scholarly journals FUNDAMENTAL STUDY ON DISSOLVED OXYGEN SUPPLY INTO DEEP LAYERS IN LAKE BIWA

2007 ◽  
Vol 63 (2) ◽  
pp. 144-153
Author(s):  
Hirokazu FURUKAWA ◽  
Kenji KAWAMURA ◽  
Toshiaki HARA ◽  
Kentaro KIDO ◽  
Shinya FUKUJU
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Supply ◽  
Lake Biwa ◽  
Fundamental Study ◽  
Deep Layers

scholarly journals Influence of climatic warming on the amount of snow cover and water quality of Lake Biwa, Japan

1993 ◽  
Vol 18 ◽  
pp. 257-260
Author(s):  
Hiroji Fushimi
Keyword(s):  
Dissolved Oxygen ◽  
Snow Cover ◽  
Oxygen Concentration ◽  
Catchment Area ◽  
Lake Biwa ◽  
Deep Layer ◽  
Climatic Warming ◽  
Dissolved Oxygen Concentration ◽  
Average Amount

The amount of snow cover in the Lake Biwa catchment area has changed significantly from 1.9 × 1012kg in 1974 to 0.3 × 1012kg in 1979. The amount of snow cover was less in the warmer winter and when the amount of snow cover was less than 1012 kg, the average amount of snow cover in recent years, the lowest dissolved-oxygen concentration in the deep layer rapidly decreases. Climatic warming will significantly decrease the amount of snow cover in Lake Biwa catchment area and the dissolved-oxygen concentration in the deep layer of the lake, which may further enhance eutrophication of the lake.

scholarly journals Influence of climatic warming on the amount of snow cover and water quality of Lake Biwa, Japan

1993 ◽  
Vol 18 ◽  
pp. 257-260 ◽  
Author(s):  
Hiroji Fushimi
Keyword(s):  
Dissolved Oxygen ◽  
Snow Cover ◽  
Oxygen Concentration ◽  
Catchment Area ◽  
Lake Biwa ◽  
Deep Layer ◽  
Climatic Warming ◽  
Dissolved Oxygen Concentration ◽  
Average Amount

The amount of snow cover in the Lake Biwa catchment area has changed significantly from 1.9 × 1012kg in 1974 to 0.3 × 1012kg in 1979. The amount of snow cover was less in the warmer winter and when the amount of snow cover was less than 1012 kg, the average amount of snow cover in recent years, the lowest dissolved-oxygen concentration in the deep layer rapidly decreases. Climatic warming will significantly decrease the amount of snow cover in Lake Biwa catchment area and the dissolved-oxygen concentration in the deep layer of the lake, which may further enhance eutrophication of the lake.

Measuring Seepage through Salmon Spawning Gravel

1955 ◽  
Vol 12 (5) ◽  
pp. 706-741 ◽  
Author(s):  
R. A. Pollard
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Oxygen Supply ◽  
Field Method ◽  
Seepage Rate ◽  
Groundwater Seepage ◽  
Salmon Eggs ◽  
Flow Through ◽  
Stream Bed

The rate of oxygen supply to salmon eggs incubating in a stream bed depends on the oxygen concentration in the groundwater and the rate of seepage through the redd. Wickett (1954) devised a simple field method of both sampling the groundwater for the determination of its dissolved oxygen content and measuring the seepage rate, using one tool, a standpipe. The theory of seepage is outlined to show the factors governing the velocity of flow through a redd. Alternative ways of measuring this velocity were examined; the best one is a modification of Wickett's procedure using a similar standpipe. A new field procedure for measuring the oxygen concentration and groundwater seepage rate in a stream bed is recommended.

scholarly journals Environmental properties of the southern Gulf of Aqaba, Red Sea, Egypt

2012 ◽  
Vol 13 (2) ◽  
pp. 179 ◽  
Author(s):  
M.M. DORGHAM ◽  
M.M. EL-SHERBINY ◽  
M.H. HANAFI
Keyword(s):  
Dissolved Oxygen ◽  
Water Column ◽  
Chlorophyll A ◽  
Red Sea ◽  
Environmental Parameters ◽  
Gulf Of Aqaba ◽  
High Concentration ◽  
Environmental Properties ◽  
Epipelagic Zone ◽  
Deep Layers

Environmental properties (temperature, dissolved oxygen, nutrients and chlorophyll a) of the epipelagic zone off SharmEl-Sheikh, Red Sea, Egypt were studied seasonally throughout a year from March 1995 to March 1996. Water samples werecollected from five water depths (0, 25, 50, 75 & 100 m). The studied parameters exhibited clear seasonal variability along the water column. The vertical distribution of water temperature showed thermal homogeneity during most seasons, and thermal stratification in summer. Dissolved oxygen attained slightly high concentrations (5.3-7.8 mg l-1) in the whole water column, with slight seasonal variation. The concentrations of nutrients reflected dominant oligotrophic conditions in the epipelagic zone and occasional mesotrophic status at some depths. Phosphate fluctuated between 0-0.7 μM, ammonium (0-2.27 μM), nitrite (0-0.72 μM), nitrate (0-1.49 μM) and silicate (0-6.48 M). Phytoplankton biomass was generally low in the epipelagic zone throughout the study, whereas chlorophyll a was less than 0.5 μg l-1, except relatively high concentration (0.7-1.12 μg l-1) in deep layers in spring. In comparison with previous studies on the Gulf of Aqaba all environmental parameters during present study showed pronouncedlydifferent values.

