegawa, Hiroshi
概要:
Waste foundry sand (WFS), which is a hazardous byproduct from the foundry industry, is often contaminated with potential
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ly toxic elements (PTEs), such as Cu, Pb and Zn, and widely re-utilized as a construction material. Therefore, the depollution of WFS has been suggested due to its environment friendly reprocessing to avoid potential long-term hazardous impacts. In the current study, a unique chemically induced technique has been proposed for the removal of PTEs from WFS. EDTA, NaOH and NH3 were used as extractants in combination or in succession. The optimum removal of PTEs was accomplished using a solid (WFS) to solution (50 mmol L-1 EDTA) ratio of 10 under strongly basic pH conditions, which was achieved with NaOH addition. The washing efficiency was further enhanced with the addition of NH3 to the solution. The complete process cycle duration was adjusted to 9 h with a washing sequence that was repeated three times for 3 h each. The ultimate efficiencies (%) for the removal of PTEs were as follows: Cu, 98; Pb, 81; Sn, 83; and Zn, 50. The leaching of residual PTEs (%) from the decontaminated WFS was also in compliance with the regulatory levels that are defined by the monitoring authorities. © 2016 Elsevier B.V.<br />Embargo Period 24 months
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| 69.
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Maki, Teruya ; Kurosaki, Yasunori ; Onishi, Kazunari ; Lee, Kevin C. ; Pointing, Stephen B. ; Jugder, Dulam ; Yamanaka, Norikazu ; Hasegawa, Hiroshi ; Shinoda, Masato
概要:
Asian dust events transport the airborne bacteria in Chinese desert regions as well as mineral particles and influence d
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ownwind area varying biological ecosystems and climate changes. However, the airborne bacterial dynamics were rarely investigated in the Gobi desert area, where dust events are highly frequent. In this study, air samplings were sequentially performed at a 2-m high above the ground at the sampling site located in desert area (Tsogt-Ovoo of Gobi desert; Mongolia 44.2304°N, 105.1700°E). During the dust event days, the bacterial cells and mineral particles increased to more than tenfold of concentrations. MiSeq sequencing targeting 16S ribosomal DNA revealed that the airborne bacteria in desert area mainly belonged to the classes Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Bacilli, Alpha-proteobacteria, Beta-proteobacteria, and Gamma-proteobacteria. The bacterial community structures were different between dust events and non-dust events. The air samples collected at the dust events indicated high abundance rates of Alpha-proteobacteria, which were reported to dominate on the leaf surfaces of plants or in the saline lake environments. After the dust events, the members of Firmicutes (Bacilli) and Bacteroidetes, which are known to form endospore and attach with coarse particles, respectively, increased their relative abundances in the air samples. Presumably, the bacterial compositions and diversities in atmosphere significantly vary during dust events, which carry some particles from grassland (phyllo-sphere), dry lake, and sand surfaces, as well as some bacterial populations such as Firmicutes and Bacteroidetes maintain in the atmosphere for longer time. © 2016 The Author(s)<br />Embargo Period 12 months
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| 70.
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Maki, Teruya ; Hara, Kazutaka ; Kobayashi, Fumihisa ; Kurosaki, Yasunori ; Kakikawa, Makiko ; Matsuki, Atsushi ; Bin, Chen ; Shi, Guangyu ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Bacterial populations transported from ground environments to the atmosphere get dispersed throughout downwind areas and
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can influence ecosystem dynamics, human health, and climate change. However, the vertical bacterial distribution in the free troposphere was rarely investigated in detail. We collected aerosols at altitudes of 3000 m, 1000 m, and 10 m over the Noto Peninsula, Japan, where the westerly winds carry aerosols from continental and marine areas. During the sampling period on March 10, 2012, the air mass at 3000 m was transported from the Chinese desert region by the westerly winds, and a boundary layer was formed below 2000 m. Pyrosequencing targeting 16S rRNA genes (16S rDNA) revealed that the bacterial community at 3000 m was predominantly composed of terrestrial bacteria, such as Bacillus and Actinobacterium species. In contrast, those at 1000 m and 10 m included marine bacteria belonging to the classes Cyanobacteria and Alphaproteobacteria. The entire 16S rDNA sequences in the clone libraries were identical to those of the terrestrial and marine bacterial species, which originated from the Chinese desert region and the Sea of Japan, respectively. The origins of air masses and meteorological conditions contribute to vertical variations in the bacterial communities in downwind atmosphere. © 2015 Elsevier Ltd. All rights reserved.<br />Embargo Period 24 months
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| 71.
