EUTECH INSTRUMENTS DO 6 PLUS Manuel d'instructions télécharger pdf (Page 43)

Instruction Manual DO 6+

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12. DISSOLVED OXYGEN THEORY

Dissolved Oxygen (DO) refers to the volume of oxygen that is contained in

water. There are two main sources of DO in water; 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 during photosynthesis.

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

1) TEMPERATURE:

DO increases with decreasing temperature

(colder water holds more oxygen)

2) SALINITY:

DO increases with decreasing salinity

(freshwater holds more oxygen than saltwater does)

3) ATMOSPHERIC PRESSURE:

DO decreases with decreasing atmospheric pressure

(amount of DO absorbed in water decreases as altitude increases)

Solubility of oxygen in water contact with water saturated air at

standard atmospheric pressure

0 5 10 1 5 20 25 30 35 40 4 5 50

Temperature °C

Solubility mg/L

DO Solubility in Water vs Temperature

1 2 ... 38 39 40 41 42 43 44 45 46 47 48

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EUTECH INSTRUMENTS DO 6 PLUS Manuel d'instructions Page 43