2006 Fiscal Year Final Research Report Summary
Study on Accumulation Mechanisms of As and Cd in Hyperaccumulator Plants by X-ray Analysis and its Application for Phytoremediation of Heavy Metals
| Project/Area Number |
17350040
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Analytical chemistry
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| Research Institution | Tokyo University of Science |
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Principal Investigator |
NAKAI Izumi Tokyo University of Science, Department of Applied Chemistyr Faculty of Science, Professor, 理学部, 教授 (90155648)
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| Co-Investigator(Kenkyū-buntansha) |
HOKURA Akiko Tokyo University of Science, Department of Applied Chemistyr Faculty of Science, Research assistant, 理学部, 助教 (20343569)
TERADA Yasuko JASRI, Research & Utilization Division, Senior researcher, 利用研究促進部門・XAFS・分析チーム, 副主幹研究員 (90307695)
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| Project Period (FY) |
2005 – 2006
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| Keywords | synchrotron radiation micro beam / XAFS / chemical speciation analysis / phytoremediation / arsenic / cadmium / high-energy X-ray / elemental mapping |
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| Research Abstract |
We have developed an in vivo micro-X-ray fluorescence (μ-XRF) imaging technique and X-ray absorption near edge structure (XANES) analysis utilizing synchrotron radiation (SR) to determine the distribution of arsenic and cadmium in the tissues and cells of hyperaccumulator plants and to investigate their physiology and mechanism of heavy-metal accumulations. These plants are expected to be used for phytoremediation.
The arsenic distribution in the arsenic hyper-accumulating fern, Pteris vittata L., was investigated using a SR-XRF microprobe. The focused microbeam (3.5 x 5.5 μm2) produced by Kirkpatrick-Baez optics was applied to the fern to reveal the elemental distribution in plant tissue and cell levels. The results indicated that high levels of arsenic accumulate at the base of sporangium with lamina of pinnae. Also, the fern was subjected to XANES analysis without any sample treatment to elucidate directly the arsenic oxidation state in fern. It was found that arsenic exists as the As(III) form in pinnae, and as a mixture of As(III) and As(V) in rachis, while As(V) is present in cultivated soil. These findings indicate that the fern uptakes arsenic as As(V) from soil and that the As(V) is then partially reduced to As(III) within the plant, and finally accumulated as As(III) in a specific area of the pinna.
On the other hand, μ-XRF imaging using high-energy SR X-ray was carried out on trichomes prepared from the leaves of Arabidopsis halleri ssp. gemmifera, cadmium hyperaccumulating plant. The two-dimensional cellular distribution of cadmium in the trichomes was first observed by in vivo μ-XRF imaging. It was found that both cadmium and zinc accumulated at high level in the base of the bifurcation area of the trichomes, whereas strontium and calcium were mostly distributed throughout the entire upper part of the trichomes. These distributions of cadmium and zinc showed striking subcellular compartmentation.
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Research Products
(13 results)
