3 Oxygen Consumption and Replenishment in Receiving
Water
Dissolved oxygen analysis measures the amount of gaseous oxygen (O 2 ) dissolved
in an aqueous solution. Dissolved oxygen is one of the most important parameters in
aquatic systems. This gas is an absolute requirement for the metabolism of aerobic
organisms and also influences inorganic chemical reactions. Therefore, knowledge
of the solubility and dynamics of oxygen distribution is essential to interpreting both
biological and chemical processes within water bodies. Oxygen gets into water by
diffusion from the surrounding air, by aeration (rapid movement) and as a waste
product of photosynthesis. Adequate dissolved oxygen is necessary for good water
quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life
forms. Moreover, oxygen affects a vast number of other water indicators, not only
biochemical but esthetic ones, like odor, clarity, and taste. Consequently, oxygen is
perhaps the most well-established indicator of water quality. Some pollutants, such
as acid mine drainage, produce direct chemical demands on oxygen in the water.
Dissolved oxygen is consumed in the oxidation-reduction reactions of introduced
chemical compounds, such as nitrate (NO 3
À ) and ammonia (NH 4
+ ), sulfate (SO 4
2À )
and iron ions. In this section, these factors are discussed.
Water Quality Models
Environments
Process
Dimintion
Process
Data type
Time variation
Hydrochemical Mixing-zone
0D
Empirical
Stochastic
Dynamic Steady-state
Deterministic
Mechanistic
1D 2D 3D
Time-of-travel
Lake
River Estuary
Fig. 3.9 Subdivisions of
water quality models in
common use
94
H. A. Aziz et al.
Water
Dissolved oxygen analysis measures the amount of gaseous oxygen (O 2 ) dissolved
in an aqueous solution. Dissolved oxygen is one of the most important parameters in
aquatic systems. This gas is an absolute requirement for the metabolism of aerobic
organisms and also influences inorganic chemical reactions. Therefore, knowledge
of the solubility and dynamics of oxygen distribution is essential to interpreting both
biological and chemical processes within water bodies. Oxygen gets into water by
diffusion from the surrounding air, by aeration (rapid movement) and as a waste
product of photosynthesis. Adequate dissolved oxygen is necessary for good water
quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life
forms. Moreover, oxygen affects a vast number of other water indicators, not only
biochemical but esthetic ones, like odor, clarity, and taste. Consequently, oxygen is
perhaps the most well-established indicator of water quality. Some pollutants, such
as acid mine drainage, produce direct chemical demands on oxygen in the water.
Dissolved oxygen is consumed in the oxidation-reduction reactions of introduced
chemical compounds, such as nitrate (NO 3
À ) and ammonia (NH 4
+ ), sulfate (SO 4
2À )
and iron ions. In this section, these factors are discussed.
Water Quality Models
Environments
Process
Dimintion
Process
Data type
Time variation
Hydrochemical Mixing-zone
0D
Empirical
Stochastic
Dynamic Steady-state
Deterministic
Mechanistic
1D 2D 3D
Time-of-travel
Lake
River Estuary
Fig. 3.9 Subdivisions of
water quality models in
common use
94
H. A. Aziz et al.