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Rahman, M. Azizur ; Hasegawa, Hiroshi
概要:
Rice is the staple food for the people of arsenic endemic South (S) and South-East (SE) Asian countries. In this region,
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arsenic contaminated groundwater has been used not only for drinking and cooking purposes but also for rice cultivation during dry season. Irrigation of arsenic-contaminated groundwater for rice cultivation has resulted high deposition of arsenic in topsoil and uptake in rice grain posing a serious threat to the sustainable agriculture in this region. In addition, cooking rice with arsenic-contaminated water also increases arsenic burden in cooked rice. Inorganic arsenic is the main species of S and SE Asian rice (80 to 91% of the total arsenic), and the concentration of this toxic species is increased in cooked rice from inorganic arsenic-rich cooking water. The people of Bangladesh and West Bengal (India), the arsenic hot spots in the world, eat an average of 450. g rice a day. Therefore, in addition to drinking water, dietary intake of arsenic from rice is supposed to be another potential source of exposure, and to be a new disaster for the population of S and SE Asian countries. Arsenic speciation in raw and cooked rice, its bioavailability and the possible health hazard of inorganic arsenic in rice for the population of S and SE Asia have been discussed in this review. © 2011 Elsevier B.V.
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| 2.
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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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| 3.
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論文
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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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| 4.
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論文
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Rahman, M. Azizur ; Hasegawa, Hiroshi ; Mahfuzur, Rahman M. ; Mazid, Miah M.A. ; Tasmin, A.
概要:
金沢大学大学院自然科学研究科物質情報解析<br />Although human exposure to arsenic is thought to be caused mainly through arsenic-contaminated
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underground drinking water, the use of this water for irrigation enhances the possibility of arsenic uptake into crop plants. Rice is the staple food grain in Bangladesh. Arsenic content in straw, grain and husk of rice is especially important since paddy fields are extensively irrigated with underground water having high level of arsenic concentration. However, straw and husk are widely used as cattle feed. Arsenic concentration in rice grain was 0.5±0.02 mg kg-1 with the highest concentrations being in grains grown on soil treated with 40 mg As kg-1 soil. With the average rice consumption between 400 and 650 g/day by typical adults in the arsenic-affected areas of Bangladesh, the intake of arsenic through rice stood at 0.20-0.35 mg/day. With a daily consumption of 4 L drinking water, arsenic intake through drinking water stands at 0.2 mg/day. Moreover, when the rice plant was grown in 60 mg of As kg-1 soil, arsenic concentrations in rice straw were 20.6±0.52 at panicle initiation stage and 23.7±0.44 at maturity stage, whereas it was 1.6±0.20 mg kg-1 in husk. Cattle drink a considerable amount of water. So alike human beings, arsenic gets deposited into cattle body through rice straw and husk as well as from drinking water which in turn finds a route into the human body. Arsenic intake in human body from rice and cattle could be potentially important and it exists in addition to that from drinking water. Therefore, a hypothesis has been put forward elucidating the possible food chain pathways through which arsenic may enter into human body. © 2007 Elsevier Inc. All rights reserved.
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| 5.
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論文
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Rahman, M. Azizur ; Hasegawa, Hiroshi ; Mahfuzur, Rahman M. ; Nazrul, Islam M. ; Majid, Miah M.A. ; Tasmin, A.
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<br />A glass house experiment was conducted to investigate the effect of soil arsenic
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on photosynthetic pigments, chlorophyll-a and -b, and their correlations with rice yield and growth. The experiment was designed with three replications of six arsenic treatments viz. control, 10, 20, 30, 60, 90 mg of As kg-1 soil. Arsenic concentration in initial soil, to which the above mentioned concentrations of arsenic were added, was 6.44 ± 0.24 mg kg-1. Both chlorophyll-a and -b contents in rice leaf decreased significantly (p < 0.05) with the increase of soil arsenic concentrations. No rice plant survived up to maturity stage in soil treated with 60 and 90 mg of As kg-1. The highest chlorophyll-a and -b contents were observed in control treatment (2.62 ± 0.24 and 2.07 ± 0.14 mg g-1 were the average values of chlorophyll-a and -b, respectively of the five rice varieties) while 1.50 ± 0.20 and 1.04 ± 0.08 mg g-1 (average of five rice varieties) of chlorophyll-a and -b, respectively were the lowest. The content of photosynthetic pigments in these five rice varieties did not differ significantly (p > 0.05) from each other in control treatment though they differed significantly (p < 0.05) from each other in 30 mg of As kg-1 soil treatment. Among the five rice varieties, chlorophyll content in BRRI dhan 35 was found to be mostly affected with the increase of soil arsenic concentration while BRRI hybrid dhan 1 was least affected. Well correlations were observed between chlorophyll content and rice growth and yield suggesting that arsenic toxicity affects the photosynthesis which ultimately results in the reduction of rice growth and yield. © 2006 Elsevier Ltd. All rights reserved.
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