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Title Transcription
コスイ カンキョウ ノ ジンイテキ カイゾウ ト テイセイ ユウコウチュウ ノ グンシュウ ヘンカ ソノ7 ケイソウ CYCLOTELLA ノ サンシュツ ニヨル タイセキ ネンダイ ノ スイテイ ト ソノ イギ
Title Alternative (English)
Benthic Foraminiferal Changes in Relation to Human Activities(Part 7) : Age Estimaton of Sediment by Using Diatom Cyclotella and its Significance
File
language
jpn
Author
Nomura, Ritsuo
Description
Recent occurrences of diatom Cyclotella spp. are significant in brackish Lake Nakaumi. Based on the surface sediment, Kashima and Noguchi(1983) suggested that these diatom taxa became developed during the time of 1960's to 1980's. If the Cyclotella occurrence can be traced in the sediment core, an age estimation may be possible with some hypotheses.
In order to elucidate this Cyclotella occurrence, I examined the sediment core from the central part of Lake Nakaumi, and found a significant change of the relative abundance at 2.5-3.0cm sub-bottom depths. Since Cyclotella taxa are basically adapted to fresh water or lower saline brackish water, the dominant occurrence of Cyclotella in Lake Nakaumi may be mostly due to the transportation from Lake Shinjiko, Yonago Embayment, and other fresh water areas. A total area of Lake Nakaumi was reduced to about 77% of the original by a land reclamation project of the Honjyo area, and thereby the transported diatom accumulated in more high abundance in main Lake Nakaumi than before. The Ohmisaki embankment completed in 1978 and then controlled the dispersion of Cyclotella occurrence. If this age applies to the sediment core, sedimentation rate can be estimated to 0.0416~0.0526g/cm^2/year. This sedimentation rate is conformable to the previously reported values.
Subject
age estimation
Cyclotella
diatom
Lake Nakaumi
reclamation project
Journal Title
Laguna : 汽水域研究
Volume
6
Start Page
123
End Page
127
ISSN
21852995
Published Date
1999-03
NCID
AN10439529
Publisher
島根大学汽水域研究センター
NII Type
Departmental Bulletin Paper
Format
PDF
Text Version
出版社版
OAI-PMH Set
Estuary Research Center
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