| Project/Area Number |
10640474
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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 |
地球化学
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| Research Institution | Nagoya University |
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Principal Investigator |
YOSHIOKA Takahiko Nagoya University, Institute for Hydrospheric-Atmospheric Sciences, Research Associate, 大気水圏科学研究所, 助手 (50202396)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1998: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | dissolved organic matter / three dimensional fluorescence property / dissolved organic carbon / allochthonous organic matter / autochthonous organic matter / stable carbon isotope ratio / タンパク質 / 腐植物質 / 自生性有機物 |
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| Research Abstract |
Origin and variation of dissolved organic matter (DOM) in freshwater environments were studied with three dimensional fluorescence (excitation-emission matrix, EEM) and stable carbon isotope ratio measurements. In the EEM, one protein-like fluorescence peak and two humic-like fluorescence peaks were identified. It was suggested that the former peak might indicate the autochthonous DOM produced in lascustrine environments, and the latter peaks might indicate the allochthonous DOM from land environments. The humic-like fluorescence peaks were partially separated by the tangential-flow ultrafiltration technique. It suggested these peaks were composed of, at least, two different compounds,. Judging from the EEM properties, humic-like peaks corresponded to fulvic acid. Because EEM showed a blue-shift from stream to lake waters, alteration of humic substance was indicated. The clear relationship between dissolved organic carbon (DOC) concentration and and humic-like fluorescent intensity was observed for the stream waters in Lake Biwa watershed. Using the linear regression between DOC and fluorescent intensity, the contribution of allochthonous (derived from forest) organic carbon in DOC was successfully estimated. Allochthonous DOC showed heterogeneous distribution in the north basin of Lake Biwa. The fraction of autochthonous DOC changed largely with the depth and the seasons. This study reveals the usefulness of EEM for investigating DOM dynamics. Since almost same results were obtained from the Lake Baikal watershed, the EEM technique would be applicable widely in lacustrine environments. Stable carbon isotope ratio (δィイD113ィエD1C) of DOC was also useful indicator for the origin of DOC in Lake Biwa. Both EEM and δィイD113ィエD1C will be the powerful tools for DOM studies in aquatic environments.
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