Which of the following best explains how heat can be a source of water pollution?

• A. Heat increases the salinity of water, making it unsuitable for freshwater organisms.
• B. Heat causes water to evaporate, increasing the concentration of pollutants in the atmosphere.
• C. Heat released into water bodies can raise the temperature, reducing dissolved oxygen levels and harming aquatic life.
• D. Heat directly introduces toxic chemicals into water, making it unsafe for consumption.

Answer: (C)

Verified step by step guidance

1. Understand that heat pollution in water bodies primarily refers to the increase in water temperature due to external heat sources, such as industrial discharge or power plants.
2. Recognize that when water temperature rises, the solubility of gases, including oxygen, decreases. This means warmer water holds less dissolved oxygen.
3. Recall that aquatic organisms depend on dissolved oxygen for survival, so a reduction in oxygen levels can stress or kill fish and other aquatic life.
4. Note that increased temperature can also accelerate metabolic rates of aquatic organisms, increasing their oxygen demand while oxygen availability is reduced.
5. Conclude that heat pollution harms aquatic ecosystems mainly by raising water temperature, which lowers dissolved oxygen levels and negatively impacts aquatic organisms.