APES 8.6 Thermal Pollution

Objectives of the Video

  • Understand the effects of thermal pollution on aquatic ecosystems.

  • Practice explaining an environmental concept in an applied context.

Understanding Oxygen Solubility in Water

  • Solubility: The ability of a solid, liquid, or gas to dissolve in a liquid.

    • In this context, it refers to oxygen dissolving in water.

  • Oxygen: Essential for all organisms, including aquatic ones such as fish which extract oxygen through gills.

Temperature and Dissolved Oxygen Relationship

  • Inverse Relationship: As water temperature increases, dissolved oxygen levels decrease.

    • Illustrated graph: As temperature rises, the amount of dissolved oxygen decreases.

  • Example: Boiling pot of water

    • Increased temperature leads to oxygen escaping as bubbles due to rapid water molecule movement displacing oxygen.

Effects of Thermal Pollution on Aquatic Ecosystems

  • Thermal Pollution Definition: Increase in water temperature due to human activities, leading to lower dissolved oxygen levels.

  • Organism Responses:

    • Increased respiration rates as organisms try to compensate for lower oxygen availability.

    • Physiological stress due to insufficient oxygen can lead to suffocation and death in severe cases.

Sources of Thermal Pollution

  • Power Plants:

    • Use cool water from nearby sources to generate steam or cool machinery.

    • Release heated water back into water bodies, causing temperature increases and reduced dissolved oxygen levels.

  • Manufacturing Facilities:

    • Industries such as steel and paper mills release warm water used for cooling machinery into surface waters, contributing to thermal pollution.

  • Urban Runoff:

    • Water from paved surfaces, e.g., parking lots, heats up and flows into drains, increasing temperatures of streams/rivers.

  • Nuclear Power Plants:

    • Require large amounts of water for cooling due to heat from nuclear fission; can significantly contribute to thermal pollution.

Mitigating Thermal Pollution via Cooling Towers

  • Cooling Towers: Devices used to cool water from industrial processes before it is released into the environment.

    • Hot water is sprayed over an exchange surface to allow air flow to cool it down.

  • Reused or Released Water: Controlled discharge of cooled water to minimize impact on aquatic organisms.

  • Best Practices: Enhancing cooling tower efficiency by improving cooling methods or holding water longer to achieve closer temperatures to surface waters.