An oxygen sag curve occurs when
A) Fish population numbers sag.
B) Heavy metals that have entered a stream bind oxygen molecules and remove them from the available oxygen supply.
C) The breakdown of biodegradable wastes by bacteria lowers the available oxygen in the water for organisms with high oxygen requirements.
D) Carbon dioxide values exceed dissolved oxygen values.
E) Oxygen content in the air around a particular body of water becomes slightly lower than normal

Question

Quizplus · Accepted Answer

An oxygen sag curve occurs when biodegradable wastes are broken down by bacteria, reducing the available oxygen in the water for organisms that require high levels of oxygen. As the wastes are degraded, the oxygen demand increases, causing a "sag" in the available oxygen levels downstream. This can result in harm to aquatic organisms, as the oxygen-depleted water can become hypoxic or anoxic, meaning that it has extremely low or no oxygen levels, respectively.

An Oxygen Sag Curve Occurs When