How does increased temperature affect water's ability to carry dissolved oxygen?

• A. It increases the ability to carry DO
• B. It decreases the ability to carry DO
• C. It has no effect on carrying DO
• D. It causes DO to evaporate

Answer: (B)

Increased temperature negatively impacts water's ability to hold dissolved oxygen (DO). As water temperature rises, the solubility of gases, including oxygen, decreases. This is because gas molecules are held in solution by interactions with water molecules, and as the temperature increases, these interactions are disrupted, allowing gas molecules to escape more easily.

Consequently, warmer water holds less oxygen, which can have significant implications for aquatic life. Fish and other organisms rely on dissolved oxygen for respiration, and lower levels can lead to stress or even death in sensitive species. Therefore, understanding the relationship between temperature and oxygen solubility is crucial for wastewater treatment operators and environmental management.

The other options do not accurately reflect this relationship, as they either suggest an increase in DO capacity with temperature or imply that temperature changes have no effect, both of which contradict the established science regarding gas solubility in water.