2004 Fiscal Year Final Research Report Summary
Identification of semi-refractory marine dissolved organic matter with life span from a half to one year.
| Project/Area Number |
14340166
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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 |
地球化学
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| Research Institution | University of Tsukuba |
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Principal Investigator |
HAMA Takeo University of Tsukuba, Graduate School of Life and Environmental Sciences, Assistant Professor, 大学院・生命環境科学研究科, 助教授 (30156385)
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| Co-Investigator(Kenkyū-buntansha) |
YANAGI Katsumi Kyusyu Sangyo University, Faculty of Engineering, Professor, 工学部, 教授 (10191149)
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| Project Period (FY) |
2002 – 2004
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| Keywords | dissolved organic matter / semi-refractor / stability / carbohydrate / bacterial cell wall / ^<15>N tracer method |
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| Research Abstract |
Experimental analyses have been carried out to study the early diagenetic processes of phytoplankton photosynthetic products, using natural microbial populations. The experimental results obtained in the last year showed that conversion to refractory organic compounds rapidly proceeds during the early stage of diagenetic process, and that bacterial population participates to this process. In this year, thus, we focused on the biogeochemical characterization of bacterial products. Further, the ^<15>N tracer experiment has been carried out as well as ^<13>C tracer one, to specify the semi-refractory dissolved organic matter. The following results have been obtained.
1.The concentration of dissolved d-alanine, which is a component of bacterial cell wall, on 240 days of decomposition experiments, accounted for 2% of the maximum concentration of cellular d-alanine. The"remaining ratio"of d-alanine is ten times higher than the other amino acids, indicating that cell wall organic materials are the possible components of semi-refractory dissolved organic matter.
2.^<15>N tracer method was applied to monitor the production and decomposition processes of dissolved organic nitrogen. The production of dissolved organic nitrogen continued until 30 days after the culture system has turned to dark, while the maximum production of dissolved organic carbon was found within a week. Thus, the C/N value of dissolved organic matter significantly varied through the early diagenetic stage of phytoplankton photosynthetic products.
3.These results indicate that organic species constituting semi-refractory dissolved organic matter, are unlikely directly supplied by phytoplankton. The transformation to refractory organic matter probably occurs during the early diagenetic stage using labile phytoplankton organic compounds.
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Research Products
(2 results)
