EUTECH INSTRUMENTS CYBERSCAN DO 1500 DO METER Instrukcja Obsługi Pobierz pdf (Strona 52)

Instruction Manual DO 300

14 DISSOLVED OXYGEN & METER THEORY

Dissolved Oxygen (DO) refers to the volume of oxygen that is contained in water. There are

two main sources of DO in water: from atmosphere and photosynthesis. Waves and tumbling

water mix air into the water where oxygen readily dissolves until saturation occurs. Oxygen is

also produced by aquatic plants and algae as a by-product of photosynthesis.

The amount of DO that can be held by water depends on 3 factors: water temperature, salinity,

and atmospheric pressure.

1. Amount of DO increases with decreasing temperature (colder water holds more oxygen).

2. Amount of DO increases with decreasing salinity (freshwater holds more oxygen than

saltwater does).

3. Amount of DO decreases with decreasing atmospheric pressure (amount of DO

absorbed in water decreases as altitude increases).

The chart below shows the solubility of DO in mg/L in water at various temperatures.

Solubility of oxygen in water contact with water saturated air at

standard atmospheric pressure

0 102030405060

Temperature °C

Solubility mg/L

Figure 38: DO Solubility in Water vs Temperature °C

1 2 ... 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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