||Electronic format that can be stored and manipulated in a computer
||A two-dimensional array of regularly spaced picture elements (pixels) constituting a picture
||A three-dimensional array of regularly spaced volume elements (voxels) constituting a volume
||Stream Water Monitoring Site Measurement: Dissolved Oxygen (DO)
The amount of oxygen dissolved in water and measured in micrograms per liter or parts per million (ppm).
Importance of Dissolved Oxygen:
The creek system both produces and consumes oxygen. It gains oxygen from the atmosphere and from plants as a result of photosynthesis. Running water, because of its churning, dissolves more oxygen than still water, such as that of a reservoir behind a dam. Most aquatic organisms need oxygen to survive and grow. Some species, such as trout and stoneflies require high levels of DO while other species such as catfish, worms, and dragonflies do not.
If there is not enough oxygen in the water, the following may result: death of adults and juveniles; reduction in growth; failure of fish eggs/insects larvae to survive; change in species present; and/or growth of toxic or smothering bacteria, fungi, or algae.
Factors Affecting Dissolved Oxygen Levels in Water:
Pollution: If organic material (e.g. algae) or waste (e.g. septic leaks) is present in water, bacteria quickly move in to decay the material. As they respire and feed on the decaying material, they use up oxygen and generate CO2 in the water. Large algae blooms (caused by events like people dumping lawn clippings or leaves, or fertilizer runoff) can create near-zero oxygen conditions in creeks.
Temperature: As temperature increases, less oxygen can be dissolved in water. When water holds all the DO it can at a given temperature, it is said to be 100 percent saturated with oxygen. Water can be supersaturated with oxygen under certain conditions (e.g. below large dams where discharged flows are very turbulent).
The following table shows the concentration of dissolved oxygen that is equivalent to the 100 percent saturation for the noted temperature (and normal barometric pressure). For fresh water only!
Dissolved Oxygen 100% Saturation at Sea Level
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