1988 Fiscal Year Final Research Report Summary
Environmental Changes of the Lake Naka-no-umi and Shinji Lake
| Project/Area Number |
60400009
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
広領域
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| Research Institution | Faculty of science, Shimane University |
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Principal Investigator |
MITSUNASHI Takashi Professor, Faculty of Sci., Shimane Univ., 理学部, 教授 (90127499)
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| Co-Investigator(Kenkyū-buntansha) |
MIYATA Itsuo Professor, Faculty of Sci., Shimane Univ., 理学部, 教授 (90069948)
HASHITANI Hiroshi Professor, Faculty of Sci., Shimane Univ., 理学部, 教授 (00156267)
TAKAYASU Katsumi Associate Professor, Fac. of Sci., Shimane Univ., 理学部, 助教授 (00127490)
ONISHI Ikuo Professor, Faculty of Sci., Shimane Univ., 理学部, 教授 (40032445)
TOKUOKA Takao Professor, Faculty of Sci., Shimane Univ., 理学部, 教授 (30025358)
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| Project Period (FY) |
1985 – 1988
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| Keywords | Natural History / Echo-sounding / Lake Sediments / Water quality criteria vegetation / aquatic plant / 植生 / 水草 |
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| Research Abstract |
In these four years the natural history of the Lake Naka-no-umi and Lake Shinji has been studied from mainly geological, geochemical and plant-ecological points of view. Recent bottom sediments were collected and analyzed at 248 points of Lake Shinji and 27 points of Lake Naka-no-umi. Columnar samples of 1 to 2 m thick have been obtained at several tens points and analysed on the basis of sedimentological and paleontological ( diatom, pollen, foraminifer, ostracoda and molluscs ) methods. Radiometric chronology of C14, Pb210 and Cs137 methods have clarified that the desiometric chronology of c14, pb210 and cs137 methods have clarified that the sedimentation rate is three times larger in Lake Shinji than in Lake Naka-noumi, that is, 0.107gr/cm/y in the former and 0.044gr/cm/y in the latter by pb210 method. The historically-known environmental changes from marine to fresh-water ( 350 years ago), and fresh-water to blackish water (150 years ago ) can be supported by faunal changes in the columnar sections. These ages can be evidenced by the above-mentioned chronologic methods. Surficial and vertical distribution of some elements contained in the sediment of bothlakes have been analyzed geochemically. Aquatic plants in Lake Shinji and vegetation of flora surrounding these lakes have been described areally and were illustrated on the vegetation map.
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Research Products
(13 results)