Size relations and yolk utilization in embryonated ova and alevins of Atlantic salmon Salmo salar L. in various combinations of temperature and dissolved oxygen

1977 ◽  
Vol 55 (11) ◽  
pp. 1892-1898 ◽  
Author(s):  
T. Hamor ◽  
E. T. Garside
Keyword(s):  
Atlantic Salmon ◽  
Dissolved Oxygen ◽  
Blood Vessels ◽  
Salmo Salar ◽  
Oxygen Supply ◽  
Gradual Decline ◽  
Yolk Utilization ◽  
Lower Oxygen ◽  
Yolk Absorption ◽  
C 30

Relations among weight (W), surface (S), and volume (V) for freshly fertilized water-hardened Atlantic salmon ova from 5 to 7 mm in diameter are: S = log V2/3, S = 1.21 log W, and V = W/1.2.Fresh weights remained relatively constant from fertilization to the establishment of blood vessels in the yolk sac. Subsequently, there was a rapid increase to 110%, followed by a gradual decline to 105% shortly before hatching. Large blastodiscs weighed 1.2 mg and embryonal weight increased very gradually until late prehatching stages, when growth was accelerated rapidly. Embryos, at hatching, after continuous incubation at 5 and 10°C and three levels of dissolved oxygen, varied from 22.1 mg (5 °C, 100% air saturation) to 11.9 mg (5 °C. 30%) and From 14.5 mg (10 °C. 100%) to 10.0 mg (10 °C, 30%).Cumulative and mean daily yolk depletion declined with lowered oxygen supply, but they were considerably greater at 10 °C than at 5 °C. Gross conversion ratios (including uptake of exogenous materials) indicate that yolk is used more efficiently at 5 °C, and 100% air saturation. Alevins, kept in their original environments, became more efficient than they were in their encapsulated state, and, at 10 °C. 100% air saturation, they overtook those at 5 °C before the completion of yolk absorption. Those in lower oxygen supplies continued to lag, at both temperatures.

Numerical Study on the Effects of Water Surface Shield and Oxygen Injection on Water Quality in Lake Biwa

2008 ◽  
Author(s):  
Daisuke Kitazawa ◽  
Michio Kumagai
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Water Surface ◽  
Lake Biwa ◽  
Vertical Mixing ◽  
Three Dimensional ◽  
Coupled Model ◽  
Floating Platform ◽  
Oxygen Injection ◽  
Water Bottom

Numerical simulation was carried out by means of a three-dimensional hydrostatic and ecosystem coupled model in order to predict the effects of water surface shield and oxygen injection on the water quality in Lake Biwa. Recent observations show the degradation of water quality particularly around the water bottom in Lake Biwa. One of the possible reasons of the degradation is the depletion in the vertical mixing of waters due to climate change. The meteorological observations at Hikone show that the atmospheric temperature has increased by 1°C in the recent 20 years. If the vertical mixing of waters is weakened, the waters with rich oxygen are not supplied enough around the water bottom during winter seasons, and the concentration of dissolved oxygen is hardly recovered to the saturated level. The depletion in the vertical mixing of waters has been increasingly worried since Intergovernmental Panel on Climate Change (2007) reported that the globally mean atmospheric temperature will increase by a few °C in a century. In order to cope with such problems, the present study proposes a feasible system to inject the oxygen produced by the electrolysis of water. In the proposed system, water surface is shielded by a floating platform, which blocks off the penetration of solar radiation through the water surface and generates the density-driven current due to the horizontal difference in water temperature. In addition, solar cell modules are installed on the floating platform to produce oxygen by means of the electrolysis of water. The produced oxygen is then released from the electrodes installed around the water bottom. As a result of numerical simulation using the three-dimensional hydrostatic and ecosystem coupled model, the effect of water surface shield was negligible since the surface area of the floating platform was quite smaller than that of Lake Biwa. The effect of oxygen injection was remarkable and localized in summer than in winter. The concentration of dissolved oxygen was then expected to increase by more than 0.2mg/l within 15m from the bottom surface in summer, in the cases when 730,000m3 of oxygen was injected in an year. The effect of seasonal change in the production of oxygen was negligible since little difference was found in the concentration of dissolved oxygen. As future studies, the nested grid system should be utilized to predict precisely the diffusion of oxygen both in the vicinity of the electrode and in the whole Lake Biwa.

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