Oxygen in lakes

H. F. H. Dobson, "Principal Ions and Dissolved Oxygen in Lake Ontario," in Proceedings of the 10th Conference on Great Takes Research, Toronto,... 

We can use Henry s law to verify that the concentration of oxygen in lake water is normally adequate to sustain aquatic life, which requires a concentration of at least 1.3 X 10-4 mol-L 1. The partial pressure of oxygen is 0.21 atm at sea level, so the molar solubility of oxygen is... 

A special model from this type (autoregression with an explanatory variable), an autoregression model combined with a moving average model was applied by VAN STRA-TEN and KOUWENHOVEN [1991] to the time dependence of dissolved oxygen in lakes. 

The final factor that affects solubility is pressure. Changes in pressure have hardly any effect on solid and liquid solutions. Such changes do affect the solubility of a gas in a liquid solvent, however. The solubility of the gas is directly proportional to the pressure of the gas above the liquid. For example, the solubility of oxygen in lake water depends on the air pressure above the lake. 

What is the solubility of oxygen in lake water at 28°C Assume that the pKH of oxygen at this temperature is twice that of C02. Give your answer in mg/L. 

Figure 7. Correlation between concentration of nitrate, phosphate, and oxygen in Lake Zurich (a and b) and Lake Norrviken (c)...

Most lakes affected by eutrophication will also have significant amounts of phosphorus in their sediments, which can be recycled into the water column (Section 4). The control of this source can be achieved by treating the sediments with iron salts or calcite to bind the phosphorus more tightly into the sediments. These methods have been used to some effect, but consideration has to be given to the quality of the materials used and whether or not the lake can become de-oxygenated in the summer. In the latter case this can be overcome by artificial de-stratification. 

Self-Test 8.7A At the elevation, 2900 m, of Bear Lake in Rocky Mountain National Park, the partial pressure of oxygen is 0.14 atm. What is the molar solubility of oxygen in Bear Lake at 20.°C ... 

Charlton MN (1980) Hypolimnion oxygen consumption in lakes discussion of productivity and morphometry effects. Can J Fish Aquat Sci 37 1531-1539... 

Niimberg GK (2002) Quantification of oxygen depletion in lakes and reservoirs with the hypoxic factor. Lake Reserv Manage 18 299-306... 

Hexachloroethane in the air does not break down to other compounds. It gradually escapes into the upper atmosphere. Some hexachloroethane that is in lakes or streams and surface soils will evaporate into the air. Some will be broken down by microscopic organisms. Microbes can break down hexachloroethane more easily without oxygen than with oxygen. That is why hexachloroethane will break down more quickly when it is buried in the soil or trapped in underground water than when it is near the surface. In one study, it took only 4 days for 99% of the hexachloroethane in soil to break down when oxygen was not present. It took 4 weeks when oxygen was present. 

In 1986, 1,700 people in West African Cameroon, suffocated when a giant bubble of naturally occurring carbon dioxide erupted from Lake Nyos and displaced the available oxygen in the immediate area. 

The solubility of most solids increases with increasing temperature. However, the solubility of gases in liquids decreases with increasing temperature. For example, if you open a cold bottle of soda and a warm bottle of soda, more gas is released by the warm soda. This is the basis of thermal pollution, in which the solubility of oxygen in stream or lake water is decreased if the water is polluted by heat. 

We will try our hand at applying the diffusion equation to a couple of mass transport problems. The first is the diffusive transport of oxygen into lake sediments and the use of oxygen by the bacteria to result in a steady-state oxygen concentration profile. The second is an unsteady solution of a spill into the groundwater table. 

EXAMPLE 2.1 Steady oxygen concentration profile in lake sediments (steady-state solution with a first-order sink)... 

Figure E2.t.t. Illustration of dissolved oxygen profile in lake sediments.

Figure E2.1.2. Solution (equation (E2.1.5)) to Example 2.1. for oxygen concentration in lake sediments with first-order sink.

Typical values of sediment oxygen demand (SOD) in lakes vary from 0.5 to 5 g/m -day. Assuming a diffusivity of 10 m /s for oxygen in the lake sediments. 

EXAMPLE 7.2 Effect of fall turnover on oxygen concentration in lake sediments (unsteady, one-dimensional transport with step boundary conditions and a first-order sink, solved using explicit, central differences)... 

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