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What is thermal pollution, and how can heated wastewater affect aquatic ecosystems?
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water
Water is the most plentiful compound on Earth and is essential to life. Although water molecules are simple in structure (H2O), the physical and chemical properties of water are extraordinarily complicated.
Thermal pollution is the discharge of heated liquids, such as industrial wastewater, into natural water bodies at temperatures that are harmful to the environment. A primary source of this pollution is the release of cooling water from power plants, which can be as much as 15 °C (27 °F) warmer than the receiving water.12
Heated wastewater negatively impacts aquatic ecosystems through two main mechanisms:
- Reduced Oxygen Solubility: Heat decreases the capacity of water to hold dissolved oxygen. Because oxygen is less soluble at higher temperatures, aquatic life faces a reduced supply of this essential gas.23
- Increased Metabolic Demand: Rising temperatures increase the metabolism of cold-blooded animals, such as fish. This forces them to consume more oxygen at the exact time that oxygen availability in the water is declining.23
This "double handicap" makes it difficult for sensitive species, such as trout, to survive, as they require higher levels of dissolved oxygen than are available in thermally polluted environments.24