Chemical and physical properties of water quality

pH

• pH ranges from 0-14– 0 is the most acidic– 14 is the most basic/alkaline

• 7 is neutral– Most healthy bodies of water in the U.S. are

between 6.5 and 8.5.– Certain macros exist in certain pH ranges

alkalinity

• Alkalinity is a measure of how well water can neutralize acids that might get added– Should be between 20-200 mg/L– Less than 20 mg/L means the water cannot easily

buffer changes in pH– Acids can be added from acid rain and other

environmental pollutants– Determined by the geology (rocks) that the water

flows through.– Link to Wilkes alkalinity info

Dissolved oxygen

• D.O. is the amount of oxygen dissolved in a body of water– The more O2 that is dissolved, the more that is

available to living organisms– Changes with temperature– Cold water holds more O2 than warm water.

Stream velocity

• Determined by depth and width of stream– Narrow streams are often faster and colder– Wide streams are slower and warmer – Will have greater velocity if the stream is the

same depth all along its route– Certain macros are adapted to live in faster

streams while others must live in slow water.

Water temperature

• Affects the amount of dissolved oxygen– Cooler water holds more oxygen

• Affects rate of photosynthesis– Warmer water = faster photosynthesis

• Affects organisms’ sensitivity to pollutants– Warmer water = higher sensitivity

• Link to temp website

Turbidity

• Measure of how much suspended matter is in the water– Cloudy water has lots of silt, sand, clay and organic

material floating– Certain macros must live in clear water (clogs up

gills, for example)– Some macros are adapted to live in more turbid

water.– Comes from erosion, runoff, algae blooms and

sediment disturbances