巻号一覧
39 巻 (1978)
- 4 号 p. 147-
- 3 号 p. 97-
- 2 号 p. 49-
- 1 号 p. 1-
39 巻, 2 号
選択された号の論文の6件中1～6を表示しています
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堀内 清司1978 年 39 巻 2 号 p. 49-54
発行日: 1978/04/30
公開日: 2009/10/21
ジャーナル フリーThe movement of lake water can be mainly divided into two, steady and non-steady movement. In small lakes, most of the movements are non-steady and among them, wind-driven current is distinguished. This current, as well as waves, sweeps over lake sediments. As a natural consequence, the grain size of sediments is greatly influenced by the movement of lake water.
In this paper, the author sampled sediments of three lakes such as Lake Kizaki, Yuno-ko and Lake Ohnuma and tried to find the relationship between movement of lake water and grain sizes based on the analysis of horizontal distribution of grain size. By this analysis, mean diameter, skewness coefficient and sorting coefficient are available. The current observation is performed by using current drag. As a result, the values of median diameter seem to represent the relative strength of lake water movement but not the absolute one. Skewness coefficient seems to be applicable to clarify the secondary state of lake water movements so that mud can be separated from sediment, then transported and deposited in some other places.抄録全体を表示PDF形式でダウンロード (922K) -
金成 誠一1978 年 39 巻 2 号 p. 55-60
発行日: 1978/04/30
公開日: 2009/10/21
ジャーナル フリーSedimentation rate in oceans and lakes is usually determined by the ratio of the core length to the incremental age between two horizons. However, the sedimentation rate determined by the above-mentioned method never represents the true value because the core length used in such an estimation is not corrected for the consolidation effect.
In the present paper, the author derives a simple theoretical relationship between the thickness of lacustrine sediments and their ages on the basis of a simple consolidation model and he introduces a rigorous expression for the sedimentation rate at the bottom surface in lakes of the past.抄録全体を表示PDF形式でダウンロード (833K) -
中尾 欣四郎, 山下 武男1978 年 39 巻 2 号 p. 61-65
発行日: 1978/04/30
公開日: 2009/10/21
ジャーナル フリーIn June of 1976, the sedimentary structures of bottom deposits were surveyed by the seismic profiler “UNIBOOM” in Lake Abashiri. The profilings were a first trial in Japanese lakes.
Lake Abashiri is situated in the Eastern part of Hokkaido Island, 7.2km upstream from the estuary of River Abashiri which discharges to the Ohotsk Sea. It is a maritime coastal lake with mean altitude of 0.35m above sea level, and the morphometric features are as follows : area, 32.8km2, maximum depth 16.1m : mean depth, 6.1m : length, 12km : maximum breadth, 4km : and shore development, 2.18.
Continuous seismic reflection profilings were made along five lines traversing the lake as shown by Fig. 1. As a result of the seismic profilings (Fig. 3), two peculiar evidences were observed in the features of strata. One was the disturbances in the strata which appeared at a water depth of about 10m, off both the shores on the each of the lines except for E-E' line, which is shallower than 10m. Another was the presence of strong reflection strata in the level of 12m below the water surface under the trench bottom. The trench (the so called fairway) is carved on the lake floor from the outlet to the point of 300m up D-D' line at the depth of 12.5m, on D-D' line the maximum water depth of trench is 12m, the floor depression is 1.2m in depth, 40m in width, while on E-E' line, the respective measurements are 8.8m, 2.6m and 100m. The trench cannot be carved by the present tidal actions because the water depth is too large to erode the lake floor.
If it is inferred from the above mentioned facts that the lake levels were lower about 10m than present lake levels at the ancient time, then the positions of disturbed strata may be situated at the ancient shore line of the lake reduced and the strong reflection strata under the trench of E-E' line may be corresponded to the past river bed.抄録全体を表示PDF形式でダウンロード (988K) -
梶原 昌弘1978 年 39 巻 2 号 p. 66-74
発行日: 1978/04/30
公開日: 2009/10/21
ジャーナル フリーFrom the point of view of flocculation, the mechanisms of particle formation and size distribution in situ are reviewed and discussed.
