巻号一覧
30 巻 (1969)
- 4 号 p. 125-
- 3 号 p. 87-
- 2 号 p. 45-
- 1 号 p. 1-
30 巻, 3 号
選択された号の論文の3件中1～3を表示しています
- |<
- <
- 1
- >
- >|
-
川村 輝良1969 年 30 巻 3 号 p. 87-97
発行日: 1969/10/28
公開日: 2009/10/16
ジャーナル フリー1. 洞爺湖においては, 1939年長和川水の導入以來, 湖水は漸次酸性化してきたが, 1963年頃より急速にすすみ, 1968年湖心でpH 5.8の低値を記録した。
2. 1958年以来湖水の酸性化に伴い, 動物プランクトン優占種に変遷がみられ, Daphnia (1958-1960) →Bosmina (1962-1967) →Cyclops (1968) と交代している。
3. 1968年10月, 11月に本湖に産したプランクトンの種類はすくなく, 動物プランクトン2種 (Cyclops strenuus, Scaphoreberis mucronata), 植物プランクトン5種 (Fragilaria crotonensis, Fragilaria sp., Synedra pulchella, Oedogonium sp., Peridinium sp.) を産するのみである。
4. 植物プランクトンクロロフィル量は10.24mg Chl. a/m2 (0.43mg Chl. a/m3) ～6.01mgChl. a/m2 (0.01mg Chl. a/m3) 程度で, 同じカルデラ湖支笏湖の量よりすくなく, また中部日本の貧栄養湖に比較してもすくない。
5. 湖心部の湖水に相当する pH 5.8の酸性水 (湖水と池用水を混合) は Scenedesmus sp.の光合成活性を著しく抑制することがたしかめられ, その活性は池用水 (pH 7.4) の1/6に減少した。
6. pH5.0の酸性水 (ベンケイ川水と池用水を混合) はDaphnia pulexを4日以内で死滅せしめるが, Cyclops strenuusは同じ酸性水で同期間全個体が生存し得る。
7. 最近の洞爺湖の第一次生産者の現存量はきわめて貧弱であり, その原因の一つとして湖水の酸性化が考えられる。抄録全体を表示PDF形式でダウンロード (1089K) -
小林 弘, 山下 不二子1969 年 30 巻 3 号 p. 98-107
発行日: 1969/10/28
公開日: 2009/10/16
ジャーナル フリーTaxonomical and floristical aspects of the diatoms from Sanpoji-ike Bog were already reported as a part of the report of the diatoms from ponds and pools in the vicinity of Tokyo (H. Kobayasi, 1968). In order to obtain more precise information on the diatom community, present investigations concerning the distribution and the ecological analysis were carried out.
Sanpoji-ike Bog is a small and shallow peaty bog located in the western district of Tokyo. It is about 300 m in length, 120 m in breadth and about 1 m in depth. At present, though it has no watersoaked bog margin or mat because of the construction of artificial promenade around the margin. There is a floating mat in the center and a considerable amount of peat deposits in the bottom.
As shown in Table 1, the pH value is about 6. 5, being slightly acidic as usual, except in a shorter period of mid-summer when it shifts to weakly alkaline side. Stations from which materials were collected are shown in Fig. 1.
Many species of Eunotia and Pinnularia and some species of Tabellaria and Frusturia which are considered to be peculiar to such acid waters were also found in this bog.
About 30% of the dominant or common species shown in Table 2, were recognizable as acidphilous forms.
Fragilaria was vigorous in the materials from the sunny St. 1, 2 and 3, whereas Eunotia was in the materials from St. 4, 5 and 6 where garden trees make them shady.抄録全体を表示PDF形式でダウンロード (4374K) -
深層水の侵入による水温分布の急変岡本 巌, 八木 和繁1969 年 30 巻 3 号 p. 108-118
発行日: 1969/10/28
公開日: 2009/10/16
ジャーナル フリーA drastic change of water temperature which amounted up to 8°C in the bottom layer was by chance found in the southern basin of Lake Biwa-ko during the period of routine observation in August 1967. At the same time, an automatic recorder for water temperature installed at Biwa-ko Ohashi Bridge caught a remarkable variation of temperature.
On analyzing the records, two kinds of oscillatory change have been indicated. One of them, whose period is 4 hours, is caused by an ordinary seiche on the occasion of horizontal gradient of temperature existing in that region. The other, which has a period of 43 hours with an amplitude of 4°C, may be caused by an internal seiche in the northern basin, because its period is computed at 42 hours on assuming a free uninodal oscillation of two layers. Successive measurements of the water current performed at the fixed station have shown that the no-flow level between the upper layer flowing northwards and the lower layer flowing southwards has gradually ascended together with the rise of thermocline level.
A remarkable depression of temperature observed in the southern basin occurred owing to the intrusion of cold deep water of the northern basin accompanied with an internal seiche mentioned above. The water volume of the intrusion is calculated at 4×107m3, on the assumption of the conservation of water mass and of heat content.抄録全体を表示PDF形式でダウンロード (1035K)
- |<
- <
- 1
- >
- >|