Science 8: Unit E: Salt and Freshwater Systems

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Science 8 Unit E Salt and Freshwater Systems

• Topic 6 Water Quality and Water Management

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How Can You Determine Water Quality?

• Just because water is clear, does NOT mean its
  potable.
• Amount and types of dissolved minerals in the
  water pH of the water amount of dissolved
  oxygen, salinity, presence of heavy metals and
  types of micro-organisms living in the water.
• Water quality is periodically checked using water
  samples taken from different areas of the water
  source.
• If a water sample is found to be toxic, the water
  cannot be used for human or animal consumption.

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Direct and Indirect Uses of Water

• Direct Uses Water used for domestic/personal
  uses.
• Indirect Uses Water used for agricultural/
  industrial purposes.
• 73 of water is used for agriculture, 22 for
  industry and only 5 for direct domestic uses.
• There are benefits and drawbacks to each of the
  above uses of water (eg. benefits jobs,
  drawback harmed ecosystems)

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Acids and Bases

• Acids and bases are water-based solutions
  containing hydrogen (H) and hydroxide ions
  (OH-).
• Measured on a pH scale. The lower the pH, the
  more acidic the solution, the higher the pH, the
  more basic or alkaline the solution.
• If a solution measures 7 on the pH scale, its
  neutral. Water is neutral.

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Bioindicator Species

• Bioindicator Species species that are very
  sensitive to changes in the ecosystems and/or
  presence of pollutants. They are helpful because
  they can tell scientists about how different
  chemicals interact with an ecosystem.
• Amphibians and certain invertebrates (insects)
  are considered good bioindicators because they
  are the most sensitive to pollutants.

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Purifying Water

• To be made potable, water must be treated it
  must be screen, mixed, filtered, and healthy
  chemicals (eg. fluoride) need to be added.
• After water has been used by humans, the solid
  and liquid waste (sewage) has to be treated again
  before it can go back to the water supply as
  effluent.
• In rural areas a septic tank is used to help
  treat sewage.
• In drier areas, desalination, distillation and
  reverse osmosis (forcing water to go from more to
  less concentrated solutions) are used to purify
  water.