Which of the following indicates the presence of VOC and dissolved gases in stagnant water?

The presence of volatile organic compounds (VOCs) and dissolved gases in stagnant water can lead to observable changes. When VOCs are present, they often have the capability to volatilize, meaning they can evaporate into the air under certain conditions. This process can produce effervescence, a bubbling or fizzing effect due to the release of gas.

This phenomenon indicates that there are dissolved gases or VOCs that are escaping from the liquid into the air. Such bubbling or gaseous release is a distinct characteristic of samples containing these substances.

While changes in color, increased turbidity, and unusual odors can also signal issues with water quality, they do not specifically indicate the presence of VOCs or dissolved gases as effectively as volatilization or effervescence does. Therefore, the ability of the water to volatilize or effervesce is the most direct and relevant indicator of VOC and dissolved gas presence.