Pollution

Pollution

• Pollution is any alteration to the environment causing conditions harmful to living things.
• Pollution sources can be categorized as point source (small, defined area) or non-point source (wide area, poorly defined).
• Examples of point sources include city streets and factories.
• Examples of non-point sources include rural homes, cropland and animal feedlots.
• Dilution reduces pollution concentration.
• Factors like wind and water speed affect pollution dilution in the air or water.

Dilution and Concentration

• Dilution means pollution becomes less concentrated.
• Stream pollution can be diluted by increased water flow.
• Air pollution can be diluted by wind.
• Factors concentrating pollution include stagnant air or water, and geographic features that trap pollutants.

Water Quality

• Water quality in Canadian rivers (2016-2018) shows varying quality with different land use categories (agricultural, forestry, mining, populated areas, mixed pressures and undeveloped).
• The percentage of excellent, good, fair, marginal and poor quality water sites are visualized for different categories using graphs.

Aquatic Environments

• Pure water (H₂O) comprises only water molecules.
• Real-world water contains dissolved oxygen, pH, heavy metals, plant nutrients (nitrogen/phosphorus), pesticides, salts (sodium chloride/magnesium sulfate).
• Higher pH decreases biodiversity in organisms.
• Water quality is categorized by provincial and federal government in five areas: human drinking water, recreation (e.g., swimming), livestock drinking water, irrigation, and protection of aquatic life.

Biological Indicators

• Scientists use organisms (fish, plants, worms, insects, plankton, protozoa, viruses) to assess water quality.
• Macroinvertebrates (like stonefly, mayfly, caddisfly, beetle) indicate good water quality, as they require high oxygen levels).

Dissolved Oxygen

• Dissolved oxygen is essential for aquatic life (insects, microorganisms).
• Levels of dissolved oxygen depend on multiple factors:
  • Photosynthesis levels by plants/algae.
  • Water temperature.
  • Water turbulence due to wind or water speed.
  • Number of organisms using the oxygen.

Quantifying Pollution

• Pollution concentration is often expressed as parts per million (ppm) or parts per billion (ppb).

Measuring Chemicals in the Environment

• Parts per million (ppm) indicates the number of units of a chemical present in one million total units.
• Parts per billion (ppb) indicates the number of units of a chemical present in a billion total units.

Toxicity

• Toxicity refers to a substance's degree of poison.
• Mixing pesticides can create dangerous combinations of chemicals.
• Some pesticides persist in the environment and have long-term effects.

Measuring Toxicity (LD50)

• LD50 (lethal dose 50%) is the amount of a substance that causes 50% of test animals to die if given in a specific dose.
• LD50 values vary greatly between different substances and can be used to assess relative toxicity. Substances like water, aspirin, caffeine, nicotine and strychnine have different LD50 values.

Risk Management

• Effects of substances can differ between animals and humans.
• Animal testing to determine toxicity can have limitations, and may not accurately reflect the human toxicity.
• Acceptable risks depend on the situation.
• Chemicals can cause harm depending on type, duration, and quantity of exposure.

PPM Practice

• PPM (Parts per million) calculation example: Given a volume of pollutant and a volume of water, calculate ppm.
• Various examples of how to calculate ppm from different word problems, including scenarios involving accidents that cause pollution.