How does temperature affect dissolved oxygen solubility in water?

How does temperature affect dissolved oxygen solubility in water?

• A. Higher temperatures increase DO solubility.
• B. No effect on DO solubility.
• C. Higher temperatures decrease DO solubility.
• D. Lower temperatures decrease DO solubility.

Answer: (C)

Dissolved oxygen in water is higher when water is cooler and decreases as temperature rises. Warmer water gives oxygen molecules more kinetic energy, making it easier for them to escape from the liquid back into the air, so the water can hold less O2 at a higher temperature. This inverse relationship means colder water can carry more dissolved oxygen than warmer water, which is why aerobic processes in wastewater treatment can become stressed on hot days unless additional aeration is provided. The other options ignore or reverse this pattern: solubility does depend on temperature, and it decreases with increasing temperature.

Dissolved oxygen in water is higher when water is cooler and decreases as temperature rises. Warmer water gives oxygen molecules more kinetic energy, making it easier for them to escape from the liquid back into the air, so the water can hold less O2 at a higher temperature. This inverse relationship means colder water can carry more dissolved oxygen than warmer water, which is why aerobic processes in wastewater treatment can become stressed on hot days unless additional aeration is provided. The other options ignore or reverse this pattern: solubility does depend on temperature, and it decreases with increasing temperature.