All issues
Volume 31, Issue 4
Displaying 1-3 of 3 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kazuki MORI1970 Volume 31 Issue 4 Pages 111-128
Published: December 31, 1970
Released on J-STAGE: October 16, 2009
JOURNAL FREE ACCESSThe depth of inflowing layer into the artificial reservoir has been studied as a problem of density current. In this paper, the author tried to make clear the behavior of the water movement in the Sagami Reservoir, in particular, the trace of inflowing water and the process of circulation at the vertical profile.
From the results of observation, it may be considered that the movement of inflowing water in the reservoir is governed by the distribution of physical and chemical properties, especially, by the formation of thermal stratification. In the Sagami Reservoir, it was observed that the river water flows into the standing water, due primarily to temperature difference. The inflowing water flows into the equivalent density layer in reservoir water, forming a clear boundary between the inflowing and the standing water. A current flowing upstream is produced at the surface of the reservoir as a counter flow of the density current.
Taking into account of these hydraulic properties, it is concluded that the inflowing water which is warmed before it reaches the reservoir flows through directly to the outlet without making strong mixing. This may results in small advective heat transfer to the reservoir making exceptional characteristics as the Japanese artificial reservoir.View full abstractDownload PDF (2089K) -
Katsuya IWATA1970 Volume 31 Issue 4 Pages 129-151
Published: December 31, 1970
Released on J-STAGE: October 16, 2009
JOURNAL FREE ACCESSFood-growth relationships in terms of the nitrogen of yearling crucian carp (Carassius auratus cuvieri) held at 20°C for 20 days and fed at various ration levels using larvae of the chironomid (Chironomus plumosus) as food, was studied.
1) The efficiency of nitrogen absorption averaged 96.0%, and was independent of ration size.
2) The rate of nitrogen excretion of the fed fish increased in a curvilinear manner with increases in the nitrogen absorption rate.
3) The exogenous catabolic coefficient (α) : the ratio of exogenous nitrogen excretion to nitrogen absorption and net anabolic coefficient (1-α) were calculated. The net anabolic coefficients decreased exponentially with increases in the nitrogen absorption rate. Growth rate, in terms of nitrogen, was expressed by the following formula : ΔWN= AN e-a-bAN-E's where ΔWN is the nitrogen increments per gram in wet weight per unit of time, AN is the rate of nitrogen absorption, E's is a constant, and a and b are the parameters of the net anabolic coefficients.
4) Gross growth efficiency, in terms of nitrogen, increased until the optimum nitrogen intake which provided the maximum efficiency was achieved, and then decreased with increases in nitrogen absorption rate. Observed values for gross growth efficiency closely approximated values predicted using the following equation :
ΔWN/AN=e-a-bAN-E's/AN
5) It is suggested that this equation can be applied to both low and high feeding levels but the K-line developed by Paloheimo and Dickie can only be used for higher one and is therefore likely to be of limited use in describing food-growth relationships in natural situations. Conversely, the present equation may have general applicability.View full abstractDownload PDF (2374K) -
I. Qualities of water and bottom mud.Kiyoaki KOIDSUMI1970 Volume 31 Issue 4 Pages 153-165
Published: December 31, 1970
Released on J-STAGE: October 16, 2009
JOURNAL FREE ACCESSCo-operative surveys were carried out on 30 and 31 August, 1969 to examine the influences of holidaymakers' activities in the resort area upon the quality and the biotic community of the water of Lake Shirakaba situated in the central plateau of Japan.
The lake and its shores are visited annually by no less than 1, 500, 000, sometimes 2, 000, 000, holiday-makers for their outdoor recreation. The lake water is slightly brownish in color with the transparency of only 1.0-1.2meters. Chemical analyses of NH4-N, Cl, COD and BOD evidently show that the lake is in a condition of eutrophy in spite of its elevation of 1, 416 meters above sea level. The vertical stratifications of the values as to Cl, COD, and BOD are all direct, while those of the values as to NH4-N show a prominent inverse distribution. NH4-N is present in so large an amount as 0.12-0.15 mg/l in the surface and 0.65 mg/l in the deeper layer of water. These constituents are all very poor incontent in the inflowing mountain streams. The lake water is saturated with oxygen at the surface, but it decreases remarkably toward the bottom and no trace of it is found in the water deeper than 5 meters.
The particles of bottom deposits are very fine in size and easily float up to the surface. The contents of total carbon and nitrogen are so large that the mud is regarded as humus in nature. The humus has been derived from the dead bodies of marsh plants accumulated at the bottom for a number of years.
The following conclusion may accordingly be drawn. The principal sources of the recent eutrophication of the lake come from the domestic sewages produced from the holiday-makers' activities at the lakeside hotels and from the dissolving fo organic constituents of the bottom deposits and the floating up of their particles.View full abstractDownload PDF (1543K)
- |<
- <
- 1
- >
- >|