In the sea, particles of different sizes are controlled by two forces; one is the cohesive force due to bacterial associations, chemical interactions and electrokinetic forces acting on particles, and the other is the destructive force mainly due to shearing stress in turbulent motion. When some agitations such as the forces accompanied with sampling and mixing are applied, particles which are in equilibrium under the two forces possibly change their size distribution. Accordingly, the size determination by a microscope and/or a Coulter Counter may possibly fail to show the real size distribution in situ. Some opinions stressed that the large visible flocculent particle do not make up a significant bulk of either organic or inorganic particles in water. However, considering the possibility that the flocculent particles in situ may be sinking with repeated coagulation and disintegration corresponding to the change of conditions mentioned above, the particle size in situ should be investigated with respect to sedimentation and the metabolism of chemical substances.抄録全体を表示PDF形式でダウンロード (1315K) -
伊藤 保1978 年 39 巻 2 号 p. 75-81
発行日: 1978/04/30
公開日: 2009/10/21
ジャーナル フリーWater samples were collected in Lake Biwa at monthly intervals from April to October in 1976 (except July) in front of Biwako-bunkakan. Each sample was passed through a Millipore filter (pore size : 0.45μm). The filtrate was concentrated by vacuum evaporation (100 : 1) at a temperature of less than 35°C. The concentrated solution was passed through a 'Sephadex G-10' column, 2.5 cm×85 cm. Ultraviolet absorbance (220 nm and 250 nm) and the concentrations of dissolved organic carbon (DOC) and carbohydrate (DCC) were determined for the eluted and concentrated solutions. The concentration of chlorophyll-a in the original water sample was determined.
(1) The concentration of chlorophyll-a ranged from 12.8 μg/l to 23.3 μg/l, that of DOC was from 1.74 mg-C/l to 3.98 mg-C/l, and that of DCC from 0.23 mg-C/l to 0.77 mg/C/l.
(2) Absorbance at 250 nm was observed to have a good relation to DOC concentration. (DOC mg-C/l =9×A250)
(3) The chromatogram was composed of four peaks. The first peak (elution volume, 150-160 ml) mainly consisted of DCC which has molecular weights of about 700 and above. The concentration of DCC increased with that of chlorophyll-a. This fact and previous studies suggest that DCC has been produced in situ in Lake Biwa. The second peak (elution volume, 160-170 ml) and the third peak (elution volume, 210-220 ml) failed to show a correlation to the chlorophyll-a concentration. The fourth peak, which was eluted with inorganic carbon at about 300 ml, decreased with the concentration of chlorophyll-a, and its ultraviolet absorption spectrum was characteristic.抄録全体を表示PDF形式でダウンロード (1055K) -
高橋 永治1978 年 39 巻 2 号 p. 82-91
発行日: 1978/04/30
公開日: 2009/10/21
ジャーナル フリーSeasonal changes of phytoplankton were studied with special reference to the Chrysophyceae in three ponds at Tsuruoka Park, Tsuruoka, Yamagata Prefecture from September in 1961 to September in 1962.
190 species, 15 varieties, and 2 forms of phytoplankton and 63 species and 9 varieties of zooplankton were recorded throughout the study period. 78 taxa of the Chlorococcales, 38 of the Chrysophyceae, and 37 of the Euglenophyceae formed 37.7%, 18.4%, and 17.9% of total number of phytoplankton species, respectively.
The highest density of total phytoplankter cells in each pond was found in August in Pond No. 1 (43, 000 cells/ml) and Pond No. 2 (90, 000 cells/ml), and in May in Pond No. 3 (19, 000 cells/ml). The lowest desity was recorded in February in Pond No. 2, and in March in Ponds Nos. 1 and 3 (300-400 cells/ml). The Chlorococcales occured abundantly throughout the years studied. The Cyanophyceae dominanted in summer, the Chrysophyceae in winter. A large number of the Volvocales, the Bacillariophyceae, and the Euglenophyceae were found at a few samplings.
The highest densities of phytoplankton cells, especially of the Chrysophyceae were found in winter when the temperature and pH values of pond waters were the lowest throughout the year. 3, 000 cells/ml in Pond No. 3 on February 6, 1962 was the highest value among three ponds, and occupied 78% of total phytoplankters in the pond.抄録全体を表示PDF形式でダウンロード (1630K)
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