1.

論文

論文
Maki, Teruya ; Hirota, Wakana ; Motojima, Hiroyuki ; Hasegawa, Hiroshi ; Rahman, Mohammad Azizur
出版情報: Chemosphere.  83  pp.1486-1492,  2011-06-01.  Elsevier
URL: http://hdl.handle.net/2297/27099
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 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. 続きを見る
2.

論文

論文
Hasegawa, Hiroshi ; Rahman, M. Azizur ; Kitahara, K. ; Itaya, Y. ; Maki, Teruya ; Ueda, K.
出版情報: The Science of the total environment.  408  pp.1684-1690,  2010-03-01.  Elsevier
URL: http://hdl.handle.net/2297/24577
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 invest igated. 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. 続きを見る
3.

論文

論文
Hasegawa, Hiroshi ; Rahman, Ismail M. M. ; Kinoshita, Sanae ; Maki, Teruya ; Furusho, Yoshiaki
出版情報: Chemosphere.  82  pp.1161-1167,  2011-02-01.  Elsevier
URL: http://hdl.handle.net/2297/27092
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 aqueous 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. 続きを見る
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論文

論文
Habibullah, M. ; Das, Kamalendra N. ; Rahman, Ismail M. M. ; Uddin, M. Ashraf ; Saifuddin, Khaled ; Iwakabe, Koichi ; Hasegawa, Hiroshi
出版情報: Journal of Chemical and Engineering Data.  55  pp.5370-5374,  2010-11-11.  American Chemical Society
URL: http://hdl.handle.net/2297/26261
概要: 金沢大学理工研究域物質化学系<br />Densities and viscosities of binary liquid mixtures of hexan-1-ol + o-xylene, + m-xylene, or + p-xylene were measured at a number of mole fractions at T = (308.15 and 318.15) K and atmospheric pressure. The excess volumes and the viscosity deviations from the mole fraction average were calculated from the experimental density and viscosity data. The experimental data were correlated with Redlich-Kister equation. Variations in the calculated excess and deviation properties for the liquid mixtures were studied in terms of intermolecular interactions. © 2010 American Chemical Society. 続きを見る
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論文
Hasegawa, Hiroshi ; Rahman, M. Azizur ; Saitoh, K. ; Ueda, K.
出版情報: Journal of Plant Nutrition.  33  pp.933-942,  2010-04-01.  Taylor & Francis
URL: http://hdl.handle.net/2297/24293
概要: 金沢大学理工研究域物質化学系<br />The effect of chelating ligands on iron (Fe) uptake and growth of radish (Raphanus sativus L.) was investigated. The ethylenediaminetetraacetic acid (EDTA) increased 55Fe uptake in roots of radish though its subsequent translocation from roots to shoots and leaves did not increase. About 70%-80% of the total 55Fe was distributed in the roots while about 5%-15% and 11%-17% were in shoots and leaves, respectively. The EDTA increased iron uptake into the roots of radish, but not in the above ground parts of the plant. The growth of radish (Raphanus sativus L.) decreased drastically in alkaline condition (pH > 9), even though the concentration of iron was sufficient in the growth medium. The growth of radish was enhanced successfully by the addition of hydroxyiminodisuccinic acid (HIDS) and EDTA. This might be because HIDS and EDTA solubilize iron from its precipitation with hydroxides at higher pH, and increase iron bioavailability. The influence of EDTA and HIDS on radish growth was comparable. Increase of radish growth by ethylenediaminedisuccinic acid (EDDS) and methylglicinediacetic acid (MGDA) was less than those by EDTA and HIDS. Considering the reproducibility of the radish growth (biomass production) at pH 10, HIDS is supposed to be more effective compared to EDTA. © Taylor & Francis Group, LLC. 続きを見る
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論文
Hasegawa, Hiroshi ; Rahman, M.A. ; Saitou, K. ; Kobayashi, M. ; Okumura, C.
出版情報: Environmental and Experimental Botany.  71  pp.345-351,  2011-07-01.  Elsevier BV
URL: http://hdl.handle.net/2297/27093
概要: 金沢大学理工研究域物質化学系<br />In this study, the effects of chelating ligands on iron movement in growth medium, iron bioava ilability, and growth of radish sprouts (Raphanus sativus) were investigated. Iron is an important nutrient for plant growth, yet the insoluble state of iron hydroxides in alkaline conditions decreases its bioavailability. Iron chelates increase iron uptake and have been used in agriculture to correct iron chlorosis. While previous studies have reported the effects of chelating ligands on iron solubility and bioavailability, the present study elucidates the pattern of iron movement by chelating ligands in plant growth medium. The apparent mobility of iron in growth medium was calculated using a '4-box' model. Ethylenediaminedisuccinic acid (EDDS) and hydroxy-iminodisuccinic acid (HIDS) produced the highest apparent mobility of iron from the bottom layer of the medium (initially 10-4M Fe(III)) to the upper layer (no iron), followed by glutamatediacetic acid (GLDA), ethylenediaminetetraacetic acid (EDTA), methylglycinediacetic acid (MGDA), and iminodisuccinic acid (IDS). Iron movement in the growth medium was influenced by the chelating ligand species, pH, and ligand exposure time. The iron uptake and growth of radish sprouts were related to the iron mobility produced by the chelating ligands. These results suggest that, in alkaline media, chelating ligands dissolve the hardly soluble iron hydroxide species, thus increasing iron mobility, iron uptake, and plant growth. HIDS, which is biodegradable, was one of the most effective ligands studied; therefore, this compound would be a good alternative to other environmentally persistent chelating ligands. © 2011 Elsevier B.V.<br />2011年8月より全文公開. 続きを見る
7.

