著者

田崎 和江 縄谷 奈緒子 国峯 由貴江 森川 俊和 名倉 利樹 脇元 理恵 朝田 隆二 渡辺 弘明 永井 香織 池田 頼正 佐藤 一博 瀬川 宏美 宮田 浩志郎

出版者

日本地質学会

雑誌

地質學雜誌 (ISSN:00167630)

巻号頁・発行日

vol.108, no.7, pp.435-452, 2002-07-15

被引用文献数

3 5

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1991年12月,排砂ゲートを設けた出し平ダム(富山県黒部川水系1985年設立)から,初の直接排砂が行われ,その際,多量のヘドロが排出された.その後も1999年までに計8回の排砂が行われた.本研究において,出し平ダム湖および富山湾堆積物の特性について分析を行った.その結果,特に芦野沖にヘドロが堆積していること,そして,富山湾堆積物は他の湾堆積物と比べカオリン鉱物,スメクタイトが多く,出し平ダム湖堆積物と類似した粘土鉱物組成を持つことが明らかとなった.実験より,ニジマスのエラにスメクタイトが吸着することで,エラの変形や脱水を引き起こすことが明らかとなり,また,富山湾で採取されたヒラメのエラ表面が,微細粒子で覆われているのが観察された.以上の結果と1991年から1999年の出し平ダム排砂量とヒラメの漁獲量の変遷には密接な関係が認められ,ダム湖や富山湾底質の経時変化を観察することの重要性が示された.

著者

田崎 和江 国峯 由貴江 森川 俊和

出版者

The Clay Science Society of Japan

雑誌

粘土科学 (ISSN:04706455)

巻号頁・発行日

vol.41, no.2, pp.64-74, 2001-12-31 (Released:2011-09-20)

参考文献数

29

被引用文献数

1

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In 1985, Dashidaira dam with discharge gate had been built for the first time in Japan, at Kurobe River in Toyama Prefecture. Six years later, in 1991, the dam sediments were flushed out for the first time and impacted on the downstream of Kurobe River. The dam sediments and the suspension contained a large amount of organic matter (with high C, N and S contents) with sludge-smell. The annual catch of bentic fishes (exp. flatfish) and the annual haul of wakame seaweed have been decreased year by year since the first discharge of the dam sediments in 1991. Until now, it has been reported that the sludge has deposited in the Toyama Bay which is apprehensive of influence of discharged dam sediments, because suspended particles affect the fish's gill respiration.In this study, suspension of river water were collected at three bridges during discharge from Dashidaira and Unazuki Dam in June 19th-22nd and in June 30th-July 2nd, 2001. River water quality and suspended solid were analyzed chemically, physically and mineralogically. Extremely low DO and Eh values were observed at the periods during first discharge in June 19th-22nd at two bridges. Moreover, during second discharge in June 30th-July 2nd, DO and Eh values were constant. Therefore it was shown that drastic decreased of DO and Eh values were a peculiar phenomenon during first discharge in June 19th-22th, 2001. The results of NCS elemental analyses were suggested that high organic contents were related with drastic decreased of DO and Eh values. Clay mineralogy of both Unazuki Dam sediments and suspended solid on the seabed at the offing of Kurobe River mouth, show abundant semctite with chlorite, mica clay minerals and kaolin minerals, suggesting those are the almost same origin. The dam sediments associated with organic matter impacted on downstream and the seabed, and was the cause of affecting bentic fishes and wakame seaweed.