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Maki, Teruya ; Kobayashi, Fumihisa ; Yamada, Maromu ; Hasegawa, Hiroshi ; Iwasaka, Yasunobu
概要:
Bioaerosol particles including bacteria, fungi, and virus are originated from marine and terrestrial environments. The a
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irborne microorganisms are transported for long distance through the free troposphere and are thought to influence the downwind ecosystems and human life. However, microbial communities in the free troposphere have not been understood in detail because the direct sampling of microbial cells at high altitude requires sophisticated sampling techniques. In this study, for the investigation of microbial species compositions in the free troposphere, air sampling using an aircraft was performed over the Noto Peninsula in Japan, where the tropospheric winds carry aerosol particles from continental areas. Two air samples were collected at 3,000 m on March 27, 2010, when air mass was carried from the Gobi Desert to Japan area. Microorganisms from one air sample grew in culture media containing up to 15 % NaCl, suggesting that halotolerant bacteria maintain their viabilities in the free troposphere. DGGE analysis revealed that the amended cultures were dominated by Bacillus subtilis, and the isolates obtained from the amended cultures were identical to B. subtilis. Furthermore, the 16S rDNA clone library (culture-independent survey) of the other air sample grew was composed of three phylotypes belonging to Firmicutes, Bacteroidetes, and Proteobacteria with the sequences of Firmicutes phylotype corresponding to that of the cultured B. subtilis sequence. Microscopic observation using FISH method indicated that B. subtilis particles occupied 80 % of total eubacterial particles on the mineral particles. The halotolerant bacteria identical to B. subtilis would dominate at high altitudes over Noto Peninsula where the prevailing westerly wind was blowing. © 2012 Springer Science+Business Media Dordrecht.
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| 72.
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Kakikawa, Makiko ; Kobayashi, Fumihisa ; Maki, Teruya ; Yamada, Maromu ; Higashi, Tomomi ; Chen, Bin ; Shi, Guangyu ; Hong, Chunsang ; Tobo, Yutaka ; Iwasaka, Yasunobu
概要:
金沢大学環日本海域環境研究センター<br />The dust event injects microorganisms into the atmosphere and could facilitate the dispersal of b
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iological particles affecting leeward ecosystem and human health. In this study, the dustborne microorganisms in the atmosphere over the Taklimakan Desert, Asian dust source, were identified by culture-independent method. Dusts were collect-ed using a balloon at about 800 m above the ground in an Asian dust source region, Dunhuang. After DNAwere directly extracted from the dusts collected filters, 16S and 18S rRNA genes of microorganisms were amplified, cloned, and sequenced. The rDNA sequence data indicated that dust particles include fungi closely related to Rickenella fibula, Ceriporiopsis gilvescens, and bacteria belonging to the genus Brevibacillus, Staphylococcus, Rhodococcus, Delftia, Pseudomonas, and Agrobacterium tumefaciens. These results suggest that dust particles in the atmosphere over Dunhuang could carry these many fungi and bacteria and might play a significant role in leeward ecosystem. © 2009 The Author(s).
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| 73.
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Kakikawa, Makiko ; Kobayashi, Fumihisa ; Maki, Teruya ; Yamada, Maromu ; Higashi, Tomomi ; Chen, Bin ; Shi, Guangyu ; Hong, Chunsang ; Tobo, Yutaka ; Iwasaka, Yasunobu
概要:
金沢大学環日本海域環境研究センター生体機能計測研究部門<br />The dust event injects microorganisms into the atmosphere and could facilitate the disp
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ersal of biological particles affecting leeward ecosystem and human health. In this study, the dustborne microorganisms in the atmosphere over the Taklimakan Desert, Asian dust source, were identified by culture-independent method. Dusts were collected using a balloon at about 800 m above the ground in an Asian dust source region, Dunhuang. After DNA were directly extracted from the dusts collected filters, 16S and 18S rRNA genes of microorganisms were amplified, cloned, and sequenced. The rDNA sequence data indicated that dust particles include fungi closely related to Rickenella fibula, Ceriporiopsis gilvescens, and bacteria belonging to the genus Brevibacillus, Staphylococcus, Rhodococcus, Delftia, Pseudomonas, and Agrobacterium tumefaciens. These results suggest that dust particles in the atmosphere over Dunhuang could carry these many fungi and bacteria and might play a significant role in leeward ecosystem. © 2008 Springer Science+Business Media B.V.
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