論文

論文
Hasegawa, Hiroshi ; Rahman, M. Azizur ; Saitou, K. ; Kobayashi, M. ; Okumura, Chikako
出版情報: Environmental and Experimental Botany.  71  pp.345-351,  2011-07-01.  Elsevier B.V.
URL: http://hdl.handle.net/2297/27307
概要: In this study, the effects of chelating ligands on iron movement in growth medium, iron bioavailability, and growth of radish sprouts (Raphanus sativus) were investigated. Iron is an important nutrient for plant growth, yet the insoluble state of iron hydroxides in alkaline conditions decreases its bioavailability. Iron chelates increase iron uptake and have been used in agriculture to correct iron chlorosis. While previous studies have reported the effects of chelating ligands on iron solubility and bioavailability, the present study elucidates the pattern of iron movement by chelating ligands in plant growth medium. The apparent mobility of iron in growth medium was calculated using a '4-box' model. Ethylenediaminedisuccinic acid (EDDS) and hydroxy-iminodisuccinic acid (HIDS) produced the highest apparent mobility of iron from the bottom layer of the medium (initially 10-4M Fe(III)) to the upper layer (no iron), followed by glutamatediacetic acid (GLDA), ethylenediaminetetraacetic acid (EDTA), methylglycinediacetic acid (MGDA), and iminodisuccinic acid (IDS). Iron movement in the growth medium was influenced by the chelating ligand species, pH, and ligand exposure time. The iron uptake and growth of radish sprouts were related to the iron mobility produced by the chelating ligands. These results suggest that, in alkaline media, chelating ligands dissolve the hardly soluble iron hydroxide species, thus increasing iron mobility, iron uptake, and plant growth. HIDS, which is biodegradable, was one of the most effective ligands studied; therefore, this compound would be a good alternative to other environmentally persistent chelating ligands. © 2011 Elsevier B.V. 続きを見る
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論文

論文
Azizur Rahman, Mohammad ; Kadohashi, K. ; Maki, Teruya ; Hasegawa, Hiroshi
出版情報: Environmental and Experimental Botany.  72  pp.41-46,  2011-08-01.  Elsevier B.V.
URL: http://hdl.handle.net/2297/27775
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. 続きを見る
9.

論文

論文
Maki, Teruya ; Hirota, Wakana ; Motojima, Hiroyuki ; Hasegawa, Hiroshi ; Rahman, Mohammad Azizur
出版情報: Chemosphere.  83  pp.1486-1492,  2011-06-01.  Elsevier
URL: http://hdl.handle.net/2297/27820
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 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. 続きを見る
10.

論文

論文
Azizur Rahman, Mohammad ; Hasegawa, Hiroshi
出版情報: Chemosphere.  83  pp.633-646,  2011-04-01.  Elsevier
URL: http://hdl.handle.net/2297/27774
概要: Phytoremediation, a plant based green technology, has received increasing attention after the discovery of hyperaccumulating plants which are able to accumulate, translocate, and concentrate high amount of certain toxic elements in their above-ground/harvestable parts. Phytoremediation includes several processes namely, phytoextraction, phytodegradation, rhizofiltration, phytostabilization and phytovolatilization. Both terrestrial and aquatic plants have been tested to remediate contaminated soils and waters, respectively. A number of aquatic plant species have been investigated for the remediation of toxic contaminants such as As, Zn, Cd, Cu, Pb, Cr, Hg, etc. Arsenic, one of the deadly toxic elements, is widely distributed in the aquatic systems as a result of mineral dissolution from volcanic or sedimentary rocks as well as from the dilution of geothermal waters. In addition, the agricultural and industrial effluent discharges are also considered for arsenic contamination in natural waters. Some aquatic plants have been reported to accumulate high level of arsenic from contaminated water. Water hyacinth (Eichhornia crassipes), duckweeds (Lemna gibba, Lemna minor, Spirodela polyrhiza), water spinach (Ipomoea aquatica), water ferns (Azolla caroliniana, Azolla filiculoides, and Azolla pinnata), water cabbage (Pistia stratiotes), hydrilla (Hydrilla verticillata) and watercress (Lepidium sativum) have been studied to investigate their arsenic uptake ability and mechanisms, and to evaluate their potential in phytoremediation technology. It has been suggested that the aquatic macrophytes would be potential for arsenic phytoremediation, and this paper reviews up to date knowledge on arsenic phytoremediation by common aquatic macrophytes.. © 2011 Elsevier Ltd. 続きを見る