2005 Fiscal Year Final Research Report Summary
Geochemical cycles of platinum group elements at the earth surface -Role of anthropogenic and cosmic sources-
| Project/Area Number |
15540466
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geochemistry/Astrochemistry
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| Research Institution | The University of Tokyo (2004-2005)
Tokyo Metropolitan University (2003) |
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Principal Investigator |
AMAKAWA Hiroshi The University of Tokyo, Ocean Research Institute, Associate Professor, 海洋研究所, 助教授 (60260519)
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| Project Period (FY) |
2003 – 2005
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| Keywords | platinum group elements / fire assay / standard sample JP-1 / sediment / PGE pattern / Nd isotopic ratio / scandium |
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| Research Abstract |
My research results are summarized as follows.
1. Development of high precision and sensitivity method for determining abundances of platinum group elements in solid samples.
I have developed high precision and sensitivity method for determining abundances of platinum group elements (PGE : Ru, Rh, Pd, Os, Ir and Pt) in solid samples by isotope dilution method (for Ru, Pd, Os, Ir and Pt) and external calibration method (only for Rh) using ICP-MS combined with a fire assay preconcentration technique. We applied this method to a standard rock JP-1 issued from the Geological survey of Japan (GSJ). The errors of PGE range 13-25%(2s ; n=5), which are comparable with those by the similar methods combined with chemical separation of PGE. Compared our data with the preferable data proposed by GSJ, the large deviations are observed for Ir. Various evidences indicate that our data are much more reliable than the preferable value.
2. Educidation of horizontal transport processes of elements in ocean using the Nd isotopic compositions of seawaters
To elucidate the horizontal transport processes of elements in ocean, I determined the vertical distribution of Nd isotopic compositions at four stations in the Northwest Pacific together with that of surface seawaters at the Northwest Pacific. These results suggest that Nd is involved in the active horizontal transport processes in the surface ocean (above 100-250m).
3. Development of high sensitivity method for determining abundances of scandium (Sc) in seawater and its application to marine chemistry
To test Sc as a possible indicator of continentally derived material to the ocean, we developed of high sensitivity method for determining abundances of Sc in seawater. The vertical profile at the station near the Hawaii Islands showed so called "nutrient type" one, which was similar with Y and lanthanides.
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