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Azizur Rahman, Mohammad ; Hasegawa, Hiroshi
概要:
Phytoremediation, a plant based green technology, has received increasing attention after the discovery of hyperaccumula
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ting 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.
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Hasegawa, Hiroshi ; Sohrin, Yoshiki ; Seki, Kayoko ; Sato, Mayuko ; Norisuye, Kazuhiro ; Naito, Kanako ; Matsui, Masakazu
概要:
金沢大学工学部<br />Arsenic transformations by freshwater algae have been studied under laboratory conditions. By the use of a
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new analytical method, we identified methylarsenic(III) species in the growth medium of green-alga Closterium aciculare incubated under axenic conditions. The arsenate concentration in the experimental medium began to decrease just after inoculation, and the levels of arsenite and methylarsenicals increased with the growth of C. aciculare. Initially, most of the arsenate was converted into arsenite, which peaked in concentration during the exponential phase. Methylarsenicals accumulated rapidly in the stationary phase. DMAA(V) production was enhanced when the ratio of phosphate to arsenate decreased in the culture medium. The levels of DMAA(V) increased continuously toward the end of the experiment. On the other hand, methylarsenic(III) species remained relatively steady during the stationary phase. Methylarsenic(III) species accounted for 0-35% of methylarsenicals. These results suggest that arsenite and methylarsenicals (containing methylarsenic(III) species) are supplied by phytoplankton, and serve as evidence of the origin of methylarsenic(III) species in natural waters. © 2001 Elsevier Science Ltd.
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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
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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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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
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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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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
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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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論文
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Tang, Ning ; Sato, Kousuke ; Tokuda, Takahiro ; Tatematsu, Michiya ; Hama, Hirotaka ; Suematsu, Chikako ; Kameda, Takayuki ; Toriba, Akira ; Hayakawa, Kazuichi
概要:
Airborne particulates were collected at a background site (Wajima Air Monitoring Station; WAMS) on the Noto Peninsula, J
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apan from January 2006 to December 2007. 1-, 2-nitropyrenes (1-, 2-NPs) and 2-nitrofluoranthene (2-NFR), in the particulates were determined with a sensitive HPLC method with chemiluminescence detection. The average concentrations were higher in winter than in summer. A meteorological analysis indicated that the air samples collected in winter were transported mainly from Northeast China over the Japan Sea. Both the concentration ratios of 2-NFR to 1-NP and 1-NP to pyrene were similar to those in Shenyang in Northeast China which located along the air transportation route to WAMS, but not in Kanazawa which near WAMS. These results strongly suggest that most of the atmospheric 1-, 2-NPs and 2-NFR at WAMS in winter were long range transported from Northeast China. © 2014 Elsevier Ltd. All rights reserved.
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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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論文
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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 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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論文
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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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