8.6 Thermal Pollution

Thermal Pollution

Definition of Thermal Pollution

• Thermal pollution refers to the process where heat released into water has negative effects on aquatic organisms.

Solubility

• Solubility: The ability of a solid, liquid, or gas to dissolve into a liquid (e.g., oxygen dissolving into water).

• There is an inverse relationship between water temperature and the solubility of oxygen: as water temperature increases, the solubility of oxygen and other gases decreases.

Effects of Thermal Pollution

• Increased heat in water leads to increased respiration rates of aquatic organisms, often referred to as thermal shock.

• Hot water has less dissolved oxygen ($O_2$), which can lead to suffocation for organisms that depend on oxygen for respiration.

Sources of Thermal Pollution

• Power Plants:

  • Use cool water from surface or ground sources to cool down machinery.

  • Steel Mills:

  • Use water for cooling and then return heated water to local water bodies.

  • Paper Mills:

  • Similar processes utilize cool water for cooling equipment, leading to thermal pollution upon the return of heated water.

• Urban Stormwater Runoff:

  • Surfaces like blacktop and asphalt absorb heat, increasing water temperatures in runoff, contributing to thermal pollution.

• Nuclear Power Plants:

  • Require significant amounts of cool water to cool steam back into water.

  • Cooling Towers:

  • Designed to cool the reactor core and steam.

  • Hold warm water before returning it to nearby surface waters.

  • Represent a standard practice in nuclear power but can be optimized for improved cooling and longer holding periods before discharge.