MIDTERMS

• • Water Quality - measure of the amount of substances in a water sample; description of how pure a water sample is
  • Example: Organisms, organic material, minerals, and other chemicals
• • The water of even the healthiest rivers and lakes is not absolutely pure
  • All water contains many naturally occurring substances (even if it is distilled)
  • Examples: sulphates, sodium, chlorides, calcium, magnesium, and potassium
• How do substances reach our water supply?

  • Surrounding vegetation and wildlife
  • Precipitation and runoff from adjacent land
  • Biological, physical, and chemical processes in the water
  • Human activities in the region
• • The most common substance that is dissolved in water is sodium chloride (Salt)
  • SalinityThe amount of dissolved salts in water
• • Fresh water can be found on Earth’s surface and underground
  • As it flows, it dissolves minerals from the soil and rocks it passes through
  • Different regions will have different dissolved materials
• • Hard water -contains a high concentration of calcium and magnesium
  • It leaves mineral deposits, called scale
  • Sinks, Tubs, Dishwashers, Coffee Pots, etc.
  • Soap doesn't lather properly when water is hard
• • Water from a well is usually safer than surface water because it is from a source deep underground that is often protected from most natural and human-made pollutants
  • Most cities and towns get their water from surface sources (lakes & rivers) and this water is at a greater risk of having pollutants within it
• • Some of the items that drinking water is tested for include:
  • Taste & Odor
  • Turbidity (cloudiness) & Color
  • Toxic substances & other pollutants
  • Bacteria
  • Hardness or mineral content
  • pH (acid/base)
  • Dissolved oxygen
  • Solids, including floating materials
  • Dissolved solids